Ice Dams Cause Unusual Texas Roof Problems

Thawing temperatures will cause roof leaks for some home and building owners in North Texas. Melting ice will cause ponding water problems behind ice dams that form at the eve of sloped roofs. When ice begins to melt due to attic warmth or sunny weather, water runs down the slope of the roof and refreezes as it hits the colder area over the eves of a roof. Ice begins to stack up, forming an ice dam.

Water behind the dam may back up beneath shingles and enter through nail holes and plywood decking seams. Ice dams can cause leaks along the eves, in valleys, and around roof penetrations such as heat vents and behind chimneys. In Texas, where extreme icy conditions rarely exist, builders seldom install waterproof underlayment that is common in icy northern climates. In cold climates, products known as “ice and water sealant” materials are installed between shingles and the decking. Ice and water sealant material is made of plastic and is more waterproof than the black asphalt felt, or “tar paper” widely used in Texas.

Heat escaping from inside the house into the attic contributes to forming ice dams. Heat warming the underside of the roof, then refreezing causes the cycle to repeat, increasing the size of the dam. When outside temperatures climb, water finds its way between seams, nail holes, and cracks. More serious leaks find their way into the house, through ceilings and down walls.

The best prevention against ice dams is a well insulated, and ventilated attic. In addition to increasing energy efficiency, proper insulation helps prevent the melt-refreeze cycle. Proper attic ventilation helps keep the underside of the roof cool and prevents moisture buildup in the attic. Good ventilation also keeps the attic cooler in the summer. Attic ventilation is achieved by installing roof vents near the top ridge, and soffit vents on the underside of the eves. Cooler air enters through the soffit vents, heats up as it enters the attic, then exits through the roof vents. Some homeowners believe that covering attic ventilation in the winter helps keep the attic and home warmer. This practice is detrimental to attic and insulation health, as moisture buildup decreases the effectiveness of insulation, promotes rust, and causes buildup of moisture in heat and A/C ductwork.

When temperatures begin to climb, homeowners should check for discoloration in ceilings and walls. Common leak areas are above fireplace mantles, below areas where plumbing and heat stacks penetrate the roof, and around vents and light panels. A reliable roofing contractor can usually make roof repairs to specific leak areas, without the need to replace large segments of the roof. Homeowners should expect a contractor to be very clear and specific as to what repair methods and materials should be used to repair the leak. Photographs should accompany any proposal.

Jim Stewart, Owner, Alltex Roofing Systems