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1917 Craftsman ...
Worried about Condensation

We have 2x4 exterior studded walls with wood clapboard attached directly to the 2x4. We will be removing the lathe and plaster to rewire and re-plumb rooms and want to insulate at that time before drywalling.

We have read many articles and are now very confused and worried about attracting condensation and damaging the insulation. We were looking at using a combination of rigid and spray foam then fiberglass batting.

Removing the siding and adding OSB and rigid foam then reinstalling the clapboard is not a feasible option.

We live in Albany, Oregon

Timothy Miller
Re: Worried about Condensation

Howdy with only at 3.5" cavity not room for much fiberglass with foam. Foam is $$ but closed cell filling cavity would insulate walls real good.

Re: Worried about Condensation

Hello- we are facing the same challenges (house built in 1920's, brick exterior with wood sheating and plaster walls but no vapor barrier.) We are getting very conflicting information on closed cell vs. open cell spray foam- I would think we need to go with the closed cell to give us a vapor barrier (since we don't have the option of removing all of the exterior brick and putting the vapor barrier there.)

What did you end up going with? Closed or open? Are you happy with the decision?

Thank you!

Re: Worried about Condensation

Normally the vapor barrier goes toward the side of the wall sandwich where the heat mostly is. In my fair city, we put the vapor barrier on the outside.

As long as the clapboards can breathe (not caulked shut) then the foam between the studs will act as one, rather thick, moisture barrier.

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