Waterproof Concrete Stem Wall Before Painting

It doesn’t matter where you live, in certain instances you will have to seal concrete and masonry with some type of waterproof paint, depending on the circumstances.

In Arizona, we do get a certain amount of stormy weather, but water is not the only thing we need to seal up and protect our concrete from.

If you ever noticed on the bottom of the exterior walls, is a small cement section called a steam wall.

On many homes, the stem wall, will have what looks like a white powder along many sections. This white powder is called efflorescence.

This can occur in one of two ways.

1.) Water infiltrates the concrete stem wall and dissolves minerals. As water evaporates from the surface of the unit the mineral deposits are left behind, thus efflorescence crystals can grow.

2.) The salt that ends up as efflorescence crystals on your walls, can come from salt-laden soils as we have in Arizona.

Cleaning the efflorescence crystals will be the same but how long it lasts will be different.

Remove the efflorescence and all other loose material with a wire brush, power brush, or low-pressure washing, and then thoroughly rinse the surface.

Let it dry thoroughly and then apply a coat of waterproof paint to seal it up.

We recommend a waterproofing with Drylock Extreme by UGL.

When that dry’s, in 2-3 hours, you need to wait 24 hours, then paint over it with good latex paint as you would use on the rest of the house.

If the efflorescence crystals came from water from the outside conditions like point #1 and soaked into the concrete stem wall, then this should take care of the problem because Drylock will seal any more water from reaching the concrete.

Should the efflorescence crystals be forming from the inside or leaching up from the salt in the soil, this will be only a temporary solution like point #2.

If the crystals return down the road in a couple of years, you will then have to do this process again on just the stem wall.

It’s a good thing that a stem wall is only 8-10 inches high, and so it will not take much to fix again.

Just keep some Drylock and your latex paint in well-sealed paint containers, so it will be available when you have to redo it again.

We have written many articles on painting in general and painting in Arizona that you may want to read by going here AZ SRB Painting Blogs