HOUSING RESEARCH REPORT - .NET Framework

HOUSING RESEARCH REPORTRetrofitting Solid Masonry Residential Buildings

This study was conducted for Canada Mortgage and Housing Corporation (CMHC) under Part IX of the National Housing Act. The analysis, interpretations and recommendations are those of the consultant and do not necessarily reflect the views of CMHC.

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RE-ASSESSMENT OF THE EXTERIOR FAÇADES OF INTERIOR INSULATED SOLID

MASONRY RESIDENTIAL BUILDINGS

Prepared for: Canada Mortgage and Housing Corporation (CMHC)

National office 700, Montreal Road, Ottawa, Ontario, K1A 0P7

CMHC CR No.: 6715-34

Prepared by: Patrick Masson, T.P., LEED AP/BD+C

Director – Building Investigations Department Patenaude Trempe Van Dalen Inc.

1320 boul. Lionel-Boulet, Varennes, Québec, J3X 1P7

PTVD File No.: RD-0109-C

March 30, 2015

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DISCLAIMER:

THIS PROJECT WAS FUNDED BY CANADA MORTGAGE AND HOUSING

CORPORATION (CMHC). THE CONTENT, VIEWS AND EDITORIAL QUALITY

EXPRESSED IN THIS REPORT ARE THOSE EXLUSIVELY OFFERED BY THE

AUTHORS, PATENAUDE TREMPE VAN DALEN INC. CMHC ASSUMES NO

RESPONSIBILITY OF ANY KIND IN CONNECTION WITH THE READER'S USE OF

THE INFORMATION, MATERIALS AND TECHNIQUES DESCRIBED HEREIN.

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Executive Summary

This report comprises of a follow-up visual assessment of retrofitted massive masonry exterior walls of several buildings in the Montreal area, previously conducted by Patenaude Trempe in 2005 for Canada Mortgage and Housing Corporation. The mass masonry exterior walls of these buildings were insulated from the interior. This study seeks to assess the in-service performance of these insulated masonry walls over the past 10 years. The study includes the review of a total of 7 interior insulated masonry buildings: 6 buildings from the original 2005 study and a 7th building unrelated to the previous study.

Current visual surveys and photo-documentation of the buildings were compared to photographs and written notes previously compiled. Some buildings did not exhibit additional deterioration; in other buildings, however, masonry deficiencies have not only become apparent in some cases, they had worsened.

Based on the comparative visual condition assessment, an overall performance rating was determined; the buildings generally varied from good to acceptable with the exception of one project in which the exterior masonry was observed to exhibited elevated levels of distress. In such instances, a more in-depth review is warranted to identify causal factors and suggest remedial actions.

In the absence of established assessment methodologies involving field evaluation, material testing and computer simulations, which is under development, the application of known building science principles, together with periodic monitoring and visual assessment and the test of time, is still the best approach to evaluating the performance of interior insulated masonry wall assemblies. Nevertheless, the case study buildings, highlighted in this report, suggest that these retrofitted mass masonry buildings, insulated from the interior, appear to be performing reasonably well over the 10 to 15 year time frame since the retrofit work was completed. With continued maintenance and repair (as with any envelope or cladding system), the masonry walls can continue to provide long-term performance.

RÉSUMÉ

Ce rapport présente un suivi de l’évaluation visuelle de l’état des murs de maçonneries massifs modifiés de plusieurs bâtiments de la région de Montréal, préalablement réalisés par Patenaude Trempe en 2005 pour le compte de la Société Canadienne d’ Hypothèque et de Logement. Les murs de maçonnerie massive de ces bâtiments avaient été isolés par l’intérieur. La présente étude cherche à valider la performance en service de ces murs de maçonnerie isolés depuis les 10 dernières années. L’étude porte sur un total de 7 bâtiments de maçonnerie isolés par l’intérieur : 6 faisant partie de l’étude originale de 2005 et un 7e non relié à l’étude précédente.

Basé sur un examen comparatif des photographies et des notes contenue dans l’étude initiale, il appert que certains bâtiment n’ont pas, en apparence, subi de conséquences, alors que d’autres montrent l’apparition de dommages où l’aggravation de secteurs où la maçonnerie extérieure était déjà altérée.

Basé sur la comparaison de l’évaluation des conditions apparentes, un taux d’appréciation général a été déterminé. De façon générale, les conditions apparentes variaient de bonne à acceptable exception faite d’un seul bâtiment dont la maçonnerie démontrait un niveau important de dégradation. Dans un tel cas, des vérifications plus approfondies permettrait d’identifier les facteurs causes et de suggérer des travaux correctifs.

En l’absence d’une méthodologie d’analyse reconnue qui inclurait un évaluation in-situ, des essais sur matériaux et des simulations informatiques présentement en développement, la mise

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en place de principe de base de la science du bâtiment, combiné à un suivi et des évaluation visuelle périodique et l’épreuve du temps est encore la meilleure approche pour évaluer la performance de mur de maçonnerie massive isolés par l’intérieur. Néanmoins, les bâtiments évalué, mis en évidence dans ce rapport suggère que la modification de mur de maçonnerie massive par l’ajout d’isolant du côté intérieur performe raisonnablement bien sur une période de 10 à 15 ans depuis leurs transformation. Avec un entretien et des réparations périodiques (requis peu importe le type de revêtement extérieur), les murs de maçonneries peuvent continuer à offrir une performance à long terme.

Société canadienne d’hypothèques et de logement Canada Mortgage and Housing Corporation

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TABLE OF CONTENTS

CHAPTER 1- INTRODUCTION ............................................................................................. 1

CHAPTER 2- BACKGROUND .............................................................................................. 3

2.1 Risk associated with insulating masonry wall structures .......................................................... 3 2.2 General guideline for insulating masonry walls ........................................................................ 5

CHAPTER 3- CASE STUDY ANALYSIS ............................................................................... 7

3.1 Current masonry wall re-assessment case study analysis ...................................................... 7

CHAPTER 4- CASE STUDY ................................................................................................. 9

4.1 Case study #1 ........................................................................................................................... 9 4.1.1 General ........................................................................................................................... 9 4.1.2 Envelope description (based on 2005 report information) ............................................. 9 4.1.3 General building description ........................................................................................... 9 4.1.4 Interview of building manager ...................................................................................... 11 4.1.5 Exterior visual review ................................................................................................... 11 4.1.6 Interior visual review ..................................................................................................... 14 4.1.7 Performance of the building façade over the years ..................................................... 14 4.1.8 Discussion .................................................................................................................... 16

4.2 Case study #5 ......................................................................................................................... 16 4.2.1 General ......................................................................................................................... 16 4.2.2 Envelope description (based on 2005 report information) ........................................... 17 4.2.3 General building description ......................................................................................... 17 4.2.4 Interview of building owner ........................................................................................... 18 4.2.5 Visual exterior review ................................................................................................... 18 4.2.6 Visual interior review .................................................................................................... 20 4.2.7 Performance of the building façade over the years ..................................................... 21 4.2.8 Discussion .................................................................................................................... 21

