Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It only takes a minute to sign up.
Sign up to join this community
I've moved into a new place that had some mould growth on the ceiling in one of the bedrooms. I found a leak in the roof that corresponded and patched that up and cleaned up the mould. A few weeks later, it's back. I couldn't see any additional moisture up in the roof though. Can mould subsist on paint? Or the latent moisture in the room? Or does this indicate there is moisture getting through still, possibly just a small amount that wasn't visible when I checked it.
Thanks
Does mould growth definitely indicate a leak?
No, not at all. Mold can grow in any suitable environment, which just means sufficient moisture and sufficient food.
Unfortunately, neither of these need be present in very large quantities.
It's relatively common to find mold growth on the ceiling in a poorly-ventilated bathroom, or even on other surfaces. Likewise, on walls in a humid basement.
These issues should be addressed with a two-pronged approach: improve the ventilation so that the humidity is kept low enough to prevent mold growth, and on painted surfaces use paints specifically formulated for humid environments and which have mold-retarding chemistry.
Of course, none of this means that the roof isn't still leaking. If you're at all concerned about that, you should go check it again to make sure moisture isn't getting through the roof. But certainly, the presence of mold doesn't prove that the roof is leaking.
That's a good sign if you didn't see any moisture looking in the attic. You did a good job patching the hole, just remember to check it periodically. It could take some time for all the moisture to evaporate.
Soap and water will not kill mold. Bleach is only good for surface mold and doesn't sink in to kill the roots. I have always used a three percent hydrogen peroxide. Spray it on the surface and let it soak in for ten minutes, then wipe/scrub off. hydrogen peroxide it great because it will kill mold below the surface which it exactly what you want to do.
