Foamular Insulation Needed?

[Terry Thillemann]

I have an unfinished basement where I've setup my wood shop. I'm finally ready to put up a partition wall to stop the dust from spreading and a closet around the DC to dull the noise a bit. I don't plan to put up any exterior walls and will leave the painted cinder block exposed. I've read when finishing a basement you should use 2" foam insulation against the cinder block before putting up studs and drywall but since I'm only putting the partition wall ends to the cinder block, I'm wondering whether I should put a 4" wide piece of 2" foam insulation against the cinder block and then studs/drywall or is the insulation really not needed?

[Doug Garson]

I would frame the wall with a 1/2" gap between the stud and the cinder blocks and fill the gap with this:
http://www.homedepot.com/p/MD-Building-Products-5-8-in-x-20-ft-Gray-Caulk-Backer-Rod-for-Gaps-and-Joints-71506/100165680
And then leave a 1/4" gap between the drywall and cinderblock wall and fill that gap with latex caulk.

[Anthony Whitesell]

There is a ship-lap style foamular insulation specifically designed for interior basement use. There are two caveats (1) it is only 1 1/2" thick and (2) it is designed to be use with furring strips. Install the insulation against the wall, then install the furring strip by nailing/drilling through the furring strip and insulation into the wall behind, then install your wall covering.

Right, wrong, or otherwise, I'm just passing along some information.

[roger wiegand]

You don't say where you are, but in a heating climate you want to get to at least R10 in your below ground basement walls. 2" of rigid foam is an easy and cost-effective way to do that. You can, if you like then use furring strips to avoid building a wall, or build a 2x4 wall inside.

In our new basement in MA we went overboard-- 4" of foam under the slab, 2" of spray foam sealer on the outside of the foundation wall, 2" of rigid foam inside, then a 2x4 wall with fiberglass batts, and spray foam in the joist bays around the perimeter. So probably R30 in total with very little infiltration. It is the first really comfortable basement I've ever lived with. No dampness, almost no temperature fluctuation year round.

[Paul F Franklin]

I would glue a 3.5" strip of foam to the wall with PL premium and then butt your interior partition wall against that. When you drywall, run the drywall over the foam to within 1/4" or so of the wall and either caulk or use a trim piece. You don't want the drywall to touch the block, and you don't want the foam to be exposed as it needs to have a thermal barrier over it to meet code. If you do it that way, and down the road you decide to insulate and finish the exterior wall, you won't have to undo or change anything you did. Remember that you need to use pressure treated lumber for the bottom plate of the wall, since it contacts the concrete floor.

Good luck!

[Jim Becker]

The caveat for putting the foam insulation on the shop walls is that you really, really should have it covered when you're using the space for more than storage. It's not exactly impervious to burning, for example, and easily damaged if you whack it with a board. Doing so will also help make the space more comfortable.

[Marty Tippin]

Seems like everybody is missing the OP's actual intentions.

If all you're doing is butting up the end of a framed wall to the block exterior wall, there's no need for foam insulation of any kind - the foam would be for insulation, not providing a barrier between the wood and block.

[Doug Garson]

Seems like everybody is missing the OP's actual intentions.

If all you're doing is butting up the end of a framed wall to the block exterior wall, there's no need for foam insulation of any kind - the foam would be for insulation, not providing a barrier between the wood and block.
Seems like you missed my post, I agree the others missed the OP's actual intention. My suggestion was to isolate the wood stud and the drywall from the block wall to prevent moisture damage to the stud and provide a seal to keep the dust from escaping to the rest of the basement.