MEETING FIRE CODE WITH ORIENTED STRAND BOARD

DAVE THOMAS, CSI-CDTLP BUILDING PRODUCTS

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© 2016 Louisiana-Pacific Corporation. All rights reserved.

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COURSE DESCRIPTION

Building code requirements related to fire and life safety can

be challenging for designers, particularly when it comes to proving fire resistance and

maintaining structural performance. As such,

understanding the applicability of available products can be helpful for designers. This presentation will provide an overview of fire-

rated cementitious-coated oriented strand board (FRCC

OSB) sheathing for wall and roof sheathing applications. Topics will

include its structural and fire performance, available wall

assemblies, and contribution to enhancing the sustainable built

environment.

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LEARNING OBJECTIVES

1. Describe the physical attributes, fire performance and code-compliance of fire-rated cementitious-coated oriented strand board (FRCC OSB) sheathing.

2. Explain how FRCC OSB sheathing can be used to reduce labor costs and construction time.

3. Describe fire-rated wall assemblies relevant to FRCC OSB sheathing in the context of wood-frame building design and building code requirements.

4. Describe common construction applications for FRCC OSB sheathing in Types II, III and V construction.

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WHAT IS ORIENTED STRAND BOARD (OSB) SHEATHING?

• Developed more than 30 years ago

• High-performance structural panels

• Strong, uniform, dense and workable

• Used for sub-floor, wall and roof applications

• Exposure 1 classification; can withstand exposure to moisture during normal construction delays

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WHAT IS FRCC OSB SHEATHING?

Panels consist of a proprietary, non-combustible coating, fiberglass-reinforced, cementitious coating that is bonded to one or both sides of a sheet of OSB

Coating is a layer of non-combustible magnesium oxide cement reinforced with fiberglass

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INSTALLATION CONSIDERATIONS

• Installs with standard fasteners

• Gapping between panels is the same as that used for OSB and plywood

• Joints do not require fire caulk

• Handling and safety requirementsare the same as those for other wood structural panels

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FRCC OSB: PANEL DIMENSIONS & PANEL WEIGHT

7/16”, 15/32”, 19/32”, and 23/32”OSB performance categories in 4' x 8', 9’, and 10' lengths

Struct-1 grade is available

Coating adds approximately 0.6 lbsper square foot to a board:

• panel treated on one side = 66lbs• panel treated on both sides = 85lbs• 4' x 8' x 5/8" gypsum board (80 lbs) plus a 4' x 8', 15/32 wood sheathing panel

= over 120lbs

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CODE COMPLIANCE

• Code-compliant applications of FRCC OSB are described in ESR-1365

• Requirements for fire-resistant construction are specified in IBC, IRC, and state and local building and safety codes

• ICC-ES considers the performance requirements of products in construction applications and establishes test criteria

• ICC-ES publishes acceptance criteria and ESRs

• Test procedures are regulated by ASTM, NFPA, UL etc.

• ESR reports specify the code-compliant applications. Code officials have the authority to permit FRCC OSB in various applications

• www.icc-es.org/evaluation_reports/

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STRUCTURAL PERFORMANCE

Fiberglass reinforcement increases strength, bending stiffness, shear capacity, and impact resistance of the panels

Coating causes no initial or long-term loss of structural performance, nor does it increase water absorption

Structural design values are the same as those for wood structural panels in the same thickness category

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STRUCTURAL PERFORMANCE

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WOOD-BASED PANELS

Sheathing Material

Minimum Nominal

Panel Thickness

(in.)

Minimum Fastener

Penetration inFraming

Member or Blocking

(in.)Fastener

Type & Size

ASEISMIC

BWIND

Panel Edge Fastener Spacing (in.) Panel Edge Fastener Spacing (in.)

6 4 3 2 6 4 3 2

Vs(plf)

Ga(kips/in.)

Vs(plf)

Ga(kips/in.)

Vs(plf)

Ga(kips/in.)

Vs(plf)

Ga(kips/in.)

