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Building Envelope Condition Assessment for Chelsea Terrace

1040 Pacific Street, Vancouver, British Columbia

4 09/30/2011

The exhaust fans and open windows should be used whenever bathing, dishwashing,

cooking, or similar activities are occurring.

Excessive condensation can damage interior surfaces and provide conditions for mould or other

fungal colonies to propagate. Some mould or fungal species are toxic to some humans. It is

beyond MAE’s area of expertise to comment on mould or fungal colonies.

During the course of our interior inspections we noted that all of the units that were inspected

have been provided with bathroom and kitchen fans.

4.5 WALLS

For the purposes of this investigation, wall assembles have been categorized into thee types –

one below grade wall assembly, and two above grade wall assemblies: stucco on steel stud

framing and mass concrete walls.

4.5.1 Stucco on Steel Stud Framing

The components that make up the stucco wall assembly are listed and shown schematically in

Figure 1 below. The schematic detail below has been reproduced from the Architectural

drawings provided for our review.

Figure 1 - Stucco Wall Assembly – Plan View

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The stucco walls assemblies can be described as face-sealed assemblies. The outer face of the

stucco is the primary defense against water ingress with no provision to handle any moisture

ingress once it occurs. Historically, face sealed wall assemblies have not performed well in our

climate.

The stucco appears to be a pebble-dash stucco and dates back to the original construction period.

It should be noted that the Construction Drawings do not show the presence of building paper or

a sheathing membrane, which is typical for this type of wall assembly. The Construction

Drawings indicate that the original sheathing is a rigid mineral sheathing. While performing the

invasive testing, plywood sheathing was observed at many locations. Batt insulation along with

poly vapour barrier were also typically observed in the exploratory openings.

The paragraphs below describe some of the components that are found in the wall assemblies

followed by descriptions of the expected behavior of the above grade walls.

Wall Sheathing

The sheathing provides backing for stucco attachment and also provides lateral support for the

steel studs.

If the wall sheathing is exposed to moisture for an extended period of time it will deteriorate.

Furthermore, moisture may be able to travel through the sheathing to the underlying structural

components, causing them to deteriorate.

If the sheathing is allowed to deteriorate, the structural capacity of the steel studs, and the

fasteners that connect the stucco to the studs, can be compromised. A reduction in the structural

capacity of the studs and/or fasteners would compromise public safety. During the course of our

investigation we observed no evidence to suggest that structural integrity had been compromised.

Steel Studs

The steel studs form part of the building’s exterior walls and are not designed to carry building

loads. The studs must transfer gravity loads from the weight of the wall assemblies along with

wind and seismic loads.

Batt Insulation

The insulation reduces heat flow between the inner and outer sides of the wall assembly. The

batt insulation’s effectiveness would be reduced if it becomes water damaged.

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Vapour Barrier

The vapour barrier resists the movement of water vapour through the assembly. If warm water

vapour is allowed to come into contact with colder components, such as the inside face of the

exterior sheathing, condensation could occur, which may allow liquid water to accumulate within

the hidden sections of the wall assembly. Vapour barriers are generally not required within un-

insulated wall assemblies that enclose unheated spaces.

Expected Behaviour – Stucco Walls

This is the wall’s exterior surface and it’s primary defense against water infiltration. Wire mesh

is embedded into the stucco and is mechanically fastened, through the exterior sheathing, to the

studs. The mesh fasteners must be strong enough to resist vertical, outward, and horizontal

forces that may be imparted on the wall. The mesh performs two primary functions: it controls

stucco cracking and it connects the stucco to the building’s structural components.

Stucco wall assemblies as described above are commonly referred to as a face sealed assembly.In a face sealed assembly, resistance to water penetration is controlled by the continuity of the

outer cladding. This system typically incorporates limited flashings not to direct water out of the

wall assembly but rather away from the assembly. The disadvantages of these assemblies are:

• In a face sealed assembly, in order to effectively resist water infiltration, the outer cladding

and penetrations through the outer cladding, such as windows or similar openings, must

remain watertight. In practice, complete water tightness of the outer cladding is difficult to

achieve.

• In a face sealed assembly, the addition of flashings is meant to assist in directing water away

from the wall assembly. In practice, however, the lack of a drainage plane behind the stucco

cladding traps water between the back of the cladding and the sheathing membrane. As such,

moisture behind the cladding is unable to flow down to the flashings to be directed out of the

wall assembly.