4.3 Case study #6 ......................................................................................................................... 22 4.3.1 General ......................................................................................................................... 22 4.3.2 Envelope description (based on 2005 report information) ........................................... 22 4.3.3 General building description ......................................................................................... 22 4.3.4 Interview of building manager ...................................................................................... 24 4.3.5 Visual exterior review ................................................................................................... 24 4.3.6 Visual interior review .................................................................................................... 27 4.3.7 Performance of the building façade over the years ..................................................... 28 4.3.8 Discussion .................................................................................................................... 28

4.4 Case study #8 ......................................................................................................................... 29 4.4.1 General ......................................................................................................................... 29 4.4.2 Envelope description (based on 2005 report information) ........................................... 29 4.4.3 General building description ......................................................................................... 29 4.4.4 Interview of building manager ...................................................................................... 31 4.4.5 Visual exterior review ................................................................................................... 31 4.4.6 Visual interior review .................................................................................................... 33 4.4.7 Performance of the building façade over the years ..................................................... 33 4.4.8 Discussion .................................................................................................................... 33

4.5 Case study #9 ......................................................................................................................... 34 4.5.1 General ......................................................................................................................... 34 4.5.2 Envelope description (based on 2005 report information) ........................................... 34 4.5.3 General building description ......................................................................................... 34 4.5.4 Interview of building manager ...................................................................................... 36 4.5.5 Visual exterior review ................................................................................................... 36

4.5.6 Visual interior review .................................................................................................... 37 4.5.7 Evolution of the building through the years .................................................................. 37 4.5.8 Discussion .................................................................................................................... 38

4.6 Case study #10 ....................................................................................................................... 39 4.6.1 General ......................................................................................................................... 39 4.6.2 Envelope description (based on 2005 report information) ........................................... 39 4.6.3 General building description ......................................................................................... 39 4.6.4 Interview of building manager ...................................................................................... 41 4.6.5 Visual exterior review ................................................................................................... 41 4.6.6 Visual interior review .................................................................................................... 42 4.6.7 Performance of the building façade over the years ..................................................... 42 4.6.8 Discussion .................................................................................................................... 43

4.7 Case study #15 ....................................................................................................................... 43 4.7.1 General ......................................................................................................................... 43 4.7.2 Envelope description (based on 1998 UMA report) ..................................................... 44 4.7.3 General building description ......................................................................................... 44 4.7.4 Interview of building manager ...................................................................................... 45 4.7.5 Visual exterior review ................................................................................................... 46 4.7.6 Visual interior review .................................................................................................... 48 4.7.7 Performance of the building façade over the years ..................................................... 48 4.7.8 Discussion .................................................................................................................... 48

CHAPTER 5- CONCLUSION .............................................................................................. 49

Re-assessment of the exterior façades of interior insulated solid masonry residential buildings RD-0109-C SCHL/CMHC

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CHAPTER 1- INTRODUCTION

The movement to convert old industrial/commercial buildings for residential usage started more than 30 years ago. The conversion of those buildings was dictated by the necessity to expand the residential offering to address the needs of an ever expanding urban center. As a result, older buildings, constructed in the 19th and 20th century, using mass masonry as the primary structural system, were saved from demolition and transformed to accommodate residential occupancies.

These old structures, composed mainly of exterior load bearing masonry walls and viewed as having sustained the test of time, were deemed to be appropriate candidates for rehabilitation. The exterior masonry walls would have been composed of several different types of masonry in a single wall section. Typically, older masonry buildings, dated prior to the 1940, used for commercial/industrial purposes were constructed with little or no added insulation and very little resistance to air and vapor flow through the building envelope. As a result, there was excessive heat loss and gain, as well as minimal buildup of humidity within the building walls.

Two different retrofit approaches were implemented for such structures. In the first approach, the exterior wall was not modified at all, preserving the architectural aesthetics of the exterior façade. In some instances, the character offered by the interior masonry wall surfaces was also a desired feature and was left exposed and un-insulated. This approach did not offer a very comfortable environment to the resident and in turn went counter to the more energy efficient approach often favoured in the building construction or retrofit community.

A second retrofit approach involved the installation of a layer of insulation on the interior surface of the exterior solid masonry wall assembly. This approach allowed promoters of such conversion projects the opportunity to preserve the unique exterior architectural appearance of the building. Although this approach could offer a more energy efficient envelope and a more comfortable interior environment for the occupants, it did raise some concerns with regards to the overall durability of the exterior wall. As a result of those concerns, insulation upgrades and improved thermal performance were kept to a minimum while increased efforts were made to provide better air leakage / air movement control through the building envelope.

Even after thirty years of implementing such changes to the massive masonry exterior walls, there is still considerable debate amongst building practitioners regarding the potential impacts that the addition of insulation may have on the durability of older masonry structures. It is well understood that the addition of interior insulation will alter the temperature gradient across the wall, due to the difference in thermal resistance values between the masonry and the insulation products. The R value of insulation could be more than five (5) times the thermal resistance of the masonry, so even a minimal application of insulation will greatly impact on the overall R value of a wall.

In 2005, Canada Mortgage and Housing Corporation (CMHC) undertook a research project to study the behaviour and performance of solid masonry wall structures retrofitted from the interior with insulation.

The objective of the study was to establish a relationship between the initial composition of the wall, the retrofit approach and the condition of the vertical building envelope element over an extended period of time. In particular, the report was intended to accomplish the following tasks:


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1. Identify a series of buildings with various types of solid masonry walls that were retrofitted using different approaches;

2. Classify the buildings according to their building envelope characteristics;

3. Evaluate the general condition of the masonry;

4. Tabulate and analyze the collected data;

5. Undertake computer simulations to predict the anticipated hygrothermal performance of the exterior wall systems prior to and following retrofit of the envelope;

6. Include a photographic record of each case study;

7. Help to establish basic design guidelines for the retrofit of older solid masonry walls based on the case study results.

The ultimate goal for that study was to compile sufficient field data in order to help determine what effect the addition of insulation has had on the long-term durability of solid masonry walls. This would then serve as a preliminary step towards helping practitioners better evaluate and understand the different retrofit strategies by sharing this knowledge on the performance of previously retrofitted solid masonry walls.


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CHAPTER 2- BACKGROUND

2.1 RISK ASSOCIATED WITH INSULATING MASONRY WALL STRUCTURES

Over the years, through field experience and research, there is a clearer understanding of the overall deterioration or failure mechanisms of a massive masonry wall structure; the presence of moisture in the masonry pore structure, together with the number and frequency of freezing and thawing cycles the masonry structure experiences play significant roles in the long-term durability of the masonry wall assembly.

In an un-insulated masonry wall assembly (Figure 1), half the masonry wall thickness can be expected to reach temperatures below freezing. In old commercial/industrial masonry structures, durability of the masonry did not represent a significant problem since the indoor relative humidity levels in these types of buildings tended to be very low.

