Frame Rigidity/Structural engineering

Well… more delay before we can start framing. My suspicions that I began to have a week ago were confirmed by the structural engineer that I met with. As designed, the frame isn’t strong enough. The good news is that the engineer felt we could work with what I have designed, the bad news, of course, is that the engineer’s time won’t be cheap and we have to further delay the start of framing.

The problems:
The two aspects that make the frame atypical also make the frame weak. The double stud wall with off center studs (for energy efficiency) and the absence of a flat ceiling above the second floor. The solution to the first problem is to align the studs and connect them with small pieces of plywood called gussets. An added benefit of this solution is I can switch to using 2×4’s for the exterior load bearing stud wall. A further explanation of the second problem is informative. If one considers a card board box when all six sides are sealed shut, it is a fairly rigid strong shape. Open the top and it becomes floppy. In essence this is the problem I have created with my design. The good news is there is some flat ceiling above the second floor; the third floor room. The challenge is to get that floor to provide rigidity for the entire house. A couple aspects of the solution are to make the floor out of plywood (instead of the tongue and groove 2×6’s I spec’ed in) and to make the floor larger.

My next meeting with the engineer isn’t until the 28th.

It looks like I have some time to catch up on some other projects.

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