The behavior of a typical face sealed stucco clad wall is described below:

The stucco, acting like a sponge, has the ability to absorb a certain amount of water. If the

amount of water that the stucco must absorb exceeds its capacity, the excess water may be driven

inward through cracks or other breaches in the cladding. The driving force can be supplied by

wind, unbalanced inward vapour pressures that can occur if the exterior face of the wall heats up

from solar energy, or from other unbalanced air pressures. Once the moisture has migrated

through the breaches to the stucco’s inner surface, wind or other unbalanced pressures can

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continue to drive the moisture to the sheathing. The exterior sheathing has a limited a capacity to

resist water damage.

If the stucco stops being wetted before its capacity to absorb water is reached, a drying process

begins whereby the stucco may be able to dry to the exterior and water ingress may desist. This

system can work provided the drying process is long enough and the wetting process is short

enough. The likelihood of water damage to vulnerable components will increase if a long wet

winter is followed by an unusually wet or cloudy summer.

Stucco, like other cementitious building materials, expands and contracts with changing ambient

temperatures and humidity levels. If appropriate allowances are not made for the

expansion/contraction forces, the stucco will crack. If the cracks are deep enough, the cracks

will breach the cladding. The expansion/contraction forces are usually accounted for by

providing appropriately spaced and detailed control joints. The control joints may be located

beside window or door openings. The British Columbia Wall and Ceiling Association, in the

1993 edition of its Stucco Resource Guide, recommends that “On walls, where the length of

stucco surface exceeds 4,500 mm provide vertical control joints not more than 3,000 mm on

centre.” It is worthy of note that the 1997 edition of the Stucco Resource Guide recommends

that “…joints be installed in framed and sheathed construction so as to create stucco panels of

approximately 14 m2 to 17 m2 in as square a configuration as possible...”

Control joints should be wide enough to accommodate the expected movement in the adjacent

stucco panels. The joints should be flexible enough to accommodate the expected expansion and

contraction of adjacent panels. The recommended style of control joint is usually “w” shaped

and accommodates movement in the materials while being fully embedded in stucco and limitingwater ingress.

4.5.2 Mass Concrete Wall

The components that make up the concrete wall assembly are listed and shown schematically in

Figure 2 on the following page. The schematic detail below has been reproduced from the

Architectural drawings provided for our review.

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Figure 2 – Mass Concrete Wall Assembly – Plan View

The exposed concrete walls at Chelsea Terrace have an exterior coating applied to provide

protection from the elements. For descriptions of remaining wall assembly components, refer to

the descriptions in Section 4.5.1.

Expected Behaviour – Concrete Walls

If the concrete has not been coated with elastomeric or similar sealer, it will absorb moisture like

a sponge. Wind can drive absorbed moisture inward or outward, depending on its direction.

Heat from the sun can remove the moisture from the concrete through an evaporation process.

Mass concrete walls are generally considered to be robust especially if they are properly coated.

Moisture absorption, within reason, is not generally thought to be detrimental to the structural

capacity of the walls provided the exposed face of the concrete is maintained in good condition.

4.5.2 Below Grade Walls

The below grade wall assemblies enclose the parking garage and some areas of the suites. The

Architectural Drawings do not indicate how the below grade walls resist water ingress; however ,

typical below grade wall assemblies have some form of dampproofing.

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A thin bituminous damp-proof membrane appears be adhered to the exterior face of most the

concrete walls at Chelsea Terrace. The presence of a damp-proof membrane was verified at

most exposed walls, and some areas appear to have had more recent repairs performed. If

present, the membrane provides the primary resistance to water infiltration. According to the

Construction Drawings, a drainage pipe is located below the wall to collect ground water and

transport it away from the building.

In the event that there is no damp-proof membrane or that it becomes overwhelmed, the concrete

wall has the capacity to store a certain amount of moisture within its thickness before allowing

water to penetrate to the interior.

Below grade concrete wall assemblies can perform well provided that:

• The drainpipes do not become clogged. Clogged drainpipes could allow a build-up of

hydrostatic pressure;

• The damp-proofing membrane is present and does not break down. Like all building

components, the membrane has a finite reliable life expectancy. In the absence information

regarding the existing membrane, it is difficult to estimate its reliable life expectancy. A

broad estimate of the reliable service of the membrane would be 20 to 30 years;

• The interface between the above grade framing components and the below grade concrete

wall remains watertight.

4.6 WINDOWS AND DOORS

4.6.1 Windows

The exterior windows at Chelsea Terrace are double glazed, aluminum-framed assemblies. The

operable windows are predominantly sliders and some are hinged awning style. Good quality

aluminum windows should provide approximately 20 years of reliable service. Notation on the

window frames indicates that they were manufactured in 1981, thus, at 30 years of age, they

have reached their expected reliable life span.

Aluminum window frames are generally assembled from four separate extruded aluminum

components – two jamb components, one head component and one sill component. The four

components are connected together at the four corners of the assembly and sealed against water

ingress with small joint sealant (caulking). Eventually, the small joint sealant breaks down and

is no longer effective.

