Does Drywall With Mold Need to Be Replaced?

David J. Allen

I spent the better part of 2 ½ years learning about mold and indoor air quality because my child's life depended on it. Now I help others avoid ever having to experience the same thing. The mold industry suffers from conflicting opinions and I do my best to distill loads of data into something practical and useful. I love hearing from and helping readers. • "A house desecrated by mildew, mold, or fungus would be a defiled place to live in, so drastic measures had to be taken." — Leviticus 14:45

When you’re dealing with mold growth on your drywall, every situation is different. In some cases, you’ll have the opportunity to eliminate the fungus without damaging or replacing the drywall. However, you won’t always be so lucky.

Sometimes, if the mold infestation is large or serious enough, your best course of action will be to replace the drywall—or at least a section of it. Whether or not the affected drywall is painted is also a factor; with painted drywall, your odds of being able to remove the spores using antifungal cleaner and old-fashioned elbow grease will be much better. 

Removing Mold from Drywall

Whenever you’re dealing with a mold infestation on drywall, the odds of removing the fungus and keeping the wall intact are relatively slim. Ultimately, it comes down to how long the mold has been there and how much it’s been able to spread. If the mold growth is fairly new, it may not have expanded much or worked its way into the pores of the drywall.

If the wall is painted, it’s typically harder for the fungus to work its way past the layer of paint, which should buy you some extra time. In those cases, the majority or all of the mold spores will still be on the exterior surface, providing you with an opportunity to clean it.

If you’ve decided to make a heroic attempt at eliminating the mold from your drywall while preserving the wall itself, you’ll need a few things. Namely, you’ll need a mold-killing agent (anti-fungal sprays usually work well, as do vinegar solutions) and PPE equipment such as goggles, rubber gloves, and a facemask. You’ll also need a brush with soft bristles or a firm sponge. 

After ventilating the area, you’ll want to spray the affected section of the wall with your anti-fungal solution, then scrub it vigorously with the brush or the rough side of the sponge. If you’re able to scrub away the entirety of the mold colony, all that’s left to do is let the wall dry and hope for the best. Once you’ve completed the process, you’d be wise to monitor the drywall for the next few weeks to see whether or not the fungus returns. If it comes back, you’ll likely need to move on to plan B. 

What if the Mold Can’t Be Removed?

If you’re either unwilling to attempt or unable to remove the mold spores from your drywall, you really have but one decision to make: Replace the entire drywall or only a section of it? To ensure that you’re making a wise choice, you need to determine whether or not the structural integrity of the wall has been compromised. If it has, your most prudent course of action will be to invest in a replacement for the entire drywall. 

So, how do you glean the status of the drywall’s structure? You can start by pressing on different sections of the wall. If it’s unusually soft to the touch in multiple areas, that’s a major red flag. Additionally, if it’s evident that the mold growth has worked its way deep into the wall, it likely means that the drywall is past salvaging. For example, if the mold is clearly visible on both sides in the same spot, that’s a pretty strong indicator that you won’t be able to save it.

If it seems that the interior structure of the drywall is intact, though, you probably have the option of cutting out the mold-damaged section and preserving the rest. If you choose to go this route, you can do so by following these steps:

  • Move all furniture and belongings away from the area and lay down a plastic sheet.
  • Ensure that the area is well ventilated and equip yourself with protective gear.
  • Use a stud finder to locate wooden supports behind the wall, as you’ll need them to attach the replacement drywall.
  • Mark the section of the wall that you intend to cut out using a pencil and a straight edge. Remember to mark an area roughly two feet larger than the visible mold.
  • Using a utility knife, carefully cut along the lines that you’ve marked.
  • Place the removed drywall pieces on the plastic sheet with the mold facing up to avoid further spread.
  • Apply an anti-fungal solution to the wall cavity to eliminate any potential leftover spores.
  • To ensure a neat fit, measure the length and width of the newly open section of the wall, then cut your replacement drywall so that it perfectly matches the size.
  • Using screws, attach your replacement piece of drywall to the wall. To patch the seams, you can use a joint compound.
  • After letting your new section of wall dry, sand it down.
  • Carefully dispose of the moldy drywall and, if necessary, vacuum the room using a HEPA vacuum cleaner.