modern building codes: keeping pace with the wood revolution

Modern Building Codes: Keeping Pace with the Wood Revolution

Wood construction and the 2012 International Building Code

Earn 1 AIA/CES HSW continuing education learning unit (LU) CEU Publish Date: May 2015

Image: Togawa Smith Martin, Inc.

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Best Practices

reThink Wood sponsors this Continuing Education Unit provided by McGraw-Hill Publishers. This course is registered with AIA CES for continuing professional education.

As such, it does not contain content that may be deeded or construed to be an approval or endorsement by the AIA of any materials of constructions or any manner of handling, using, distributing, or dealing in any material or product.

Credit earned on completion of this course will be reported to AIA CES for AIA members. Certificates of completion are available for self-reporting and record-keeping needs.

Questions related to the information presented should be directed to reThink Wood upon completing this program. Please contact info@reThinkWood.com.

AIA Provider Number: K029 AIA/CES Course number: K1505JAIA Credit: 1 AIA/CES HSW learning unit (LU)

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Copyright Materials

This presentation is protected by U.S. and international copyright laws. Reproduction, distribution, display and use of the presentation without written permission of reThink Wood is prohibited.

© 2015, reThink Wood, reThinkWood.com

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Learning Objectives

1. Discuss provisions in the International Building Code (IBC) intended to ensure that wood buildings provide the same level of fire performance as other building types.

2. Evaluate techniques that allow designers to safely increase the allowable heights and areas of building projects beyond the base limits stated in the IBC.

3. Identify the advantages of wood-frame structures in seismic and high-wind events.

4. Explain how advances in wood products and building systems are influencing the evolution of building codes.

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Table of Contents

Section 1

Wood Construction and the 2012 IBC

Section 2

Fire Protection

Section 3

Seismic Performance

Section 4

Wind Resistance

Section 5

Sound Transmission and Acoustics

Section 6

The Evolution of Wood Construction

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Table of Contents (continued)

Section 7Green Building Codes, Standards & Rating Systems

Section 8

Wood: The Sensible Revolution

Section 9

Endnotes

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WOOD CONSTRUCTION AND THE 2012 IBCSECTION 1

8Photo: Mark Herboth Photography

• Uniform code adopted by most jurisdictions

• Recognizes fire protection techniques for wood construction

• Consolidates max allowable areas and heights

• Allows use of wood in a wide range of building types

IBC Offers Opportunities for Wood

The pioneering nature of building design encourages architects and engineers to push beyond the conventional.

Photo: Mark Herboth Photography

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KEY PROJECTDesigning with Alternate Materials

Promega “The Crossroads”Madison, WisconsinArchitect: Uihlein/Wilson Architects, Inc. / EwingColeCompleted: 2013

Photo : EwingCole

IBC Section 104.11 states: “An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of the code.”

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American National Standards for Wood Design

• 2015 National Design Specification® (NDS®) for Wood Construction

• 2015 Special Design Provisions for Wind and Seismic (SDPWS)

• 2015 Wood Frame Construction Manual (WFCM) for One- and Two-Family Dwellings

• 2015 Permanent Wood Foundation (PWF) Design Specification

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2015 National Design Specification® (NDS®) for Wood Construction

• New chapter for cross laminated timber (CLT) that covers:• Member design• Connections• Fire design

• Structural composite lumber (SCL)• Now permitted for fire requirements

• Updated design properties for visually-graded southern pine dimension lumber

Click image to view

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2015 Special Design Provisions for Wind and Seismic (SDPWS)

• New provisions for seismic and wind design of cantilevered wood-frame diaphragms

• Revisions to protocol for determining equivalent deformation-based shear distributions:• Allows more efficient seismic

design of shear walls

Click image to view

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• New tabulated spans for lumber framing members

• Tables provide prescriptive wood-frame solutions for rafters and ceiling joists• Meet new deflection limits for

ceilings using gypsum wallboard or brittle finishes

2015 Wood Frame Construction Manual (WFCM) for One- and

Two-Family Dwellings)

Click image to view

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2015 Permanent Wood Foundation (PWF) Design Specification

• Load-bearing wood-frame wall system

• Used for above- and below-grade use

• Foundation for light-frame construction

Click image to view

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FIRE PROTECTIONSECTION 2

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Wood’s Code-Compliant Fire-Resistive Performance

IBC specifies a basic allowable area based on:• Single story• Construction type • Occupancy

IBC then increases the allowable area based on features of the building, such as:

• Addition of an automatic sprinkler system• Side yard open space• Fire walls• Augmented exiting • Additional stories• Use of FRT wood in exterior walls

Wood-frame construction has an excellent history of code-compliant fire-resistive performance.

