Roofing Services
Chimney Flashing and Roof Flashing Repair
At a Glance
- Flashing fails long before shingles do
- Caulk over bad flashing is a one year fix at best
- Step flashing has to be woven in, one piece per course
- Old Davenport brick chimneys need counter flashing cut in
A roof is not really a surface. It is a surface plus a set of joints, and the joints are where it fails. Chimneys, walls, dormers, skylights and vent pipes all interrupt the field of the roof, and every one of those interruptions is sealed with metal rather than with shingles.
Step Flashing, Done Right and Done Wrong
Where a roof runs into a wall, the correct method is one bent piece of metal per shingle course, each lapped over the one below, woven in as the shingles go on. Water hitting the wall runs down, hits a step and gets sent out onto the shingle below it.
The wrong method is one long strip of metal bent into the corner and sealed with caulk. It works while the caulk is new. Caulk in Iowa goes through a hundred and twenty degrees of temperature swing every year, and it cracks. Then water runs behind the strip and into the wall, and the stain shows up downstairs where nobody thinks to look at the roof.
Chimneys in an Old River Town
Davenport has a lot of brick chimneys on houses built before 1940, and they need two layers of metal. Base flashing lies on the roof and turns up the brick. Counter flashing gets cut into a mortar joint, bends down over the base flashing and sheds water onto it.
Surface sealed counter flashing, which is metal stuck to the face of the brick with sealant, is the common shortcut. It always lets go eventually.
Pipe Boots, the Ten Dollar Flood
The rubber collar that seals around a plumbing vent pipe has a service life of around ten to fifteen years in this climate. It splits at the top where the sun hits it hardest. The part costs very little and replacing it is a short job.
It is worth saying clearly because it is the single most common leak we are called to and the single cheapest to fix before it happens.
Questions About Chimney and Flashing
Can flashing be replaced without a new roof?
Pipe boots and counter flashing, yes. Step flashing means lifting the shingle courses along that wall, so it is straightforward on a young roof and awkward on a brittle old one.
Is caulk ever the right answer?
As a seal on a properly built joint, yes. As the joint itself, never.
My chimney leaks only in driving rain. Why?
That is the signature of a flashing or masonry problem rather than a roof problem. Wind pushes water sideways into a gap that gravity alone never reaches.
Get It Looked At First
No sales call. A roofer looks at the roof and tells you what it needs.