How to Fix a Bad Drywall Mud Job: Step by Step Guide

Last updated:

The interior of a house is as essential as the exterior. For the interior design to be effective, the drywall mud needs to be installed properly. But what would you do if someone messes up the drywall installation? Can you still fix a botched drywall mud job?

A bad drywall mud job is unsightly to the eye. There is no “universal fix” for any bad drywall problem. However, if the cause of damage is known, there is always a fix. Painted drywall can still be repaired, but it often needs to be reprimed and repainted. 

Drywall (or plasterboard) is a material used on interior walls. It defines the overall appearance of walls. With the right tools, even DIY carpentry enthusiasts can apply drywall and drywall mud. 

Common Drywall Mud Installation Mistakes And Solutions

If you messed up a drywall mud installation on your first try, don’t let this get into you. A lot of people usually don’t get their drywall installation perfect on their first try. Even competent builders can encounter problems once in a while.

Below are the most common mistakes that cause lousy drywall mud jobs and methods of fixing them. 

1. Drywall Tape Peeling

A loose drywall tape installation is the most common type of lousy drywall finishing. In most cases, it can cause bubbles to appear on the surface (bubbling will be discussed with further details below.) But the worst thing that can happen is when the edges of the tape get undone. It reveals the blemishes underneath and also breaks the layer of drywall applied nearby. 

Peeling drywall tape is often caused by excess humidity. However, if there is not enough force applied on the edges of the tape during the installation, this will likely make the tape more vulnerable.

How To Fix:

  • Pry the drywall tape from the wall using a knife putty. Remove the portion of the tape with weak adhesion to the wall.
  • Using 150-grit sandpaper, smoothen out the area where the tape was attached. This is to remove any uneven areas and leftover tape. Make sure to sand in the direction of the removed tape strips. 
  • Remove the dust with a vacuum or other means. Make sure that there is no leftover dust from sanding in the immediate area. If the vacuum is unavailable, use a dry cloth and knock away the dust.
  • Replace the drywall tape with a slightly larger-sized tape (1-2 inches of overlap is fine.) Press the tape to the surface properly to avoid bubbles from appearing.
  • Use a joint compound and apply it to the newly-installed tape. Make sure that the direction of the compound application is the same direction as the tape. Spread the compound evenly and wait for at least 36 hours before doing anything else with it. If dealing with a smaller patch, a fast-setting compound joint is preferable. 
  • Sand the area again to make the surface smoother and even. Conceal the fix by painting over the patch with the same-colored paint.

2. Drywall Bubbles

Just like the peeling drywall tape problem, bubbles appear because of lousy installation. This time, the tape is not pressed properly into the surface, trapping air bubbles inside. Leftover dust due to sanding is also a possible culprit. 

The fix for this problem is to cut the portion of the drywall tape affected. Unfortunately, you might have to re-do the whole drywall tape, similarly in most cases of drywall bubble problems. Painting the surface will not make the situation better, because the paint would make the air bubbles more visible. 

How To Fix:

  • First, cut the area on the upper and lower portion of the affected area. This is to disconnect the bubbled out tape from good drywall tape. 
  • Pry the tape between the cuts by digging your knife putty to drywall and lifting the bubbled out area. Pull the tape upwards to completely remove it from the wall. 
  • Apply drywall compound with proper consistency to even out the area where the bubbled tape was used to be. Leave an overlap if necessary.  
  • Install a new drywall tape directly to the compound. This time, make sure that the tape is pressed evenly to avoid bubbles. Let the mud dry properly. 
  • Use a trowel to apply a thin layer of drywall compound to the newly dried tape. Do this repeatedly until the area is even. 

3. Popped Drywall Nails And Screws

If you drive a screw or nail too hard, causing the wall material surrounding it to pop. Nail pops are unsightly. To make this repair, you have to know basic carpentry skills and a little bit of drywall compound available. 

Get a 4-in-1 screwdriver, a drill and screws, a hammer, a putty knife, and nail set, and a lightweight patching compound.

How To Fix: 

  • It might be counter-intuitive, but you need to drive one or more new screws near the popped nails to even out the area and reduce the bump around the nail pop. 
  • Use a utility knife to carve out the bump. Ensure that the cut is clean and that no bits of paper or drywall is in the way.
  • By using a nail set, give the popping nail a tap to bury it in the wall. This way, you don’t need to pull the nails back to the surface. 
  • Use a flexible putty knife to apply the lightweight patching compound. It will fill the surface completely and evenly. Focus on the carved area (where the bump was located before) and fill it evenly. But don’t forget to patch the screws you used to remove the bump. 
  • If you over-patched the area with the drywall compound, use sandpaper to remove excess. Get a dry towel and pat the dust off.
  • Paint the wall with the same color and shade as the ones in the surrounding. 

4. Drywall Sanding (Over-Sanded or Under-Sanded) 

There are DIY drywall installations that are keen to make the smooth as smooth and even as possible. In return, they tend to over-sand the area, which causes damages in the paper or fiberglass tape. But on the other hand, some DIY installations are under-sanded. When this happens, the surface can sustain bubble damages, roughness, and uneven painting shades.

In either case, you need to reapply the drywall and possibly re-fix the tape. This is not an easy task for first-time drywall mud installations. But once you’ve done it correctly, even if only once, you should have a feel for the sanding process.

If you’re not confident in your sanding, what you can do is to install a low-angle light. This will show any rises or bumps in the area. 

Prevention is better than fixing the drywall, so make sure that you have proper edge support and framing. Use an adequate sheet size to avoid having to deal with joints completely. And make sure that you plan for other wall additions like electric boxes to prevent adjustments.

Is It Possible To Fix Drywall In Painted Walls? 

Most people would attempt to fix their drywall flaws by painting over the surface and hope that it will not be noticeable. Unfortunately, this method will only highlight the bad quality and poor drywall mud installation.

Even if you apply layers upon layers of paint, the uneven surface will not disappear because the color will follow the finishing shape. So try to fix the drywall first before applying paint.

Unfortunately, it is not possible to fix the drywall of a painted wall without re-painting it again. Most drywall fixes require repriming the walls with the compound. There are even times when sanding and re-taping the whole area is the only fix for a drywall problem (e.g., drywall bubbles). Hence, you need to reapply both compound joints and wall paint to finish the job. 

Drywall installation is a basic yet tedious construction process, and you might want to consider calling for a professional if you don’t have the time. But for DIY enthusiasts give it a go if your up for a challenge!