ATD

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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

Does the MI code require R-19 INSULATION or a wALL ASSEMBLY of R-19? Can be a significant difference when you include the R-value of any siding, the block, the DW and interior air layer.

I agree that foam layer on the exterior has advantages. In fact with a large mass like the blocks it is prefered from a thermo standpoint. But in practice it is limited to thickness. And in this case we don't know what the exterior finish is and it might require all new siding.

There are two problems with FG insulation in this application.

There is no drying surface. Moist air can get through gaps in the "vapor barrier" and work it's way to the block. With the insulation the block will be even colder and you will get condensation tha can not try out through the DW because of the vapor barrier.

There is fix for that ATD (air tight drywall) or sealed vapor barrier. But that requires sealed electric boxes, gaskets, use of accostical sealant and the like. But not everyone is going to be able to do that correctly.

The other problem is that when FG gets cold it starts having internal air currents is not as affective as rated R-value.

The advantage to foam sheets is that they for a continous thermo barrier and moisture barrier so that the internal surface will be above the dewpoint.

Possiblely a dense pack celuslose insulation would work. Either spray into a mess or use damp spray. But damp spray would have to be done when the walls are dry and then wait a while for it to dry out before putting up the DW. And no vapor barrier so that it can dry out though the DW. Not 100% sure that it will work in that climate and construction.