Figure no. 1: Uninsulated masonry wall1

… 1 The computer simulation does not take into consideration the mass effect of the wall that would increase the internal temperature of the brick wall from radiation and convection.

Above Freezing Below Freezing


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The renovation of mass masonry walls during the conversion of the buildings from industrial to residential occupancy resulted in two significant changes:

1. The addition of a thermal barrier; i.e. the exterior masonry walls were typically insulated on the interior surface, and

2. The interior air was heated and conditioned (with moisture) to provide a more comfortable indoor environment for the new occupants.

During winter conditions, the addition of interior insulation tends to render the majority of the masonry wall in sub-freezing conditions (Figure 2). In consideration of only thermal exposure conditions, the durability of the masonry wall is not expected to be compromised; materials such as mortar and masonry are particularly resilient to temperatures below freezing.

Most of the risks, however, are associated with the presence of excessive moisture within the masonry wall assembly during the heating season. The primary moisture sources include exterior sources (such as rain, snow and ice) and the warm interior moisture conditioned air making its way into the masonry assembly by vapour diffusion and/or by air leakage resulting in moisture condensation and accumulation within the pores of the masonry.

Figure no. 2: Masonry wall insulated on interior surface

Other factors impacting the durability of the masonry walls include the material properties of the wall components including water absorptivity, pore structure and size, the water managing capability of the façades, the magnitude and direction of the differential air pressure regimes of the building and the indoor environmental conditions within the building.


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2.2 GENERAL GUIDELINE FOR INSULATING MASONRY WALLS

The 2005 study [1] outlined the following general guidelines for insulating masonry walls:

An emphasis should [...] be directed towards including both a continuous and effective air- and vapour-barrier systems and in ensuring that potential thermal bridging and associated condensation in these areas are identified and addressed.

It was previously stated that masonry can withstand temperatures below freezing without negative repercussions to the durability of the wall, particularly in the absence of moisture. In fact, most non-insulated masonry buildings in service today regularly see the temperature of the masonry wall system fall below freezing without any signs of deterioration. To minimize the risks related to increasing moisture accumulation within the wall system when adding insulation to the inside face of the exterior solid masonry wall, the following preliminary guidelines are suggested towards helping to control exterior and interior humidity sources:

Minimize rain penetration into the wall assembly:

Rain penetration is a potential large source of water ingress within a wall assembly and is often reflective of the quality and condition of the masonry units and mortar joints. The addition of insulation must be combined with a detailed review and repairs of the exterior face of the masonry and mortar joints in order to minimize water intrusion. Other aspects of the building envelope should also be designed to reduce water infiltration and improve water shedding capabilities to direct water away from the wall surfaces, such as the incorporation of suitable window and wall flashings, drip edges, gutter systems, and parapets in order to ensure that the building envelope performs as a continuous rain screen.

Minimize penetration of indoor humidity into the wall assembly through water vapour diffusion:

In order to prevent humidity transfer through diffusion, it is necessary to include a continuous vapour barrier within the wall assembly. The vapour drive, location, and rate of condensation within a wall assembly depend on several factors. These factors include the type of wall materials used, their order of assembly, the quality of their installation and the temperature and relative humidity conditions maintained inside the building during the heating season.

Minimize penetration of rain water and indoor humidity into the wall assembly by controlling air infiltration and exfiltration:

The wall assembly must include a continuous air barrier system throughout the building envelope. A well-constructed air-barrier will minimize moisture transfer into the wall system caused by the exfiltration of indoor air. The air barrier also contributes in minimizing the air pressure differential across the masonry wall assembly and consequently reducing rainwater penetration


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induced by air pressure differentials. Reduced air leakage also increases the level of occupant comfort and energy efficiency.

Minimize the air pressure differential across the exterior wall assembly via the mechanical systems of the building:

The air pressure differential across the building envelope is the driving force for exfiltration of warm, moist indoor air through the wall assembly for buildings under positive pressure (higher indoor pressure versus lower outdoor pressures) and for rain penetration for buildings under negative pressure (lower indoor pressure versus higher outdoor pressure). The pressure differential across the exterior walls of a building is influenced by stack effect, wind loads and the operation of the mechanical systems. Mechanical systems design and configuration should be so that a relatively neutral air pressure exists across the building envelope.

Control Indoor Relative Humidity

As a means to limit or control the amount of condensation within the wall assembly, the level of indoor relative humidity should be kept to a minimum during the heating season through mechanical means by incorporating air-exchange systems which dehumidify the heated air and supply, and operation of suitable exhaust fans in areas of high humidity such as kitchens, bathrooms, and laundry rooms. Maintaining a level2 of between 20% - 30% interior relative humidity for most modern residential construction in Montreal during the heating season is also recommended in order to maintain a reasonable balance between occupant comfort and potential effects of condensation.

Increasing Thermal Resistance

When considering occupant comfort and energy efficiency, it is often deemed necessary to increase the thermal resistance of the existing exterior walls. However, increasing the thermal resistance along the interior surface of solid masonry walls will lower the mean temperature of the masonry and significantly increase the drying time of the wall assembly and the cross section of the wall exposed to freezing temperatures. If the guidelines for moisture control are not followed, the combination of colder masonry and increased drying time may result in an increased risk of moisture accumulation, condensation and frost formation within the solid masonry wall, which can lead to freeze/thaw damage and effectively reduce the durability and lifespan of the masonry wall.

… 2 Even if this level serves as a reference for the industry, it does not meet Health Canada recommendations for residential occupancy


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CHAPTER 3- CASE STUDY ANALYSIS

3.1 CURRENT MASONRY WALL RE-ASSESSMENT CASE STUDY ANALYSIS

Periodic reviews (post-retrofit) are necessary to evaluate the longer term performance of solid masonry wall assemblies with thermal insulation installed on the interior surface, thereby allowing the collection of data that could prove invaluable in coming up with better approaches to insulating masonry walls.

Hence, this study comprises of a follow up visual review and assessment of the exterior façades of solid masonry residential buildings, previously undertaken in the 2005 CMHC research study [1], in which ten (10) solid masonry buildings (referred to as Case Studies 1 to 10, respectively) in the Montréal region had been or were undergoing retrofit work, including the installation of insulation on the interior surface of the masonry walls (see Appendix 1 [1])

A list of five (5) buildings (see Appendix 2 [1]) which were also undergoing retrofit work at the time, but were not included as part of the 2005 study, were to be considered as optional candidates for further review. They are referred to as Case studies 11 to 15.

Tables 1 and 2 [1] highlight the following building information:

Year of construction

Year of retrofit

Location

Exterior wall retrofit composition (cladding, insulation, interior finish)

Observations

The following Case Study Numbers represent those buildings whose owners/managers provided permission and authorization to gain access to the site to undertake the required assessment: 1, 5, 6, 8, 9, 10 and 15. Details of the follow up reviews are included in Chapter 4 of this report.