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Techniques to Increase Allowable Building Size

• Use fire walls to create separate buildings; each is measured separately and subject to its own height and area limits for area

• Add automatic sprinkler system

• Use IBC’s open frontage provision, which allows an increase in building area if the building fronts on a public way or open space

• Increase to a higher construction type

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Minimizing Fire Risk and Impacts

StellaMarina del Rey, CaliforniaArchitect: DesignARCCompleted: 2013

Photo: Lawrence Anderson, www.lawrenceanderson.net

Regardless of material, building components such as walls, floors and roofs are designed and rigorously tested to ensure they provide the necessary structural performance to allow occupants in a building to escape should fire occur, and for emergency responders to perform their duties.

19Photo: Davis & Church LLC

Passive:• Limit height and area of the

building• Prescribe use of fire-rated

building elements• Provide egress

Active:• Automatic fire detection system• Automatic sprinkler system• Alarm or other detection system

Codes are relying increasingly on active systems, since—with proper maintenance and alarm supervision—they have a high degree of reliability.

Passive and Active Building Fire Safety Measures

20Photo: Davis & Church LLC

Fire-resistive assemblies:• Vertical (wall)• Horizontal (floors, roofs)• Structural frame members

(columns, beams)

Most assemblies are required to have a 1- or 2-hour fire-resistive rating, as measured by ASTM Test Method E-119.

Fire resistance of wood assemblies may be calculated using the provisions of Section 722.6 of the IBC.

Rated Assemblies

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Construction Types

• Influence Allowable Heights and Areas• Example: Type III allows greater heights and areas than

Type V

• Permit FRT wood in different locations• Type III and IV: FRT allowed in exterior walls, interior

walls and partitions

• Type I and II: FRT allowed in non-bearing partitions, non-bearing exterior walls and portions of roof

• Type I: allows heavy timber roofs without FRT

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KEY PROJECTDesigning for Fire Protection

Cityville CityplaceDallas, TexasArchitect: JHP Architecture/Urban DesignCompleted: 2013

Photo: JHP Architecture

23Photo: Davis & Church LLC

Member types:• Sawn stress-grade lumber• Tongue and groove decking• CLT• Glulam

Achieves fire resistance through:• Use of wood members with specified minimum thickness and

composition (char)• Meeting fire resistance requirements in exterior and interior

walls• Avoids concealed spaces• Uses approved fasteners, details and adhesives

Type IV Construction utilizes heavy timber elements as the structural members.

Heavy Timber Construction

24Photo: Davis & Church LLC

• Building is vulnerable until fire doors, smoke alarms and sprinklers are in place

• IBC Chapter 33 outlines safety precautions:• Fire extinguishers• Standpipes• Egress

IBC Chapter 33 details provisions for fire extinguishers, standpipes and means of egress during construction.

Fire Safety During Construction

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SEISMIC PERFORMANCESECTION 3

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Wood Meets DemandingEarthquake Design Requirements

• Wood is a lighter weight building material; wood buildings resist less earthquake-induced force

• Numerous nail connections provide more load paths, less chance of collapse and better ductility

• Properly-constructed building elements (frames, shear walls, diaphragms, etc.) reduce weak links between structural members

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KEY PROJECTDesigning for Seismic Performance

South ParkLos Angeles, CaliforniaArchitect: Togawa Smith Martin, Inc.Completed: 2016 (planned)

Rendering: Togawa Smith Martin, Inc..

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WIND RESISTANCESECTION 4

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System Integrity Key to Wind Resistance

When structural wood panels are properly attached and used to form diaphragms and shear walls, they also form some of the most solid and stable roof, floor and wall systems available.

Photo: Arch Wood Protection

All components—including framing, structural panel sheathing and inter-element fastening details—must be designed and installed correctly for diaphragms and shear walls to be effective.

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Building System Failures Under Wind Forces

Most local building codes require a minimum of 33 fasteners for a standard 4×8 panel installed over roof supports at 24 inches on center.

• Loss of roofing materials and sheathing

• Improper connection detailing between structural systems

• Inadequate sheathing fastening

• Interrupted load path causes change in loading dynamics; diaphragm ceases to function

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SOUND TRANSMISSION AND ACOUSTICSSECTION 5

32Photo: Davis & Church LLC

IBC provides minimum requirementsfor sound protection between floors:

• Sound Transmission Class (STC) rating• Impact Insulation Class (IIC) rating

Wood provides natural acoustic performance.

