Building insulation at slab.

[JStructsteel]

Got a building department saying slab insulation does not provide required R value. Current detail has insulation edge of wall, tapered to a point at the slab top.

New detail is something like this. I dont like it at all (focus on the insulation mainly)



What details are you folks using?

 

[EngDM]

I agree outside makes more sense but it gets torn up by the weed whacker and looks like crap after a while.

Add flashing to avoid this maybe?

 

[JStructsteel]

The tapered detail is garbage, too. There's a reason we chamfer 90 degree concrete edges to make a pair of 135 degree edges. How do you think a sharp 45 degree point of concrete is going to perform?

In most one and two story applications, the little overhang isn't going to hurt anything. Structurally, you can use a stud that's 2" shallower anyway. So whether you check it with a reduced section or a little eccentricity between center of bearing and center of applied load, it's probably okay. Where the real issue will lie is in the connection of the sole plate to the foundation wall. You're usually pushing those in a bit to get edge distance on the exterior if you have a 2x4 wall...but now that interior edge is encroaching and you'll run out of room. And don't say that it's fine, it'll be embedded down below. Most of the shear resistance occurs at the surface - if it doesn't work at the surface, then you're assuming it's cantilevering 8" out of the block below...

You would allow this detail then?

 

[phamENG]

will your aggregate even fit in that little protrusion? It's likely to be mostly just concrete paste hanging out there. and how will they cut that insulation?

 

[phamENG]

You would allow this detail then?

Generally, no. I've never been able to make the connection calcs work with a 4" thick foundation wall. I'm just stating that the parts of the detail that immediately look bad aren't as bad as they seem. It's the other stuff that you miss from being distracted by the insulation that really bite you on these.

 

[JStructsteel]

will your aggregate even fit in that little protrusion? It's likely to be mostly just concrete paste hanging out there. and how will they cut that insulation?

TBH, there would not be any load on that, more than likely covered by the wall board. I would rather have that than the wall hanging over.

 

[JStructsteel]

Generally, no. I've never been able to make the connection calcs work with a 4" thick foundation wall. I'm just stating that the parts of the detail that immediately look bad aren't as bad as they seem. It's the other stuff that you miss from being distracted by the insulation that really bite you on these.

Im only looking at wind load, and a 1/2" anchor I should be good for 800lbs doing a quick calc, so I can adjust the spacing as needed