Porch slab and wall interface detail
The front porch of my house has failed due to what I can only assume to be an improper foundation, I am looking to replace it and the foundation with a proper depth and thickness poured continuous footing with CMU block wall at both the perimeter and the two porch columns. The wall CMU will be poured full and tied into the slab rebar. My only question is the interface at the building connection, currently the brick there is showing signs of degradation, not to mention it doesn’t fit at all with the overall style of the house. The top of the rim joist is about the same elevation as the top of the current slab. the house is located in climate zone 6 (Michigan)
How do I connect the slab to the house frame without causing a water issue at the connection?
Do I bite the bullet and strip the brick off of the front of the house? then what would that connection look like?
Potentially I would follow this up with a natural stone at partial height vs. the full height brick currently in place.
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Replies
Hi Kenneth -
You need to completely decouple the exterior porch slab from your structure both in terms of heat and moisture management.
Is your rim joist against the porch slab currently insulated on the interior? As part of the decoupling you could use rigid insulation on the exterior, with the rigid insulation serving as a capillary and thermal break. You will need a finish detail when you redo this, but since the new thermal and moisture break between the porch slab and structure is sheltered well by a roof, you can do a finish cap with any number of materials that simply protect the insulation below.
Peter
Peter,
Thank you for the input, Unfortunately I don't know exactly what the current connection is... it appears that maybe they installed the brick exterior first and the poured up to it, so the brick air gap /back plane would act as a capillary break.
So if i tore off the brick and put a rigid foam panel (POLYISO probably) on the sheathing/ framing would I need to install a foundation around the entire porch perimeter?
Hi Kenneth -
I think the best approach is to take off the brick veneer. That way you can get a decent level of insulation in the wall and an air barrier as well.
Do you need to re-found the porch slab? If the existing slab is moving enough to create cracks, and since your porch roof is tied into your home, you probably need to re-found the porch slab. I don't know your climate and that likely has impact on just how much your slab moves over the course of a year (frost-heaving in a cold climate being the main source of movement).
Peter