I recently acquired a late 40’s vintage brick veneer house located in southwestern Pennsylvania. The house is a two story 30′ x 22′ rectangle topped with a hip roof. Like virtually every other house in this area, it has no overhangs other than oversized half-round gutters. Having said that, the bricks all seem to be in very good condition, and there are no signs of water damage on the interior walls or ceilings. Additionally, there is no insulation in the exterior walls. The attic is insulated with a combination of old rock wool batts and blown fiberglass; however, I’m in the process of removing this material and replacing it with sixteen inches of cellulose (after careful air sealing of all penetrations).
Now for my question. I would like to insulate the exterior walls and have talked with a number of insulation contractors about the best way to accomplish this. Basically, I’ve been given two options (both involving dense packed cellulose). The first being to drill 1 1/2″ holes through the rock lathe and plaster through which the material will be blown. This interior approach would also involve drilling a number of holes in the first floor ceiling in order to insulate the second story rim joist. This approach seems straight forward but messy. The second approach involves drilling a number of 3/4″ holes through the mortar joints and the underlying sheathing boards (two holes per stud bay on both floors, and additional holes for the second story rim joist). I’ve researched this second option, and apparently it is quite common in Canada. My concern with it is that it will leave a number of holes in the felt paper that covers the sheathing boards and perhaps make them more prone to rotting. Does anyone have any experience with this method, and do you think my concerns about the penetrations in the felt paper are warranted?
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