Expert: Dave Johnson - 12/25/2007

Question
QUESTION: Ok, heres one better.  We have an old grange building that is constructed of cinderblock.  Im not sure if the block extends to the basement but I can almost bet it does.  I was very interested in the answer not to insulate that because of frost heave.  Never thought of that.  The building does need to be done though.  We had thought of attaching ridgid high density foam to the inside walls and then paneling somehow.  Vapor barrier.  Oh yeah, that would be good.  Sigh.  Anyway.  We need to get this building warmer so that we can use it in the winter.  The windows are glass block. Those should be replaced mostly because of means of egress from the building.  So here we are.  What would you suggest?  Cheap is best, Im fairly handy and can do lots of things so keep it fairly simple.  Then the next big job is refinishing the floors.  That I can do.  LOL.  thanks Judy

ANSWER: Judy, Judy, Judy...
O.K., heres the deal, you can insilate with ridgid foam (best material) but then the extreme cold will attack the blocks and who knows what'll happen (maybe nothing) as before there was a lot of heat escaping into the walls
to help keep them reasonably safe from frost.
HOWEVER: If there has been enough lateral wire installed in the horizontal mortar joints, there will be a much better chance of no damage...
My reason for telling you this is that I've seen older brick homes insulated in this way and the mortar joints
deteriorate quite quickly.
Having said all that and scaring the ... out of you, My
choice if I were you would be to do the interior with the foam ,and make sure that on the outside you applied at least a thorough coat of masonry paint or sealer.
Best of luck, and have a great Holiday
Dave

---------- FOLLOW-UP ----------

QUESTION: Ok, there is a lot of issue with the heat mass being the wall.  On several places it said you should have your insulation on the outside because of the heat mass of the blocks.  How about polyureathane blown on the outside creating a stucco effect.  I know that you have to paint it almost immediately with a latex paint.  If we do insulate on the inside, should we put a vapor barrier between the wall and the insulation?  Then we would have to put something on the foam.  Like wallboard or paneling?  I briefly entertained the idea of Liquid Stucco but it turned out not to be the best way. Cripes.  What a royal pain in the patooee.  thanks Judy

Answer
Hi, Lets tear it down and start over.....:)
No vapor barrier. It would create a lot of condensation because the dew point would be on the outside of the poly.
Sprayed on urethane is quite expensive, but not a bad idea. It can be finished with a paint, sprayed stucco,(perma-crete for example) or a brushed on material such as "stack and bond". You can put the ridgid foam on the outside as well, and finish the same way.