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A South St. Louis, MO home had a leaking dormer (shown above) that was problematic for years. The interior walls of the dormer were often condensated, and heavy rains would lead to water damage on the lower level foyer ceiling.

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Even though these were previously billed as solutions for the leak, a new roof and new siding did not stop the leaking. The heavy snows and ice of winter 2013-14 compounded the problem when ice damming on the roof backed up into the dormer and poured through to the foyer ceiling, creating the situation shown above.

With a reputation for solving water leaks, the family called Mosby Building Arts for help. A Mosby Consultant went up on the roof for a look and immediately noticed that the cable company had drilled a hole to run a wire through the roof that wasn’t properly sealed up. That was considered a contributing factor because the hole wasn’t big enough to create the kind of damage seen in the foyer. Something else was at work.

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Lifting up the shingles revealed step flashing that stopped too short (shown above). Short flashing can act as a conduit directing water into the house rather than away from it. So a cable company hole in the roof and improper flashing were working together to let moisture inside, but what causes the major leak during heavy snow and ice?

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The Mosby Consultant crawled into the attic area, and in the corner where the leak started there was no insulation in the dormer wall (shown above) that was installed 30 years ago. And this was the last piece of the puzzle.

Because there was no dormer insulation, interior heat kept that part of the roof warm. When the roof was snow and ice covered that part of the roof would melt faster, causing water to pond which was then wicked up by the dormer structure. This was the cause of the long-standing interior moisture issues.

In the case of heavy snow and ice during the last bad winter, that’s even more ponding water than usual. And now the water had a cable company hole and improper flashing to work with, sending the water straight down through to the foyer ceiling, soaking the plaster and creating a mess.

Solution to the Dormer Water Leak

Water leaks tend to be complicated to solve because water does not follow a logical path, it follows the path of least resistance. In this case, an uninsulated dormer made it easy for moisture to seep inside. Add a hole and improper flashing from a recent roof installation to the mix, and the water had an open invitation to run into the house.

Just as the source of a water leak can be difficult to detect, the solution to solve it is usually multi-faceted. The Mosby Consultant found the causes, and a Mosby technician enacted the solutions. The scope of work for this project included:

Inside the house, insulation was added to where it had never been before. This keeps the warmth inside the house where it belongs, not heating the roof to cause problems.

In the foyer, the damaged plaster was chipped out and replaced with drywall that was mudded, taped and skim coated to match the existing plaster finish of the undamaged walls and ceiling. The owner chose to complete the painting themselves.

Outside the house, the new vinyl siding on the side of dormer and the new roofing in a large area around the leak area were removed and saved for re-installation. Mosby installed an ice and water shield at the roof transition from the front porch and along the roof gutter line. This was overlapped by new housewrap and topped with new, properly sized flashing.

With layers properly added to repel and divert water, the vinyl siding and roof shingles were re-installed. Oh, and the cable line was relocated and its hole sealed up!

This dormer leak repair has kept the house waterproof ever since, and the workmanship has a 10-year warranty. Learn more about Mosby’s water management services. And if you need help solving a pesky water leak, call the Mosby office at 314.909.1800 or contact them here.

Why Work with Mosby Building Arts?

If efficiency, knowledge and quality craftsmanship are of the utmost importance, then Mosby is the partner for you. We are a design build firm that handles every aspect of your remodeling project from beginning to end. All team members needed to complete your project (designers, architects and production crews) are under one roof to provide time and monetary efficiencies, quality control, and seamless communication throughout.

Window Replacement & Installation

Windows should complement the style of your home, as well as provide security. Exteriors by Mosby works with you to select and install quality windows that meet and exceed your needs and expectations. Whether it is time to replace builder grade windows, you’re wanting a fresh new look or you need to replace your old aluminum windows, our Home Consultants will guide you through the process.

Learn more about window replacement and installation here.

Replace Builder Grade Windows

Replace your builder grade windows with high-quality, premium windows with Exteriors by Mosby.  Mosby’s team of home consultants, architects and craftspeople think as carefully about the look of your home as well as its safety and function. Unlike other window companies who try to push a single window line, Mosby recommends a window matching the architecture of the home with the style and taste of the homeowner.

Learn more about replacing your builder grade windows here.

Home Remodeling Peace of Mind

There’s no need to deal with multiple companies, or the frustration of the left hand unaware of what the right hand is doing. Mosby takes the guesswork out of home remodeling by planning the work and working the plan. You will know the scope of work and price before the first hammer swings. And the work will be done with a commitment to excellence and your happiness. All of Mosby’s remodeling work is backed by our 10-year workmanship warranty.

You can trust you’re in good hands with Mosby:

  • 10-Year Workmanship Warranty
  • 70+ Years Experience