Is Your Roof Leaking? Or is it Just High Humidity?

By Dymon BradyOver the last few months, one of our clients has called us several times to fix various leaks in his 12 year old pitched roof installed by another roofing contractor. He had originally had a tar and gravel flat roof. He had his roofing contractor convert it to a 4/12 pitched roof, leaving the tar and gravel roof on underneath. He called us when, after only 12 years, his shingled roof was leaking in various places. When I got on the roof I noted the poor workmanship of his roof and shingles. We did several repairs and ended up replacing the entire roof, installing new shingles, an ice shield, synthetic felt and new flashing. It was a 30 year system and I was confident he wouldn't have any future leaks in his roof.Last night, I had a bizarre experience as I received yet another phone call from him reporting a leak in one of the same places the roof had leaked before. I couldn't figure out how a brand new roof could be leaking in the same spot. I called one of my employees and we went to check it out around 5:30. We inspected the entire roof and could not find any place that could be leaking. Because it was a converted flat roof, there was no attic access. Without any other options, I was forced to tear of a portion of the new roof and cut away the plywood underneath to gain access to the cavity between the flat roof and the pitched roof. As I dropped down into the cavity, I was confident there was no leak in the pitched roof we had recently installed. The tar and gravel roof was bone-dry and coated with a layer of dust.Because the tar and gravel roof was no longer needed, we began tearing the flat roof off to find the problem. When we had gotten down to the plywood under the tar and gravel, I found that the wood was completely saturated. Somehow, high humidity levels there had caused this house to leak from the inside out.After talking to the owner of the house, I learned they kept a humidifier hooked to their furnace, which was located directly under the area of the leak. This humidifier was on during the winter. Every time that it rained or snowed outside, creating a high humidity, that humidity was magnified inside, creating an overall humidity that is higher than average. This humidity caused condensation to form on the underside of the tar and gravel roof just as it would form on the underside of a pot's lid when water boils. When the condensation became heavy enough, it would drip through the ceiling, appearing as if there were a leak. In reality, that water came from the inside of the house.When a building has high humidity, a vapor barrier such as Visqeen should be installed on the warm side of the insulation. In this case, the vapor barrier was the actual tar and gravel roof, and consequently was installed on the cool side of the insulation, forcing the condensation to travel through the ceiling, insulation, and plywood before reaching the barrier. To fix this issue, we cut out the roof sheeting from the tar and gravel in the effected area so that it could breathe. As we cut it off, a burst of hot, humid air hit us in the face. I had never seen anything like this, it was simply amazing. Our client is going to replace the damaged material in this area.To avoid this issue in a typical home, simply keep your humidifier turned off in the winter, as it is not necessary. You may own a home or building that naturally has unusually high level of humidity. This would usually come from an indoor swimming pool or fountain. In this case, be sure you have an architect and a roofing contractor that are familiar with building for this environment. A large number of roofing contractors are unaware of these procedures and cautions. To my knowledge, only 5 or 6 roofing contractors in the salt lake valley are experienced in installing a roof for this type of environment. Brady Roofing is experienced in this area. We recently installed a roof for a Hampton Inn with a similarly humid environment. To contact Brady Roofing for a free estimate, contact us here.UPDATE:Since writing this post in April of 2010, we have had some noteworthy experiences with finding condensation and humidity causing leaks in a home.  Below are some pictures from a home that had an indoor swimming pool.  The insulation and wood were soaked, there was mold growing in the attic, and you could actually see the drops of condensation formed on pipes and other hard surfaces.  We were able to help diagnose and resolve this issue.