Interior Use Approved
Although the ICC Codes permit the use of certain types of foam insulation, in certain situations, to be used and left uncovered on the interior of houses, a State of Maine law prohibits the use of any foam without the use of a fifteen minute thermal barrier being applied. This state law takes precidence over what the ICC code might permit.
The state law allows the State Fire Marshall to approve a foam product to be used without the fifteen minute thermal barrier in place. In a letter dated January 17, 2012 the State Fire Marshall's Office aproved the use of Thermax Sheathing and Thermax White Finish complying with specific ASTM standards, to be used without a fifteen minute thermal barrier (like 1/2 sheet rock) in place.
Other specific actions by the installers are required. The installers must provide property owners a certification of correct installation of the Thermax. A copy of the cut sheet and the certification shall be kept by the owner for verification of compliance.
Download a copy of the Fire Marshall's letter here.
This approval will now provide an attractive alternative for compliance with the R10 insulation requirement for basement walls.
1.55" thick Thermax has an R-Factor of 10. So it can be put on the interior of basement walls to meet the R10 requirement and nothing more would have to be done. Since no covering is now required, savings in material and labor would be realized.
The Thermax White Finish has an attractive white covering instead of the silver foil covering of the the regular Thermax. Rolls of white matching seam tape are also available.