Replies

1. 
   Guest_ | Feb 20, 1999 04:39am | #1

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   Seems like a little overkill but should be fine.

   Are you in some kind of earthquake or hurricane zone?

   Normally a kneewall simply supports the load from above, in order for it to collapse the house would have to flex or bend which is impossible. Your floor and roof form the basis for a waffer and will not allow any movement in the kneewall.

   As long as your walls are either covered with solid boarding or plywood or diagonal bracing, nothing can move.

2. 
   Nick_Roberts | Feb 22, 1999 07:48pm | #2

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   Gabe,
   thanks for the response, but my concern is pressure from the exterior on to the now taller basement wall.The top of the existing wall is held against exterior pressure by the floor joists, but if you raise these up, what now stops the wall from buckling inward at the point where the poured wall joins with the new two foot knee wall? Don't forget that there will now be two feet more back fill.

3. 
   Guest_ | Feb 22, 1999 10:24pm | #3

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   Sorry Nick, I thought that you were just raising the house, didn't know that you were raising the neibourhood.

   You should know your situation best, but you may want to backfill with clean sand if you have concerns about pressure against your existing concrete wall. I'm assuming that you are not going to raise the ground level past the concrete elevation. Which brings up another concern, the protection of joint between the old and the new.

   Make absolutely sure that you have it properly sealed and flashed or the ground water will enter and do damage. Don't know where you are located, if snow is a problem then you still required to maintain a least a foot of clearence between the ground and the seam separating the concrete and wood foundation wall.

4. 
   Nick_Roberts | Feb 22, 1999 11:50pm | #4

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   Gabe,
   You will find that due to my continued stupidity in the field of computers that this discussion is being carried on elsewhere. If you hit that location (same title just lower case) you will see my latest update. Yes snow is a problem.

5. 
   Guest_ | Feb 23, 1999 12:26am | #5

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   Nick:

   You have reason to be concerned about your kneewall. Gabe, how do you account for wind loading against the side of the house? Soil and hydrostatic pressure? And how do you justify removing one of the foundation wall supports? The loading is not just vertical. Your kneewall to concrete anchors need to be capable of resisting the horizontal loading load. Can you use concrete block and dowels instead of a wood kneewall? Also, your concrete basement foundation wall is designed as a beam supported at the top and bottom; top by the floor joists, bottom by the floor slab. Since Im sure your wall is not-reinforced (no, one bar at the top and bottom does not constitute reinforcing) it is unstable without these supports in place since it cannot act as cantilever. You need to think this through a little better and get an engineer involved if you are unsure of how to calculate the loading and do the anchorage design

   Dave

1. 
   Guest_ | Feb 27, 1999 09:01am | #7

   *How are you planning on lifting the house? The guy that lifted ours used steel I-beams some 60' long and gas-powered hydraulic jacks.

6. 
   Nick_Roberts | Feb 27, 1999 09:01am | #6

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   I want to give myself more basement headroom by raising my house off the foundation wall. I'm concerned about pressure from the exterior when I build up the foundation wall. I plan to build a two foot pressure treated knee wall on top of the existing concrete foundation wall. I will then tie the floor joists to this knee wall with 2x stock at 45 degrees. This will not only give me resistance to outside pressure, but the basement ceiling will be coffered. Does anyone see a problem?