Quote:
Originally Posted by roadrnnr
Got new house in Moultrie creek and am going to put some cabinets in the Garage Pre cast walls
Does anybody know what is a safe depth to hammer drill concrete anchors in these wall as not to hit any electrical?
I have a Stud finder that supposedly picks up metal and A/C but It can't be trusted
Thinking of 1 3/4 concrete anchor bolts to hold the Cabinets
Thanks
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When I used the precast Superior Wall System in a house I had built in Pennsylvania 25 years ago, it was about 2” of high strength concrete with fiberglass strands , an inch of styrofoam, and 2x6” steel reinforced concrete studs capped with 1x2” pine nailing strips. Thus, from the surface of the drywall to the back edge of that nailing strip, you had 1 1/4”. Depending on what you were attaching, you could determine how long your drywall screws should be.
However, if the walls today are like the drawing below, instead of that system, Superior Wall Systems in Florida (and they really are Superior!) no longer use concrete studs, but incorporated steel u-beams backed with 6” of foam.
This means you DO NOT need an impact hammer, and you DO NOT want to use those big bolts! You are drilling through a half inch of drywall and 1/16” or less of steel.
Note on the drawing that there are TWO channels in the foam where the wires are run (see those little red circles?). In a garage, chances are that any wires run through the bottom holes and then up to any higher outlets.
Use a stud finder to find the steel studs and mark them each with a bit of tape. Aim for the center, but as you can see, they are a couple inches wide. Drill a pilot hole with a small drill bit, say 1/16”, to be sure you are on the stud. If it goes right through, you aren’t on the stud. If it stops in a half inch, you are on it.
I have used sturdy drywall screws, specialty screws for installing cabinets, deck screws with square head or star drives. I have used regular electric drills and bigger, stronger drills. With screws, remember that you need threads where the studs are, not smooth necks on the screws. I strongly recommend using a ladder when working above chest level so you can put a little weight against the back of the drill. You won’t need to drill pilot holes, so long as you go slow and use enough weight. I installed a bunch of disability grab bars last week doing this. Worked really well. If you are hanging wall cabinets, use the dedicated cabinet screws, not drywall screws. They are more brittle and more likely to snap off with a lot of weight.