Okay, everyone…
First, thank you to everyone for the mountain of information. My wife and I have been planning our new house for about 2 years and are very close to breaking ground. We have found this forum invaluable.
Our new home will be a timberframe/ SIP hybrid. TF with cathedral ceilings in the greatroom with 2-storey SIP structure attached. The question concerns the transition. The only construction details I have seen for a SIP wrap on a TF all seem to use a 2×12 sill on an 8″ or 10″ foundation wall. The TF posts sit on the sill, over the foundation wall, and the SIPS rest on the remainder of the sill. Since the TF is supporting the SIP shell, the loads are transferred directly through the foundation.
The problem is with the rear wall of the home at the transition point of the TF to the structural SIP. At the TF, the SIPs are essentially cantelevered out over the foundation to some degree. The 6 1/2″ walls would have 3 1/2″ of bearing on the sill with about 2″ of that directly over the foundation. I have no problem with this since the TF is carrying the load. But after the transition this same wall becomes load bearing. The two options as I see them are to either frame a small zig-zag in the wall (which due to other constraints would not be practical) or a zig in the foundation at that point to set the wall entirely on the foundation.
Has anyone encountered anything like this before? Is there a better way to do this?
Replies
Frenchy's doing one of these. Search him out and send him an email to get him over here.
I think I figured out how to e-mail on this board. Hopefully French will join us. Thanks
I am very interested in this topic, too.
Why not just keep it simple and do the whole thing with timber frame plus SIPs?
The design of our foundation uses 12" wide ICF blocks, the top row of which are tapered to increase the bearing surface out to 10" wide. Our wall SIPS are 6 1/2" wide and we overhung them 1" outside the foundation. that gave 4 1/2" of SIP on bearing surface, and 5 1/2 of bearing for the Posts of the Timberframe. In the corners where the intersection of the walls pushed the TF Posts inside enough that we didn't have enough bearing surface we ran additional posts in the basement as support for the frame. You need to be able to hide and design around that. In our house we will frame an angle across the wall to hide them.
This gets rid of any requirement for a jog in your foundation when you transition to the 100% SIP walls. It also means that the TF no longer supports the SIP panels since they are actually sitting in the foundation.
Robert
T dog, main reason is $ and design constraints imposed in a timberframe. There is only the one wall where this is an issue. Easy fix would be to just bump the wall out a few feet and use two 90 turns, but that would obstruct the view on the site and open another can of worms.
RVanDer,
Wouldn't you want the full Timber post bearing on the foundation with such a large point load? How large are your posts? 8x8?