advice on drywall water damage repair

[Stan Calow]

I'm hoping for the usual good advice here on how to repair the damage to this wall just outside a step-in shower. It looks to me as if its greenboard underneath, not regular drywall. Maybe joint compound at the corner that is swelling? And after repair, what can I coat or cover the paint with to keep water out without radically changing appearance? Thanks for input.
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[Frederick Skelly]

Stan,
I had a pretty similar problem. Mine was fixable with just joint compound and paint.

Have you figured out why it is getting wet in the first place? Mine was a deteriorated sweep on the door bottom that was letting spashes hit that wall. (It was at exactly the right height.) I put in a small drip rail and all was well. If you can nail down the cause, that will help prevent a recurrence (at least it did here at my place).

If you cant figure that out, then you can prolong your fix by just running the towell over that area to remove any water drips, after every shower.

Good luck.
Fred

[Jamie Buxton]

Do you have any more of that stone which is used as a baseboard? If you do, use it to cover the damaged sheetrock. And the added stone would not be damaged by further water intrusion.

[Stan Calow]

Source of water is the towel rack that is just above this - wet arms reaching for the towel, dripping down the wall. I will move this but all the other walls might have same issue. I was hoping there would be a clear coat waterproofing I could put on top of a repainting. Using extra pieces of the tile backsplash is a good idea.

[Bill Dufour]

hard coat plaster not drywall compound. Probably hard to find just use stucco mix or mortar. Maybe sanded tile grout.

Bil lD

[Stephen Tashiro]

I'm hoping for the usual good advice here on how to repair the damage to this wall just outside a step-in shower.

Is grout washed out from the bottom of the stone in the baseboard? To me, it looks like you have water getting into the wall from the backside, not from splatter on the front. Since you are going to make a repair and presumably paint, I'd cut out a portion of the drywall to examine the back side of it and the inside of the wall.

[Doug Garson]

I agree with Stephen, water must be getting into the wall. I can't see water dripping off your hand reaching for a towel causing the problem. If you do cut out a section to inspect a better choice of material for wall board in a wet zone is Kerdi board.

[roger wiegand]

I agree this is very unlikely to be casual dripping, probably a failure of caulking around the door, or worse, that corner of the pan. (unless you routinely have puddles on the floor-- in which case get in the habit of wiping them up) Look harder for where the water might come from before repairing lest you be doing it again in a couple months or years.

I have much better success with any drywall/ or plaster repair if I tear it back to sound material rather than patching over weakened material. Cut out the offending piece and patch in a new piece of drywall or blueboard, then tape and finish with setting drywall compound or, better plaster over blueboard.

[Dave Zellers]

I agree as well. That bubbling of the paint looks like it is coming from behind. It's been going on for a while- the corner bead is badly rusted. I'd find the source before I did any repairs. Is the plumbing on that wall in the shower? Maybe you have a small but persistent leak. Is it possible to get a look at the floor under that spot?

[Stan Calow]

Thanks everyone. There is no sign of water damage underneath the floor (unfinished basement). The piping to the showerhead is about 3' away on a perpendicular wall. The inside of the shower, up to that corner is a 8' solid (seamless) sheet of Onyx (a thick material used for lavatory tops) as is the molded one-piece floor with threshold. There is no dripping door, its a walkout. There is probably some splashing that gets on the threshold from walking and makes its way over, but I'm sure its all external. The grout is breaking up under that one tile, I believe because the expanding material is pushing it out. Should be caulk not grout anyway. If I cut out and patch, is there some other water-resistant material I could use in place of plaster or drywall compound? Like a urethane sealant or something paintable?

[Bruce Wrenn]

After removing damaged dry wall, use setting compound to tape and finish joints. Setting compound is just that, it sets rather than drys. Be aware, because it's a chemical reaction, you can't mix left overs from first batch with a new batch. They both will set up at the same time. Mud pans, and knives have to be completely cleaned between batches. Setting coumpounds come in various setting times. Remember setting times, and working times are not the same DAMHIK, but I do!

[Tom M King]

If you were closer, I'd give you what you need to make a waterproof plaster. I don't know where you could buy it. It would be best if you could stay away from Gypsum. The interior of sheetrock is gypsum, and any commercial plaster I know of has gypsum in it.

The ingredients I would use cost very little, for the quantity you need, but I don't know if they are even available in small quantities. Without going into a long text, that probably wouldn't be used anyway, I would mix Lime Putty (which is nothing but hydrated lime sifted into water, and left to sit for as long as possible), Portland Cement (I use white for my mixes of plaster-as gauging), and Marble dust (really nothing more than ground up marble, which is a type of limestone), and install that over expanded metal lath. Cement and marble dust is used for casting figurines, and can be quite strong with the right proportions.

I make my own Lime Plaster, to my own recipe, for work in old houses. They used to use gypsum for gauging, which is really nothing more than something added to make it set up in a little shorter time than forever. A small amount of Portland cement can do the same thing, and if you don't add too much, it can have the same flexibility as that which uses Gypsum for gauging, and has the added advantage of being water resistant.

Gypsum expands when it gets wet-the reason sheetrock disintegrates when it gets wet.

Sorry this is probably no help at all, as it would cost more than it's worth to buy even the smallest quantities to make this with, unless you have some of it laying around. The chemistry is all really simple. You can buy small quantities of marble dust off ebay, or if you are close to a marble mine, they will give it to you.

edited to add: Using Portland Cement in plaster is not something I invented. The best commercial finish coat plaster I know of, Diamond, strangely enough sold by a company called US Gypsum, has Portland Cement in it.

[michael dilday]

You could try a 4x8 plastic wall panel glued to the sheetrock after the sheetrock replace/repair. Available at Home Depot for $21.56.

[Thomas McCurnin]

I don't believe that a few errant drops of water each day is causing this. I believe it’s coming in from behind that wall, and my best guess without pictures of the interface between the curb and the wall is that this may be a shower pan issue. Unless you know for a fact that the membrane was installed correctly, I think it’s a lack of a proper membrane wrapping the curb.

That membrane is supposed to completely wrap the curb and the curb is supposed to be sloped about half a bubble to the inside. A lot of hacks skip this step.

You can figure it out by removing a portion of that drywall and seeing if the studs are wet or there is black mold. Another way is to do a shower leak test just like your county building and safety would do, purchasing a shower drain plug and screwing it in place (you’ll have to remove the grate) then fill the shower with water unto just below the curb. Mark the water level with a sharpie.

Wait 48 hours and if the level of water has gone down, you have problems.