Hi,this about sagging counter top in corner,I put down (2)opposing sheets of 3/4 inch plywood
Then installed a sheet of laminate on top got ready to put back splash on and the corner I had
A gap of about 1/2 inch which really surprised me,has anybody had this happen to them.
What appears to make it hard to fix is it is the corner and behind a lazy susan.
What I thought about doing is to go under the house in the area where the corner of cabinets
Are and if measure right bore a hole up through the floor and put some kind of screw like a jack
And push corner of counter top up so that back splash is flat and yes we put a level on the top of cabinets and they were level before we added the plywood to top of cabinets,thank,s

Boy that's is a tough position. This why I drill into my guys head to add a nailer in the corners behind the corner base cabinets.
I would cut out a small section of the drywall 3 inches up from the counter top, and the 4' back splash will hide that cut Pry it up from there. Find a stud on either side of that corner and cut a 5'1/2' long 2by stud scab. Lift the counter top up and slip the scab under it , lay the 2by sideways/flat perpendicular on that stud with the extra under the counter top someone just lifted for you and holding it. Once you get the correct height put two screws in the scab to the stud. Like a floor overhang or a shelf bracket and use the stud to anchor the scab and the extra is under the counter and it hangs on the scab. If you get a good solid set up now you can pilot drill a hole close in that corner and screw the counter to the scab and make sure the screw is hidden under the 3/4 back splash when you set it. Now it's a piece of drywall to fill in the one cut and the back splash will set in and glue to it. Since you kept the drywall cut 1' below the back splash there is not need for paint or compound.

Think of it as a roof over hang off the stud that the counter sits on and the scab is a good permanent solution and no jacking that way.

Signed 21 Boat

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