I have a basement that I am planning on finishing. There was a mold problem. After washing the basement walls, I soaked them in Concrobium. I then painted the walls with a masonry waterproofing paint that's antimicrobial. Two days later, I see brown mold stains coming through the paint. Is the mold still living? What can I do here?
Basement – mold on basement walls
basementmoldpaint
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I did a lot of research when finishing our basement. I eventually went with a wall model recommended by building sciences corporation that, from outside in, is:
- existing exterior wall (concrete, concrete block, etc)
- foam board insulation (XPS or EPS, I went with EPS)
- stud wall
- sheet rock (I went with a paperless product called Densarmor
This is a system that Fine Homebuilding magazine also recommends and is considered valid by the US Department of Energy. I know this because our local building codes were still using the antiquated 'fiberglass + plastic' model and I had to do a ton of research to educate the local code enforcers before they'd approve this.
I went with metal studs for the following reasons:
- they're all perfectly straight
- I can carry 20 of them at a time (makes it REALLY easy to haul into a basement)
- easy to build in-place (no need to frame then tilt-up walls)
- cut with tin-snips in a matter of seconds
- mold can't grow on it
- can be installed without screws (can be crimped in place)
- at the time, were the same cost
- wiring channels are built-in
- you can use thinner studs (it's impossible to find straight 2x2's in wood around here)
There are a few cons, though:
- you can't easily nail into them for attaching baseboard
- you still need to frame out your doors with wood for the added strength
- you can't mount cabinets to the wall with metal studs
As for baseboard, I decided to use the new synthetic foam pre-finished trim. It looks pretty good, is super light, easy to work with and...it's not wood. So I thought it was another great product for a basement. Because it's so light, it was really easy to toe-nail it in to the sheetrock with an pneumatic trimmer.
As for mounting cabinets and such, on the walls where I knew I wanted to do this, I added 2x2's inside the metal studs for support.
The only corrosion issue that I'd be worried about is rust, and that should only be an issue if you still have a moisture issue in your basement. It'd also take a really long time for a stud to rust through and be any sort of problem.
Some tips:
- be sure to separate the floor plate from the concrete. I used 1/4 XPS for that and then power-actuated hammered them into the concrete. This thermal break will prevent moisture coming in through the concrete to condense on the metal
- don't screw them in. I did and while it's not that big of a deal, they make crimpers just for this purpose. Invest in the crimpers as it'll make things go really fast.
- be sure to buy plastic grommets for the electrical channels. You don't want your electrical cables rubbing up against the bare steel edges.
- wear really good gloves
As for your plan:
barrier (tar paper) on all exterior walls, Framing a stud wall, insulating, installing a vapour barrier, and dry-walling over top
...I STRONGLY recommend against that.
for starters, your plan involves two vapor barriers...that is a really bad idea. That will only trap moisture inside the walls. The modern recommendation (at least in colder climates) is to not use any vapor barrier in an old basement. Instead, use foam board for the insulation. Foam board is permeable, and the idea is that if water ever got on one side or the other, it could eventually dry to the other.
The other issue is that you want the insulation on the OUTSIDE of the stud wall. The foundation wall will be the coldest surface and is where moisture would condense. You want all of your framing on the inside of the conditioned space.
The proper way to put a water barrier in a basement is on the OUTSIDE of the foundation. Ideally, you'd have a water barrier and insulation on the outside of the concrete. But that's obviously really hard to retrofit.
The most likely reason for you feeling worse is leftover dust from the work performed. That will include dust from the drywall, from sanding the filling and especially mold particles from the disturbed wall. The room may look clean, but replacing drywall will produce a lot of tiny dust particles that will settle everywhere and make an allergic person feel really bad until the dust is removed.
It might also be allergy to the new paint components and if that's the case then the paint has dried by this moment and you'll feel better.
So the number one thing is to clean the room thoroughly - wipe everything where the dust and mold particles may have settled at least twice.
As to painting over. Latex paint will form soft yet rather strong film that will bond and contain the mold for a while. If there's any amount of humidity and mold is indeed in the wall then mold will continue to grow and will likely resurface at some moment. However until that happens you can feel more or less safe - the dried paint is like soft plastic covering and containing everything.
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Best Answer
I have never used Concrobium. I have cleaned foundation walls with hot water and bleach. Now that you have painted you have added something else into the mix. The paint can actually harbor the mold. I would simply get a heavy bleach and hot water solution with some heavy duty metal brushes and scrub the crap out of the whole area. The paint probably has to go. Make sure you have gloves on, goggles, and a mask.
Fan the area out for 2-3 days. You need to wait a minimum of 2-3 weeks and possibly a few months before I would even think about drywalling.
I would really try to get at the source though. Even if mold is growing it needs food. It wouldn't have returned that back unless your basement was feeding it water. If you don't take care of the moisture issue first you will keep fixing a mold problem.