PERFORMANCE OF CLT ASSEMBLIES IN FIRE

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1 PERFORMANCE OF CLT ASSEMBLIES IN FIRE Noureddine Benichou, Ph.D., National Research Council Canada Christian Dagenais, Eng., M.Sc., FPInnovations May 28, 2015

2 Background Mass timber, such as CLT, are generally known to perform well under fire conditions Slow rate of charring Factors that may influence fire performance are: Wood species Type of adhesive Thickness & number of laminates Fire exposure Joint details Protective membranes 2

3 Outline Fire Resistance of CLT Assemblies Flame Spread in CLT Panels Fire Stops and Service Penetrations CLT Design Methods and Guides Fires in Compartment with CLT Construction Fire Testing in Support of TWBs Conclusions 3

4 Fire Resistance of CLT Assemblies Objective: To determine the fire-resistance of CLT panels through full-scale testing 8 full-scale testing in accordance with CAN/ULC S101 (FPInnovations / NRC Test Program) Charring rate Fire performance of adhesive (PUR) Calculation procedure for standards Additional full-scale tests were also conducted with wood industry partners and CLT manufacturers 4

5 Facilities and Test Observations 5

6 Tested CLT Assemblies and Results 6

7 Modes of Failure of CLT Assemblies Floor failure mode Integrity* (panel-to-panel joint) Wall failure mode Buckling (P- effects) * Integrity can be improved by other means 7

8 Charring Rate in CLT Assemblies 8

9 CLT FR Calculation Methods 2014 Canadian Calculation Method 9

10 CLT FR Calculation Methods Canadian Method vs. US Method 10

11 Summary of Fire Resistance Tests CLT can exhibit significant fire-resistance, comparable to traditional non-combustible systems Charring rate similar to massive timber 0.65 mm/min (one-dimensional) Stepped charring model (not constant throughout) Influenced by the thickness of laminates Failure modes are different from walls to floors Fire integrity can be resolved using flooring/topping More studies on PUR fire performance are needed 11

and ASTM E84) Does not establish performance criteria Does not establish the heat

12 Flame Spread Rating in CLT Panels Dimensionless comparative surface flaming characteristic of a material based on a standardized test method (CAN/ULC S102 and ASTM E84) Does not establish performance criteria Does not establish the heat release rate Does not allow to quantify the actual fire behavior in real fire scenarios 12

13 Flame Spread Rating in CLT Panels Factors influencing flame spread Type of combustible material Presence of fire-retardant chemicals Thermal properties Thickness Surface initial temperature Surface orientation Spread direction Continuity of the surface 13

14 Flame Spread Rating in CLT Panels 14

15 Flame Spread Rating CLT vs. Other Products 15

the expected level of compartmentation Penetrations and

16 Fire Stops and Service Penetrations INTEGRITY and CONTINUITY of fire separations are fundamentals for achieving/providing the expected level of compartmentation Penetrations and junctions are to be firestopped (tested per CAN/ULC S115 or ASTM E814) 16

17 Fire Stops and Service Penetrations Junctions evaluated per CAN/ULC S115 Floor-to-wall (sealant on unexposed side) Floor-to-wall (sealant on exposed side) Wall-to-Floor (sealant on both sides) Floor-to-Floor Stair landings FT-rating of 1 to 2 hours 17

18 Fire Stops and Service Penetrations 6 penetrations tested per CAN/ULC S115 F-rating of 1½ hrs. 18

19 Fire Stops and Service Penetrations 19

20 CLT Design Methods and Guides Methods provide information for CLT design Collected information in tests used to: Validate/refine calculation methods from CLT Handbooks Facilitated Code implementation in North America Already implemented into 2015 NDS, and soon-to-be in CSA O IBC now recognizes CLT as Type IV construction 20

21 Fires in Compartment with CLT Construction - Objectives To develop information to alternative solutions for mid-rise wood construction Large-scale fire experiments were conducted to evaluate the fire performance of: Cross-laminated timber (CLT) system Lightweight wood-frame (LWF) system Cold-formed steel (CFS) system 21

22 Test Setup Rationale Test setup represents a code-compliant CFS system permitted for 6-storey residential buildings Noncombustible construction benchmark Comparison of CFS vs. encapsulated CLT systems CLT structural elements used 3-ply panels for walls and 5-ply panels for floors Test arrangement was 8.5 by 6.5 m (28 x 21.5 ) to represent a one-bedroom apartment footprint No sprinkler system replicating a worst-case scenario 22

23 CLT Apartment Test Structure under Construction 23

24 CLT Apartment Test Setup 24

25 Compartment of Fire Origin 25

26 Compartment of Fire Origin 26

27 Instrumentation in Compartment Smoke alarm in bedroom Thermocouples (trees and single) in rooms and wall/ceiling/floor assemblies Heat flux meters close to ventilation openings Duct Measurements (smoke temperature and concentrations of O 2, CO and CO 2 ) 27