The scope of the current study includes the following tasks:

1. Conduct and document interviews with the building owners/managers to determine if any significant retrofit work had been completed on their respective building that could affect the performance of the exterior envelope. Topics for discussion include:

a. Obtain information on occupant comfort related to the exterior wall performance. Any reports of discomfort that were noted as well as the potential source;

b. Obtain building façade maintenance history when available;

c. Obtain building façade retrofit work that had occurred since the last evaluation;

d. Obtain information on recurring or isolated problems affecting the building façades.


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2. Conduct a visual review of the masonry façades from the exterior; from ground level or from balconies (where access is provided):

a. Prior to undertaking the visual reviews, a review of the available documents and files pertaining to the building’s previous evaluation and retrofit work will be conducted;

b. Document and photograph the condition of the masonry, mortar joints and other components. Compare with initial conditions;

c. Assess probable causes of the observed deterioration since not all deficiencies could be associated with the addition of insulation.

3. Where possible, conduct an interior visit of some of the units to identify potential elements which could affect the performance of the exterior masonry walls;

4. Tabulate and analyze the collected data;

5. Undertake a photographic record of each building;

6. Rate the general condition of the evaluated building facades: very good, good, acceptable, poor, very poor;

7. Prepare a summary report highlighting key observations regarding the condition of each buildings facades.


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CHAPTER 4- CASE STUDY

This section of the report presents the results of our visual review of the buildings and compares the current results with the previous reviews.

4.1 CASE STUDY #1

4.1.1 General

Location: Montréal, Québec

Initial construction: 1884

Date of retrofit: 1984

Date of Previous Survey: Feb 2003

Date of Present Survey: Feb 2015

4.1.2 Envelope description (based on 2005 report information)

Solid red clay brick masonry (2+ wythes);

¾” – 1” polyurethane foam insulation;

1 ¾” glass fiber batt insulation;

½” gypsum board with aluminum foil backing on 1 ¾” steel furring.

4.1.3 General building description

The complex consists of three 4 storey buildings (with the principal buildings identified by the manager as Block A, B and C) built in the late eighteen hundreds. They were originally constructed for industrial purposes and were converted for residential use in 1984.

The original façades were preserved with no major modifications during the retrofit process. The foundation walls consisted of concrete and stone; the walls were built with red fired clay brick with limestone elements used at the window sills and to provide accent elements.

Timber has been used as the primary structure for the building with tiebacks to link the masonry exterior walls to the wood structure. On the exterior wall, part of the wood structure in imbedded in the masonry. A portion of the wood structure is still exposed from the inside.

Based on the previous report information, during the retrofit work, polyurethane foam insulation was spray-applied over the interior surface of the solid masonry walls. The assembly was completed with a steel furring frame filled with glass fiber insulation and finished with foil-backed gypsum board sheathing.


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Figure no. 3: Buildings in case study #1 with identification of the different blocks

Source: http://www.bing.com/maps

Picture nº 1: Typical façade Picture nº 2: Typical exposed wood structure


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4.1.4 Interview of building manager

An interview with the building manager (in place since 2010), revealed the following information:

Repointing work has been ongoing every year on Block B façades since 2010. The work, recommended by a study undertaken in 2010 by an independent firm consists mostly of uncompleted work from the time of the retrofit;

Structural repairs were done in 2004-05 on some exterior severally corroded steel support beams;

Caulking replacement was performed on Block C tower;

No recurring repairs was or is required on the building façades;

No complaints from the individual owners with regards to the occupant comfort;

No follow up on the scope of work is done by the building manager or the board with regards to potential alterations or modifications of the exterior envelope composition when a unit is renovated;

Building manager and board have not implemented a renovation guide addressing limits of interventions with regards to the exterior walls.

4.1.5 Exterior visual review

Several deficiencies were observed on all façades of the complex as summarized below:

Presence of efflorescence at several locations, but more significant on the North-East façade of Block C and the main entrance (Pictures 3, 4, 5 and 6);

Multiple open mortar joints and spalled mortar (Pictures 7 and 8);

Evidence of multiple repointing interventions at different stages in time. Different mortar was used, while some appears to be portland cement based mortar (Picture 9);

Multiple diagonal cracks on both sides of a window brick lintel (Pictures 10, 11 and 12);

Spalled brickwork at several locations. Some areas are subject to heavier wetting (under window sill – no drip or eroded drip) (Pictures 13, 14, 15 and 16);

Poor quality repointing observed in several locations. Thin layer of mortar applied over the old mortar without proper preparation;

Cracked and broken window sills;

Masonry displacement (Picture 6);

Cracked bricks (Picture 17);

Vertical cracks (Picture 18);

Missing tiebacks;

Corrosion apparent on structural steel components (lintel, beams).


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Picture nº 3: Evidence of efflorescence Picture nº 4: Presence of efflorescence

Picture nº 5: Presence of efflorescence Picture nº 6: Important efflorescence and cracked pilaster

Picture nº 7: Open masonry joints; missing mortar Picture nº 8: Spalled mortar


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Picture nº 9: Repointing from different periods Picture nº 10: Diagonal cracks between lintel and sill

Picture nº 11: Diagonal crack and displacement above window

Picture nº 12: Diagonal crack between lintel and sill

Picture nº 13: Spalled brickwork Picture nº 14: Spalled brickwork


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Picture nº 15: Spalled brickwork Picture nº 16: Spalled brickwork

Picture nº 17: Broken, damaged or dislodged - bricks

Picture nº 18: Vertical crack

4.1.6 Interior visual review

Access was provided to a total of five (5) units to review and assess the condition of the exterior walls from the interior.

In all units visited, part of the wood structure is still visible. A gypsum board is present on the interior surface of exterior walls.

The general condition of the walls was very good with only small deficiencies around the windows; such as peeling paint and cracked joints.

In two of the units, water stains and surface damage were visible on the walls. From our visual review, those problems appear related to window performance issues and not the exterior wall modifications.

4.1.7 Performance of the building façade over the years

Some of the observed damages were also present during the 2003 survey, more than 12 years ago. Those deficiencies range from open joints to efflorescence, cracks above the windows and even spalling brickwork.


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Photo 19 was taken in 2003 and Picture 20 in 2015, at the same location. The extent of the damage appears similar. The deterioration process has continued since 2003 but to a limited degree.

Similarly, Pictures 21 and 22 show that open joints were present in 2003, suggesting the deterioration from 2003 to 2015 appears minimal.

Even the presence of efflorescence appears to date back to 2003; Pictures 23 and 24.

Picture nº 19: Photo taken in 2003 Picture nº 20: Photo taken in 2015



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4.1.8 Discussion

Based solely on the 2015 survey and condition assessment, given numerous observed cladding deficiencies, one might be inclined to deem this façade as having performed poorly, perhaps since the retrofits were completed .

