Caution Urged with Composite Floors

[Emtmom]

Here's a little something for you all to discuss!

Caution Urged with Composite Floors
Several Cases of Firefighters Falling Through Floors Have Been Reported
Fairfax , Va. , Dec. 4, 2006...

The Safety, Health and Survival Section recently became aware of a potential
hazard to firefighter safety. They asked the IAFC to share the following
notification with all members.

There have been several cases of firefighters falling through floors made of
composite structural components and an even greater number of near-miss
situations. This type of construction is being investigated as a contributing
factor in a line-of-duty death.

There is a proliferation of engineered floor systems in residential
occupancies across the United States . Many newer residential occupancies incorporate
lightweight, engineered wood or composite structural components, including
trusses, wooden I-beams and lightweight flooring systems. In most cases, these
systems are structurally sound and designed to support the appropriate loads
under normal conditions; however, they are likely to fail very quickly under
fire conditions.

These components and systems are most often found in situations where
applicable codes do not require any rated fire resistance between floor levels.
They have much less inherent fire resistance than conventional wood joist floor
systems and conventional wood decking. Remember ⤓ many codes do not require
any fire resistance in residential floors!

In the several cases of firefighters falling through floors, those floors
had been exposed to fire from below for relatively short periods. Sometimes the
weakened area is relatively small and the damage is concentrated to the area
immediately above the seat of the fire.

Firefighters should pay special attention when entering above a basement
fire, where the floor could have been weakened to the point that the weight of a
firefighter could cause a localized failure, dropping the firefighter into a
burning basement. This can occur with no indication of imminent failure from
above.

Extreme caution should be exercised in any situation where entry is made
above a basement fire. Conventional methods such as sounding ahead with a tool
and checking for sponginess may not provide sufficient warning of a weakened
floor. Using a thermal image camera is recommended to sweep the floor for hot
areas before entering and to help avoid areas that appear to be hotter than
the surrounding flooring. Be aware that thick carpets or tile floors may
compound the risk by making it even more difficult to detect hot spots.

In summary, members should consider the following regarding lightweight
floor systems in residential occupancies:

Know the local codes that require fire resistive construction and/or limit
combustible storage in unprotected basements.

Conduct pre-incident surveys of new housing developments to check the types
of floor system being used.

Use extreme caution when fighting basement fires in all occupancies,
including newer residential occupancies.

Work is being done by a number of our fire service partners to investigate
this phenomenon and more information will be provided in the future. In the
meantime, go to the following web sites for more information:

http://www.ksdk. com/news/ news_article. aspx?storyid= 107868
http://firefighterc losecalls. com/weeklydrills .php
http://www.rapidint ervention. com/media/ monthly_training _topic/february2 005/
http://www.firenugg ets.com/dunn2. htm
http://www.cdc. gov/niosh/ 99-146.html

[wsfd44]

What used to be called “Lightweight” construction is now “Flyweight” construction. Risk assessment, and risk versus gain are an integral part of size up these days. In other words, with the new construction techniques and materials (Oriented strand board, truss floor joists, truss roofs, newer adhesives) if the structure is heavily involved to the point where the structural material itself (not simply contents contained by the sheet rock) is involved and there is no life hazard, we are going to make parking lots. Officers need to really read buildings these days. Thermal imagers moving WITH the hoseline and watching the floor are vital. Truck Companies, who most always try to “Make the floor above” need to know what is going on beneath them more than ever. The truss roof standard, which states that catastrophic and sudden failure of the roof structure may occur after as little as five minutes after the space is involved in fire now applies to floor systems as well.

These structural issues, coupled with hotter fires due to the modern plastics and adhesives, along with better PPE that let us get in further and faster, create a deadly mix for our people.

Just my two pennies. :mad:

[Three891883]

I found it interesting recently to add to the lightweight steel, wooden cord, strand board i beams that are certainy dangerous enough, a type of hybrid which has a wooden base string with lghtweight steel cords or struts... if the steel doesn heat up enought to deform and collaps on you , then the wooden stringers will allow the whole thing to fall apart on you...

I will see If I can find the post again and in which forums set up they were in...

Ultimately pay attention to your new construction... and be aware, If your department doesnt preplan these places underconstruction then you should yourself
we have one new frame in our neighborhood
of many balloon franes thats wooden trussed each platform is build on them, 20 years from now who will ever know that this single family residence is fully trussed in a area full of balloon and platform framed homes

[wsfd44]

We have the entire menu of construction in our 1st due area. Factory Mutual Heavy Timber, Balloon, Residential solid joist and rafter, residential chord truss roofs, new flyweight truss roofs and floors with OSB, commercial flat roof steel truss, commercial chord truss (the Christmas Eve three bagger was one of those), churches, etc., etc. The only thig I DON'T think we have is a bowstring truss.