Timber over non-combustible Podium Structures

High Performance and Low Cost

Scott Nyseth, PE

“The Wood Products Council” is a Registered Provider with The American Institute of Architects Continuing Education Systems The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

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distribution, display and use of the presentation without written permission of the speaker is

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© The Wood Products Council 2011

Learning Objectives At the end of this program, participants will be able to:

1. To examine relevant IBC code provisions applicable to mid-rise podium structures. 2. To discuss the structural design challenges such as lateral load transfer, high vertical

loading and effects of shrinkage. 3. To explore the fire and life safety code requirements and the use of fire retardant

treated lumber. 4. To identify opportunities for implementation of new products and techniques.

Five story Timber over Podium Structure Fire and Life Safety

Parking Level Meets the definition of a basement , does not contribute to area or height limitation.

Ground Floor Type IA Construction – Occupancy S2, B, E, A2.

Allowable Height - Unlimited Allowable Stories - One Story Allowable Area - Unlimited

Podium (2-6) Type IIIB Construction – Occupancy R2 Allowable Height - 55’ Allowable Stories - Four Stories Allowable Area - 16,000 sf

Modifications to height

Use automatic sprinkler system to add one story and 20’ to allowable height.

Modified height Allowance (fire and life safety) = 75’

Structural height allowance for plywood shear walls = 65’

Both limitations need to be checked

Type IIIB details IBC 602.3 “Type III construction is that type of construction in which the

exterior walls are of non combustible materials and the interior building elements are of any material permitted by this code. Fire Retardant Treated Wood framing complying with section 2303.2 shall be permitted within exterior wall assemblies of a 2hr rating or less.”

IBC Tables 601&602 • Exterior Bearing Walls – 2hr • Exterior Non-Bearing Walls – 1hr (0hr if building separation>30’) • All other walls, floors, and roofs – 0hr

• The project I visited today was at Bethany Village in NW Portland. What I learned: • · Fire Retardant treated material looked surprisingly good, even the header stock (so I may

stand corrected on previous statement). • · Due to 25% reduction in structural capacity for FR treated lumber, more studs or heavier

columns needed in exterior walls for bearing. (Corrosion, Engineered Lumber – Scott) • · This was Washington County job, but they only required them to take the 2 hr ext wall rating

to top of the plate line at the upper floor. The ends of the trusses were not FR treated and they were not installing 2 layers of gyp on the interior side of the truss.

• · The end studs on all walls intersecting the 2 hour ext walls were held back 1 ½” so that 2 layers of drywall could pass through, both top plates were tight to the ext wall.

• · Any beams that intersected the exterior walls were required to have solid blocking inside the wall.

• · 1st layer of Exterior Dens was tacked on. 2nd layer was nailed with 2 ½” gun nails thereby eliminating nailing off each layer individually. Approved by structural.

• · I am attaching the 2 hour details used on this project but I think a 3x8 top plate ripped to 7” and cantilevered inside the wall to carry a top flange hanger would work better than this.

• · Floor plywood intersecting the 2 hour walls was not required to be FR treated material. • · Area separation wall that I observed appeared to be at least 3 hour and was framed with

shaft wall both sides with a seismic joint in the middle. • · All FR treated lumber is marked with a blue paint stripe. When the framers are nailing up the

exterior walls they need to make sure the paint is visible from the interior side (for the inspector) • Larry

Congested Exterior Walls = poor building envelope Consider using corridor walls to resist lateral forces

Consider using 3x or 4x studs at 24”oc at shear walls. Use more shear walls to minimize double sided. Avoid 4” walls unless absolutely necessary.

Continuous Threaded

Rod Holdown

Consider 1-1/8” T&G plywood flooring for blocked rigid diaphragm analysis.

Window Washing Davit Detail

No Cantilevered Wood Balconies! Knife plates below deck for maintenance

Brick Veneer supported off Timber • Already Fire Retardant Treated • Beware of solid sawn rim board • Joint often for seismic/wind • Joint for floor to floor deflection • 1” gypcrete, eco-roof, and brick

veneer creates heavy building (more plywood shear walls)

• Better than 30’ of brick off of podium for shrinkage compatibility

Be prepared for panelization

Prefabrication/Modularization using integrated modeling software • Can interface directly with computer controlled fabrication • Direct output of materials/order lists • High quality and low moisture content • High speed of construction. Follow on subs will control critical

path.

