Stamp out Damp in Concrete Walls Before Redecorating
May 6, 2018
It’s a major red flag when you see signs of moisture on interior walls to be repainted. Before recoating you’ll need to do some detective work in order to best resolve the problem.
When moisture gets into the wall, penetrating damp causes paint to bubble and peel. Even more seriously it can cause interior steel to corrode, expanding and fracturing the surrounding mortar.
Job number one is to find the source and eliminate it.
Here are some of the most common culprits:
- Leaking roofs (from broken or loose tiles or damaged flashing),
- Guttering – where the gutter has become blocked or broken and water courses down the wall
- Improper or damaged sealing around windows or other outlets
- Water seepage in ground floor or below ground situations.
Once identified, where possible, make the necessary repairs to eliminate the source of moisture.
Preparation for Repainting
- Remove all loose or flaking paint and then test to ensure the substrate is firm by pressing tape to surface and quickly removing. If the tape does not pull away clean, the remaining paint needs to be taken down to the surface by wire-brushing and sanding.
- If mildew exists ensure this is properly removed before painting.
- As there may still be moisture in the wall, prevent any further water seepage by applying
1-2 coats of a waterproof coating that will penetrate and seal the surface. Apply to whole wall to avoid flashing. Allow to dry overnight before applying the finish coat.
In situations where damp is found close to ground or in below ground situations there may be additional need for exterior waterproofing or the installation of a drainage system depending on the cause found.
Check out our other great articles in this January edition of Paint Pro!