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Reverse Flashing Causes Water Damage

A St. Louis homeowner had problems with windows that needed attention, so he called us for the Mosby Home Consultation. The problem window was the ground floor double window, shown in the center of the photo above.

On the interior of the window frame was a series of paint blisters that had “popped” and split open. Our homeowner wanted to know why this was happening on a 6-year old home, and was thinking he needed to replace the window. The reason he hired us to assess the problem was so he could get an honest answer and take care of this problem once and for all.

To the untrained eye, this would be a scrape and re-paint, but that doesn’t address what caused the problem in the first place. From decades of experience, our Mosby Consultant knew the blistering paint was a sign of water swelling the wood frame around the window.

All the homeowner saw was a break in the caulk and small leak. The Mosby Consultant knew there would be far reaching consequences and proposed a solution that addressed and communicated the real problem. The homeowner decided to choose Mosby to take care of this.

When the Mosby Building Arts carpenters popped off the interior casing trim, the evidence confirmed just what the Consultant suspected: that water had leaked into the structure for many years.

After removing some of the exterior vinyl siding, the Mosby crew confirmed that reverse flashing had, indeed, occurred during original construction, and no water seal existed.

As shown in the photo above, the water-resistant house wrap comes up to the window, the window frame overlaps it to create an additional water barrier, but it is missing several crucial steps the prevent water from leaking into the window frame.

This is a perfect example of reverse flashing, which means that instead of repelling water, the installation method channels the water into the wall cavity and showing a leak at the window opening. Structural lumber was wet, warped and rotting. The insulation above the window was soaking up water like a sponge.

Prolonged water infiltration weakens the building structure and creates air contaminates such as mold and mildew, and eventually damages the cosmetic surfaces of your home’s interior. In this case, the internal water leak finally showed itself as paint blisters on the interior window frame.

The Mosby Consulting method accurately detected and exposed this destructive construction practice which is very common throughout the country today. In this case, the window leak was only the symptom that suggested the underlying problem of prolonged water leaking and potential structural decay.

Shown above is a Mosby Building Arts training model illustrating the proper way to plan, flash and perform window and door installation. This story demonstrates the difference between traditional construction methods and the Mosby practice of getting it right the first time.

This is the flashing method used on a windowsill to direct any water outside of the wall cavity and keep it on the outside of the building. In effect, we create an obstacle course of barriers that keep watering from penetrating your home.

The way our production crew does flashing and water protection is not common practice in the building or window trades. After years of fixing bad flashing mistakes, we developed these preventive measures so homeowners would have lasting quality for the investment they made in their homes.

This repair job is now completed properly, and it’s a testament to the talents of Mosby carpenters that it looks exactly the same as before. But there is one major difference: not a drop of water will leak into the interior!

The value of a Mosby Home Consultation is that it’s a highly effective tool for uncovering hidden problems in your home, and correcting them properly. You get peace of mind when Mosby house detectives uncover your reoccurring problems and solve the problem once and for all. Click here to get the help you need.