adding joist support, new foundation section, in crawlspace
I’m working on a very old rock faced block house. It’s balloon framed, with joists penetrating the block foundation and walls (in other words, the “rim joist” is the concrete wall with niches for the joists to sit in). A long-ago heating duct addition broke out an 8 foot section of the block foundation (in the center of the house, not perimeter) and the 10 foot long joists that were supposed to end in that wall are now just hanging there – a few inches shorter than originally because they were cut out their niches. The joists are in great shape, I just need to put up a new “foundation”, and rim joist for them to land on.
The concrete foundation wall will repaired separately. It is load bearing.
I’m having a hard time interpreting the foundation section of IRC2018 as it pertains to my specifically odd situation. (Code office is too busy to provide advice!)
To create a parallel rim joist, I was told by a local contractor to dig 12x12x12 holes (IS THIS RIGHT SIZE/DEPTH?), pour concrete footers (HOW THICK?), then install steel columns (HOW MANY FOR AN 8′ SPAN?) to support an LVL as the new rim joist. Then I would use joist hangers to hang the loose ends of the joists.
Very grateful for any advice and comments on proposed plan.
Replies
The 12x12 footing is 12 deep. Usually I have inspectors asking for 2x2x1, but if that’s what the inspector specified go with it or make it bigger if you want to surpass code or have poor soil conditions. The number of posts depends on what size lvl you install and how much weight is on it. You should look at a lvl span chart to size the beam. Two posts is what I’d shoot for. It’s hard to exactly understand your situation without pictures but I’m wondering why the floor joists don’t pocket into the wall or why a ledger can’t be installed to skip the posts and footings altogether.
12x12x12 inches for footers might be excessive for this application. The depth depends on your soil conditions and the load it will support. A local building inspector or soil engineer can provide specific recommendations.
The concrete thickness for the footers also depends on the load and soil conditions. A minimum thickness of 4 inches is often used for residential applications, but this can vary. https://ativader.com/reloader-ativador/