Tip of the Month – June 2010

Eighty proof?......enough of that and you won’t care if your buildings are waterproof!  There is a big misperception that stucco and paint are what keeps the moisture out of your buildings.  Stucco is a cement product and is actually quite porous.  This is why small cracks in stucco are typically  more of a cosmetic issue than a moisture intrusion concern.  While there are some paints that do in fact provide a moisture-proof barrier, in most buildings, it is the tar paper underneath the stucco or siding that makes them waterproof. 

After putting up the frame of a building (generally wood in Southern California) it is wrapped with either a tar paper (60-minute building paper) or a film product such as Tyvek.  It is this element of the building that actually stops bulk moisture from entering the building.  When applying the tar paper, it is very important to lap it in a specific manner, starting at the bottom of the building and overlapping the next levels over the one before it a bit to make certain moisture is directed down and out the weep screed (the metal vent at the bottom of stucco walls), and not into the building.  There have been instances where it was lapped improperly, causing water to flow into the building.  In this case, the most cost-effective means of waterproofing the building is to apply waterproof coatings to the exterior of the building surfaces.

Most of the time, the design and construction of buildings perform as they are expected to.  When they don’t, there are products and processes available to waterproof buildings and they require a greater degree of preparation and application.  Having applied waterproof coatings to thousands of residential units in Southern California, we can answer any specific questions you may have.