Hazards to Firefighters from Engineered Wood Products MFRI Drill of the Month – October 2017

Engineered Wood Products are taking the Building Industry by storm Some obvious advantages: light weight equal or better load bearing capacity environmental friendliness

BUT, there are some serious concerns when FIRE enters the equation!

Laminated Veneer Lumber (LVL) Basically a beam made of plywood Dimensionally stable with no splitting or warping Because of construction it can be longer than conventional solid beams Very high strength

Parallel Strand Lumber (PSL) Laminating veneer that is clipped into long strands High bending strength All strands parallel to the long axis of the lumber Used for beams, headers and columns

Laminated Strand Lumber (LSL) Similar to PSL Utilizes wood flakes instead of long strands Not as strong as LVL or PSL Pressed into large mats or billets, then cut to size Used for studs and millwork

Oriented Strand Lumber and Board (OSL & OSB) Flakes of wood pressed together to make a sheet or lumber Virtually the same as LSL Used for flooring, decking, studs and millwork

Glulam Laminating layers of solid wood to make a larger component Heavy beam similar to older heavy beams, but made from smaller pieces Used to make arches and exposed beams Does not quickly degrade in heat

Everyday Uses in Construction Glulam ridge with Composite I-beam rafters

LVL beam with composite I-beam floor joists

PSL beams with conventional sawed lumber joists and OSB flooring

Composite I-beams. This model has web and flanges made of engineered lumber. Flanges can also be of conventional sawed lumber and webs can be of plywood

Wood trusses with OSB decking Wood trusses with OSB decking. This model is made of sawed lumber, but we are now seeing them made completely of engineered wood members.

Engineered wood studs

An example of all engineered wood construction Studs, Headers, Beams, Sheathing, Flooring— ALL ENGINEERED WOOD!

And It’s Not Just Single-family Homes Condominiums

Multi-family Apartments

Combination Commercial and Apartments

Large Multi-Family

The List Goes On . . . On a side note, notice the lack of apparatus access!

Implications to the Firefighter Open trusses and I-beams provide more voids for fire spread  Softer woods burn faster and more intensely Large open areas in current designs provide a ready oxygen source  Exterior siding materials melt easily and expose sheathing to heat Engineered products lack mass and burn quicker

Underwriters Laboratory Tests 12 fire furnace tests of various construction assemblies Measured time to collapse Fires simulated typical fully-involved contents fire utilizing ASTM E 199 criteria 1000°F at five minutes 1700° F at 60 minutes

Note: the two firefighters are mannikins placed for the test 12-inch wood I-beam floor without ceiling below Note: the two firefighters are mannikins placed for the test Collapse time = 6 minutes and 3 seconds!!

Note the extreme deflection of the floor The center web of the I-beam is completely burned through

Typical gusset plate teeth are less than one inch Metal gusset plates are 18 gauge or 1/20 of an inch thick!

Metal teeth conduct heat into the wood fibers causing rapid failure

Failure of OSB sheathing causes loss of support and shingles collapse into opening

OSB flooring completely destroyed between floor joists

Notice that the temperature on the surface is only 85° F (1200 ° F+ below) just prior to the floor collapse!

How Should This Affect Your Next Response? Keep These in Mind: There may be no warning of imminent collapse. Flooring and roofing materials may insulate sufficiently so the surface temperature may give no indication of the heat and damage below Due to the quick deterioration of the engineered materials, there is no margin of safety. Some elements have failed in as little as six minutes in test situations. Much new residential construction has the same fuel load as commercial structures of the past

Thermal Imaging Cameras DO NOT provide an adequate indication of weakened structures and imminent collapse Fire Codes are minimal or non-existent for Type II and Type V construction in regard to fire resistant floor, roof and exterior assemblies Due to the high fuel loads, you are likely to need additional manpower and high water flows High GPM flows may also weaken the structure as most designs do not have a built-in safety factor

The average response time in the U.S. is just over 10 minutes Many lightweight structural elements may be near, or have already failed before the first units arrival EVALUATE RISK VERSUS BENEFIT In many cases, the safest recourse is a defensive exterior attack

Type V Construction approximately 15 minutes elapsed time

These materials have been called “solidified gasoline” by Fire Chief Steve Lohr, Hagerstown, Maryland, formerly Chief of Mongomery County, Maryland.

We cannot fight fires like we have done in the past—it’s going to get firefighters injured or killed Tactics need to keep up with the quickly-changing construction industry

REMEMBER— EVERYONE GOES HOME!