Creating studs on top of a concrete wall

Submitted by Twebified t3_11usyxx in DIY

Basically my walls don't have studs (1970s rigid foam construction) and I want to mount my 80" TV.

Unfortunately the concrete wall is almost 4 inches behind the drywall so I'm considering tapconning a 2x4 into the concrete and then mounting the tv to the wood.

If I tapcon a 2x4 sideways, or alternatively two 2x4's on top of each other, into the concrete, with a 6" tapcon, and then mount the tv to the wood, would the weight actually be supported without splitting the tapcon in half, or pulling the second 2x4 out of the first 2x4?

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LaoWai01 t1_jcpvizq wrote

Is it solid concrete, i.e a poured concrete wall, or cinder blocks? If solid, or the cinder blocks are filled, you can use red-head expansion bolts to fix a pressure treated 2x4 to the wall, the another with 3ā€ screws and glue to come out the distance you need. If the cinder blocks are hollow you may be able to stick a 2x4 to it with a ton of pl500 and a few tapcons to hold it until the glue dries.

Edit. PL premium may be better

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Twebified OP t1_jcpw81v wrote

It's solid concrete.

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LaoWai01 t1_jcpwfxd wrote

If you decide to use the expansion bolts Iā€™d recommend renting the giant drill and concrete bit from Home Depot if you can. I installed a deck once and the rental drill made installing the bolts a breeze.

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Razkal719 t1_jcqgtds wrote

The "giant" drill LaoWai is recommending is a Hammer Drill. Get the appropriate sized masonry bit for the anchors you'll be using when you rent it.

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nalc t1_jcqrhrh wrote

Minor nitpick, it's a rotary hammer, not a hammer drill.

Rotary hammer uses a special sliding bit called a SDS bit that moves back and forth. Only the bit moves. It also has a mode where it can hammer without spinning and use chisel bits for demolition.

Hammer drill uses a normal masonry bit in an adjustable chuck and has a mechanism in it to vibrate the entire chuck back and forth

Rotary hammer is really what you want for anything beyond just doing a couple 1/8" holes. Having both, a rotary hammer can do a 1/2" hole in a granite boulder faster than a hammer drill can do a 5/32" hole in brick.

Both are colloquially called "hammer drills" but you've got to make sure it's actually a rotary hammer and uses a SDS bit.

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UseABiggerHammer t1_jcq1fk1 wrote

It sounds like you're saying your wall is drywall, layer of foam, concrete.

Your drywall is adhered to the wall somehow which means you can use toggle bolts through it to hold your TV. Use a wall mount system that distributes the load by attaching to the wall through a wide rectangular frame (this is a common style), put a big toggle in each corner, and you'll be fine. If your mount is more of a point load, use the toggles to attach 2x4s or a 1'x4' rectangle of 3/4" plywood to the drywall (you could glue it for good measure) and bolt your mount to that. Drywall is a lot stronger that we give it credit for.

We were removing a large commercial duty flat panel monitor (metal case, heavy) held onto drywall with one of these mounts and toggle bolts in a space slated for demolition, and my tech forgot the tool to loosen the mount. Since the walls were coming down anyway, he figured he would just rip the monitor out of the wall. He was a hefty dude but those toggles and mount supported his full body weight plus the weight of the monitor and it took a lot of energetic yanking and shaking to get the drywall to break. When it did finally come down he took a good 2x3 section of wall with him.

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