another basement wall 1

I've been sub contracting the framing on a hill side residential project. On the up hill side I have 40' long by 16' high concrete stem wall. My plywood subfloor has been unable to hold back the wall and the fill behind it, throwing everything in the basement 1/2" out of plumb. the wall has #5 hor. and #6 vert rebar one foot on center and is 8" thick. Construction goes like this, Piles drilled to bedrock on 20' center. a footer 8" x20" spans the piles. the basement wall is poured on the footer without rebar tieing the two together, not even a key-way . the basement floor is hung from the walls, so flooding should not be a problem. The general contractor has had the engineer look at previous homes on this hill and was told that everything is ok. It doesnt seem ok to me when all my walls get moved.
what do you think?

 

[dik]

I don't know what a 'stem wall' is, but without getting into the numbers, a 16' high wall that is only 8" thick with a lateral soil pressure looks a little "shakey", unless the lateral loading is fairly small.

The 8" deep footing may also be problematic if the wall were attached to it! and, if there is a significant horizontal load. The lack of a keyway or dowels would give the base of the wall little or no restraint and I gather that your wood flooring system is used for transferring horizontal load into other elements of the building.

If the design relies on the wood floor to restrain the base of the wall, then it should be adequately attached, in particular, the floor sheathing to the joists to provide a diaphragm and the diaphragm to adjacent walls. This would transfer the forces to the sidewalls. In this area, this type of construction would normally be considered beyond the realm of a normal framing contractor and, likely, engineering drawings would be required. What attachment is used and are you working from drawings or have you decided on what attachment is required (this latter could be a problem)?

Since there are many of these, what you are describing may be common construction in your locale, but, I've never heard of it before. You may want to get a copy of the engineer's report to review. Even though an engineer has reviewed it, it might be prudent for you to contact an independent structural engineer to review the manner of construction; this could cost several hundred dollars or more.

An independant review may be difficult as a subtrade and you might want to make the visit as 'low profile' as possible. The general may not appreciate a subtrade taking this type of action and it could have some long term 'fallout'.

 

[phuduhudu]

The construction does not seem to allow for any base moment in the wall as there is no rebar between the footing and the wall. Some shear could still be transferred from the wall to the footing and hence to the piles but not a great deal. This means the wall needs to be supported at the top at the very least and probably at the bottom as well. These supports need to be able to transfer the loads back to the ground by some crosswalls. As dik says this sounds like an issue that needs a thorough engineering design. The problem with soils and retaining walls is that people find it difficult to imagine them exerting very large pressures so a wall may feel safe but actually is not. Carl Bauer

http://www.bauerconsultbotswana.com

 

[dik]

Curious about this one... can you let us know what the resolution was?