How To Fix A Wobbly Half Wall on A Slab

In opening up the wall between the dining room and kitchen at my current project, I've found that the remaining half wall is very wobbly and tends to lean back and forth. This is a problem because we'll be putting a bar top on this wall and it's likely that someone will lean on it from time to time.

This particular wall is resting on a cement slab. Here's how I successfully stiffened up the wall...

1. Remove enough drywall to access the floor plate (the flat 2x4 that runs along the bottom of the wall.)

2. I'm using something called a "hex sleeve anchor" to secure the bottom plate to the floor. The idea is to drill a hole in the cement then drive these down. As you tighten the nut it draws the bolt upward and spreads the anchor out which makes a very tight fit in the concrete. I'm using 3/8" diameter bolts that are 3" long.

3. Drill a 3/8" hole through the floor plate with a standard wood bit, then, switch to a hammer drill with a 3/8" masonry bit to drill at least a couple inches into the concrete. You want the hole to be deeper than the bolt by at least 1/2" or more. This gives some space for the debris that accumulates at the bottom.

4. Carefully tap the anchor into the hole you just drilled. Make sure you strike it squarely so you don't bend the bolt and make it impossible to tighten the nut. (Trust me on this one... :) Drive it down until the washer is resting on the 2x4.

5. Use a socket wrench to tightened the nut until the floor plate is snug against the floor.

I used this process to insert four bolts and it did the trick. I found this to hold better than other methods such as using Tapcon screws.

The anchors hold the bottom plate very securely and greatly reduced the movement of the wall, but I also needed some extra bracing to keep the studs from moving back and forth on the bottom plate. For this I used a couple scrap 2x6's with 45 degree angles on each end. I nailed it in place and even drove some heavy duty Spax screws into it as well.

In the end the half-wall felt much more solid and is ready for the countertop which will also strengthen it up even more.

-Peter

www.CarpentryGuy.com