Thread: Styrofoam insulation question

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Hey Folks,

I'm looking to construct a wall for the front of my garage this year, something along the lines of a crypt or dungeon entrance theme with stone walls and wooden door.

Well, I need to justify my Hot Foam Factory kit purchase over the winter so I'd like to build it out of styrofoam boards. I have usually used the 1.5 or 2-inch pink insulation in the past for gravestones, etc., but I haven't had much luck trying to find some used or discarded pieces locally, especially in the large size I'm looking for.

My question is this. My local Lowes has 4x8 sheets of the blue styrofoam insulation, but they are 1/2" thick. They do have the thick pink insulation but only in 2x8 sheets, and it would be cheaper to work with the 4x8 sheets. I'm wondering if these 1/2" blue sheets would be suitable for what I'm looking to do, or are they just too thin? Once I start carving the stone joints, etc. will the board hold up? Obviously I wouldn't be able to create very deep joints, which is probably fine. And I am planning on building a 2x2 or 2x3 stud frame for the sheet to attach to so keep that in mind.

So has anyone worked with the 1/2" sheets before that could offer an opinion? Or even if you haven't worked with them I'm open to comments.

Thanks in advance.

I believe that 1/2" is way too thin for an entire wall especially if youll be carving it. Even a 1/4" cut into the foam will only leave 1/4" of foam to support the rest of the structure. I would imagine the first time someone "inspects" it or inadvertenly leans up against it, or even a good gust of wind (believe me, those 4x8 sheets act as sails on a windy night!) would snap the board at the cut joint lines. I even think its too thin for tombstones so I glue two pieces together. You might want to beef it up with another sheet of insulation glued to the backside or even add a a plywood or wooden frame structure to the backside. Probably the most affordable option would be a lattice structure made of those lathes strip you find at home improvement stores. They're very cheap and a frame made with central supports ought to support the foam and give it some rigidity just fine.

I agree with "CycloneJack" the 1/2" would be to thin without a backer of some sort to support the foam. Ive used the thiner foam and glued it to a 1/4 plywood and its worked great.

You can glue sheets together and still carve, no problem. I normally work in half-inch foam for my projects and just sandwich the right thickness together.

If you are looking to keep it light-weight and cheap you could mount the blue polystyrene to the regular 4x8 white styrofoam with liquid nails or locktight.