vw vw vw vw

Wood Structural Panels—Structural I4,5

Nail(common or galvanized

box) OSB PLY OSB PLY OSB PLY OSB PLY

5/16 1–1/4 6d 400 13 10 600 18 13 780 23 16 1020 35 22 560 840 1090 1430

3/82

1–3/8 8d

460 19 14 720 24 17 920 30 20 1220 43 24 645 1010 1290 1710

7/162 510 16 13 790 21 16 1010 27 19 1340 40 24 715 1105 1415 1875

15/32 580 14 11 860 18 14 1100 24 17 1460 37 23 785 1205 1540 2045

15/32 1–1/2 10d 680 22 16 1020 29 20 1330 36 22 1740 51 28 950 1430 1860 2435

Wood Structural Panels—Sheathing I4,5

5/161–1/4 6d

360 13 9.5 540 18 12 700 24 14 900 37 18 505 755 980 1260

3/8 400 11 8.5 600 15 11 780 20 13 1020 32 17 560 840 1090 1430

3/82

1–3/8 8d

440 17 12 640 25 15 820 31 17 1060 45 20 615 895 1150 1485

7/162 480 15 11 700 22 14 900 28 17 1170 42 21 670 980 1260 1640

15/322 520 13 10 760 19 13 980 25 15 1280 39 20 730 1065 1370 1790

15/321–1/2 10d

620 22 14 920 30 17 1200 37 19 1540 52 23 870 1290 1680 2155

19/32 680 19 13 1020 26 16 1330 33 18 1740 48 22 950 1430 1860 2435

FIRE RATINGS - REFERENCED & REQUIRED BY IBC

Fire Resistance Ability of a material or an assembly of materials to resist burn-through and, in load-bearing assemblies, to support a given load for a specified time period under standardized fire conditions

Flame Spread A measure of the speed of travel of flame on the surface of aproduct or material under a standardset of conditions

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FLAME SPREAD TESTING

“Tunnel Test”

ASTM E84, or UL 723

Flame Spread Ratings (Standard 10-Minute Test)o Class A or 1o Class B or 2o Class C or 3

§ Test extended to 30 minutes for certification of FRT wood

§ Burn-through resistance is not measured

§ Smoke development is measured

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CRITERIA FOR FRT WOOD (IBC SECTION 2303.2)

• Flame spread index of 25 or less in the 10-minute test

• Flame progression of less than 10.5 feet when the test is extended for 30 minutes

• Does not exceed the criteria for smoke development

• FRCC panels carry a stamp indicating that it satisfies the performance requirements of Section 2303.2 of the IBC. Code officials have the authority to permit FRCC OSB in various applications

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BURN-THROUGH RESISTANCE

ASTM E119 (Standard Method for Fire Tests of Building Construction and Materials) is used to determine fire resistance ratings for wall and floor/ceiling assemblies.

Wall Test Furnace Wall Assembly Test

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ASTM E119 TIME-TEMPERATURE CURVE

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ASTM E119 WALL ASSEMBLY TEST

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CONSTRUCTION TYPES (PER IBC TABLE 504.3 & 504.4)

*FRCC OSB must be treated on both faces of panel

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Type of Construction FRTW or FRCC OSB

Type I (fire-resistive) Mainly non-structural*

Type II (non-combustible) Roof deck, non-structural*

Type III (ordinary) Throughout*

Type IV (heavy timber)

Type V (wood frame) Throughout

VERTICAL CONTINUITY OF FIRE WALLS

A common application for FRCC OSB is in roof decking on either side of a fire wall in Type V construction

IBC 706.6 requires a 30” parapet for walls rated up to 2 hours

As an exception, fire walls canterminate at roof deck if code-compliant FR sheathingis installed for 4 feet alongthe wall

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MULTI-FAMILY ROOF DECK CONSTRUCTION

Gypsum underlayment, FRT or FRCC OSB panels

4'4'

Fire wall with the adjacent trusses and Class A-rated roof deck

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VERTICAL CONTINUITY OF FIRE WALLS IN ROOF DECKS

FRCC OSB, treated on one side, is code-compliant and meets vertical continuity requirements with a single panel solution, with full load and span ratings and an Exposure 1 Classification

Condominium project, Southern California

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SUMMARY: FRCC OSB IN ROOF DECKS

Why consider FRCC OSB in roof decks?

• Designed to withstand exposure to moisture during normal construction periods

• Lower labor and material costs as compared to gypsum option

• Panels lie flat, with no delamination

• 7/16 thickness category available

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EXTERIOR RATED WALLS IN THE IBC

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WHAT IS THE FIRE SEPARATION DISTANCE (FSD)?

FSD is the distance measured from the building face to one of the following:

• The closest interior lot line• The centerline of a street, an alley or public way• An imaginary line between two buildings on the property

IBC Section 705.5 – For most use and occupancy categories, walls can be

rated from inside only when FSD is 10 feet or more.

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EXTERIOR WALLS OF TYPE III CONSTRUCTION

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EXTERIOR WALLS TYPE III: 2-HOUR

Traditional approach: 2 layers of Type X GWB on the interior, wood framing, a shear panel layer if needed, then 1 or 2 layers of exterior GWB and a non-combustible exterior

wall covering

TYPE IV

A B Ae

B Ae

B HT Ae

B

Bearing walls

Exteriorg

3 2 1 0 2 2 2 1 0

Interior 3b 2b 1 0 1 0 1/HT 1 0

Nonbearing walls and

partitions Exterior

Nonbearing walls and

partitions Interiorf

0 0 0 0 0 0

See

Section

602.4.6 0 0

Floor construction

Including supporting beams 2 2 1 0 1 0 HT 1 0

Roof construction

Including supporting beams 1 1/2c

1c, d

1c, d

0c, d

1c, d

0c, d

HT 1c, d

0

For SI: 1 foot = 304.8 mm.

g. Not less than the fire-resistance rating based on fire separation distance (see Table 602).

