How to Repair Wall Cracks

Being a homeowner comes with its fair share of maintenance and repair projects, many of which – like fixing minor cracks in the wall – you can do yourself at home. Whether you’re dealing with drywall, plaster, or concrete, it’s possible to repair cracks in just a few hours with a handful of basic materials.


EditFixing a Crack in Drywall

  1. Buy prepared joint compound or mix it yourself. If you buy it premade, look for all-purpose compound which can be used for all coats. If you make your own, use setting-type compound powder and follow the instructions provided on the container.[1] All of these compounds can be found at a hardware store.
    Repair Wall Cracks Step 1.jpg
    • Setting-type compound powder is more difficult to sand and to prepare properly so it is not the best option for beginners.
  2. Cut a V-notch along the crack. The “V” shape will help keep the compound in place.[2]
    Repair Wall Cracks Step 2.jpg
    • Remove any debris inside the crack with a vacuum hose or by simply scraping it out.
  3. Apply coats of joint compound over the crack. Use a putty knife. Let the compound dry completely between coats. Layer on as many coats as necessary to fill the crack. The average is 3 coats.[3]
    Repair Wall Cracks Step 3.jpg
    • Depending on what type of compound you use, it can take anywhere from 45 minutes to 24 hours to dry.[4]
    • If the cut is deeper than , you may need to press a strip of mesh or paper tape into the first layer of compound before it dries to better seal the crack.[5]
    • Thinner coats are ideal as they’re easier to sand down to match the wall once dry.[6]
  4. Sand the dried joint compound with medium-grit sandpaper. Use a sanding block to smooth out the section to the flatness of the wall. Always wear a dust mask when sanding to avoid inhaling particles.
    Repair Wall Cracks Step 4.jpg
    • 80-grit (medium-grit) sandpaper can eliminate larger bumps whereas a finer 120-grit can be used for finishing touches.[7]
    • One option is to sand in between coats to avoid having to sand as much at the end.[8]
  5. Paint over the crack with latex primer followed by wall paint. If you don’t use primer first, your patched area won’t blend in properly with the rest of the wall.[9]
    Repair Wall Cracks Step 5.jpg
    • The exception to this is if you used a paint and primer in one. Then you only need a coat or two of the paint directly on the affected area.

EditRepairing a Plaster Wall Crack

  1. Press gently on the wall near the crack to see if it gives. If it’s easy to press down or if the wall flexes at all, the plaster has likely come apart from the lath.[10] This requires reattaching the two together and cannot be fixed by a simple patch job. Contact a professional for help.
    Repair Wall Cracks Step 6.jpg
  2. Widen the crack using a putty knife if it’s less than wide. It sounds counterproductive but scoring (lightly scratching) the crack creates a wider surface for the joint compound to more easily adhere to.[11]
    Repair Wall Cracks Step 7.jpg
  3. Spread a coat of joint compound over the crack. Do so with a taping knife. Use a setting-type compound instead of drywall compound as it is stronger and can affix to plaster more securely.[12] Apply in thin layers.
    Repair Wall Cracks Step 8.jpg
    • Dampening the crack before applying the compound will remove any loose particles and help the compound hold better.
  4. Press fiberglass mesh tape firmly into the wet compound over the crack. Cut the strips to size with scissors. This self-adhesive tape will prevent the crack from growing.[13] Let dry.
    Repair Wall Cracks Step 9.jpg
    • For the setting-type compound to dry thoroughly, your room should be between .[14]
  5. Apply 3 layers of compound over the taped area. Let each coat dry completely in between. With each additional layer, extend the compound another outside the previous layer’s edges. Your last layer should extend beyond the original area.[15] Lightly sand each layer with a fine sandpaper to remove bumps in between coats.
    Repair Wall Cracks Step 10.jpg
    • Use a feathering technique when applying the compound. With the knife at a 70-degree angle, start at the center and pull the knife to the outside edges of each coat, increasing pressure the further away from the middle you get.[16]
  6. Paint over the patched area to match the rest of the wall. If you can see a raised section where you did your repair, sand it flush to the wall before painting so it blends seamlessly.
    Repair Wall Cracks Step 11.jpg
    • It’s smart to wait at least 24 hours prior to painting to ensure the compound is completely dry.[17]

EditFilling a Crack in a Concrete Wall

  1. Enlarge the crack with a chisel and hammer. A technique known as undercutting (which is essentially chipping away at the concrete) should be done to below the edges of the crack. This provides more surface area for the patching material to grip.[18]
    Repair Wall Cracks Step 12.jpg
  2. Clean debris from the crack using a wire brush. A vacuum can also help get rid of dust, pieces of concrete, or dirt lurking in the crack. Rinse it with water and dry thoroughly with a towel.
    Repair Wall Cracks Step 13.jpg
    • If you don’t have a wire brush, a flat head screwdriver or air compressor will work.[19]
  3. Prime the area with a concrete bonding adhesive. This will help the patching material adhere better to the concrete. You’ll want to use an old paintbrush to spread a thin layer around the edges and deep into the crack.
    Repair Wall Cracks Step 14.jpg
  4. Apply multiple coats of concrete patching with a putty knife. Press each layer into the crack and let dry completely in between coats. Repeat until the crack is filled and level with the rest of the wall.
    Repair Wall Cracks Step 15.jpg
    • You can also use a pointed trowel if you don’t have a putty knife. This is good for pushing the patching into the crack.
  5. Add texture to the patched area before it dries. Matching new concrete to old concrete is difficult because it’s so smooth. Rough the last layer up with a broom or any tool while it’s still wet to make it look more worn.[20]
    Repair Wall Cracks Step 16.jpg
    • Sealing the patch with a heavy-duty water-based polyurethane with a brush can prevent stains and other marks.[21]


  • If cracks are long or very deep, the repair process is much more involved and beginners may want to hire a professional.

EditSources and Citations

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Source: how

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