Recently while carrying out a real estate home inspection and infrared scan on a stucco home in Houston we came across one of the lessor-known, yet quite common sources of moisture damage, the decorative parapet wall. A parapet wall is essentially an extension of an exterior wall extending above the roof line. In the case of this real estate inspection and thermal scan, the parapet wall extended along the front of a sloped roof, acting as a water dam for water draining down the slope. See roof picture. Any structure that inhibits drainage and increases water accumulation (i.e., chimney, dormers, parapet walls) have a higher potential for water infiltration behind cladding or into any penetration.
The best home defense against this is proper installation methods by the builder or contractor, especially the metal flashing in the transition between the composition shingles and parapet wall. During this home inspection and infrared scan, it was clear that proper installation methods were not used by the builder. Usually, the problem is the step flashing does not extend high enough along the base of the parapet wall to prevent water running down the roof and getting behind the flashing barrier and parapet wall.
Particularly in stucco homes, this type of moisture penetration will manifest itself in ways that are not visible or obvious to the naked eye for long periods of time, until catastrophic damage has been done and is eventually visual to the naked eye. Using thermal images from the infrared camera, we were able to see evidence of moisture behind the stucco parapet wall. If you own a stucco home, we recommend a non-destructive stucco evaluation using thermal imaging every 2 years.