How to Fix a Bad Mud Job on Painted Drywall – DIY Guide

Author: Pat Freling | Updated: | Affiliate links may be present.

If you’ve noticed dips or bulges underneath your painted drywall, it could be that a previous patch job or mud application didn’t go as expected.

While it may be unnoticeable to your guests, as a homeowner it’s something that can truly bother you. Luckily, there are a few easy solutions you can try and successfully fix a bad mud job on your painted drywall.

If there is a dip in your drywall mud, a second application of mud can help even things out. If there is a bulge, you will need to sand the excess mud away. If the patch job is uneven, consider putting in a whole new patch in that area of your wall.

How to Spot a Bad Mud Job on Drywall

Sometimes, the defective spot on a wall is fairly obvious. But if you’re a new homeowner and looking to spot any defects in your drywall, follow these steps:

  • Visually examine the wall from every angle, paying close attention to the corners.
  • Run your hand along the middle of the wall, feeling for dips and bulges.
  • Take a flashlight to change the direction of the lighting. Sometimes imperfections only show up in certain light.
  • If you are unsure if there’s any flaws, ask an inspector or contractor to examine your wall.

It’s important to find any flaws in drywall, especially in areas where you will mount heavier fixtures like TV’s and mantles. Though some areas might be apparent, be sure you know where each flaw is so you can fix it accordingly, and fix them all at once.

Necessary Tools

Just as with any repair job, you need to be prepared before you start fixing any flaws in your drywall. Be sure you have the following items:

  • Utility Knife — this will help you cut through your existing drywall or cut any purchased drywall to size.
  • Joint Compound — this is your drywall mud.
  • Nails, screws, or other fasteners per the spec of your drywall.
  • Putty Knife — this helps to smooth out the applied joint compound.
  • Sandpaper — to smooth out the dried compound after application.
  • Spray Texture — this is especially important if you have textured walls. After sanding the dried compound, you will want to finish with a coat of texture to match your current wall texture.
  • (Optional) 2×4 pieces — if you are hanging a large piece of drywall, and additional 2×4 piece may be needed in order to fasten it correctly so it doesn’t fall.

Repairing with Additional Mud Only

If you are only adding more mud to areas that have dips or nail holes that were not filled correctly, the process is pretty simple. Take your putty knife and scrape out a small amount of the drywall compound, then apply it on the nail hole or dipped area.

Smooth and scrape off any excess with the putty knife and wait for the compound to dry. If necessary, sand it and use spray texture, then sand it again. Wait at least 24 hours before applying a coat of touch up paint.

Repairing with Sanding Only

If there is a bulge where too much mud was used previously, repairing this area is as simple as sanding away the additional compound, spraying texture if needed, and then using a coat of touch up paint.

Be warned, if you can push in on the bulging spot and there is obvious give to the wall, simply sanding away the excess will not fix the problem. There is most likely a previous drywall patch that has come loose. This will require placing a whole new patch on the wall.

Full Drywall Repair

If you find yourself needing to remove and replace an existing area of drywall, the process is a little more in depth.

Measure and Cut the New Drywall

Start by using a drywall hammer or utility knife to cut a square around the existing flaw. Completely remove the damaged piece of drywall. Afterwards, measure the entire area to be repaired and mark it on your new drywall.

Cut your new piece of drywall per your measurements. Try to place it in the hole in the wall and make sure it’s a snug fit. You may need to sand the edges for this to happen. You want it to fit like a puzzle piece.

Fasten the New Drywall into the Hole

If you have a fairly small patch, smaller than 6×6 inches, you can use mesh tape to secure the new drywall to the hole and mud over it.

However, if it is a larger repair you will want to securely fasten your drywall using the existing studs in your wall. If there are no studs behind the repair area, use a small piece of 2×4 to create a new backerboard.

Measure and cut the 2×4 so that there is at least 1 ½ inch space on both the top and the bottom. Insert it into the hole and drill the drywall screws through the old drywall, then fasten the new drywall to the new backerboard.

Place Your New Mud

Using your putty knife, spread the joint compound over the seam first, being sure to taper it as you spread outward. Then spread it evenly across the middle of the patch. Allow to dry for a minimum of 8 hours.

Sand the Wall

Using drywall sandpaper, sand the dried joint compound evenly until it is flush with the wall. You may apply a second coat of joint compound if needed, just be sure to give it time to dry before you start sanding.

Using a straight edge tool, such as a 4-foot level, place it against your wall to see how flush it is. If you notice it not laying flat, you may need to sand some more in the middle of your patch job.

Add Spray Texture If Needed

Using either knockdown or orange peel texture, apply an even coat on top of sanded mud. Allow to dry and use primer then paint to finish the repair area.

Final Thoughts

Fixing a bad mud may seem like a daunting task, but with a quick trip to the hardware store and some pre-game knowledge, you can have your walls looking good as new in no time.

Avatar photo

About Pat Freling

Pat has been into DIY painting since he was 14 years old. He's painted interior walls, decks, patio, and even the first car that he'd purchased at 18.

Leave a Comment