However, in consideration of hindsight and the 2003 and 2000 benchmark information, it is evident that much of the 2015 observed degradation was already present at that earlier period in the buildings life.

Nevertheless, some deficiencies appear to have increased in size and frequency of occurrence including the presence of efflorescence staining and the quantity (and area) of spalled brickwork; although, present in 2003, localized areas appear to have deteriorated further.

Spalled brickwork, observed in 2015, could be the result of already failed brick that had not been previously removed or had not fallen off in 2003. The cause of the masonry deterioration should be further investigated with the implementation of a program of periodic review.

Overall this building façade is considered to be in acceptable condition. Maintenance and repairs to address existing deficiencies are required to limit further deterioration of the envelope and also allow the owners to fully benefit from the initial retrofit work on a long term basis.

4.2 CASE STUDY #5

4.2.1 General

Location: Léry, Québec

Initial construction: Between 1890 and 1905





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18" to 24" limestone masonry;

1” polyurethane foam;

liquid vapour barrier;

2” wood stud wall;

½” gypsum board.


This single-family residence is a three-storey building made with solid stone masonry walls and structural wood elements. This single dwelling house was left unoccupied for several years prior to the retrofit project. At the time of the retrofit, an addition was also built using conventional wood framing with a stone masonry veneer intended to match the existing home’s appearance and detailing. The extension resulted in having some of the original exterior walls becoming interior walls. All the windows and doors were also replaced and the limestone rubble foundation wall was insulated from the outside.

Based on the information from the earlier report, the retrofit approach was to spray 1” polyurethane foam on the interior of the above-grade masonry walls, which would act both as insulation (thermal barrier) and as the air-barrier system. To complete the assembly, a liquid vapour barrier was applied to the polyurethane foam to limit moisture diffusion into the masonry.

Figure no. 4: Buildings of case study #5



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Picture nº 25: Main façade Picture nº 26: Interior view of rubble foundation wall

4.2.4 Interview of building owner

An interview with the building Owner revealed the following information:

No retrofit work was done since 2001;

At the time of the retrofit, the exterior as well as the interior masonry joints were repointed;

No damage has been noted on the inside of the house (water, condensation, etc.);

The exterior wall that became an interior wall due to the addition has resulted in a cold kitchen area since it is still an exterior wall for a part of the second floor;

The remainder of the house is very comfortable and a constant temperature is easy to maintain.

4.2.5 Visual exterior review

For the purposes of this report, a review of the newer portion of the house (that is, the addition) is not within the scope of work since the addition is not constructed as a mass masonry wall. The following is a summary of the deficiencies observed during our survey:

Limited efflorescence visible on the underside of the stone arch lintels (Picture 31);

Degradation of the mortar joints along the gutter downspout (Picture 27);

Crack mortar joint located between the stone lintel and the window frame (Picture 28);


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Multiple micro cracks in the stone walls (Picture 30);

Deficient protective detail at the top of the foundation waterproofing membrane (Picture 33);

Cracks in the upper part of the chimney masonry and in other random locations (Picture 29);

Open or cracked window sill vertical joints;

Suspected presence of humidity in the masonry next to the mechanical cleanout (left hand side façade). In the same area, eroded mortar joints, micro cracks, cracks and biological growth were found;

Spalling stone (Picture 32).

Picture nº 27: Damage masonry next to the downspout

Picture nº 28: Cracked mortar joint between the lintel and the window

Picture nº 29: Crack joint and stone Picture nº 30: Micro cracks in mortar joints


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Picture nº 31: Efflorescence under window lintel Picture nº 32: Spalled stonework

Picture nº 33: Unadhered waterproofing membrane

4.2.6 Visual interior review

The interior of every room of the house from the basement to the roof was available to be reviewed. All interior finishes of the above ground floors are in very good condition without any signs of damage.

In the basement, only part of the rubble foundation wall was left exposed. In some of the rooms, degraded mortar was observed; all of those damages occurred in the underground portion of the foundation wall. Note that the foundation wall was insulated from the outside and protected with a waterproofing membrane.


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Picture nº 34: Degraded mortar joints Picture nº 35: Degraded mortar joints


Since the retrofit occurred only two years prior to the initial review, no deficiencies were apparent at the time.

Since then, minor deficiencies occurred as noted above.

4.2.8 Discussion

The type and location of deficiencies noted during the review could easily be related to construction details implemented during the retrofit stage. The overall condition of the building is very good and the deficiencies cannot be related to the addition of thermal insulation from the inside.

The damaged stone and mortar along the downspout appears related to the downspout itself. The cracked joints between the lintel stone and the window frame are due to the size of the mortar joint. The suspected presence of humidity in the wall is related to the exhaust pipe coming from the mechanical equipment.

Also, the damaged mortar joints in the basement appear to be linked to the deficient detail at the top of the waterproofing membrane.

Overall, the retrofit could be considered as a success for this Case Study.


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4.3 CASE STUDY #6

4.3.1 General


Initial construction: 1854 to 1946

Date of retrofit: Started in 2003




Variable brick wythes, from 8” to 35”;

1” polyurethane foam;

Steel stud wall assembly;

½” gypsum board.


Case Study #6 consists of ten (10) buildings that were constructed between 1854 and 1946. They were originally constructed for industrial purposes and were converted in 2003 to residential units with ground floor commercial units.

The project was done in three phases. Phase 1 included the retrofit of building A, B, C and D. An additional floor was added on top of building D.

Phase 2 included the complete reconstruction of building E, F and G. Those buildings were in such bad condition that saving them was not a feasible option. At the same time, building H was demolished and only the foundation ruins were kept for historical value.

Phase 3 included the retrofit of buildings I and J and the addition of a floor above building I.

Every original façade was preserved to some degree, in some cases, undergoing modifications during the retrofit process. The foundation is built with limestone; the walls are all built used red fired clay brick. There are several (approximately twelve) different exterior masonry wall configurations.

Wood and steel has been used as a primary structure for the building with tiebacks to link the masonry exterior walls to the interior structure. On the exterior wall, part of the structure is imbedded in the masonry.

A complete study was performed by Patenaude-JBK in 2001 before the retrofit project to assess the condition of all of the buildings. The report serves a good benchmark to evaluate the actual condition.

Based on the previous report information, during the retrofit work, polyurethane foam insulation was spray-applied over the interior surface of the solid masonry walls. The wall assembly was completed with a steel furring framework with gypsum board sheathing.


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Figure no. 5: Buildings of case study #6


Picture nº 36: Typical façade Picture nº 37: Interior view of a commercial unit with exposed wood structure


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An interview with the building manager revealed the following information:

Repointing was performed on building D;

Isolated repairs were done to the exterior walls of buildings B and C;

Brick replacement on part of building B was done;

On building J, bricks were installed because they were left missing after the completion of the retrofit project;

No complaints from the individual owners with regards to the occupants’ comfort;


Building manager and board have not implemented a renovation guide addressing limits of intervention with regards to the exterior walls.


