Ask the Architect

What’s with our shingles?

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Q. As per our engineer’s recommendation in 2012, a new roof was installed on our “new” cape, to replace the flat old brittle roof. Within a year, shingles began to bulge and curl, and the roofer returned to repair them. The bulging and curling returned in 2014, and it has continued to worsen. The roofer has stated that it’s not his responsibility any longer, and suggested that we contact the shingles’ manufacturer, which we’re doing, since it’s still within the shingles’ warranty period.

They bulge and curl only on the south-facing roof, over both the house and the attached garage. The house has gable vents on both the east and west sides. There’s no direct access to the attic; the garage attic is used for storage. Can you tell us why this is happening, offer us possible solutions and suggest who may be able to fix this condition once and for all before it develops into a major expense?

A. I regularly see roofs like what you described, and recently learned that Underwriters Laboratories and Consumer Reports downgraded asphalt shingle roofs, stating that claims of 30- to 40-year lives and even “lifetime” are exaggerations. South-facing shingles are subjected to much greater expansion and contraction due to the extremes of the sun’s heat and radiation. I’ve often commented here that roof membranes and shingles need to breathe, need to ventilate and cool. If they’re baking in the sun under extreme stress, they will separate, curl and fail.

Your roof has no overhang, just a rain gutter at the edge that is barely attached and leaning forward. That tells me that the design of the house is wrong, that there are no soffits with a surface area under the eves that would allow air to flow upward. That’s problem No. 1.

Problem No. 2 is that the end venting only works when the wind comes from that direction, since it cannot flow through the entire attic and relieve heat at the other end. If insulation between the rafters of your finished sloping ceiling was stuffed tightly in place, without an air space just below the roof shingles, then air cannot flow. The shingles will overheat and react like leaving a fish in the sun.

Roofs are systems. They are not finishes. Unless you have insulation in the right place, toward the room, with an unobstructed air channel space above, clear airflow at a high point (since heat rises) and a calculated venting area large enough to get the air moving, your shingles will keep failing. Ridge vents, by themselves, aren’t enough. You’ll need a vent fan to draw air through the attic space. Solar vents will avoid electric costs, and may be your best choice.

© 2016 Monte Leeper. Readers are encouraged to send questions to yourhousedr@aol.com, with “Herald question” in the subject line, or to Herald Homes, 2 Endo Blvd., Garden City, NY 11530, Attn: Monte Leeper, architect.