Fire Resistance Design Primer for Mass Timber Construction

(AWC presentation DES602-2)

Paul Coats, PE, CBOSoutheast Region ManagerAmerican Wood Council

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Participants may download the presentation here: http://www.awc.org/education/resources

The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider # 50111237.

Credit(s) earned on completion of this course 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 course 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.

Fire-Resistance Design Primer for Mass Timber Construction

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COURSE DESCRIPTION

This presentation examines how fire resistance ratings in the 2015 International Building Code (IBC) apply to mass timber and heavy timber construction. Topics include how the IBC incorporates fire testing and calculation methods to quantify fire resistance as well as how various materials, including wood, behave when exposed to high temperatures in fires. Discussion will include code compliant calculation methods for fire resistance ratings of wood frame assemblies and for wood members exposed to fire per the 2015 National Design Specification® (NDS®) for Wood ConstructionChapter 16. Mass timber fire resistance ratings when fully exposed or provided with some degree of noncombustible protection is addressed based on current and proposed future code provisions. Also included is information on fire testing, practical considerations for navigating 2015 IBC Chapter 7 on fire and smoke protection features, and an introduction to cross laminated timber (CLT).

Fire-Resistance Design Primer for Mass Timber Construction

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LEARNING OBJECTIVES

Upon completion, participants will be better able to:

Visualize how mass timber and heavy timber building elements behave when subjected to fire.

Understand basic methods to achieve fire resistance ratings in the 2015 IBC.

Learn how fire resistance ratings of wood assemblies and mass timber are calculated.

Utilize an introduction to CLT as incorporated in the 2015 IBC along with future code change concepts to form a basis of understanding about taller and larger timber structures.

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Fire-Resistance Design Primer for Mass Timber Construction

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Paul CoatsSoutheast

pcoats@awc.org803-980-7304

Fire-Resistance Design Primer for Mass Timber Construction

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Fire-Resistance Design Primer for Mass Timber Construction

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Fire-Resistance Design Primer for Mass Timber Construction

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Fire-Resistance Design Primer for Mass Timber Construction

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Fire-Resistance Design Primer for Mass Timber Construction

E n t e r P r e s e n t a t i o n T i t l e H e r e 1 1

• Outline – fire resistance design for mass timber

1. IBC principles--heavy timber and mass timber

2. Fire resistance rating methods and details

3. Mass timber fire testing

Fire-Resistance Design Primer for Mass Timber Construction

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Image courtesy of Fast + Epp

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Cross-laminated timber

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CANADIAN PROJECTS

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

mass timber ≠ conventional frame

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

mass timber ≠ traditional heavy timber

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TYPE IV HEAVY TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

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TYPE IV HEAVY TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

MINIMUM

NOMINAL SOLID

SAWN SIZE

MINIMUM

GLUED-

LAMINATED NET

SIZE

MINIMUM

STRUCTURAL

COMPOSITE

LUMBER NET SIZESUPPORTING: HEAVY TIMBER CONSTRUCTION ELEMENT Width,

inch

Depth,

inch

Width,

inch

Depth,

inch

Width,

inch

Depth,

inch

Floor

loads

only;

combined

floor and

roof loads

Column;

Framed sawn or

glued-laminated timber arches, which

spring from the floor line;

Framed timber trusses

8 8 6 ¾ 8 ¼ 7 7 ½

Wood beams and girders 6 10 5 10 ½ 5 ¼ 9 ½Roof

loads

only

Lower half of: Wood-frame or glued-

laminated arches, which spring from the

floor line or from grade;

6 8 5 8 ¼ 5 ¼ 7 ½

Column;

Upper half of: Wood-frame or glued-

laminated arches, which spring from the

floor line or from grade;

6 6 5 6 5 ¼ 5 ½

Framed or glued-laminated arches that

spring from the top of walls or wall

abutments; Framed timber trusses and

other roof framing

4 a 6 5 6 7/8 3 ½ 5 ½

Source: 2018 IBC Table 2304.11

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TYPE IV HEAVY TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Exterior walls: Noncombustible materials, FRTW, or protected CLT

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TYPE IV HEAVY TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Heavy timber fire resistance = minimum prescriptive dimensions

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Heavy timber fire resistance = minimum prescriptive dimensions

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Heavy timber fire resistance = minimum prescriptive dimensions

Mass timber fire resistance = minimum dimensions for a

calculated fire resistance; or

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Heavy timber fire resistance = minimum prescriptive dimensions

Mass timber fire resistance = minimum dimensions for a

calculated fire resistance; or

noncombustible protection for the wood; or

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Heavy timber fire resistance = minimum prescriptive dimensions

Mass timber fire resistance = minimum dimensions for a

calculated fire resistance; or

noncombustible protection for the wood; or

BOTH

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Waugh Thistleton Architects(Stradthaus – Murry Grove)

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IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

Noncombustible(703.5)

