People often call me with the same problem. They tell me they have mold on their walls, behind their bed, for example. I ask a few probing questions, eventually coming to the same conclusion. At some point in time, their stucco has been painted.
It is very common in our region to find painted stucco. This does not make it right. Stucco is a porous product. It is made of sand and cement and is meant to stay porous. When you paint your stucco it can no longer breathe.
The black paper behind the stucco is designed to keep water out of your house. As the water migrates through the stucco it hits this paper. Water then runs down the paper and back out through the stucco towards the bottom of the wall. If the stucco has been painted, any water that enters the wall will be trapped in the bottom and begin to mold, eventually rotting the paper and stucco. Remember that water always travels in the easiest direction. In most cases that is inside your house.
In the mid ’70s, the Federal Housing Authority invented a screed (metal trim) to go along the bottom of the house. This screed allows any water in the wall to escape. Most Clairemont houses don’t have this screed. The stucco goes right down into the dirt. The moisture in the dirt wicks up into the wall. If your stucco has been painted, it stops the stucco from drying out. It then decomposes. I call it stucco cancer.
Look around your own home to see if you are experiencing any of the same problems. Many Clairemont homes need to be re-stuccoed. The correct method is to sandblast and re-stucco. This removes all the paint from the stucco. Then it can breathe again. This is also important when we re-stucco. It makes the stucco even more porous and helps get much better adhesion. The new color coat attaches to the old effectively.
The top layer of stucco is called “the color coat”. It is approximately 1/8″ thick. This surface should last for up to 30 years. (As long as you don’t paint it!). If you find that your stucco has not been painted, you can water blast then re-color coat. The new color coat will last a long time if the preparation is done properly. A common technique is to put an acrylic bonder (glue) on the wall first and in the mix.
Fresh stucco is an elegant look on a home. We prefer a Spanish lace texture as this hides some of the imperfections on the surface of an old house. The smoother the finish the harder it is to conceal the problems. There are many colors to choose from. It is a good idea to re-paint any wood or metal trim before re-stuccoing. We suggest sandblast, paint, then re-stucco.
One thing to think about before you re-stucco is replacing your windows. Wait, that’s another story.