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Roof Flashing Installati

Roof Flashing Installation Issues


Richard A. Acree

Roof flashing is the component of most roof installations that uses thing strips of metal to create a water proof transition from one surface to another. Most commonly from roof shingles to adjacent exterior shell material like brick veneer or siding. The installation of roof flashing is a common source of water leaks, especially when installed improperly or not maintained. This article shows some of the commone issues that go wrong with with roof flashing. Look at the picture below. What's wrong?

HINT: Actually there are three things wrong. One involves the metal flashing, one involves wood, and one issue involves proximity. Please see the picture below for the first issue discussed, the metal flashing issue.

ANSWER: Hopefully the metal issue jumps out at you. For locators, you are standing on a ladder looking at a 2nd floor corner of a house where the roof joins the brick veneer. Look at the metal flashing. Look at the cracks, or gaps, in the flashing caulk as it comes around the corner of the house. You should be able to see the vertical gaps in the caulk were they have opened up and the flashing has pulled away from the veneer. This is a water leak waiting to happen. The next picture is a closeup of this discrepancy.

HABITEC suggests that caulk be considered a temporary repair to any roof component. Home or building owners should be aware of any component of their roof that relies on caulk to maintain a water tight seal. Even the best caulk is only good for about 5 years before it starts to dry out and crack. Especially on the south and west sides of the building. All caulked components on the exterior of the house should be inspected at least annually to make sure they have not started to fail.

Another more subtle issue also lurks in the photos above. This issue involves some wood. See the picture below for another view. Remember, water flows downhill following the path of least resistance.

So in the pic above where is the water flowing down the valley on the right going to go? Looks like it terminates at the piece of vertical wood trim. So the wood trim acts like a bit of a dam, doesn't it? See another closeup of this installation below.

Sure, eventually the water in the valley comes down and kicks out around the end of the wood trim and valley and goes on down the roof, but was it really necessary to point the valley exactly at this corner of the house. NO! A better design would terminate the valley to the right of the corner of the house so the majority of the water runoff does not flow into the wood trim and the side of the house. This installation combined with the cracked flashing caulk makes a roof leak at this corner likely.

And the third issue with this installation is proximity. Most manufacturers of wood or composite siding require at least 1" spacing between adjacent roof shingles and their siding products. Failure to provide this spacing can allow water from the roof to wick onto and into the siding material and damage it. In the pictures above you can see the composite siding and wood trim are all the way down and into contact with the roof shingles. In fact, if you look close at one picture above, and look up the roof somewhat, you can see where some of the composite siding has already started to be damaged (flaking) due to moisture. The 1" spacing would have prevented this. Another picture of this damage is provided below.

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Thank you,

Richard Acree

Comments in this article are the copyrighted intellectual property of Richard Acree, President, HABITEC Home and Building Inspections, LLC, and are provided to assist home owners, sellers and buyers, building owners, sellers and buyers, realtors, real estate investors, property managers, and lenders in the process of owning, buying or selling homes or commercial buildings. HABITEC is a residential (home) and commercial building inspection company serving Middle Tennessee including Nashville, Brentwood, Franklin, Murfreesboro, Smyrna, Mt. Juliet, Hendersonville, Dickson, Belle Meade, Columbia, Spring Hill and more! In addition to building inspections HABITEC offers Environmental Services for mold assessments, radon testing and water quality analysis. Additional information about HABITEC can be found on our website at, or call 615-376-2753.

Richard Acree is the author of the HABITEC Home and Building Inspections ActiveRain Blog and founder of the ActiveRain Group Tennessee Home and Building Inspectors. All are welcome to join and see more blogs like this one. You can also join HABITEC on Facebook or Linked .

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