How to deal with mold on basement drywall?

We had a very rainy May. Suddenly noticed mold on finished drywall in a below the ground finished basement. Cut out the moldy drywall and noticed the concrete blocks were wet behind the drywall, also there was a lot of wet sand stacked about a foot up between the block wall and the drywall. It has been an expedition trying to figure how the wet sand got there. That being said... contractors have all kinds of costly ideas about what to do. I was wondering if there is anyone here that knows how to proceed. We know the outside gutters are working properly.

  3 answers
  • Swinnen Lisette Swinnen Lisette on Jan 08, 2019

    I am sorry, but you will have a big job on your hands, but nothing you can't do yourself if you are fit.

    First of all a question : on the outside of that wall, what is there? soil? concrete?

    If it is sand, you could clear the whole wall on the outside, check for holes in the wall and fill them up with cement. After that, now that you are so far, you could paint the wall with that black rubber stuff that prevents water to come in..

    If it concrete, I hope you know someone with a concrete driller.....

  • William William on Jan 08, 2019

    You may need to have the block sealed on the outside and a french drain installed. Which means digging down to the foundation wall. The sand is actually from the breakdown of mortar. Another solution which may work is to remove all the drywall, clean the block, and let the block really dry out. Then paint the block with Drylock waterproofing paint. Leave the walls bare to see if this repair has worked.

  • Oliva Oliva on Jan 10, 2019

    Hi, Judy,

    Although your gutters may be working, they may not be adequately sized for extreme downpours, resulting in splash over. Further, unless all 4 sides of your roof have gutters (unlikely), water could find it's way to the side of your house.

    Do your downspouts discharge water at least 10' away from your foundation?

    Do other properties sit above yours at any point? Proprerties hundreds of feet away could inadvertently deposit excessive rain water onto your property, given the right slope and momentum.

    If your location has high humidity, your basement could have a continual problem, requiring frequent use of a dehumidifier set no higher than 40%.