I’m investigating insulating a crawlspace. Closed cell foam looks like a good choice. Several “foam” manufactures claim an E-84 fire rating, does this mean that their products don’t need to be covered? If anyone has had an experience with a foam spray installation any information would be helpful. Thanks inadvance;
lukes
Replies
Lukes, you came to the right place.
The E-84 test involves making a duct, with brick bottom, brick sides, and the top made of the material to be tested. At one end, a huge flame is applied, and a very strong draft is drawn through this 'tunnel' Materials are rated by comparing how long it takes for the fire to move from one end of the duct to the other.
As a guidepost, unfinished red oak flooring is used to represent "100" on the scale. Materials that test at less than 25 are generally considered fire resistant. Note that I said GENERALLY.
When it comes to testing foam insulation, manufacturers have found a way to 'cheat.' Simply put, the test material near the flame immediately falls to the bottom of the duct. Once there, it burns like rocket fuel- but, because of the draft, does not ignite material that remains on the top of the duct. Thus, the material appears 'fire resistant,' when it is anything but.
This is why ALL foam needs to be protected - especially when used on a ceiling.
The E-84 test is a very useful method for comparing the surface burning characteristics of many materials, but it is not perfect. The weaknesses of the test are most apparent when testing foams and carpeting.
Not sure how the code reads, but I've understood that foam cannot be left exposed. Not sure how that works with a crawlspace, but some codes say that it has to be in "substantial contact" w/ a fire rated material (e.g. drywall). A typical floor may be considered properly rated. Maybe ask the building official. It's a lot of work to cut it for the floor joists (I'm assuming after the fact). But almost any option is not fun on a retrofit basis. Need to place it all the way up against the floor. Secure it so that it won't fall down ... may or may not be a big issue. Are you covering the ground w/ 6mil polyethylene?