100% gut and replace it all. With a qualified pro. https://www.ceramictilefoundation.org/homeowners-guide-to-hiring-qualified-tile-installer

Remove everything that's damaged. Treat with concrobium and let it dry.

It sounds like you are trying to save the curb. You can't. The shower floor is a system of several layers that each serve a purpose. The curb is installed as a part of that process. Companies like Kerdi sell hard foam ones that you may like better, anyway. Figure out what waterproofing method you are going to use, and study it so that you know what you are doing. Or go back up to Mackdolan's post and hire the right pro. Half the people who call themselves pros seem to not know what they are doing, so start your conversation with them on their waterproofing method and then research it so that you understand how it is installed and discuss it with the pro to be sure they are going to do the right steps before you hire them. Have the contract written so it says that they will install the shower using TCNA standards (Tile Counsel of North America).

Yes, like others have said the whole thing needs to be removed (including the tile floor) and redone. The waterproofing on the walls needs to be tied into the floor, they can’t be done individually.

is that the old floor on the shower floor? just take everything out and redo. looks like the shower was never properly waterproofed. so, the shower floor prob isn't done correctly. you can't salvage one thing, so just rip it all out. It will be easier that way, believe it or not.

start from square one and do it correctly. If you don't know how, hire a qualified tile expert.

wear a mask when handling and cleaning the mold. they have mold killer at the big stores you can buy. chlorine bleach apparently, from what I've just learned, will not do the job.

Gut the entire thing. Don't tile over ANYTHING in there. Get a pro. DIY is not for this. You want water PROOF. Which in the end means no more mold. You also never want to tile a curb. Use a solid surface . Please.

Go to a "tile shop" which is defined thus; they sell TILE. They do not have pallets of tile, or grout, or tools. They do have Tile Pros...on speed dial.

No, chlorine bleach will NOT do the job. It's perfectly acceptable to tile a curb if that is what you prefer.

This is not a DIY job unless one of you is a licensed builder and plumber. The entire shower needs to be removed, the mold removed, damaged wood replaced, and all of the shower walls and floor must be waterproofed to meet code.

"Can I spray the mold with bleach in the process to kill it?"

I'll simply re-emphasize what catbuilder wrote. I'll even use caps to get the point across:

BLEACH DOES NOT ERADICATE ESTABLISHED MOLD.

Bleach is not approved as a "mold killer" by any government agency. It's not authorized in flood cleanups, or mold remediation. In the simplest of terms, the sanitizing agent in bleach can not penetrate into porous materials. It simply sits on the surface. The agent (water) that carries the sanitizing molecule can penetrate into porous materials. So again, in simplistic terms, what can happen is "bleach" will kill the surface mold, but the carrying agent, water, will penetrate into the material and actually feed the mold roots, possibly generating new growth. Bleach may eradicate LIGHT surface mold that has not yet penetrated into the substrate.

Think of using bleach the same as going at lawn weeds with a weed wacker. You eradicate the top growth, but the roots remain unscathed.

Concorbium, the product that catbuilder recommended, is also a product that I use. It's available at big box retailers and is quite effective.

As to your rebuild question, yes, since you're gutting this, certainly remove the rotted curb as well. After gutting, as a precaution you can spray the entire area; the subfloor and the opened up framing bays, with Concorbium or equivalent. It'll eradicate any mold spores that may remain.

Then rebuild.

OMG-get a pro involved ASAP.

You should hire some professionals instead of DIY. Showers are constantly clad in moisture and humidity. These factors make it an easy ground for the birth and development of mold and mildew. I got rid of all my shower mold and mildew with the help of D’Sapone’s shower restoration service.

You need apro waterproofing is an art and best not DIYed gut the whole space curb and all

We have kept going with the demo and are down to the subfloor and the studs. We found old water damage in the drywall by the shower so we ripped all of that out. We also took up the old tile floor. And the vanity. And most of the drywall. What started out as a "simple" shower retile is turning into an entire new bathroom. We found the source of the mold. When the old homeowners switched out the shower doors for a frameless glass one, they didn't plug the old anchor holes in the tile curb and water had slowly been getting in there over the course of three years. It's a good thing that shower doesn't get much use or it would have been much worse. The shower pan and curb were hot mopped (we are located in SoCal) but the walls had no waterproofing whatsoever. That may have been code back in 1994 but we all know it's not code now. Thinking about using a kerdie board system on the new install. Does anyone have any experience with that? We called a professional to come in today to look and see where we are at, but we do plan to do a lot of this ourselves.

I wonder if something like this can be covered under homeowners insurance? I'm thinking no since not an accident nor act of God, but curious to know for certain.

Not covered under insurance. I would caution you that even highly experienced DIYers shy away from building a shower. There’s a lot of complexity involved, and it takes months to come up to speed in the proper way to do things.

I’ve used Kerdi, but there are other foam board systems that are just as good, and less costly. If Wedi is in your area, I’d highly recommend that. If you are going for Kerdi’s lifetime warranty, you need a professional who is used to providing that service, registration, and the documentation that is needed to go along with that choice

We wondered too about the insurance but there's no way to prove the water damage and mold didn't come from us (it didn't) it came from the previous owners who were lazy and incompetent.

OMG they did the demo diy, and nothing went wrong....Good job, Futura4....

Nothing went wrong other than mold spores scattered throughout the home because it wasn’t sealed off and an HEPA air scrubber used to create a negative pressure zone. Nor was a HEPA vac used to aid in debris removal. Nor was PPE worn to protect during the demo and subsequent treatment.

Mold isn’t as deadly as the black mold alarmists would have. But it’s a pretty nasty health issue if even basic safety procedures that any pro would use aren’t followed.

Kerdi Board is fine. I used Kerdi membrane over cement board in my shower about 20 years go.

I'll recommend you look at USGs Durock Foam Board system as well. Here's a link to their shower pans, You can buy a stock size, or they'll custom fabricate one for your shower with a 5-7 day turn-around.

They have installation guides and there are plenty of videos out there that show the basic steps. Don't get entrapped by a one-off yahoo looking for click hits. There are some pretty competent professional tile guys that have great channels.

IF you understand that planning and prep is ever so important. IF you can follow installation instructions. IF you don't take short cuts...do it once, do it right...when you recognize you've made a mistake? Step back, take a breath, and realize it's easier in the long haul to take the hit on the timeline, correct the mistake, and move on. Many people find that it's the glossing over of mistakes that cause myriad problems later in the project. And of course, you need the skills and perseverance to carry you through the project.

Showers are within the realm of a competent DIYer.

Good luck!

" It's important to take proper precautions to prevent the spread of mold. "

WOW, such great advice......................

I also have some mold issues in my bathroom after I renovated the entire house.

And? : ) If you have mold or a question? Start a thread . Most don't read anything four years old as this thread is

I'm no expert, but I've heard vinegar works well for killing mold on wood surfaces. Maybe give that a shot before bleach? And yeah, mold spores are tricky, so sealing the wood with a mold-resistant primer could help. Definitely want to prevent that stuff from spreading. Considering you're in Houston, TX, maybe look into a local mold remediation company for some pro advice. I stumbled upon this company, mold remediation houston they seem to know their stuff. They might have some tips or even offer a consult. Anyway, good luck with your project!

Bad advice. There are now specific mold-killing products. No need for vinegar or bleach to do half-@$$ed jobs.