I’m doing an attic insulation job, Maine, 2 story colonial, full unfinished attic. Removing old fiberglass batts, air sealing and blowing in cellulose. I’ve found that the top plates of most of the exterior walls have holes (1/2″) drilled into the wall cavity. The only reason I can see is for some sort of venting, which I’ve never seen before. Exterior walls and ceiling are covered with 1″ of foil faced foam on interior, 2×6 walls with batts, plywood, typar, vinyl siding. House built in 1988.
I think I’ll seal up all these holes, I can’t see them helping anything and would think that they only promote air being drawn into the wall cavity and into the unheated attic. Has anyone run into this before, was this a common practice? Any problem with sealing them up?
Thanks for any thoughts.
Replies
I suspect that the holes were drilled to inject insectacide. Was the house ever treated for termites?
I can't imagine termites were ever an issue, being in central maine, maybe carpenter ants, but I doubt that is it. It looks like the holes were drilled from below, prior to insulating etc. By the looks of it I'd say they were original to the house.
I was going to guess pour in foam.
not pour in foam
i don't have a clue, but how old is the house/
House was built in 1988...
Never seen or heard of it. I'd plug them w/ foam or other (e.g. stuff fiberglass in them). Anything to keep air flow at bay.
I've seen plumbing freeze on interior walls because of a weakness such as this.
Any other unusual details?
Red, sounds to me like they might have been trying to ventilate the wall cavity, possibly because of the interior foil foam. Any other unsual details? Solar heating, batt insulation with vapor barrier facing out, poly sheeting as housewrap?
unusual details
Mike,
I enjoy the articles you write, thanks for weighing in.
Wall is as follows, from exterior: vinyl siding, typar, plywood, 2x6 with unfaced fiberglass batts, 1" foil faced rigid foam, drywall.
No special solar heating, although hous is oriented south and we definitely get some nice winter heat as a result.
So, nothing unusual with the exception of the rigid foam, but in my mind that acts as a vapor barrier as would poly sheeting on the inside wall and I've never seen vent holes with that.
If you built the wall as above, would you want "vent holes?" I've got to think it does more harm than good - constantly sucking in warm air from the house through outlets/other holes in the winter, etc. What do you think? Seal them up?