Updating our late 70s house we bought in 2020 and and after removing tiles, found out the 2018 installed drywall touches the slab.

3 questions:

  1. Is the easiest way to fix this use an oscillating tool and cut a 1/4 gap into the concrete?

  2. The area seems to be a source of bugs where there are gaps in the drywall. Can I fill the gap with backer rod to make it harder insects to come in?

  3. I may have to level the floor for the laminate we put in. If I use self leveling compound is there a way to user backer rod or better system to dam it at the drywall (I still have to check level after removing all thinset and might be able to only grind high spots. TBD.)

2018 drywall on left side making contact and 2022 drywall on right with gap (would like to fill with backer rod)

1 Answer 1


You have multiple questions. I will answer in order.;

1- The idea of having drywall off the floor is to give some insurance the drywall won't absorb water if some is spilled or leaked. Cutting with an oscillating tool is the easiest way to achieve this.

2- Do not use backer rod. This defeats the purpose of the gap. The bugs don't get in through the gap. They get in from outside. Find and correct the issue outside. If you don't, they will just find another gap.

3- You don't need to dam leveling compound at the wall. It will stop at the bottom plate. If there is an area where a large gap or a hole exists you can tape around it. I have used both aluminum AC duct tape or even 2 inch wide painters tape applied as an "L".

I know if the leveling compound is needed to be quite thick it will meet the drywall. You can opt to trim it again, or realize that in the event of water on the floor you have a dam to contain it in one room. (You have lost the protection from water getting to drywall.)

If you prefer another measure of protection, say for a kitchen or bathroom, You can tape all the way around the room with a waterproof tape. Place it at least 1 inch up the wall and be sure it is sealed well. Then your drywall will be protected.

  • Solid answer. I'd suggest a vinyl baseboard after all is done.
    – Cheery
    Sep 5, 2023 at 11:29

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