How to Fix a Big Hole in a Cement Wall

When a posted a little while ago about sealing and patching holes in my garage, I conveniently left one small thing out of the narrative.

Or, rather, one very large thing: a huge hole in the cement wall that separates our garage from our basement. Here it is with Brad for scale.

It is kind of a not very good thing. It is pretty bad for energy efficiency to have big holes from the inside to the outside. Through willful ignorance, we hadn’t even known quite how big it was all the way through, because the previous owner had it stuffed with exposed fiberglass insulation and covered with a bookshelf on the other side.

I was very worried about this step of the garage project. I had no idea how to fix a big hole in a cement wall, and was afraid that this might be a structural issue for the house, especially since there were some cracks visible in some of the cement blocks once I cleared away all the old insulation.

However, I emailed the extraordinary contractor who did our renovation before we moved in, and he wasn’t worried about the structural issues and said I could go ahead and patch it up.

But patch HOW?  I considered a lot of options. The guys at Home Depot had a lot of fun lamenting the fact that the hole existed to begin with, and then suggested that I build a mold on one side of the wall and fill it in with a pour of concrete. After hearing that, I seriously considered just gluing a piece of plywood over it and calling it a day.

Instead, I decided to split the difference and fill it in a way that would be more accessible for a beginner DIY-er like myself, but also solidly still a wall and not a random piece of plywood. My plan was to brick it in and then cover the bricks with a thin coat of concrete so that it would mostly blend into the wall once everything was painted.

I gathered a bunch of random bricks that we had laying around in our yard.  I also picked up some mortar mix, cement sand, and a trowel for a total cost of about $16.  (If I had to buy the bricks, it only would have added about $7 to the total cost.)

I pumped myself up by telling everyone that I work with that I was going to learn masonry over the weekend, in hope that they would consider me to be daring and interesting.  (I’m really popular.)

I also read a lot of tutorials and watched a lot of YouTube videos (this one was the most helpful for working with mortar and laying bricks). It turns out that I didn’t need to be nervous, because this project was super easy!

I started by mixing the mortar. I did this in relatively small batches so I could be sure I was getting the right consistency and that it wouldn’t be too hard to mix.

I could tell it was a good consistency when it looked wet and clumpy, and when a glob of it would easily stick on the trowel at a 90 degree angle.

It was a little tricky to get the bricks in neatly because I wasn’t starting with a flat surface, but that didn’t really matter since this would be covered with cement anyway.

To lay them, I applied a layer of mortar with the trowel.

Then, I used the trowel to apply a small amount of mortar to the side of the bricks (apparently called “buttering the brick”).

And then pressed it into place, scraping away any excess mortar that seeped out.

It took about an hour to get them all up, and I was going very slowly and wasting time by only mixing a small amount of mortar in each batch. But I was so pleased when it was all bricked in!

I let it cure for a week before applying the cement.

That process was very similar (surprise). I mixed batches of cement, going for a pretty thick consistency that would stay up on a vertical surface.

I used a soaked sponge to wet the bricks and mortar, making it easier for the cement to get a good bond.

To apply the cement, I grabbed a good handful, and worked it into the right shape, breaking up any clumps.

(Always wear gloves when handling cement.  It will burn your skin, and you won’t feel the burns until later after a lot of damage has been done.)

I then smooshed (technical term) it against the wall and blended the edges.

Finally, after I had done this over an area, I smoothed it with the back of the trowel to a nice flat surface.

It wasn’t possible to get it totally flat. My skill level was certainly involved, but the previous owner had also done some rough application of cement around the outside of the hole, which wasn’t flush with the wall. I did my best to smooth these spots out and to patch in chipped areas, but it was still somewhat imperfect.

Still, I’m betting that once it is covered in paint it will look pretty good!

What a beautiful after photo! (You might not think so, but I certainly do.)

This is the first of the garage projects that really feels like progress. This was a major barrier between us and getting to a point where we can paint this space, and we weren’t sure we’d know how or be able to pull it off. It feels great to have it done!

While I was at it, I also cemented in the interior wall (for if we ever decide to finish that space) and caulked around the edges (because cement won’t flex as the house shifts).

The interior wall has a bit more of a bulge, but, once again, I’m betting that if this gets painted it will still look pretty good.

Hey, it is definitely better than a big gaping hole!

I know this garage project feels like it is taking forever (is that just me?), but it is tough when you only have a little time each weekend to work on the big projects. Still, I feel like we just took a big step forward!

(Sharing at Brag Worthy Thursday, Think and Make Thursday,  Idea Box Thursday,  Weekend Retreat Link Party, Two Uses Tuesday, Tip Me Tuesday, Whimsy Wednesday, and Create It Thursday)