If you are a homeowner that enjoys DIY renovation, you've probably had the opportunity to patch a hole or two in your drywall. If you're an owner of an old home, especially one with plaster, you've probably had the pleasure of trying your best to patch a hole or two and trying to make it blend with the rest of the wall. And, if you're Wendy and me, you've had the joy of spending years patching cracked and failing plaster, giant holes in the walls and ceilings, and holes that you've created in your own walls.
Lucky for you, our pain is your gain! We've gotten quite adept at patching plaster over the years, and we're going to share the step by step secrets to our success. Whether you're patching drywall or old horse hair plaster and lath, these steps will apply to your situation. So sit tight and enjoy, we hope it is helpful the next time you run into a hole or crack in your walls that need a little attention.
For this project you will need:
When we were doing our quick guest bedroom makeover a little while back, we were faced with several large holes around the outlets throughout the room. We had installed these outlets several years back when we had to do some major work to our kitchen below this room (thanks, Termites...), and I just never patched the horrible job I did cutting holes in the plaster. When we started this little patching project, the plaster was jagged and falling apart around each outlet in the room. The first step to the process was to cut a larger hole with a more consistent edge around the outlet to give us something stable to which we could attach the drywall patch. I used the utility knife and a lot of patience for this step, otherwise I would end up with even more crumbling plaster.
Once we removed the plaster, we had exposed enough lath that we would be able to firmly attach a drywall patch directly to the lath. This allows the lath to really support the back of the patch, which lets you secure the junction box to the drywall. In this situation, we've used the remodel style junction boxes that clamp to the drywall with little tabs that tighten with screws (visible at the top of the box in the following photo). These are available at any hardware store.
Our next step involved preparing a small drywall patch that we could screw directly to the lath. In this case, the wiring had already been run and we didn't want to take the whole thing apart, so we cut two pieces of drywall, a small one for the left side and a large one that wraps around the top, right, and bottom. Ideally, you would be doing this before installing the junction box, so you could cut a single drywall patch and then mount the box to that. Either way, the point of this is to give the box something to rest on, and to give structure to the area around the box. In this situation I cut the patch to size with the utility knife, then I make minor modifications to the size with the drywall rasp, shaving off just what I need to give it a nice and tight fit.
With the patch cut attach it to the wall with a few 1 1/4" drywall screws. At this point you should be beginning to sense progress. In our case, after several years of ignoring it, the outlet was finally not hanging freely out of the wall. Go figure.
The next step is applying a fiberglass mesh of some sort to make sure the joints don't end up causing a crack in the wall down the road. This lets the joint expand and contract over time without transferring the crack through to the surface. We prefer to use simple window screen that you buy in large rolls at the hardware store. This fiberglass screen is strong, sturdy, inexpensive, and does a great job. You can also use the yellow self adhesive drywall mesh if you'd like. Try not to use the paper tape in this situation, unless you are working with drywall to drywall joints. If you use the paper, you will probably end up with a crack where the edge of the paper sits before too long. The mesh lets the joint compound really work between the surfaces and bond things together.
Make sure you pre-cut your piece of fiberglass screen that will cover the area. It is much easier to cut it before it has joint compound all over it. The screen should cover every joint around the patch and should overlap the joints by at least a few inches. Once your screen is cut, apply a generous layer of your joint compound to the patch. Make sure you work the mud into the joints really well and that all of the wall where the mesh is being applied has mud on it. Once the whole patch is covered, apply the mesh over the patch and smooth it into place.
If you need to add a little mud to make sure the mesh is embedded, feel free to do it at this point.
Once you have the mesh pushed into the mud, and before the first bit of mud dries, cover the whole thing with a generous and thick coat of joint compound. Try to get the joint compound smooth, but don't obsess too much about it, you're going to be sanding it smooth after the first coat is dry.
Let the first thick coat of mud dry thoroughly. If you've used the bag mix style of mud, you should be set after a couple of hours. If you've used the pre-mixed bucket, you'll probably need to wait at least 24 hours, maybe a bit more. Don't worry if air bubbles show up, the surface shrinks and cracks as it dries, or the surface is quite uneven, this is normal.
Once dry, using your drywall sanding block or sanding sponges, lightly sand the dried joint compound relatively smooth. The point with this sanding is to take all of the high spots off of the wall to give your surface a consistency for the next coat, not to make a perfect surface, so don't worry that it is still really wonky. Once all of the high spots are removed with sanding, use the Shop-Vac to pick up all of the dust, otherwise the second coat might have a problem adhering to the first.
Applying the next coat of mud, your goal is to fill in the low spots left from the first coat to begin smoothing out the whole patch. This coat should be far thinner than the first coat, and you should be using the taping knife to scrape off the excess mud to give a somewhat smooth surface. Using a wide taping knife will give the best results here because it uses the even high points from the first coat as a guide to give a level second coat. Once complete, let the mud dry again. Since this coat is much thinner than the first, it should only take a couple of hours to dry.
As you can see from the photo above, after the second coat the surface is still a bit uneven, but it is starting to get smooth. Next up, another round of sanding. This time, sand a little lighter. If you're using a sanding sponge, stick with a 180 or 220 grit from this point forward, otherwise you will end up putting gouges in the wall that will show through the paint.
Sanding is tedious and messy, but cleanup isn't difficult as long as you aren't sanding it in front of a fan or open window that blows the dust everywhere, and as long as you have a Shop-Vac with a drywall filter bag in it. Without the filter bag, the Shop-Vac will eventually start blowing the dust all over the place once it clogs the less restrictive filter.
Once sanded, repeat the mud step one more time, let dry, and sand a final time. You should be left with a smooth and consistent surface that looks great. No pits, no gouges, no bumps.
At this point, your patch should be looking great and is ready for paint. If it isn't as smooth as you'd like it, it doesn't hurt to do a fourth or fifth coat. Each successive coat should be thinner than the last, and each time you should be using the already smooth surface as your scraping guide.
In our project, I also had to caulk the cracks in the baseboard and let them dry. Before painting, wipe the patch clean with a rag to get all of the residual dust off of the wall and surrounding areas, otherwise the paint will pick up the dust and leave it in clumps all around the wall. Then you're ready to prime and paint. Since this is fresh joint compound, it is very important to prime the area before painting. Once painted, you should be left with a smooth and great looking patch that visitors would never know just how horrible it once looked.
Since this was a quick patch job and not a major overhaul of the room, there is still a fair amount of unevenness at the baseboard and bumpy paint. We'll have to correct all of that when we get around to really doing this room over in the future. But I hope these steps help you to tackle the next drywall or plaster patching project in your home with courage and confidence. Plaster is a beautiful thing in old homes, but people are often too scared to attempt a patch and instead have the knee jerk reaction to tear it out and start over.
What do you think? Patching plaster or drywall isn't that hard, especially once you've done it a time or two and know what to expect. Do you think you can take on your next patch with more confidence? Any tips or tricks I've not covered here that you like to include in your patching process?