BUILDING ELEMENT

FIRE-RESISTANCE RATING REQUIREMENTS FOR BUILDING ELEMENTS (hours)TABLE 601

a. The structural frame shall be considered to be the columns and the girders, beams, trusses and spandrels having direct connections to the columns

and bracing members designed to carry gravity loads. The members of floor or roof panels which have no connection to the columns shall be

considered secondary members and not a part of the structural frame.

b. Roof supports: Fire-resistance ratings of structural frame and bearing walls are permitted to be reduced by 1 hour where supporting a roof only.

c. Except in Group F-1, H, M and S-1 occupancies, fire protection of structural members shall not be required, including protection of roof framing and

decking where every part of the roof construction is 20 feet or more above any floor immediately below. Fire-retardant-treated wood members shall

be allowed to be used for such unprotected members.

d. In all occupancies, heavy timber shall be allowed where a 1-hour or less fire-resistance rating is required.

e. An approved automatic sprinkler system in accordance with Section 903.3.1.1 shall be allowed to be substituted for 1-hour fire-resistance-rated

construction, provided such system is not otherwise required by other provisions of the code or used for an allowable area increase in accordance with

Section 506.3 or an allowable height increase in accordance with Section 504.2. The 1-hour substitution for the fire resistance of exterior walls shall

not be permitted.

f. Not less than the fire-resistance rating required by other sections of this code.

TYPE VTYPE IIITYPE IITYPE I

See Table 602

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2-HOUR EXTERIOR WALL ASSEMBLIES WITH FRCC OSB

UL U349 & UL W408

• 2 layers of Type X GWB on interior side • 1 layer of FRCC OSB on exterior side of studs (FRCC OSB

must be treated on both sides)• 2 hours from interior, 0 or 1 hour from exterior

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* The following slides contain several ASTM E119 tested wall assemblies. Other similar assemblies exist and are well documented (e.g. UL V314 and UL U330)

FRCC ASSEMBLY U349

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Exterior

Cladding

2-Sided

FRCC

Fiberglass

Insulation

2” x 4”

Studs

(minimum)

Type X

Gypsum

Exterior

Interior

Application • Exterior load-bearing wall

Fire rating • 2 hours (from inside only)

Construction type(s)

• Type III (5-6 story commercial or

multi-family)

Advantagesover competing assemblies

• Removes one layer of gypsum

• Switches fiberglass in for mineral

wool; contractors find that

mineral wool is more difficult to

install

• Allows for standard OSB design

values, while FRT plywood must

take deductions

FRCC ASSEMBLY W408

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Exterior Cladding

2-Sided FRCC

Mineral Wool

Insulation

Type X Gypsum

Exterior

Interior

Application • Exterior load-bearing wall

Fire rating • 2 hours (2 hours from inside, 1 hour from outside)

Construction type(s)

• Type III (5-6 story commercial or multi-family)

Advantagesover competing assemblies

• Removes two layers of gypsum• Allows for standard OSB design

values, while FRT plywood must take deductions

2” x 4” Studs

(minimum)

UL DESIGN W408 VARIATIONS, SUPPORTED BY ENGINEERING EVALUATIONS

• 2hr/2hr rating can be achieved by adding 1 layer of 5/8” exterior gypsum

• 2hr/1hr rating with fiberglass insulation where standard brick is exterior facing

• 2hr/2hr rating where 7/8”, 3-coat stucco is exterior facing

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FRCC ASSEMBLY W408 EXTENDED(ENGINEER EVALUATION)

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Exterior Cladding

Exterior Type X Gypsum

2-Sided FRCC

Mineral Wool

Insulation

Type X Gypsum

Exterior

Interior

Application • Exterior load-bearing wall

Fire rating • 2 hours (2 hours from inside, 2 hours from outside)

Construction type(s)

• Type III (5-6 story commercial or multi-family)

Advantagesover competing assemblies

• Removes one layer of gypsum• Allows for standard OSB design

values, while FRT plywood must take deductions

2” x 4” Studs

(minimum)

CODE-COMPLIANCE IN TYPE III EXTERIOR WALLS

Code Compliance of FRCC OSB in bearing and non-bearing exterior walls of Type III buildings, in accordance with IBC Section 602.3, is described in the ESR-1365. Code officials have the authority to permit FRCC OSB in various applications

2-hour rated wall assembly with FRCC OSB in Type III construction(Student housing, College Park, MD)

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TYPE III EXTERIOR WALLS

34Park Crest Project, Lynchburg, VA

ADVANTAGES OF USING FRCC OSB IN TYPE III CONSTRUCTION

• Labor savings• Reduced dead load • Reduced wall thickness• Better substrate for fastening of exterior cladding

