Temporarily attach plywood to concrete wall?

Question

I need to install a new basement door at my in-laws house, which will require new concrete to be poured under the door sill. The original foundation was notched out lower, then someone later poured a slab outside, so the opening under the door is a real mess.

My plan is to take down the current stairs, and attach a 2'x4' piece of plywood to the existing concrete wall as a form so I can pour in more concrete. Shouldn't take more than 4-6 bags of concrete. I'm planning on drilling into each side of the opening and adding a few pieces of rebar to tie everything together.

However, I'm wondering what the best and easiest way to attach the plywood form to the existing foundation would be. I was planning on drilling holes and using masonry anchor bolts, but I don't really want the bolts to be permanent. I've never used Tapcon screws before. Would they be strong enough to hold the pressure of the concrete, and are they removeable once installed?

Thanks,

Anthony

Pete C. · Accepted Answer

You want to use insert anchors (drill hole, insert anchor, set with hammer and setting tool), which will give you threaded holes to bolt the plywood to. Make sure when you set them you set them a bit deeper then the surface of the concrete and then when complete you can patch over them with mortar / concrete.

Robert Allison · Answer

One way to do this with the least hassle and less money is this method:

Drill a 1/4" hole through a 2x4 every 12" or so, the same heighth as your side form. Place the 2x4 against the wall so that your plywood form can be nailed to it to form the side. With a masonry bit and a hammer drill, drill a hole into the concrete through the top hole in the 2x4. Drive 2 16 penny common nails through the hole into the concrete. Repeat through every hole in the 2x4. Attach your plywood form to the 2x4. (You can attach the side form to the 2x4 first if you wish, but sometimes that makes it more difficult to level the form.

When removing, pry the 2x4 and side form off the wall as a unit. The nails usually pull through the 2x and will have to be removed from the wall. You will probably not believe how well this works. I usually break the nails trying to pull them out. Try it first, if you don't believe me.

DanG · Answer

Robert your method works quite well, but I have changed to using a Topcon lead bit (because I own them), sliding in a piece of #12 copper with the insulation left on ( I cut up a bunch them and keep them in the hammer drill box), drive in a 16d duplex or screw in a drywall/deck screw.  You'll need a 3 or 4 foot crowbar to pull the nails.

Temporarily attach plywood to concrete wall?

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