During construction of a new home, the floor joists and plywood subflooring were subjected to significant rain. The house is now closed in, but mold/mildew has formed all over the floor joists and the bottom-side of the subflooring. What is the best way to remove it?

Hi rnfred,

The first question I have is: How sure are you that the mold/mildew has 'stopped' forming? In other words, if it's STILL 'growing', then it's getting fed.

What I mean by fed is that mold/mildew thrive under certain conditions. Relatively high humidity, relatively warm temperatures, and relatively 'stable air' will keep the garden growing. If you dramatically reduce, or better yet eliminate, one or more of these conditions, your problem may go away. However, until you're sure that your problem isn't being fed, my suggestion may only work for a limited time.

So, assuming this is a 1-time 'fix', mix a solution that's relative to 1 cup of Bleach to 1 gallon of Water. (If you're using a pint of water, use 1/8 cup of bleach.) You can certainly go heavier than what I'm recommending based on how bad your problem is but, in short, pure Bleach isn't necessary (nor is anything near that saturation.)

Spray the mixture on the area and wait 5-15 minutes. Spray it until it drips a little (so be sure you cover the floor w/newspaper, or something.) Then, spray it a 2nd time and wait again. THEN, wipe it off w/a rag. Rinse the rag regularly and thoroughly, making sure the water (if it's in a bucket) is kept clean.

If, after a few weeks you see the problem return, then you'll know that the problem wasn't a 1-time problem. This is where you need to look at what's feeding the problem and decide which 'variable(s)' you're gonna change to 'fix' it on a more permanent basis.

My best to ya and hope this helps.

Jay J -Moderator