Can further reduce sound transmission using:• Gypsum board attached using resilient metal channels• Glass-fiber or rock-fiber insulation

Wood-frame construction is particularly efficient in residential buildings where sound insulation is required.

Acoustical Considerations

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KEY PROJECTAcoustic Performance

University House Arena DistrictEugene, OregonArchitect: Mahlum ArchitectsCompleted: 2013

Photo: Lincoln Barbour

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Wood Absorbs and Disperses Sound

Arena Stage at the Mead Center for American Theater

Poplar wood slat wall system with basket weave design absorbed and dispersed sound in “The Cradle,” a small oval-shaped theater.

Photo: Nic Lehoux, courtesy of Bing Thom Architects

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THE EVOLUTION OF WOOD CONSTRUCTIONSECTION 6

36Photo by Matt Todd, courtesy of WoodWorks

• Typically Type III or V Construction• V = allows use of untreated wood throughout• III = requires exterior walls to be non-combustible

construction/FRT wood

• Four stories common, economical

• IBC permits five stories (six for office occupancy)

• Podium structures common

Mid-rise/Multi-family

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KEY PROJECTBeyond Five Stories with the IBC

1201 Mercer / RivetSeattle, WashingtonArchitect: Ankrom Moisan ArchitectsCompleted: 2014

Photo: Casey Braunger, CBPhoto

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Schools

Benefits of wood construction

• Cost effective• Speed of construction• Design versatility• Meets green building goals• Reduces stress, creates

positive learning environment

The IBC has well-established parameters for wood-frame schools, which is good news for school districts trying to meet a limited budget.

Photo by Bethel School District

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Originally designed in steel and masonry, El Dorado High School was changed to wood-frame construction—saving $2.7 million.

Motivating Environment

El Dorado High School

• Exposed wood and natural light enhances learning and motivates students

• Warm spaces

• One of the first schools in Arkansas to make extensive use of wood

• Successful implementation prompted change in school board policy to allow use of wood in school construction

Photo: Dennis Ivy, courtesy WoodWorks

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Mass Timber

Cross laminated timber / CLT

• 3, 5 or 7 layers of solid dimension lumber glued to create full-depth solid wood panels

• Cross lamination provides exceptional strength, stability and rigidity• Low-carbon alternative to concrete and steel• Fast installation• Reduced on-site waste• Light weight/reduced foundation requirements• Thermal performance• Design versatility• Chars slowly, providing fire-resistive protection Photo courtesy of naturallywood.com

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CLT Code Approvals

2015 IBC allows CLT use with Type IV Construction; ANSI/APA PRG 320-2011 Standard for Performance-Rated Cross-Laminated Timber provides quality assurance. Download a free copy of the CLT Handbook here.

Photo courtesy of Lend Lease

IBC recognizes CLT products manufactured to the ANSI/APA PRG 320-2011 Standard as code-compliant.

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GREEN BUILDING CODES, STANDARDS AND RATING SYSTEMS

SECTION 7

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Environmental Evolution• U.S. Green Building Council

• California Green Building Standards Code (CALGreen)

• ASHRAE 189.1, a code-intended commercial green building standard published by ASHRAE in cooperation with the Illuminating Engineering Society of North America (IES)

• International Green Construction Code (IgCC)

IgCC’s key mandatory requirement is that at least 55 percent of materials (based on mass, volume or cost) be used, recycled, bio-based and/or indigenous in any combination.

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Life Cycle Assessment (LCA)Encourages design professionals to:

• Compare different building designs based on their true environmental impacts over their entire life cycle, from extraction or harvest through manufacturing, transportation, installation, use, maintenance and disposal or recycling

• Make informed choices about the materials they use

Source: Building Green With Wood www.naturallywood.com LCA studies consistently show that wood is

better for the environment than steel or concrete in terms of embodied energy, air and water pollution, and greenhouse gas emissions.

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WOOD: THE SENSIBLE REVOLUTIONSECTION 8

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Building Codes Recognize Wood’s Safety

IBC allows wood use in a wide range of building applications.

Wood provides:• Cost effectiveness• Functionality• Design flexibility• Beauty• Environmental performance

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ENDNOTESSECTION 9

48Photo by David Lena; courtesy of HMC Architects

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