Image from Cost Effective Home Building: A Design and Construction Handbook by the NAHB

Advanced Framing Alignment

Approximate Lumber Savings –

Equivalent to about 2.9 acres of 30 year old Douglas Fir

Savings

Wall Studs 30,000 BF

Top Plates 23,375 BF

Trimmers 10,800 BF

NL Bearing Headers 5250 BF

Corners/ Intersections

10,000 BF

Totals 80,000 bf

Design for deflection!

• Advanced Framing = 33% less shrinkage • Modified Balloon Framing = no solid sawn rim to shrink • On the Structural Plans, put a minimum of 3/16” to a ¼”

per floor shrinkage notation. Beware of shrinkage calculations that are significantly less that this. MEP needs to account for deflection.

• Be cautious of 30’ brick veneer supported on podium. • Use shrinkage compensating hold down system

Photo – back sloped flashing

Calculation of shrinkage is only an estimate and varies greatly

How about CLT? • Easiest initial commercial market is roofs

and floors until AWC incorporates into code (total system is still ok under AM)

• ~6” floor/roof panels will work in most multi-story apartment and affordable housing projects

• Eliminates small headers (two way action) • Low floor to floor • High floor performance • Fast installation

Typical CLT dimensions: Length: up to 60‘ Width: up to 15‘ 6“ Thickness: from 2“ – 12“

™

www.fpinnovations.ca

CLT – Acoustic Performance

Sylvain Gagnon, Eng. February 8, 2011 Vancouver

Revolutionary CLT Floor

Conventional wood floor

Cross-section of a CLT floor

© 2011 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011 3

Bare CLT Floor

(IIC) dB

© 2009 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011

Floor Composition

Airborne (STC) dB

Impact

5-layer CLT panel 146 mm

39

24

(IIC) dB

© 2009 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011

Floor Composition

Airborne (STC) dB

Impact

1 Particleboard panel 22 mm 2 Sound insulation material (≈ 40 mm) 3 Lumber sleepers 4 REGUPOL underlayment 5 5-layer CLT panel 146 mm

52

45

(IIC) dB

© 2009 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011

Floor Composition

Airborne (STC) dB

Impact

1 Gypsum fibre board FERMACELL 25 mm 2 Sub-floor ISOVER EP3 20 mm 3 5-layer CLT panel 135 mm

≤ 53

≤ 49

(IIC) dB

© 2009 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011

Floor Composition

Airborne (STC) dB

Impact

1 5-layer CLT panel 146 mm 2 Resilient supports and rails (100 mm) 3 Sound insulation material (100 mm) 4 Gypsum board 13 mm 5 Gypsum board 13 mm

64

59

© 2009 FPInnovations. All rights reserved. 10/02/2011 Copying and redistribution prohibited.

(IIC) dB

Floor Composition Airborne (STC) dB

Impact

1 Particleboard panel 22 mm 2 Particleboard panel 22 mm 3 Sound insulation material (≈ 40 mm) 4 Lumber sleepers 5 REGUPOL underlayment 6 5-layer CLT panel 146 mm 7 Resilient supports and rails (100 mm) 8 Sound insulation material (100 mm) 9 Gypsum board 13 mm 10 Gypsum board 13 mm

67

≥ 62

Bare CLT Wall

(STC) dB

© 2009 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011

Wall Composition

Airborne

1 3-layer CLT panel (95 mm ~ 115 mm)

≤ 32~34

(STC) dB

© 2009 FPInnovations. All rights reserved. Copying and redistribution prohibited.

10/02/2011

Wall Composition Airborne

1 Gypsum board 15 mm 2 3-layer CLT panel (95 mm ~ 115 mm) 3 Gypsum board 15 mm

≤ 36~38

© 2009 FPInnovations. All rights reserved. 10/02/2011 Copying and redistribution prohibited.

(STC) dB

Wall Composition Airborne

1 Gypsum board 15 mm 2 Mineral wool (~ 60 mm) 3 Lumber studs (38 mm x 63 mm) 4 3-layer CLT panel (95 mm ~ 115 mm) 5 Mineral wool (~ 60 mm) 6 Lumber studs (38 mm x 63 mm) 7 Gypsum board 15 mm

≤ 58

Five stories Timber frame over podium: • Maximizes density in urban settings • Functional, durable, economical, and carbon friendly • Modularization, panelization, CLT and advanced framing, are

versatile tools for a sustainable natural resource.

This concludes The American Institute of Architects Continuing

Education Systems Course

QQuestions?

Scott Nyseth, PE Stonewood Design LLC scott.nyseth@stonewood-design.co

Wood Products Council 866.966.3448 info@woodworks.org