28 Test Results Smoke alarm in the bedroom was activated in 19 s Fast t²-fire growth (more severe than std fire curve) Flashover in bedroom occurred within 3 min (> 600ᵒC) and around 6 min in living room Door between bedroom and living room failed at 5 min Bedroom peak temperatures of ᵒC at 12 min 28

29 Test Results Temperatures decreased after the peak Corridor fire rated door failed at 128 min The test was terminated at 185 min Type X GB was still attached to most parts of exposed boundaries Fire was contained within the room boundaries 29

30 Flashover in Bedroom and Living Room Areas 30

31 Ventilation Conditions through Exterior Openings Apt CLT at 115 min 31

32 Ventilation Conditions through the Exterior Openings for all Tests Apt CFS at 26 min Apt CLT at 115 min Apt LWF1 at 40 min Apt LWF2 at 49 min 32

33 Reaction of Structural Assemblies to Fire - Encapsulation Encapsulation time provided for structural elements For wood structural elements, encapsulation times were determined using criteria as follows: Average temperature rise value over the exposed surface of the protected element limited to 250ᵒC Maximum temperature rise value at any point on that surface does not exceed 270ᵒC Walls: 2 layers of 12.7-mm Type X GB on exp. side Ceiling/Floor: 2 layers of 12.7-mm Type X GB or cement board on exp. side 33

34 Reaction of Structural Assemblies to Fire Wall Assemblies Encapsulation times (at interface board-clt panels): min for exterior walls 66 min for fire separation walls (apartment-corridor) Min. of 65 min for loadbearing fire separation walls 36 min on bedroom side and 43 min on living room side for the loadbearing wall After encapsulation time, interface temperatures reached a ᵒC plateau until end of test Charring occurred on exposed side of CLT panels CLT panels did not contribute to fire growth/spread 34

35 Reaction of Structural Assemblies to Fire Floor/Ceiling Assemblies Encapsulation times (at interface board-clt panels): 36 min for floor 28 min in bedroom and 48 min in living room for ceiling Max temperatures at interface remained at 500ᵒC until 170 min Floor CLT panels charred without contribution to fire GB Base layer stayed in place until near end of test After 170 min, flames observed on CLT panels in living room, then spread to the entire ceiling Test was terminated at 185 min 35

36 Summary of CLT Apartment Fire Test Encapsulation times for CLT wall panels varied between 38 and 65 min Encapsulation time for CLT floor panels was shorter CLT walls and Floor panels charred but did not contribute to fire growth/spread For the CLT ceiling, there was minimal flaming combustion on panels until 170 min, after which visible flames/fire spread observed in living room Test was terminated at 185 min CLT structure performed better than CFS structure in limiting structural material involvement and contribution to fire growth/spread 36

37 Fire Testing in Support of TWBs Project «Origine» in Quebec City Part of NRCan s initiative 13-storey mass timber Challenges Code compliance «Combustibility» emotional issue Vertical shafts 37

38 Fire Testing in Support of TWBs Fire-resistance tests of floor/wall Fire performance of exterior walls Fire demonstration of CLT stair/elevator shaft 38

39 Fire Testing in Support of TWBs Fire Demonstration of CLT vertical shaft Funded by Quebec MFFP In support to an alternative solution to a 2-hr noncomb. construction for the Quebec project Consisted in mostly bare structure except for interior of room of fire origin and around fire door Fuel load of 790 MJ/m² (95 th percentile) 45-min fire-rated door (vs. 20 min.) Lasted for 2 hours No fire penetration through walls, floor or ceiling 39

40 40 Fire Testing in Support of TWBs

41 Conclusions CLT assemblies detailing can provide for highly fire-rated compartmentation in buildings CLT assemblies exhibited high fire resistance performance (vs. noncombustible construction) Flame spread of mass timber slabs exhibited much lower rating (vs. that of thinner slab) Installation of fire stopping and service penetrations should not interfere with the anticipated charred layer Design methods and guides are readily available 41

42 Conclusions Test results showed the effectiveness of the encapsulation approach in delaying contribution of wood structural members to fires Compartmentation provided by CLT structural assemblies allowed complete burn out of contents CLT panels did not contribute to fire growth/spread until 175 min (visible flames spread after that) CLT apartment fire test lasted for nearly 3 hours Inherent fire performance of CLT makes it suitable for sound alternative solutions 42

43 Acknowledgements Natural Resources Canada (NRCan) Provincial governments, namely RBQ, MFFP, OMMAH and BC FII FPInnovations industry members FPInnovations and NRC dedicated staff 43

44 44 Thank you!

Copyright 2018 American Wood Council 1

Copyright 2018 American Wood Council 1 Fire Tests in Support of Tall Mass Timber Buildings DES603 Sam Francis Senior Director, National Programs American Wood Council Jason Smart, P.E. Manager, Engineering Technology American Wood Council The