How can I effectively address an old mold issue in my 70s addition built on a slab with block walls, without signs of moisture?
Asked by Franklin Washington 
6 months ago
Last Updated: June 10, 2024
So, I noticed a mold problem in the house. The addition was built in the 70s and it’s on a slab with block walls. I saw what looked like black mold at the base of all the exterior walls, and about 3 feet of the wall is underground. Oddly, there doesn’t appear to be any moisture, even after two days of rain. I’m thinking it might be old mold that the previous owners just covered up. What’s the best way to tackle this? Is there a product I can use to get rid of it?
Before anything else, I suggest checking out the mold to understand the situation. This way, you’ll be prepared. Also, avoid bleach because it’s not effective; instead, consider using hydrogen peroxide. After treating it, consider using Caliwel paint to prevent mold from returning for up to five years.
Hey , have you heard about using white vinegar for that as well?
If the wooden base plate is sitting directly on concrete, it may absorb moisture. You might want to think about replacing the base plate with pressure-treated wood and sill tape so it’s not in direct contact with the concrete.
Do I really need to replace the framing? I was already going to replace the bottom plate. None of the framing provides structural support. It’s just there to support the drywall because the room is made of block. If I use a spray solution, shouldn’t it seep into the wood?
https://www.homedepot.com/p/Concrobium-32-oz-Mold-Control-025326/100654126
TSP (trisodium phosphate) has a variety of uses
One issue with building on a slab is the potential for mold. I think may have a solution for this. It might be a good idea to use a potent mold killer for treatment.