Ten Most Common Roofing Mistakes - Part 2

Valley Problems
We see more leaks in valleys than any other part of the roof. The valley is where water from two areas of the roof intersect, and then the water flows like a river to the gutter. If the valleys are not properly installed, they leak.

Valleys should have valley flashing installed underneath to act as a secondary barrier against leaks in case water makes it through the shingles. This is often not the case. For closed valleys (valleys covered with shingles) the flashing should consist of one ply of smooth rolled roofing complying with ASTM 224 and be at least 36 inches wide. Most of the time we see only standard 15# roofing felt which is not thick enough and can easily leak.

Also, we see the shingles improperly installed. If the shingles are not lapped far enough or have improper orientation, this can lead to leaks.

If the wall flashing is not properly installed, it will probably leak. Flashing cannot be easily seen and is often not inspected by the municipal inspectors.

Flashing against a vertical wall must be the step flashing method. You place a shingle, and then install a piece of flashing on top of the shingle, and then repeat the process all the way up the wall. Any water running under the flashing will run on top of the shingle below and eventually into the gutter. Step flashing rarely ever leaks. Most of the time we see continuous flashing which is one long piece of flashing.

Most of the older homes have wide chimneys with no way to divert the water around the chimney. Water runs down the roof and hits the back of the chimney and sometimes finds its way into the structure. This is normally noticeable on the inside by the water stains on the ceiling in front of the fireplace.

To eliminate the problem, a cricket can be installed to divert the water around the chimney. It is nothing more than a pitched section of roof that will divert the water around the chimney. This can be added to any roof when the shingles are replaced.

Attic ventilation is extremely important for two reasons. First, it expels heat from the attic and then prevents that heat from entering through the insulation into the living area below. This will lower the heat load the air conditioner has to cool. Second, it will eliminate moisture from the attic. Excess moisture can cause unhealthy mold growth.

It is very common to see under ventilated attics. This is very easy to check by measuring the temperature in the attic on a hot day. If it is 140 degrees, you may want to consider increasing the amount of ventilation to help remove the excess heat.

The most effective way to ventilate the attic is by using continuous ridge vents or ridge caps. When the hot attic air rises, it will be trapped at the highest point which is at the ridge of the attic. A ridge vent allows the heat to easily escape.

As in all products on the market, there are good ones and bad ones. The good ones are rigid, and the ridge shingles can be easily nailed down the vent and designed to prevent rain from blowing into the sides and into the attic.

The bad ones are flexible  and do not provide a good nailing surface for the ridge shingles. Also, sometimes the installation leaves a lot to be desired. Some roofers will cut corners and not follow the manufacturer’s installation instructions. Over time, the vents can curl or twist, allowing water in.

Quote Of The Month

"Life isn’t about how to survive the storm, but how to dance in the rain.”

Tip Of The Hat To:

Stephanie McCarty
Prudential Georgia Realty
1551 Janmar Road
Snellville, Georgia 30078

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