I tried searching for this answer but only found one other question that seemed relevant, but doesn't exactly answer my question.

My water heater blew while I was on vacation. I didn't have insurance on my home at the time due to a lapse that occurred to a disruption in my employment so now it seems I'll have to clean up the mess without help.

After removing the bottom 14" Of drywall it was clear that the studs nearest to the heater have a fair about of mold damage near the floor. As these studs face the exterior foundation, I'd like to remove the moldy studs to prevent it from spreading.

After cutting out the stud and replacing the plate, how do I replace the bottom part of a stud that has mold?

  • Do I just cut an equivalent block of wood and place it under the hanging piece?
  • Do I need to brace the block? should I brace it on one or two sides?
  • What type of bracing should i use? Aluminium? Wood?


Moldy Plate and Stud

  • 2
    Sorry if I'm being dim, but why would you need to cut the stud out in the first place? Is it rotted? If it's sound, but moldy, wash it down thoroughly with a bleach solution. Jan 21, 2018 at 22:52
  • Sure, I guess I could be more clear that I'm planning to cut the stud. Cleaning a moldy stud with bleach, only kills mold at the surface, it will still be rooted inside the stud, and as this is facing an exterior sub-grade wall, its likely to see a bit of moisture again and the mold would grow right back.
    – virtualxtc
    Jan 22, 2018 at 1:22
  • Your insurance company would have never covered what you thought you needed but I am glad you were able to repair it did you add any shear bracing since you compromised the wall?
    – Ed Beal
    Oct 1, 2020 at 22:36

4 Answers 4


You can repair the cut studs by replacing the removed portion with new material of the same length and then adding a "sister" stud right next to the repair. the sister should extend all the way to the bottom plate and be toe-nailed to it and it should extend past the repair overlapping the remainder of the old stud by a good three feet. Nail both the replacement piece and the remainder of the old stud to the sister with 16d nails every foot or so. Assuming you are replacing one foot of the old studs and the sister needs to overlap the remainder of the old stud by three feet, you will be removing about four feet of sheetrock. Because you are committed to installing some new sheetrock already I would suggest "In for a dime, in for a dollar" and just remove the entire wall. Then you could skip replacing the cut off portion of the old studs and simply run the sister all the way from plate to plate. Any extra time installing the extra rock will be regained by not having to replace the bottoms of the studs and not having to tape up the joint from new rock to the old, painted rock. (this kind of joint is much easier at the ceiling)

  • Ouch - removing the whole wall and ever just sistering with 3' of lumber means I'm gonna have to talk out a lot of wall that has already been mitcoulsly cut out for gas, drain, electrical and water supplies. I was hoping to only need to touch the bottom 2'. Perhaps I just cut a second 'plate' that could be raised above the floor adorned plate by short 1' studs?
    – virtualxtc
    Jan 29, 2018 at 18:42
  • I had a lot of wall mounted appliances on the wall above the plate, so this isn't really practical as a solution. I did end up a box framed with studs in it that aligned to the studs above - kind of like splitting a jack stud, but am wondering what the advice on this is.
    – virtualxtc
    Mar 28, 2018 at 7:27

For a 1 time event like a broken waterheater or pipe failure I doubt the studs need to be replaced. A 3% Hydrogen peroxide works better than bleach and dosent stink. All wood has mold spores at the lumber mill we spray the wood after the finish cuts or it will look ugly in a few weeks. The fungicide is only a short term preventive measure, keeping the wood dry is the only way to prevent growth. Using a screwdriver push in on the wood If it is rotten the blade will go in with ease If just surface mold the screwdriver won't go very deep unleaded pushed hard. If the wood is sound a 3% hydrogen peroxide and water solution is all that is needed to kill the surface mold once the area is dry replace the insulation and sheetrock.

  • +1 for the peroxide recommendation as I was unaware of it. The flood lasted for more than a week (long story), thus I'm worried the mold is pretty deep. However this doesn't answer my question and the wood pushes in pretty easily, though as you can see it almost looks like it had large mite, or ant issues at one time (holes are too big to be termites).
    – virtualxtc
    Jan 29, 2018 at 18:35
  • 1 week is not long enough to cause rot, yes some mold but no structural issues.
    – Ed Beal
    Jan 29, 2018 at 19:42

Marking Peter's answer as correct, as for most people tearing out the extra drywall and sistering in a stud is the correct thing to do. However, I figured I should outline what I did in case someone else ends up in a similar situation to me where tearing out all the drywall seems impractical.

I'm not sure if I'm using the correct framing terms, I'm just using what I could find as defined when building a doorway/window.

  • I cut all the rotted / ant eaten studs at the same height and cut out the rotting the floor plate below them.

  • I replaced the floor plate with a ground contact treated 2x4 that I ripped down to 2x3 (to match my studs).

  • I drilled a pilot though the with a wood bit then 1.25" deeper into the cement with a masonry bit and fasted them with cement screws (tapcons).

  • I cut a single header plate to span the length between the uncut studs.

  • I then cut jack trimmers and cripples to fill the distance between the header and floor plates (but wasn't able to cut all of them perfectly).

  • I used my longest cut pieces as jack trimmers and fastened them to the header plate with screws from above, then to the existing (King?) with screw at the sides, and into the plate on angle. (I did this to to prevent the new frame from possibly bowing.)

  • I tapped in (or shimmed) the remaining cripple jacks so that they were directly supporting the cut studs above, then drove screws on angles to hold them into the floor plate and new header plate. (I wasn't able fasten them with a screw from above as indicated in my planning diagram below.)

  • I drove screws on angle from the cut off studs into the header plate to secure them.

enter image description here


How bout sistering (on both sides) aluminum 2 by 4s and remove a couple feet of the wood 2 by 4 off the bottom as it may get wet again anyway.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know the details of contributing here. Oct 1, 2020 at 22:57
  • I've barely heard of and have never seen aluminum 2x4s before -- are you sure you aren't thinking of cold-formed steel (CFS) C-studs? Oct 1, 2020 at 23:48
  • I agree with 3 phase I have built hundreds of homes and have been involved in clean room builds and have never seen a aluminum 2x4 but have seen a lot of metal studs that are galvanized steel.
    – Ed Beal
    Oct 2, 2020 at 0:35

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