Since each building presents different problems, the following section will be separated according to buildings of similar construction and with similar deficiencies. This report does not include a review of buildings E, F, G and H since those buildings are not retrofitted mass masonry walls.

4.3.5.1 Buildings A, B and C

Presence of efflorescence in several areas;

Spalled brick. Smaller areas near downspout or at window sill. Major areas on the main façade;

Bulging of portion of the parapet;

Diagonal cracks above and below the windows;

Vertical crack in the foundation wall;

Spalled cement parging;

Isolated vertical cracks;

Broken stone sills.


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Picture nº 38: Efflorescence staining Picture nº 39: Spalled brickwork and efflorescence

Picture nº 40: Diagonal crack above the window Picture nº 41: Spalled brickwork

Picture nº 42: Spalled brickwork and efflorescence Picture nº 43: Efflorescence staining


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4.3.5.2 Building D

Open mortar joints;

Cracked stones;

Spalled stones;

Vertical cracks;

Open joint between some window jamb stone and field stone;

Displaced masonry;

Diagonal cracks above some windows.

Picture nº 44: Broken stone Picture nº 45: Gap between the jamb and the stone

Picture nº 46: Unstable bricks Picture nº 47: Broken bricks and vertical crack

4.3.5.3 Buildings I and J

Vertical crack in one corner;

Presence of efflorescence;

Broken and displaced brick;

Spalled and cracked or damaged bricks;

Open joints;

Cracks above and below some openings.


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Picture nº 48: Crack in masonry Picture nº 49: Vertical crack

Picture nº 50: Broken and displaced brick Picture nº 51: Large amount of efflorescence

Regarding deficiencies presenting a danger to the public, the building manager was advised, of the potential risks and was informed of the possible actions to be taken.


Access was provided to a total of six units to review and assess the condition of the exterior walls from the interior.

In all units reviewed, part of the structure, either steel or wood, is still visible. A gypsum board finish is present on the exterior walls.

The general condition is very good with only small deficiencies around the windows such as peeling paint and cracked joints.

In some of the units, the floor appeared to be colder than in other units. Apart from the noted discomfort, this does not seem to have impacted the performance or integrity of the walls.


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Since the retrofit project started in 2003, there is no real data available to compare the existing condition of the building façade to its condition at the time of the retrofit completion. The available photos from 2003 were taken as construction photos, showing different stages of completion without any part being in service yet.

However, for building A, the efflorescence visible in 2015 can be traced back to the efflorescence present in 2003. The extent of the efflorescence at the time was even greater than it is now.

Picture nº 52: 2003 picture Picture nº 53: 2015 picture

4.3.8 Discussion

The most significant façade deficiencies were observed on buildings A, B and C. The amount of spalled brick suggests a potential problem that requires further investigation to determine the cause. Also, even if the presence of efflorescence was visible in 2003, it was not present in 2001 when the first evaluation was done. This would indicate a potential problem even if the extent of the deficiency seems to be stable.

The causes could vary; from uncontrolled interior environment to poor quality brick or deficient water management by the wall components (parapet, drip edge, etc), allowing too much moisture into the masonry structure and in the masonry material.

Building D performed better. No recurring anomalies were observed. The deficiencies are isolated and unrelated to the addition of insulation from the inside. Some problems are directly linked to the poor attention given to the exterior repairs during the retrofit project. The owners will have to address those issues to ensure the building can perform adequately over the long term.

Block I and J are in overall good condition but are showing some isolated problems which should be investigated.


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Since the retrofit project started in 2003, this visual review constitutes the first benchmark and should be used as a future reference for follow up reviews.

The overall rating of this Case Study varies from poor for buildings A, B and C to acceptable for buildings I and J to good for building D.

4.4 CASE STUDY #8

4.4.1 General





Date of Present Survey: January 2015


4” red fired clay brick;

2” air gap;

8” concrete block;

1 ½” polyurethane foam;

3 ¾” steel furring;

Type 1 vapour barrier;

½” gypsum board.


This old commercial building was converted into a commercial/residential building in 1996. At the time of the retrofit, the building was significantly altered resulting in only the front façade being retained and retrofitted. The rear façade is now a standard, cavity wall with a brick veneer and both side walls are interior party walls unexposed to the elements.

On the front façade, the limestone, present at the base of the building wall, is covering a concrete foundation wall. The main body of the wall uses a red fired clay brick with two limestone horizontal insertions at the second and sixth floor. The parapet copping is also sandstone.

A single level underground parking garage was added under the existing building and a pool was added on the rooftop.


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Figure no. 6: Building of case study #8


Picture nº 54: Main façade Picture nº 55: Back façade, cavity wall


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An interview with the building manager (in place since 2007) revealed the following information:

No work was performed on the building’s front façade since the retrofit with the exception of caulking replacement (2008-10);

Some complaints from the individual owners with regards to the occupants’ comfort. Complaints received concerned air infiltration;

No follow up on the scope of work was done by the building manager or the management board with regards to potential alterations or modifications of the exterior envelope composition when a unit is renovated;



For the purposes of this report, the newer façades related to this building are outside the scope of this study since they are not retrofitted mass masonry walls. Several deficiencies were observed on the old (front façade) part of the building, summarized as follows:

Open joints at the foundation level and at the parapet. In the latter case, the joints between the copping stones are not protected from the elements;

Presence of a vertical crack on the right hand side corner from parapet to second floor. Cracks varies in size from floor to floor but is continuous;

Presence of significant efflorescence staining mainly at the upper levels;

Vertical cracks between the window lintel and window sill;

Biological (mold) growth at some locations;

Pilaster on the ground floor being pushed out by corroded pieces of steel;

Damaged foundation wall leaving parts of the stone unsupported;

Important cracks in a concrete beam.

Picture nº 56: Vertical crack Picture nº 57: Vertical crack


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Picture nº 58: Efflorescence Picture nº 59: Efflorescence

Picture nº 60: Displaced masonry Picture nº 61: Displaced masonry


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Picture nº 62: Cracked concrete beam Picture nº 63: Partially unsupported masonry


Access to the interior of the residential units for a visual review of the exterior walls was not provided.


The 2005 report stated that no efflorescence or symptoms of masonry deterioration were observed. The 2015 survey clearly shows damages at several locations on the façade with large masonry surface areas affected by efflorescence.

4.4.8 Discussion

The efflorescence affecting large areas of masonry are often observed below the stone band located between the 5th and 6th floors. The efflorescence can be linked to defective vertical joints of the stones but not in all instances. Clearly further investigation will be required to identify the phenomena and cause of the façade deterioration.

At the time of the retrofit, the bottom portion of the façade was modified to some extent to accommodate new openings between pilasters. Part of the existing steel components, that appear to serve as large door frames, are now causing further deterioration to the façade. The imbedded steel is heavily corroded and is pushing the entire brick pilaster outwards.

