Last Updated on March 17, 2023
Drywall corners are difficult to finish and often crack. Finishing drywall corners can be tricky, and if they’re not done correctly, they may crack.
This is a common problem that can be fixed, but it’s important to understand the underlying cause of the cracks. By understanding the causes of corner cracks in drywall, you can take steps to fortify them and prevent them from happening again.
If cracks do appear, this guide will show you how to repair them quickly and easily.
Why does drywall crack at corners?
There are a few different reasons why drywall corners may crack. The common causes are:
Too much mud.
Often, when drywall corners crack, it’s because the installer simply applied too much joint compound (mud) to finish the corner. The excess weight of the mud will eventually lead to cracking.
Plaster and lath behind the sheetrock
Anytime plaster and/or lath is visible through a gap in the drywall, it’s possible for that gap to crack. If lath or plaster is visible through a gap in the drywall, make sure there’s no gap between the back of the new piece and the existing walls (or ceiling).
Strong right angles are less flexible than curved sections. Strong joints with 90-degree angles can crack as they try to accommodate slightly crooked walls.
Out of square walls
If the walls are not straight, drywall corners tend to crack where one side meets another.
Warped or uneven boards
Anytime a board is warped, it will need extra mud at the corner to cover up that warp. When too much mud is used, it can seep out and cause a problem.
Ultra-thin paper drywall
The thinner the paper (or fiberglass) in the drywall, the more likely it is to develop cracks over time because it has less strength and durability than thicker grades of paper or mesh-faced drywall.
Hot and humid climates will increase the rate of drying, causing the compound to dry too fast and crack. Drywall cracks most often during periods of very high humidity or heat.
How to Repair Drywall Cracks in Corners like a Pro?
The best way to prevent drywall cracks in corners is by taking steps to fortify them before they happen. There are a few different ways to do this. Here we want to show you how to repair drywall cracks in corners in the most effective way possible.
What You Will Need?
Drywall compound (joint compound)
45- and 60-grit sandpaper
What is the Proper Procedure for Repairing a Drywall Crack?
Many cracks can simply be filled with a good compound and sanded down. However, if the crack is so severe that it needs more than just mud, you can use fiberglass mesh tape and drywall compound to reinforce the corner before finishing.
Remove loose material and clean the area
Run a putty knife over the crack to pull out any loose pieces of mud or gypsum from it. Use a damp cloth to wipe down the surrounding area, then allow it to fully dry before continuing.
Reinforce the corner with mesh tape
Cut a piece of fiberglass mesh tape to fit over the drywall crack. Apply a thin layer of drywall compound or spackle to both sides of the tape using a putty knife, ensuring that there are no gaps between the mesh and your wall. Feather out both layers of mud so they blend with your existing wall.
Finish the corner
Once the compound has dried, use a drywall knife to apply a thin layer of mud over the tape and compound. Allow it to dry, then sand it down so that it is flush with your existing wall.
Prime and paint your repair
Prime and paint the repaired corner so that it blends in with its surroundings. You can also try using a matching paint or wall finish to minimize the difference in color if your surrounding walls are not smooth.
Prevent future cracks by fortifying the walls and adding corner bracing
To prevent future cracks in your drywall corners, you can take a few steps to fortify the walls themselves. You can also add corner bracing to help keep the walls from moving and compromising the drywall joint.
Fortify the walls by adding sheetrock anchors.
Sheetrock anchors can be inserted into wall studs to provide extra support and stability to the surrounding drywall. This will help to prevent the walls from shifting and compromising the corners.
Add corner bracing to keep the walls in place.
If you’re seeing a lot of cracks in your drywall, it may be because the walls are out of square or are otherwise not straight. You can install corner bracing to keep the walls in place and prevent future cracks.
Use “lucky mud”
One way to make your drywall stronger and less likely to crack is by using lucky mud. Lucky mud is a quick-drying compound that can be used instead of a joint compound. It’s slightly thicker than regular joint compounds, which makes it ideal for filling larger cracks.
The downside? It’s not as easy to sand as regular mud, so you’ll have to do a little extra work after it dries.
Use corner tape
If you’re looking to save time in the long run, consider using corner tape products instead of filling cracks in your drywall.
Corner tape is specifically designed for use in corners and around the edges of walls. It works similarly to fiberglass mesh tape but comes pre-cut in a rounded edge shape. This makes it perfect for quickly and easily filling cracks with a few layers of compound.
Use a putty knife with your mud
When applying mud to drywall, use a putty knife rather than a taping knife. Putty knives are much larger and will help you distribute the mud over any large areas more quickly and evenly than most other tools will allow.
Don’t layer too much mud in one spot
It’s important to remember that you only need to apply enough compound or spackle for your repair in one thin, even coat.
If you find yourself applying several thick layers of mud to the same area, it means you’ve applied too much at once. Stop and allow the first layer to dry before applying another.
Use a damp sponge or cloth for spackling
If you’re using spackle to fill holes in your drywall, try dampening your sponge with water rather than throwing it directly into the bucket. A slightly wet sponge will help you pick up more compounds while also creating an instant bond between the new mud and your wall.
Choose a primer before painting
You probably won’t need to use a primer when repairing small holes in drywall, but if you’re filling larger cracks or are unsure about whether your repair will be enough on its own, it’s best to play it safe.
Tips for working with do-it-yourself on how to repair drywall cracks in corners
If you’re a homeowner who is looking to patch up some minor cracks in your drywall, here are a few tips to help make the process go a little more smoothly:
- Make sure that all of the compounds have dried before attempting to sand them down. This will help to avoid creating a mess and make the repair job more difficult than it needs to be.
- If you’re using a matching paint or wall finish to minimize the difference in color, be sure to apply it after the repair has been completed.
- To fortify the walls and prevent future cracks, you can add sheetrock anchors or corner bracing.
- When applying mud to drywall, be sure to use a putty knife rather than a taping knife.
- If you’re using spackle to fill holes in your drywall, try dampening your sponge with water rather than throwing it directly into the bucket.
- You only need to apply enough compound or spackle for your repair in one thin, even coat.
- If you want to be sure that your paint or wall finish matches perfectly, apply it after the repair has been completed.
- For small cracks, you most likely won’t need to use a primer; however, if you’re unsure about whether your repair is going to be adequate on its own or if you’re filling larger cracks, you should apply a primer before beginning the painting process.
- If you’re having trouble with cracked drywall, consider installing some sheetrock anchors or corner bracing to reinforce the walls and prevent future cracks from occurring.
What is the best way to apply mud to drywall?
Ans. Apply in thin, even coats.
What should I do if I have applied too much mud to an area?
Ans. Stop and allow the first layer to dry before applying another.
What is the best way to fill holes in drywall?
Ans. With a spackle and a damp sponge.
Do I need a primer before painting?
Ans. If you’re unsure, it’s best to play it safe and apply a primer. For small cracks, you most likely won’t need to use a primer.
What primer is best for repairing drywall cracking in corners?
Ans. A primer specifically designed for repairing drywall is best. However, you can also use an acrylic primer.
Dealing with minor cracks in your drywall is a lot simpler than you may think – just follow these simple tips and you’ll be able to repair them in no time.
Not only will this help to keep your walls looking their best, but it can also prevent more serious damage from occurring down the road.
Your walls will thank you for it, and so will your wallet.