Asphalt Shingles and High Winds
DEAR TIM: Within the past few weeks, I had a new asphalt shingle roof installed on my house. Several days after the roof was installed, a fierce winter storm blew 30 percent of the shingles off my house. The manufacturer has indicated that the shingles were improperly installed. My roofer disagrees and says that the self sealing compound didn't work properly. I'm in the middle. What do you think? Also, the manufacturer noted that felt paper was not installed under the shingles. Was this a mistake? J. M.
DEAR J.M.: Based upon the photographs you sent to me, I feel that the manufacturer is telling you the truth. There are numerous problems with the workmanship on your roof. There is a chance that the self sealing compound is defective, however, this can easily be tested.
Asphalt shingles are far and away the most common roofing material used by American homeowners. They are well engineered and, when properly applied, will provide many years of leak-free performance. Unfortunately, your shingles were not applied properly.
The self sealing compound that your roofer is speaking of is a thermoplastic asphalt compound. It is a common ingredient of virtually every asphalt roofing shingle currently manufactured. This compound was introduced, at first as an option, during the mid-1960s. Its purpose is to bond each shingle to the one immediately below it. When the bonding process is completed, the shingles are less likely to develop wind-related leaks and failures.
This self sealing compound is activated by heat from the sun. In your case, a majority of your shingles didn't stand a chance. The greatest amount of wind-related failure on your roof occurred on the exposure which faces north. That portion of the roof, in your geographic location, doesn't even receive direct sunlight until April. The installation of asphalt shingles, in colder climates, during the winter months is not always prudent. If you wish to test the integrity of your self sealing compound, simulate the heat of the sun with an electric hair dryer. Do this inside with some of the pieces of the shingles that are scattered about your yard. Don't climb on the roof this time of year!
Your photographs also indicated two major problems. Many of the nails that were used to install the shingles were driven in the wrong location in each shingle. In many cases, they were installed through or above the self sealing asphalt strip. This practice is clearly wrong. Because your roofer was installing a shingle which exposes 5 inches of the shingle to the weather, the nails should have been installed 5 5/8 inches up from the bottom edge of each shingle. A minimum of four nails should be used for each shingle. If you live in an area subjected to high winds, a minimum of six nails should be used.
The starter course of shingles was also improperly installed. Your roofer simply rotated a full shingle and applied this under the first course of shingles. This is unacceptable. The starter course, or strip, is made by trimming the bottom 5 inches from a standard shingle. This places the ever-important self sealing compound at the bottom of the roof. This prevents wind from lifting the first course of shingles.
Felt paper is a must. Roofers that fail to use it under asphalt shingles are making a big mistake. Without felt paper, your shingles lose their fire rating. Shingles, in and of themselves, are not fire rated. They are a component of a system, of which felt is an important part. Felt also helps to prevent leaks from wind driven rains that may, somehow, penetrate the shingles. Imperfections in the wood decking also can be a problem in the absence of felt underlayment. These imperfections will more readily telegraph through today's thinner fiberglass shingles. Finally, many manufacturers will not warrant their shingles unless felt is used over a bare wood deck. It's that simple.