concrete counter support bracing installation

[al ladd]

I'm a boxmaker, as an excust for needing to ask this. I'm making the bracing system , 1.75 x 4" hard maple as shown in this rendering for a 1.5" thick concrete countertop, with a small sink on the left, and cooktop in back. My concern is whether trouble will result if I don't strip back the sheetrock where the top rear cleats attach to the wall, (maybe the bottom rear cleats too?) and also whether I need to remove tile beneath the braces at floor , or will this load be supported adequately without these precautions?

[Brett Bobo]

From what I'm understanding from the photos, the skewed bracing at the floor would be my biggest concern. Not the wood itself, but the actual connection of the skewed bracing to the horizontal kickers that attached to the bottom cleat. I assume this connection would be made from two separate pieces so the connection is critical. A gusset plate on each side of each connection and horizontal bracing between connections would greatly improve this but it probably goes against the look you're wanting. As a quick calculation (and not exactly correct for the total weight based on the cutouts or the weight per brace), the countertop weighs approximately 1000 lbs and with 6 braces, each brace carries approximatley 165 lbs.

Alternatively, the design could be modified slightly to tie the skewed braces back to the wall studs and still provide the "open" look. In that case, you could face screw each brace to the existing studs (and modify the braces to match the stud spacing at every other stud, for example). I would also toenail with screws the existing studs into the sill plate instead of just relying on one or two nails that were probably placed during construction. A bit more demolition and drywall patching this way, though.