Control Joints in Large Residential Monolithic Slabs. 1

[XR250]

Is it even worth specifying these? What would be the purpose? I have never seen any contractor take special measures around the joint when laying floor finishes or other framing. Thickened slab areas at the interior and perimeter always screw them up regardless. Where the slab is exposed, I think it makes sense from an aesthetic standpoint though.

 

[WesternJeb]

Not too familiar with residential. If control joints will bother the owner from an aesthetics perspective, my point of emphasis would be the aftercare and curing. Misting concrete with a water hose every few hours after finishing, pouring in acceptable weather. etc. Try and emphasize/require those points if control joints aren't preferred.

 

[canwesteng]

Is this a basement in a house? Or a slab on grade in a large multi family building? No CJ on a massive slab could leave you with sizable cracks that might be felt below the floor.

 

[phamENG]

XR - I don't do it. I put the 'typical details' on the drawing, and tell the contractor they are responsible for laying out saw cuts at whatever maximum spacing/aspect ratio OR develop another suitable alternative crack control regime. I usually don't get RFIs, and I'm pretty sure nobody actually cuts them anyway.

 

[XR250]

It is 4000 sq. ft. house. Thanks for the info, Pham.

 

[TheDW]

We show a control joint layout on all slabs from porch additions to 10k square foot houses. So we can lay them out intelligently around the thickened footings.

I haven't ever had an RFI about them either. I'm sure our layout is ignored half the time...we did an addition on my house last year and I got a kick out of the contractors surprise when I pointed out my layout as they were in the process of cutting their own.

Our office was involved in a lawsuit around slab cracks before I started here...my impression is that we show as much detail as we do, in part as a reaction to that. We want to be able to point out how much care we took in our crack mitigation efforts, so a lawyer can't say we didn't follow standard of care. I hope I don't ever find out if that holds up

 

[XR250]

My experience with control joints on tract houses is that they cut the joints and the slab just randomly cracks elsewhere.

 

[TheDW]

Yep, they love to pour Friday afternoon and cut Monday morning, once cracking has already started elsewhere.