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Leonard Stansbury
Posted: Mar 08, 2009 08:03 PM
igniton barrier
i am getting confused.where i live i have been in many of houses. in these houses the attic had exposed foam. how do i know if it is required to coat or not? i am just getting into the insulating part of spray foam
Posted: Mar 09, 2009 07:47 AM
To be safe assume that the foam should be covered by an ignition barrier. When the new testing protocol goes into effect, I doubt that any foam plastic would be able to pass without a covering, (unless it is a very small surface areaa, such as a sill plate)
Posted: Mar 10, 2009 03:05 PM
What do you suggest as a good cheap ignition barrier? I know where a thermal barrier is required and etc but it is already hard to sell foam with the economy taking a dump and any additional costs are killing us.
Posted: Mar 13, 2009 08:44 AM
Talk with your foam suppliers and find out who has an inexpensive coating that has been tested and approved as an ignition barrier according to a full scale fire test such as UL 1715, NFPA 286 or FM 4880, UBC 26-3. I was tallking to one supplier the other day who said they got approval for their coating at a very low application rate. The intumescent coatings have a wide range of costs from around 40 cents to 1.50 cents a sq ft. Ask about the dry film thickness required and the solids by volume content, Multiple the solids by volume content by .16 and your will get the theoretical dry film thicknes per gallon of coating. Add at least 25% waste factor (more if the foam surface is rough or uneven) for example a coating with 100% solids by volume would yield 16 dry mils per gallon per 100 sq ft. A coating with 60$ solids by volume would 9.6 dry mils per gallong per square.

Don't go by the sales sheet that says gallons per square, these typicially assume no waste factor and you would come up short on coating.

By the way one of the cheapest ignition barriers is 1-1.5 inches of fiberglass (not kraft paper faced). Just staple it to the foam or studs, or blow it on top of the foam (if you are spraying a floor of an attic.
Posted: Mar 13, 2009 01:23 PM
I found a coating that states "will not burn" in the flash point section of the MSDS. It also says it has passed the Class A Fire Rating Test ASTM E84-01 per NFPA 101 Life Saftey Code. Does this qualify it as a 15 minute thermal barrier?
Posted: Mar 13, 2009 07:54 PM
No, to be a thermal barrier the coating must pass an E 119 test or the whole assembly (foam and coating) combined pass a full scale room corner test such as UL 1715, UBC 26-3, NFPA 286 or FM 4880. Each foam must be tested with the coating for compliance. You cannot test one foam with the coating and get approvals with another foam.

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