Another concern is the vertical crack on the right hand side of the façade. The crack extends from top to bottom of the building and is accompanied with apparent brick displacement. This crack is also causing adjacent portions of the wall to crack. Further investigation is required to stop and correct the degradation of the masonry façade.

The overall rating of this building is acceptable. The building rating would have been higher had it not been for the number of potential problems observed during the survey.


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4.5 CASE STUDY #9

4.5.1 General




Date of Previous Survey: April 2003

Date of Present Survey: January 2015


13” red fire clay brick (3 courses);


3 5/8” steel furring;

½” gypsum board.


This old commercial building, retrofitted in 1999 and converted to a residential building, was somewhat modified to accommodate a more linear façade than the original. The left hand side façade was cut in the middle to incorporate a courtyard and provide balconies to the residential units. Therefore, the courtyard façades are entirely new façades and were built using a rain screen approach with a brick veneer facade.

The original building façades are built with red fired clay bricks with a limestone foundation and limestone architectural features such as window sills, lintel key stones and linear insertions.

Based on the 2005 report information, during the retrofit work, polyurethane foam insulation was spray-applied over the interior surface of the solid masonry walls. The assembly was completed with a steel furred frame with gypsum board sheathing.


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Picture nº 64: Front façade Picture nº 65: Rear façade

http://www.bing.com/maps


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No work was performed on the building’s original façade since the retrofit with the exception of caulking replacement (2008-2010) and local repointing of the right hand side façade (required because it was not done at the time of the retrofit);





For the purposes of this report, the newer portion of the building is outside the scope of this study since the façade is not a massive masonry wall. Very few deficiencies were observed on the old part of the building and are summarized as follows:

Open joints in some locations;

Minor signs of efflorescence, mainly under window sills;

Some cracked stone was observed;

Loose steel shims meant to support the masonry. Cracked masonry above the loose shims;

Cracked masonry foundation wall;

Isolated instances of spalled brick;

The masonry of the left hand side party wall was not cleaned at the time of the retrofit. Paint is still present for a good part of the wall;

Eroded and spalled joints noted on the party wall. Some repointing was done.


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Picture nº 66: Open joints, efflorescence and cracked stone

Picture nº 67: Loose shim

Picture nº 68: Cracked masonry Picture nº 69: Spalled and eroded joints


Access to the interior of the residential units for a visual review of the exterior walls was not provided.

4.5.7 Evolution of the building through the years

The 2005 report stated that only minor deficiencies were present on the building. A crack was present on the right hand side corner. That crack has since been repaired.


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Picture nº 70: 2003 picture Picture nº 71: 2015 picture

4.5.8 Discussion

Small isolated deficiencies are present, which is not unusual for a building of this age. Simple maintenance will resolve those issues.

The presence of efflorescence under the window sill is indicative of poor water management from the sill itself. Verification of the drip size and location should be done to ensure proper evacuation of the surface water and avoid brick saturation.

The party wall is showing the most degradation with its open and deteriorated joints. The condition is not related to the addition of insulation from the inside but to the lack of maintenance and maybe the presence of the paint over the masonry.

The overall rating of the building façade is good.


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4.6 CASE STUDY #10

4.6.1 General







Existing stone/brick;


3 5/8” steel furring;

½” gypsum board.


This five storey building was converted to a residential building in 2003. The main façade is built entirely with limestone with the remaining three façades composed of red fire clay brick. Both side façades are party walls and only a portion of each are exterior walls. The rear façade in its lower section is also a party wall.

At the time of the retrofit, the project included the addition of a new building on the right hand side.

Based on the 2005 report information, during the retrofit work, polyurethane foam insulation was spray-applied over the interior surface of the solid masonry walls. The assembly was completed with a steel frame furring with gypsum board sheathing.


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Picture nº 72: Front façade Picture nº 73: Side and back façade


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An interview with the building manager revealed the following information:

No work was performed on the building’s original façade since the retrofit;

No complaints from the individual owners with regards to occupant comfort;




Some deficiencies have been observed on the building. Hereafter is a summary of our survey:

Multiple eroded and cracked stones;

Several cracked stones linked to vertical cracks in lintels with displacement;

Open joints;

Spalled stone near the foundation;

Cracked mortar joints;

Very minor and localized efflorescence on the brick masonry of the side wall;

Old and degrading mortar of the party wall;

Spalled brick;

Split window sill.

Picture nº 74: Eroded stone Picture nº 75: Crack stone lintel with masonry displacement


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Picture nº 76: Spalling stone Picture nº 77: Open and cracked joints

Picture nº 78: Eroded and degraded mortar joints Picture nº 79: Split window sill


Only one unit was reviewed from the interior to assess the condition of the exterior walls.

General condition of the exterior wall is very good with no apparent damages.


Since the retrofit project started in 2003, there is no information available to compare the condition of the building and its evolution since the completion of the retrofit. The available photos from 2003 relate to the condition of the building prior to the retrofit.

We can relate some of the deficiencies visible in 2015 to the photos taken in 2003 hence allowing us to conclude that the deficiencies were present prior to the addition of insulation.


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Picture nº 80: 2003 picture showing the presence of the crack above the window

Picture nº 81: 2015 picture

4.6.8 Discussion

Even though this building is showing several deficiencies, most of them can be related simply to age. The limestone used in 1861 for the façade is more than 140 years old. It is normal to expect degradation of the stone created by erosion of water seeping into small natural cracks creating splits or spalls.

The movements associated with lintel cracks were present in 2003 and appeared to have been repaired at that time. There is no visible increase in the movement of the stone and no cracks in the mortar joints around the failed stone.

The deficiencies located at the foundation appeared to be related to snowplow activities adjacent to the façade and not degradation caused by the addition of the insulation.

As for the brick masonry, the degradation of the mortar joints date prior to the retrofit project. The condition is not related to the addition of insulation from the inside but due to the lack of maintenance and maybe the presence of the paint over the masonry.

The overall rating of the building façade is good.

4.7 CASE STUDY #15

4.7.1 General

Location: Ottawa, Ontario

Initial construction: 1873 to 1876


Date of Previous Survey: May 1998



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4.7.2 Envelope description (based on 1998 UMA report)

Existing stone/brick;

3 ½” batt insulation;

3 1/2” wood studs;

Vapor barrier (polyethylene);

Gypsum board.


The original Wallis House was much smaller in scale than the present building. It served as a catholic hospital when it was built. The building changed function on several occasions and was even left unoccupied on two separate occasions. After several modifications and additions, it was finally converted for residential use in 1995.

The façades are composed of different types of walls; the main walls consist of painted red fired clay brick, and the upper sections have wood and an Exterior Insulated Finish System (EIFS) in place. The foundation is of limestone construction.

Decorative elements using sandstone and limestone are incorporated into the building walls.




