Re-using brick pockets in an exterior wall
I am working on the design phase of a rowhouse renovation in Baltimore, Maryland. This rowhouse is 14’x50′ and is an end-of-group, with an east facing exterior side wall. Existing floor joists sit in “brick pockets” in this exterior wall.
Contractor has recommended re-using these brick pockets for the new floor system. It would definitely be an economical solution but I am hesitant to put new framing lumber in a masonry exterior wall, but I do not have technical facts to back me up. A few things that come to mind are potential rot issues and air leakage through the pockets (plus disruptions in the insulation).
Are there real issues with re-using these brick pockets?
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Replies
You could wrap the ends of the joists in sill seal foam to create a thermal/moisture barrier between the joists and brick. If it's at least 18" above grade and water is appropriately managed (ie not directed into or trapped within the wall assembly), then it shouldn't rot. As for air sealing, you're either using poly or spray foam on the interior and whether the joists are pocketed or not doesn't really change much, unless I'm not understanding.
I'm just about to do something very similar. It's a frame building with a brick foundation. The first floor joists are pocketed into the brick wall. We're not replacing all of them, but the ones we're touching we'll add sill foam to the ends and eventually it will all be spray foamed.
Charles,
Depending on your climate zone, your plan could definitely lead to problems -- and I wouldn't trust sill seal to be enough of a solution to prevent these problems. The danger is that cold bricks will lead to moisture accumulation in these areas. The problem is made worse if you decide to insulate the brick wall on the interior.
More information here: Insulating Old Brick Buildings.
There's also Building Science Digest 114 - Interior Insulation Retrofits on Load-Bearing Masonry Walls in Cold Climates. We were in a similar situation and decided it was too risky. If you do decide to pursue it, I'd make sure you bury some wireless or retrievable temp & rH meters so you can monitor conditions at beam end.