Foam Insulation Not Practical

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Moderator Post (s) for this thread: > Cinder Block home by Billhart on 01/30/2007 > CCinder block home by Billhart on 01/30/2007 > ATD by Billhart on 01/31/2007

Foam insulation on the interior isn't really practical for a case like this.

First, foam is the costliest type of insulation....3-5x more costly than fiberglass with no added benefit for the extra cost.

Second, Michigan Code requires a minimum of R-19 for wall insulation. If your walls currently have no insulation you will need to add 4" of foam to meet that R-19 minimum. Add to that 3/4" for furring strips and you have increased the wall depth by nearly 5 full inches and reduced the usable space in the room all around by nearly a foot along the length and width.

Better to simply frame a stud wall in front of the block in such a case and simply use fiberglass. It would cost less and intrude into the room by less distance.

But the BEST approach would be to fill the block cavities with insulation if you have hollow block construction and add perhaps a single 1" layer of foam to the outside of the structure.

By insulating the exterior of the structure you do not also have to consider any rewiring that may become necessary for already existing recessed electrical receptacles which may no longer be able to reach to the surface of new interior walls no matter how they are framed.