I got my house removed from our existing foundation and I was trying to lay out where my sill plates were going to go and things are a little off. I snapped a chalkline across the front and it looks to bow in in the center about 1/2" over 40', doesn't really seem too bad but it leads me to another question. I'm using 6" Mgo sips and the drawings show a sheet of magboard over the rim joist for the exterior. Now should I just square it up as best as I can on the 8" foundation wall or does the load on the exterior sheet have to transfer down to the foundation. If I run a line from corner to corner, the center will overhang about 3/8". If I set it back I'll have that 3/8" as a ledge that probably won't ever be seen but I guess could collect moisture. Any advice?? Thanks, Sean

sgo70,

I don't think you have given us enough info to comment.

But... if you have dimensional lumber splines every 4' at the joints of the panels and your wall panels are nailed or screwed to these splines and your walls are around 8' and your roof load isn't severe, I wouldn't worry about it.

One thing that comes to mind is do you want your rim joist w/ MGO board to be flush with the outer surface of your MGO panels because your exterior wall finish passes down over the rim of your floor? That could influence your decision.

I guess a little more info might help. It's a two story home, 1500 sq ft per floor L shaped(40x24' rectangle with 18x24' addition to rear), wide open main floor (only two point loads with in the structure), upper floor is main roof line with two dormers on the front and one on the addition, all cathedral with no loadbearing walls I've had three engineers help with design and one to sign it all off but no where does it have any mention of this in the plans. I was thinking maybe the subfloor sheeting would overhang the thickness of the magboard and the panels would transfer the load all the way to the foundation. I figure I'll call the SIP engineers today considering that's what I paid them for is stuff like this. Thanks for the input, any other suggestions welcome, Sean

You know, you may want to leave the MGO board off of the rim joist and make sure the outer surface of your panels are flush with the rim joist. That way you will get the bearing you need and then your wall and floor edge is all flush and ready for your water/moisture protection and exterior finish. The extra peice of MGO board on the rim is throwing you off. I think...

Thanks Simon, I talked to the engineer and he said I can set the LVL's back 1/2" to add the magboard and not to worry about it so much. His other suggestion was the same as yours which I think I'll do. Basically that way I can just get the best square off the foundation and build away. Sometimes I tend to overthink things. Sean