≠Fire resistant

(703.2 and 703.3)

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Noncombustible =

Section 703.5: ASTM E136 tested(elementary materials)

plus 0.125” thick material with flamespread≤ 50 per ASTM E84 or UL 723

(composite materials)

IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

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Fire resistant =

Section 703.2: ASTM E119or UL 263 tested; or

Section 703.3: Other methods for establishing fire resistance (based on the fire

exposure and acceptance criteria of ASTM E119 or UL 263)

IBC PRINCIPLES FOR HEAVY TIMBER AND MASS TIMBER

Fire-Resistance Design Primer for Mass Timber Construction

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FIRE RESISTANCE RATING METHODS

Methods for establishing fire resistance (703):

1. Tested fire assembly (ASTM E119 or UL 263)

2. Fire-resistance designs documented in approved sources

3. Prescriptive assemblies using fire-resistance rated designs in Section 721

4. Calculation of fire-resistance per Section 722

5. Engineering analysis based on a comparison of building element, component or assembly designs that have been tested

6. Alternative protection methods per Section 104.11

7. Fire-resistance designs certified by an approved agency

Fire-Resistance Design Primer for Mass Timber Construction

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FIRE RESISTANCE RATING METHODS

Methods for establishing fire resistance (703):

1. Tested fire assembly (ASTM E119 or UL 263)

2. Fire-resistance designs documented in approved sources

3. Prescriptive assemblies using fire-resistance rated designs in Section 721

4. Calculation of fire-resistance per Section 722

5. Engineering analysis based on a comparison of building element, component or assembly designs that have been tested

6. Alternative protection methods per Section 104.11

7. Fire-resistance designs certified by an approved agency

Fire-Resistance Design Primer for Mass Timber Construction

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Wood at high temperature:

- low thermal conductivity

- dimensionally stable

- inner portion remains cool

- does not lose strength

CALCULATED FIRE RESISTANCE

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

Chapter 16IBC 722.1 TR-10

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

Glued-lam: tension lam provisions

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

CLT: modified char depth model

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

7.5”4.5”

Determination of effective CLT residual cross-section

• Assume 5-plies @ 1.5” each ply = 7.5”

• Determine thickness for 1-hour rating

• achar = 1.8” (NDS Table 16.2.1B)

• d = 7.5” – 1.8” = 5.7”

• Could conservatively assume 3-ply panel for design

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Heavy timber fire resistance = minimum prescriptive dimensions

Mass timber fire resistance = minimum dimensions for a

calculated fire resistance; or

noncombustible protection for the wood; or

BOTH

CALCULATED FIRE RESISTANCE

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FRR of Element = FRR of Wood + FRR of Added Gypsum

CALCULATED FIRE RESISTANCE

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

2012 IBC Code & Commentary

PERCENTAGE OFMATERIAL STRENGTH

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CALCULATED FIRE RESISTANCE

Fire-Resistance Design Primer for Mass Timber Construction

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Source: US CLT Handbook

CALCULATED FIRE RESISTANCE - CONNECTIONS

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Source: US CLT Handbook

46

CALCULATED FIRE RESISTANCE - CONNECTIONS

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AB C

CALCULATED FIRE RESISTANCE - CONNECTIONS

Source: US CLT Handbook

47

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Source: US CLT Handbook

48

CALCULATED FIRE RESISTANCE - CONNECTIONS

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CALCULATED FIRE RESISTANCE - CONNECTIONS

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

CLT Test Report WP-1950

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

Residential Fire Load Demonstration - 2015

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

Residential Fire Load Demonstration - 2015

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

Residential Fire Load Demonstration - 2015

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

Residential Fire Load Demonstration - 2015

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

Residential Fire Load Demonstration - 2015

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

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Type IV:

-minimum heavy timber dimensions;

-no concealed spaces

?

Type IV-C:

-minimum heavy timber dimensions

-MINIMUM fire resistance ratings

-protected concealed spaces

Type IV-B:

-minimum heavy timber dimensions

-INCREASED fire resistance ratings

-protected concealed spaces

-PROTECTION required (gypsum covering, multiple layers, most surfaces)

12 STORIES ?

Type IV-A:

-minimum heavy timber dimensions

-MAXIMUM fire resistance ratings

-protected concealed spaces

-COMPLETE PROTECTION required (gypsum covering, multiple layers, for all surfaces)

20 STORIES ?

MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

ATF Fire Research Laboratory - 2017

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

ATF Fire Research Laboratory - 2017

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

ATF Fire Research Laboratory - 2017

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

ATF Fire Research Laboratory - 2017

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

ATF Fire Research Laboratory - 2017

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MASS TIMBER FIRE TESTING

Fire-Resistance Design Primer for Mass Timber Construction

ATF Fire Research Laboratory - 2017

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This concludes the American Institute of Architects Continuing Education Systems Course

My contact info: pcoats@awc.org | 803-984-7304