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How to fix moisture in the basement

Basement moisture

Basement walls are in constant contact with the soil. And even the plastic sheets or bitumen paints, which should prevent this, do not last forever. Our guide will show you how to fix moisture in the basement to stop seepage, and prevent mold and mildew from damaging your basement or possessions.

In most cases, problems only appear in individual places – in light cases in the form of saline efflorescence, referred to by laymen as saltpetre. In more severe cases the same applies to really wet spots or even chipped paint and crumbling plaster.

Fix moisture in the basement: What happens if I do not fix it?

The wall is getting wet. This increases the risk of mold. In addition, the water washes, although for years to decades, but continuously, the substance of the basement wall, until at some point only a sandy mass without carrying capacity remains – then there is acute danger of collapse.

How do I proceed?

But until that happens, the careful handyman has already taken precautions. First and most important step: The affected basement wall is dug, preferably in late spring or summer, generously around the damp place to the foundation – either by spade or excavator.

Then you can let a few weeks into the country while the wall gets the opportunity to dry out well. Once that is done, the interior is renovated from the outside:

  1. The plaster of the basement outer wall is generously removed around the wet spot, the underlying wall richly painted with deep ground
  2. The site is generously resurfaced with a suitable, moisture-resistant plaster
  3. This is followed by a thick bituminous paint, followed by a dimpled sheet, which decouples the masonry completely from the soil
  4. Inside, the affected area is also cleaned from the plaster
  5. Then special restoration plaster is applied at the place. It prevents further efflorescence from the masonry.

How do I avoid it in the future?

Ideally, by carrying out the above steps not only in one place but along the entire length of the affected wall. And then it is time to observe – both in the basement and in the direction of the gutter – often basement walls are suddenly wet, because it overflows a clogged gutter and moisten the floor.

gerhardt-richter Gerhardt Richter is a writer and a trainer at trade technical colleges, specializing in carpentry, plumbing, mechanics and construction.