Foam board under sunroom

[Mr. Inspector]

They have foam board attached to the underside of the joists under the sunroom. The sunroom under floor area is open to the air, just like under a deck. I told them they needed a ignition barrior. But the 2009 IRC only requires it in a crawl space. Is this a crawl space? There is no definition in the IRC for crawl space.

 

[Min&Max]

Not a crawl space, at least not in my opinion.

 

[tmurray]

I agree with Min&Max. Off-gassing is generally not a problem in areas that are well ventilated.

 

[north star]

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I do not like the lack of definitions in the IRC.......That said,

I would consider the underfloor areas a crawl space, but not

an enclosed crawl space.

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[Keystone]

Foamboard, rated exposure to elements of weather?

 

[tmurray]

The intent of this section is to prevent the rapid spread of fire in the early stages of a fire. When most foam products burn they produce a gas that as a low flash point. As the gas and the heat increase in the building flash-over is reached, spreading fire instantly everywhere the gas has penetrated. It is important to note that the foam itself may not contribute to the spread of fire, or even sustain flame.

Given that this product is outside the intent of the code is satisfied. The only way this could contribute to the rapid spread of fire would be arson, which is outside the scope of most codes.

 

[Mr. Inspector]

Couldn't somthing happen if the owner or a neighbor was burning leaves or there was a brush fire and the wind blew some burning leaves under the room?

 

[tmurray]

Couldn't somthing happen if the owner or a neighbor was burning leaves or there was a brush fire and the wind blew some burning leaves under the room?

It would burn anything unless the materials used were non-combustible.