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Picture nº 82: Typical façade Picture nº 83: Archive picture of the main portion of the building



The brick painting was done during the retrofit project. Note that information from a previous review report (from a third party source) suggests that the brick paint was applied much earlier than 1996;

Major restoration work was done on the right hand side façade after the removal of an underground adjoining cold storage room;

Damages on the left hand side façade staircase was noted in 2013 during major street repair work (blasting);

Water infiltration issues remain unresolved on the back façade;

Complete roof replacement in 2010;





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Several deficiencies have been observed on the building. Only the review of the brick portion of the building is included in this report. The following is a summary of our observations:

Peeling brick finish paint in several areas;

Corroded steel lintel;

Vertical crack below window sills and in some corners;

Multiple diagonal cracks in the masonry, some in the foundation wall;

Unsealed openings in masonry;

Open joints at several locations;

Spalled brick and deteriorated mortar joints in wetter areas;

Multiple open and cracked mortar joints in the foundation wall;

Cracked brick and cracked stones;

Multiple arch brick lintel displacement;

Cracked stone window sills;

Corroded steel structure imbedded in the masonry wall;

Location of the mechanical exhaust creating ice buildup on the masonry.

Picture nº 84: Peeling paint Picture nº 85: Peeling paint under a window sill


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Picture nº 86: Open foundation wall joints Picture nº 87: Cracked stone

Picture nº 88: Mechanical exhaust Picture nº 89: Window arch lintel displacement

Picture nº 90: Diagonal crack in masonry wall Picture nº 91: Diagonal crack starting in the foundation wall


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A total of five units and two staircases were reviewed from the interior to assess the condition of the exterior walls.

General condition of the exterior wall is very good for all units. In one unit, air infiltration issues were raised during our visit by the unit owner.

Some settling was observed by some owners in their own units (for example, doors no closing properly).

Damages (vertical cracks) were observed in both staircases: one crack in the drywall finish, the other one in the masonry wall perpendicular to the exterior wall.


The 1998 inspection report stated that several units had large areas of exposed brick and that no attempt was made to ensure continuity of the air/vapour barrier at electrical outlet boxes.

Those two remarks suggest that air leakage through the building envelope and excessive heat loss are to be expected.

In the 1998 report from UMA, several important deficiencies were noted on the exterior facades, such as extensive repointing required for the foundation wall, peeling paint, broken sills and even structural movement.

Based on visual review, it appears that these deficiencies were corrected over time and are performing well. Nevertheless, the building is still affected by a peeling paint problem, and roof water runoff onto masonry walls.

4.7.8 Discussion

This building is showing signs of wear and tear on the inside and the outside. Multiple cracks in the interior walls and outside foundation walls raise concerns about the structural stability of the building. This is reinforced by the comments received by the owners during the interior review of the units.

The condition of the brick and stonework is allowing water to infiltrate and cause even more deterioration. Moreover, water management details, such as faulty downspout, mechanical exhaust location, and roof runoff are contributing to the deterioration of the masonry work and the brick coating.

The observed degradation of the building façade does not appear to be caused by the addition of the thermal insulation from the inside.

The overall rating of the building facade is acceptable.


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CHAPTER 5- CONCLUSION

In 2005, Canada Mortgage and Housing Corporation undertook a research project to study the behaviour and performance of exterior solid masonry wall structures retrofitted from the interior with insulation.

This 2005 study comprised of a visual review and assessment of the exterior façades of solid masonry residential buildings, in which ten (10) solid masonry buildings in the Montréal region had been retrofitted with the installation of insulation on the interior surface of the masonry walls.

The present follow-up study was carried out on six (6) of those ten (10) buildings initially reviewed and on one (1) other building that also had undergone retrofit work but was not included in the 2005 report.

In order to evaluate and assess the success of the addition of insulation from the inside on the exterior solid masonry walls, the review and assessment of each building consisted of an interview with the owner/manager, an interior review of the exterior walls from the suites and a visual inspection of the façades from the outside.

The collected information, for each building, was analyzed, evaluated and an assessment was made regarding the condition and performance of the exterior masonry walls. As shown in the table below, each of the case study building facades received a rating assessment; (very good (no apparent impact of the retrofit on the exterior masonry walls), good, acceptable, poor and very poor (evident and important signs of deterioration of the masonry walls). The rating assessment is based solely on a visual review and could greatly be influenced by not only the internal condition of the masonry wall itself but also of the embedded elements such as steel components or timbers.

Case study number Rating

1 Acceptable

5 Very Good

6 (buildings A, B and C) Poor

6 (Buildings I and J) Acceptable

6 (Building D) Good

8 Acceptable

9 Good

10 Good

15 Acceptable


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Of the six (6) case study buildings facades previously surveyed in 2005, the masonry walls associated with Case Study 6, Buildings A, B and C were not considered to be performing well. The facades of all the other case study buildings revealed a level of performance ranging from acceptable to very good. This suggests that the interior insulation retrofits of solid masonry exterior walls do not appear to have accelerated or compromised the durability of the masonry structure and with appropriate maintenance and repair, can continue performing reasonably well in the years ahead. Most of the case studies included in this report were retrofitted using sprayed foam insulation, but the same conclusion could be said with the use of other the type of insulation if all the design requirements are properly implemented during the retrofit process. Obviously, sprayed foam insulation seems to be the insulation of choice maybe because of its ability to adapt to the masonry profile and ensure the absence of voids between the insulation and the masonry wall.

Some of the building facades that are rated “acceptable” are showing some evidence of deterioration, mainly in the form of efflorescence stains on portions of the building façades requiring additional investigation to assess the cause(s) and determine remedial solutions.

Ongoing research is taking place to develop and implement better evaluation measures and protocols to predict whether or not mass masonry structures are suitable candidates for an interior insulated retrofit. Currently, the protocols consist of a series of steps including

a condition assessment and evaluation of the masonry wall to determine the condition of the bricks and mortar and the overall performance of the system to date;

laboratory testing of the masonry (and mortar materials) to assess physical properties of the materials including porosity, pore size, water absorption characteristics and the ability of the materials to withstand freeze thaw cycling; and

computer simulations to assess whether or not the expected exposure and environmental conditions for the retrofitted wall assembly may be detrimental to the performance of the materials in the wall assembly.

Until these methodologies are better developed and refined, the knowledge and application of known building science principles, in conjunction with periodic monitoring and the test of time, are still the best tools available to evaluate the longer term performance of a retrofitted mass masonry wall structure. The case study buildings highlighted in this report, suggest that the interior insulated retrofit of these mass masonry buildings appear to be performing reasonably well over the 10 to 15 year time frame since the retrofit work was completed. With continued maintenance and repair (as with any envelope or cladding system), the masonry walls can continue to provide long-term performance.

References

[1] Performance Evaluation of Retrofitted Solid Masonry Exterior Walls http://publications.gc.ca/collections/collection_2011/schl-cmhc/nh18-1-2/NH18-1-2-116-2005-eng.pdf, 2005.

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HOUSING RESEARCH REPORT - .NET Framework

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