Austin, TX Issaquah, WA

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EXAMPLE: COMMON 1-HOUR EXTERIOR WALL

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• UL Generic Design U305: Load-bearing assembly with 5/8" Type X GWB on each side

• Rated for 1 hour from both sides

• Structural panel may be added without compromising fire resistance

1-HOUR WALL ASSEMBLY, FRCC OSB

• 5/8" Type X GWB on interior side

• 2” x 6" framing

• 5.5" mineral wool insulation

• FRCC OSB against studs with cementitiousside facing exterior

• Wood, fiber cement, steel, or stucco as exterior wall covering

• 2145 pounds per stud load limitation

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1-Sided LP® FlameBlock®

Mineral Wool Insulation Type X

Gypsum

Exterior Cladding

2˝x 6˝ Studs

(minimum)

1-Sided FRCC OSB

ADVANTAGES: 1-HOUR EXTERIOR WALLS WITH FRCC OSB

Advantages in 1-Hour Exterior Walls• Labor savings• Reduced dead load • Reduced wall thickness• Better substrate for fastening of exterior cladding

1-Hour Wall Along Property Line 1-Hour Walls – Multi-Family Project

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PARTITION WALLS BETWEEN LIVING SPACES

Red Leaf Townhomes, Seattle, WA39

TWO-HOUR EXTERIOR WALL ASSEMBLY FOR MULTI-FAMILY CONSTRUCTION

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BXUV U350 2-Hr Party Wall Assembly

FRCC ASSEMBLY U350 – TYPE A

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Type X Gypsum

1-Sided FRCC

Fiberglass Insulation

2” x 4” Studs

(minimum)Application • Interior load-bearing wall

Fire rating • 2 hours (2 hours from both sides)

Construction type(s)

• Type III (5-6 story commercial or multi-family)

• Type V (1-4 story wood-framed single or multi-family)

Advantagesover competing assemblies

• Removes two layers of gypsum• Removes need for extra

equipment (C channels, H studs, breakaway clips)

• Allows for standard OSB design values, while FRT plywood must take deductions

Fiberglass Insulation

1-Sided FRCC

Type X Gypsum

Interior

Interior

Between units

FRCC ASSEMBLY U350 – TYPE B

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Type X Gypsum

Resilient Channel

Fiberglass Insulation

2” x 4” Studs (minimum)

Interior

Interior

Application • Interior load-bearing wall

Fire rating • 2 hours (2 hours from both sides)

Construction type(s)

• Type III (5-6 story commercial or multi-family)

• Type V (1-4 story wood-framed single or multi-family)

Advantagesover competing assemblies

• Removes two layers of gypsum• Removes need for extra

equipment (C channels, H studs, breakaway clips)

• Allows for standard OSB design values, while FRT plywood must take deductions

1-Sided FRCC

2” x 4” Studs

(minimum)

Fiberglass Insulation

Resilient Channel

Type X Gypsum

Between units

ADDITIONAL APPLICATIONS

• Return ducts and plenums (per ICC Report PMG-1089)

• Commercial roof decks (UL listings available)

• SIPs

FRCC OSB EPDM EPDM

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WILDFIRE ZONES

California Building Code (CBC) requires that building materials and products used in the Wildland Urban Interface (WUI) zones meet certain ignition resistance and fire standards

Recognizes FRCC OSB sheathing as an approved component of certain wall and soffit assemblies meeting the requirements of Chapter 7A of the California Building Code.

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CALIFORNIA 12-7A-1 WALL TEST

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FRCC OSB certifies various Cal-Fire

Listings

WUI ZONES

• CAL-FIRE Under-Eave Listing also approved for closed soffits

• Listed ignition-resistant material for underside of roof in open-eave construction

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Various Cal-Fire listings certified with FRCC OSB

COURSE SUMMARY

• FRCC OSB sheathing consists of a non-combustible, fiberglass-reinforced magnesium oxide coating bonded to PS-2-certified OSB panels

• Designed to resist ignition, inhibit the spread of flames and slow the rate of heat transfer through the panel

• Applications: a component of fire-resistance-rated wall assemblies, roof decking (to satisfy vertical continuity of fire wall requirements), a component of assemblies meeting California WUI fire hazard zone requirements, roof decks in Type II construction, SIP panels, and applications requiring a 15-minute thermal barrier

• Designed to withstand exposure to weather during normal construction periods

• Code-compliance is described in relevant code reports and assembly listings. Code officials have the authority to permit FRCC OSB in various applications

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© LP® Building Products 2012

QUESTIONS AND COMMENTS?

DAVID THOMASPHONE 224.651.6253

DAVID.THOMAS@LPCORP.COM

www.LPCorp.com

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