wooden i beams

Fire Science ProgramDutchess Community College

Poughkeepsie, NY

TGI (Wooden I beam)Test BurnApril 4, 2009

Dutchess Community College Fire Science program2

Wooden I Beams

• Large surface area with little mass.• 2 Wood “beams” with OSB acting as web

member (TGI)• OSB-Oriented Stand Board web- Many small

pieces of wood held together by combustible glue.

• Strong until subjected to high heat.

Dutchess Community College Fire Science program

OUR TESTS STATS• Four 16’ TGI’s, • ½ “Plywood roof• Supported by two 6 high 2x4 walls with fire side

covered by sheetrock.– Joints not taped– Nails not spackled over

• Fireload- hay, pallets, 1 couch, 1 stuffed chair, 1 dresser

• Weight on roof- approximately 300 lbs (water in plastic barrel)


Side B


Side D


Some of the DCC Fire Science students

Left-right: Scott Steinebach, Patrick Rose, Erik Swingle Brendan Nugent, Tyler Carlson, Preston Kinzel, Doug Palmesi, Tim Conboy, Sarah Baker, Dominic Boscardin. Dutchess Community College Fire Science

program


1 min. after ignition


2 mins after ignition


3 mins after ignition


4 mins. After ignition

Drum is falling through-

roof is failing.


Center two TGI’s have failed (where weight was) and little is left of remaining 2 TGI’s

Note-sheetrock held back fire. Note where fire came through joints that

hadn’t been taped and spackled.


After sheetrock was removed, nail was easily removed from wood as heat had conducted to the wood via the nail and pyrolytic decomposition started on the wood,

loosening its grip on the nail.Note-nail head had not be spackled over.


Top of 2x4” stud where fire lapped over sheetrock on the wall


Char on unprotected wood stud from wall


Compare the mass; wood beam vs TGI/wooden I beam


Test Burn Observations• TGI’s burn quickly• High surface area coupled with little mass cause

early failure• Without weight on them, they can appear to

remain in place even with substantial burn time. Application of any weight will cause immediate failure.

• ** Cases have been reported of carpet holding remnants of I beam in place. Unsuspecting firefighters who fail to continually test floor ahead of them immediately fall through.


TEST NOTES• This was not a scientific test, just a “let’s see what

happens” event.• TGI’s were not protected by sheetrock which they

likely would in “real world”, but……….• Fireload was:– Less than normal (hay and wood pallets possess 1/3 BTU

energy of today’s synthetic fireload.– Fire area was wide open; heat could readily vent out

(escape)– Weight (water barrel) was able to fall through when

center 2 TGI‘s failed, thus catastrophic floor collapse did not occur. If weight had been distributed, undoubtedly floor would have catastrophically failed, without warning.


Our Thanks Go To:

• Williams Lumber, Rhinebeck, NY• Dutchess County Department of Emergency

Response, Poughkeepsie, NY• Rhinebeck FD• Pleasant Valley FD


Beware of Lightweight Construction

Wooden I beams (TGI’sTrusses

• Never operate above or below any truss or wooden I beam (TGI) that is being exposed to heat from a fire


The End-Be Safe

Expect the Unexpected


wooden i beams

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