What type insulation board do I have?


Old 02-20-09, 10:59 AM
Thread Starter
Join Date: Jul 2005
Location: western NC
Posts: 9
What type insulation board do I have?

A friend gave me 25-2" thick double foil sided insulation boards
left over from his log home kit. These are labeled ceotex (or
something close) Im at work and dont have them in front of me now.
The say polystyrene (or something close to this) however it
looks like and feels like dark yellow fiberglass foam board. They
are 4x8 sheets 2" thick - R14 and I need to cut them to fit. Im trying to figure out the best way to make a long straight cut?
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Old 02-20-09, 12:43 PM
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
The description sounds like foil-faced polyisocyanurate. This is an excellent insulation board but it (like all other insulation) needs to be covered with a fire-resistant material like drywall.

What I have done to cut long straight pieces is simply use the rip fence with my table saw. If you don't have a table saw you can set a radial arm saw at 90 degrees and run the sheets through against the rear fence (I'd extend the fence with some 1X4 stock) or if all you have is a hand held circular saw (Skilsaw) then clamp a straight edge to the board (be sure to use a pad on the underside to spread the pressure from the clamp) and run the saw against the straight edge. Use a blade with quite a few teeth and don't forget the dust mask and eye protection.
Old 02-21-09, 08:06 PM
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Join Date: Dec 2004
Location: USA
Posts: 20,499
Furd is right except for the part about Celotex Thermax always needing to be covered with drywall. ISO foam board is quite resistant to fire. And since it has a foil facing, there are many instances where it can be left exposed, unlike all EPS and XPS foam products. In such situations, it's seams are often sealed with foil tape to create a seamless barrier. The product is frequently covered because of its low density, it is not durable and can absorb liquid moisture.

The problem with ripping foam is when the blade becomes gummed up with foam residue, it becomes tacky and wants to grab and throw the foam, or pull the saw, so be careful and have someone assist you if at all possible.

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