One of the most common causes of new roof leaks is defective roof flashing. Roof flashing consists of the metal pieces that provide an underlayment where roofing intersects at an angle or at an edge, such as in a roof valley, or where the roof meets an object protruding from the roof, such as a chimney. On a new roof that leaks, shingles for the metal valley flashing may have been improperly cut. Water flowing off the roof down the metal valley snags on the angled edge of the shingle and is diverted toward the roof deck, where it may drip into the attic or wall cavity.
In climates that have freezing and thawing cycles in winter, ice dams may form on the roof and cause leaks inside the home. New roofs are not immune to ice dams, but proper insulation and ventilation will quickly alleviate the leaks. Driving rain with heavy winds may force water into small crevices or cracks in the chimney or siding. On rare occasions, an errant tree limb may have blown over the new shingles, puncturing the surface and allowing water to infiltrate the roof deck.
A new contractor or a hasty worker may neglect the basics of a good roof installation. The roof deck must be firm and tightly secured to the roof rafters. Shingles must be installed over exposed nail heads. Flashing must be precisely cut and tightly installed. Hasty or sloppy roofers may use caulk as a filler for gaps in roof flashing. Caulk is no replacement for a good installation. Caulk dries out and shrinks, leaving behind gaps that gulp water. In the event of a substandard roof installation, the contractor must be held accountable and should repair the work promptly.
Check the Guarantee
Most roofing contractors stipulate their work guarantee and replacement policy on the contract signed by the homeowner. In the event of a leak, contact the contractor to inspect the roof and repair the problem. Some contractors may charge a fee for the job, especially if the problem is with a weather-related issue not related to his installation. A good contractor typically will fix any errors quickly and courteously. Many municipal codes departments maintain a listing of licensed roofing contractors and keep a roster of complaints.