Home Addition - Unique Work Arounds, Any Opinions?

stubits · 09-12-2009, 11:43 AM

All-

We are in the design stages of a three story addition off the back of our DC rowhouse. I've posted posted a number of threads along the way looking for help and have received excellent advice. Thanks! We're nearing the end of the design stage with the architect and I've got some questions, hoping to benefit from the collective wisdom of the forum here. Just so everyone knows, I've met with the City at an earlier phase and they see no problems with the project.

There's lots of quirky aspects to this project, but two big ones. The architect has developed workarounds to both, but I'd love your thoughts on the attached planes. The problems are:

1) the foundation of the addition must not exceed our property line, of course, but a city ordinance requires that the foundation go right up to the property line (our property is at a slightly higher elevation than the neighbor)

2) there is currently a 6' high double wye brick privacy wall separating my property from my neigbor's, it runs right down the property line and the neighbor is adament that we not remove it (even though legally we can). We've had an SE confirm that it is structurally strong enough for us to build on top of it.

It is also probally important to note thatall joists and rafters run north south so that most the loads are taken to the south wall where there's a typical deep footing. The architect has also included a 6x6 post at the west end of that south wall, which the ledgers will connect to, hoping to also take some of that load away from the west wall. The west wall is 2x4 framing all 3 levels and the south wall is 2x6 all 3 levels, to better carry the roof loads. The west wall “cantilevers” off the existing brick party wall with ledgers. There is a 2x10 ledger at each of the 2 heights in the brick wall. The ledgers are continuous to the southwest 6x6 post.

I am including a couple of photos of the area along with a bunch of different drawings from the architect. I think they show her plans well. Any alternate suggestions? Any thoughts on how hard this will be to execute?

stubits · 09-12-2009, 11:47 AM

And here are some photos of the house... and couple of specific questions...

1)Do these bolts in the ledgers on the existing brick wall need to be through-bolted, or can they be epoxy-bolted into the brick using something like http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-12139? What part of the code establishes spacing and depth?
2. The only load that the turned-down footing on the west side was intended to bear is the wall on the basement level, however the sheathing and siding is continuous to the other levels which load onto the side existing brick walls. Does there need to be some sort of separation or expansion joint between the top plate of the basement wall? Or should we not worry about this idea of bridging and just let the west wall carry all that load?

3. Is it okay for a turned down slab to butt into a deep footing, or is there some specific way to make that connection?