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Window frames are generally flush with the exterior face of adjacent walls and are typically

surrounded by continuous stucco cladding. Photo 4 shows a typical exterior window/wall

interface. Head flashing has been installed at window heads, however the lack of end dams has

significantly reduced the effectiveness of the head flashing. Windowsill flashing was not present

at the building. A good portion of the windows are located directly beneath roof/balcony

overhangs, which provides the windows with protection from bulk water penetration.

Photo 4 – Typical windowsill/ wall interface. Photo 5 – Typical Window head and head flashing

detail.

The Architectural Drawings do not indicate how window assemblies interface with adjacent wall

assemblies. Sealant has generally been used at the window-to-wall interfaces to provide

protection against air and water infiltration. The condition of the sealant ranged from fair to

poor.

Deteriorated sealant will increase the likelihood of water infiltration and allow air to pass

through the window-to-wall interfaces. Water ingress can deteriorate interior finishes and

structural components, while the increased air flow will:

• Increase the likelihood of water infiltration;

• Reduce the building’s energy efficiency;

• Increase the likelihood of condensation on the inside face of the window assemblies, and;

• Increase the cold drafts in the vicinity of windows.

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4.6.2 Doors

Suspended balconies and patios are accessed via aluminum framed sliding glass doors. The

majority of the sliding glass doors are located beneath roof or balcony overhangs and are thus

protected from wind driven rain. Sliding glass door details are similar to window details.

The exterior doors at Chelsea Terrace are typically metal assemblies that have been mounted inmetal frames. The overhang varied from door to door, but was generally present. The main

entrance doors are glazed storefront assemblies under a large overhang.

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5.0 OBSERVATIONS, DISCUSSIONS, AND RECOMMENDATIONS

This section describes relevant observations and, where applicable, our recommendations to

address observed deficiencies. Time frames for implementation of the recommendations are

given. Delaying the implementation of these recommendations may, over time, increase the

magnitude of the noted deficiencies, which in turn will increase the eventual cost of implementation.

Each recommendation is presented with an order of magnitude budget, which has been derived

from our perusal of the Construction Drawings and our experience with similar projects.

It is difficult to provide an accurate cost estimate without some preliminary design work and a

clearly defined scope of work. The actual cost of the work cannot be known until material

quantities have been reliably estimated, project drawings and specifications have been produced,

contractors have bid on the project, and the extent of any hidden damage is known.

Where applicable, budget values account for consulting fees, taxes, and contingency for hidden

damages, but do not account for inflation.

5.1 OCCUPANT SURVEY

All of the completed occupant surveys have been reproduced in Appendix C. A summary of the

survey results is presented in Table 4.

Table 4 – Occupant Survey Results

Total number of units at Chelsea Terrace: 112

Total number of units that responded to the survey: 57 (51%)

ANALYZED DATA

# of

Responses

% of Units That

Responded

% of Total #

of Units

Units reporting signs of interior water stains 19 33% 17%

Possible water leaks 7 12% 6%

Probable window condensation 14 25% 13%

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A review of Table 4 and the raw data that is presented in Appendix C indicates that one third of

the collected surveys report some evidence of leakage or condensation, which is 17 percent of

the total units in the building.

5.2 ROOFS

The low-slope roofs will be divided into two categories for this report: the main roofs and the

lower tier roofs. The roofs are comprised of SBS sheet membrane over a concrete substrate.

The main roof will include the large roof above the ninth level (including the mechanical room

roofs), the roof above the eighth level (west side and southeast corner), and the roof above the

fifth level (west side). The lower tier roofs will include all the smaller roofs projecting from the

building. Refer to Drawing A2 for the roof plan.

The main roofs appear are roughly 14 years old. A good quality 2-ply SBS roof membrane that

has been properly maintained should provide 20 years of effective service. The roofs are

generally in good condition for their age. Refer to Photo 6. The roofs cover the majority of the

building and have few mechanical penetrations compared to their size, which provides a simple

roof configuration and drainage plan. No leaks were reported from the main roofs during our

investigation.

Photo 6 – Main roof above ninth level. Photo 7 – Roof penetration detail on upper

mechanical roof required some maintenance.

The main roofs should receive regular maintenance to ensure they reach their expected service

life. It was noted that some SBS cap sheet is beginning to delaminate at the seams of some

penetrations, which should be addressed as a maintenance item. Refer to Photo 7. Additionally,

a patio furniture set was observed set up on the roof above the eighth level, west side. Refer to

Photo 8. The roof membrane is not designed to accommodate such point loads and foot traffic

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