Posted: 4/12/2011 4:36:23 PM EDT
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I'm planning to build an addition off the back of my house. The ground elevation near the addition is pretty much locked in, since it is surrounded by by the driveway, garage, and of course, the existing house.
For the addition, I plan on pouring a concrete footer at frost depth (42" here), and then using CMU blocks to build my stem wall. The problem I'm having is that using a traditional stem wall and floor framing, the bottom of my framing will be flush with my existing exterior grade....bad news and won't meet code. (I'll clear this up by explaining that when I say traditional, I mean platform framing, 8" blocks forming the stem wall, then a sill plate, then joists/rim joist, then subfloor, then soleplates and studs). What are my options for keeping the floor elevation of the addition at (roughly) 11" above exterior grade, yet making sure I pass code in regards to proper clearances from my framing to soil (assuming I'm not going to do a slab on grade). Also, I will not be pouring a concrete slab adjacent to the addition. It will be a mix of pavers, crushed stone, and soil. |
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Yes, the plan was to dig a crawlspace. The issue is around the exterior, the bottom of sill plate elevation is very close to grade.
I'm able to maintain my 18" (or whatever is necessary) from crawlspace grade to bottom of sill plate elevation.....thats just a matter of digging. |
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Maybe turn a cap block on edge on top of the flat cap block on top of the stem wall flush on the outside
That would leave you 4" on the inside to put a pt plate and so long as you use felt or rubber the non-pt joists can butt up to the vertical block use pt on top of the block on edge to get it's height the same as the floor joist again, use rubber or felt and put the decking all the way flush to the outside edge of the vertical cap block to tie everything together Then frame normally Hope this makes sense |
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Quoted:
So if the addition floor height is the same as the existing structure, does that mean the grade around the existing house doesn't meet code? MS Paint would be helpful here. It may or may not meet code, there are code variances for when you have a concrete slab adjacent to your structure, and of course this was built 60 years ago, so its grandfathered in. Here's a picture: 
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Quoted:
Maybe turn a cap block on edge on top of the flat cap block on top of the stem wall flush on the outside That would leave you 4" on the inside to put a pt plate and so long as you use felt or rubber the non-pt joists can butt up to the vertical block use pt on top of the block on edge to get it's height the same as the floor joist again, use rubber or felt and put the decking all the way flush to the outside edge of the vertical cap block to tie everything together Then frame normally Hope this makes sense Yes it does. I was thinking of something similar, but ran into some problems that your explanation cleared up. I'll draw up a sketch and see what the inspector thinks of this. Thanks. Other than this, I think I may be looking at a slab on grade. Not exactly an easy task for a one man crew who can't get a concrete truck near the area. |