I recently purchased a fully gutted ~1850’s brick farmhouse with a new steel roof, and I’m getting ready to start rebuilding. I’m in central Pennsylvania (Zone 5A), the walls are 3-wythe structural brick. 

This house needs some major masonry work / repointing / parging, and long-term I’d like to add insulation and air seal as much as reasonable. Unfortunately anything that requires a minimum cure temperature above freezing won’t happen until spring, but I’d like to get started on detailing the attic so that after the masonry is taken care of we’re ready to blow in new insulation (or possibly even insulate up to the joists now, then add more after repoint and parge).

Existing roof: A new steel roof was installed in the last 2 years. The soffits are vented and flashed over the brick, peak of the roof is vented, and Reflectix (or something like it) was installed under the metal roof. The joist spacing varies 16-19″ in rough cut lumber of roughly 3×7″.

 

Attic stairs removal?: There is an old staircase up into the attic that used to be excluded from the building envelope by blown-in cellulose between plaster/lath walls and under the stairs — see photo 1. I think I want to remove them altogether and add an (insulated) ceiling hatch as attic access. I won’t “gain” much space inside (those stairs are above a staircase from 1st to 2nd floor) and I lose the attic as storage space. However, those stairs will always be a huge heat loss, head room of the attic will be low with modern insulation depth, and air sealing / detailing around them doesn’t seem to add much value. Maximum insulation depth is limited by the 4″ framing of the walls of the stairs, with tons of thermal bridges and weird air seal detailing .

 

This is my current plan and some questions, and I’d love feedback / suggestions.

 

-Add rigid soffit / wind dams flush with the brick exterior, and hung beneath the rafters up to ~6″ (?) above final insulation level (see photo 2). Is foam board for the lower section, any rigid sheathing (foam, OSB, plywood, etc) for the upper section appropriate? Air seal seems important esp. along the lower edge of the blown insulation to keep drafts out, less important above the joists. I don’t want to buy a ton of foam board if not necessary / beneficial from an R-perspective.

 

–Should I permanently seal the old attic windows? Build insulation / wind dams around them? (Photo 3)

 

-Install canisters for ceiling lighting, junction boxes for ceiling fans, bathroom exhaust fan, and electrical

 

-Remove the attic staircase 

 

-Hang and detail / air-seal drywall ceiling. 

Is there a benefit to installing a smart vapor retarder (or even kraft paper?) between the drywall and studs? I realize a painted / taped drywall sheet can serve as an air / class 2 vapor barrier, but I don’t like the idea of relying on paint and any shifting / cracking producing air leaks into the insulation. 

 

-Blow in loose fill insulation due to inconsistent joist spacing. I’m thinking cellulose to R-49, but I’m open to feedback on alternative insulation / going to R60? 

 

Right now the house needs a whole host of envelope upgrades (masonry repair then parge, rotted out window sills, original uninsulated wood doors), but it seems like if I can get an attic and heating system running I can at least keep the structure warmer and drier this winter. Heck, maybe I could even start on interior masonry repair.

 

Eventually I’d like to insulate the walls, safely. I entertained rigid exterior sheathing, but I think that would start a war (“the entire charm is the brick!”). The engineer in me says brick under rigid sheathing is a beautiful thermal mass, stays warm and will wear better, easier to air seal (esp. joists), and doesn’t consume floor space. The more likely compromise will be interior “house-in-a-house” insulation with vapor barrier (I’m referencing 475 masonry retrofit ebook and Building Science BSD-114).

 

In the meantime, it seems that air sealing and a warm attic are my best bet for making the space livable. Sorry for being long-winded!