Art, I know you know this, but a structural engineer is going to be the one that knows how to do this. Maybe we have one in the midst that can give you some better ideas.
But......Looking at the photos, strictly from a non structural type lay person, I'd guess the floor joists from the rooms beyond the photo of the upper hallway were long and that part creates the cantilevered hall section. They are resting on 2 load bearing walls, with upper walls on top of them. The part you want to put the new extension of the hall does not have that. So, you would have to pull subfloor from above or ceiling from below, and add by securing on to the existing joists by bolts. I'd guess 2 to 3 times the length of the section cantilevered for the hall if not all the way to the other load bearing wall. Another issue is the existing section has the closet walls that will help support to some extent, so while are not truly load bearing for the building, they do bear some of the load of the walk way, cutting down the amount of stress of the cantilevered section. You won't have that on the other side. How wide is this lower room? (the one open to the walk way) A glue lam to replace the rim joist (is that the right term here?) that the existing walk way has that spans from load bearing wall to load bearing wall would make things much easier, if it is possible to do that.
Oh, are you planning on living there while the work is being done? Jim.
Last edited by Jim O'Dell; 04-18-2010 at 02:13 PM.
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