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Discussion Starter · #1 ·
I currently have a slab on grade ranch home in Ohio. I would like to add 16'x20' addition. I am trying to figure out if I can build a crawlspace for the addition without raising the finished floor height from the house to the addition. I would prefer to not use a slab foundation for the addition.
 

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Discussion Starter · #3 ·
My confusion came from the added height from the rim joist. So I would just have to make sure that the stem wall of the addition was lower than the height of the existing slab. That height difference being the height of my rim joist?

That would also lower the grade of the ground at the foundation by the height of the rim joist too. So I would just have to take that into account when planning drainage and water runoff, right?
 

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retired framer
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My confusion came from the added height from the rim joist. So I would just have to make sure that the stem wall of the addition was lower than the height of the existing slab. That height difference being the height of my rim joist?

That would also lower the grade of the ground at the foundation by the height of the rim joist too. So I would just have to take that into account when planning drainage and water runoff, right?
Or you make it look the same by imbedding a treated rim joist on the inside top so you can hang the joists off the one in the concrete,
you add to the top of the embedded one something that can be removed later so the finished height is the same as the slab of the main house. And build the wall right on the foundation.
The down fall of this plan is if you use form like ours the inside can float a little and some times the top of the embedded one is a little high and need to be trimmed.
 

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Discussion Starter · #5 ·
Thanks for the advice Nealtw. I am nervous about the idea of embedding the rim joist in the stem wall in case it rots. That would be very difficult to repair.

I have done some more research and I am leaning towards using a normal sil plate with top flange joist hangers allowing me to lower the floor joists to be flush. Is there a common practice to protect the end of the joists from rotting from the direct contact with the stem wall?
 
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