I'd like to use SIPs for floors in an area of my cabin that is on piers and open to the elements below.  The span is 10'.  It looks like 12" EPS panels with TJI splines meet the deflection requirements with ease.  My question is -- has anyone experienced this kind of floor, and is there any problem with "bounce", that feeling that you are walking on a springy floor, as opposed to a rock-solid one?

Also, any thoughts on a floor system (either SIP or conventional) coupled with SIP walls?  It seems there are two ways to do it.  At the foundation level, you can make the foundation wall thicker, allowing the SIP wall to sit directly on the foundation sill plate, then butt the floor joists (or SIP floor up) against the wall, with the floor also resting on the sill plate.  Or, you can hang the joists (or SIP floor?) on the foundation. 

For the second floor (conventional only), it seems like the two methods are to either put the SIP walls on top of the floor system, or hang the joists from the SIP wall.  The latter worries me a little bit because of the torque on the SIP wall, but I'd rather do it because it means very little break between the lower and upper SIP wall sections.  Any thoughts?

Normally, SIP floors use 8.25" panels. The floors feel solid. In fact they feel stiffer than the TJI floor that I have in my house(due to long spans).


You've got the right idea, and I recommend it.

We have designed the exact system you are thinking of building. The thickness of the floor panels depends on the manufacturer of the panel and what their span tables call for but 8”, 10” or 12” will probably work. We run beams (usually PT sawn lumber) between the piers and bear the floor panels on the beams. The floor panels run to the exterior of the house and the wall panels bear on the floor panel. Panel screws are used to attach the wall sill plate through the floor panel and into the support beam below.

For the second floor we always hang the floor joists using top flange hangers. The eccentricity of the connection is minor and will not affect the panel performance. We then run the floor sheathing to the outside of the wall panel and nail it to the top plate. This ties the floor diaphragm into the shear walls. The sill plate for the second floor walls is nailed with 16d nails through the sheathing and into the top plate. This method reduces the break I the environmental envelope to a minimum.

Thanks Avant and Panelcrafters.  Is it fair to say that on the foundation level (main floor), it's better to mount the SIP walls on the floor system (as Avant is doing), than to try to use a wider foundation wall and place the floor system directly on the wall, butted up against the SIP wall? Or alternatively, hang the floor from the foundation (I should clarify that this part of the floor system will be conventional, not SIP, because it is over a basement).

Avant,

Like the idea of no rim joist and stacking panels. I am wondering how you deal with finding electrical chases and accessing them.  Also, if you have an exterior deck, what do you use to attach the ledger joist to the wall?  My engineer is now requireing us to use LVL for rim joist where ever we have to attach a deck.  This is a great forum and am enjoying learing from all of you.

Terry Hackbart