Ask the pros-
April 2010

By Reggie Bullard





 Dormer or chimney leaking-counter flashing


I have a "one-coat" stucco home and have recently experienced significant leaks during heavy tropical rains as hurricane remnants passed through our area.  The leak is occurring at the intersection of a dormer and the main roof, which is asphalt.  I inspected the shingles and found no damage or holes.  I noticed that in certain locations the step flashing is visible (the shingles do not fully cover the step flashing -- there is ~1/2" gap in some locations).

Should I just patch this gap with some roof sealant or is the proper fix to install counter flashing.  Are there any other locations I should inspect or problems I should look for on the roof.  Please help.
Gaps between
                            step flashing
Here is a typical step flashing as we find it before we put the stucco on. BTW, we put on the kick out flashing ourselves. The kickout flashing prevents water from running behind the stucco.
Water runs in gaps

With no counter flashing, the step flashing will likely leak, particulary in cold weather. This can happen even when the stucco goes down all the way to the roof. There will invariably be a gap between the roof and the stucco. Remember, also, that stucco is porous an water will go through.

                            flashing Counter
                            flashing finished
A counter flashing we made with a metal brake covers the step flashing and extends out onto the roof. Finished wall with the top flange covered with tarpaper and stucco. For more about counter flashings, please click here.
Chimney flashing

We made this counter flashing from a pre-bent piece of apron flashing I got at home cheapo.
An apron flashing is a simple "L" flashing.
Note the flashing we put at the top to keep water from running under the counter flashing.
Bottom of stucco is cut off to allow room for a new counter flashing. After putting on the counter flashing, we patched the stucco, overlapping the counter flashing with tarpaper, metal lath and 3/4" of cement mortar. This won't leak, I promise.

Chimney leaks are usually from on of two reasons:
1.Lack of counter flashing, or old steel counter flashing that has rusted through. 
2. A deteriored roof cap. For more on roof caps,  please click here.

                            chimney flashing

Stucco news home         previous question