Icicles along a roofline are largely perceived as a beautiful winter staple, yet often indicate ice dams and a potential for water damage to the structure. Ice damming blocks roofing drainage systems, diverting the flow of water under roof coverings and into the building envelope. Once within, gravity carries this permeation through insulation, ceilings, walls, and floors causing widespread water damage. At this point, immediate water damage restoration is essential to prevent the possibility of mold contamination.

What Causes Ice Dams?

Ice damming occurs when upper roofing sections warm, while the edges remain below freezing. Often the result of insufficient insulation and/or inefficient ventilation, heat escaping into the attic warms the wood and shingles directly above causing the snow to melt. Meltwater then flows to cold roof edges and again freezes, resulting in an ice dam that blocks roofing drainage systems.

Once formed, ice dam removal is difficult and dangerous. Preventive measures are essential to limiting the possibility and severity of ice damming. Properly engineered attic ventilation and sufficient insulation will keep attic temperatures down, limiting the daily snow melt and in turn the severity of ice dams.

Preventing Ice Dams

As stated above, preventing ice dams is the best way to keep your roof safe in the winter. To prevent ice dams, you need to keep the temperature in your roof and eaves consistent by limiting heat loss from the living space into the attic and managing airflow in the attic.

Heat transfer into the attic is largely due to air leaks. Avenues of warm air penetration include plumbing ports, electrical runs, fixture sites, drywall gaps, plaster cracks, chimney intrusions, access hatches and other ceiling penetrations. Preventing this phenomenon requires plugging gaps to limit this air exchange and ensuring that insulation R-values are correct, and installation is properly installed.

Caulk and spray foam sealants can be used to effectively close air infiltration avenues, while adequate insulation will block the transfer of radiant heat from warm building materials into the attic. Building codes require about 12-in. to 14-in. of fiberglass or cellulose, we suggest upgrading to R-40 blown-in insulation, which fills more tightly around building members and leaves fewer gaps than hand-placed batts.

Proper Ventilation

Attic ventilation draws in cold outdoor air, flushes warmer attic air and cools the attic as well as the roof in the process. Some roofing systems are difficult to vent by virtue of design and may require a custom approach. Determining correct vent size and placement is complex and best left to professional analysis and implementation.

Attic vents must remain clear of debris to be effective. Ironically, the aforementioned solution can inadvertently contribute to ice damming. Improperly installed insulation can cover soffit vents and choke off airflow contributing to the problem. Attics with blown-in insulation are especially susceptible to this possibility. Attic vents must always remain clear of blockage, the implementation of air baffles usually prevents such blockages.

Ice & Water Barriers

Ice and water barriers are a type of self-sealing underlayment that is installed onto the roof decking before shingling. These barriers are installed approximately six feet up from the roof edge and along roof valleys, waterproofing those areas most susceptible to ice damming. Adding the ice-and-water barrier to an existing roof is neither cost effective or practical as an otherwise sound roof would need to be removed to do so. When reroofing is necessary, this failsafe is relatively inexpensive and often required by building codes.

Snow Raking

Consisting of an aluminum scraper mounted at a right angle on a telescoping aluminum pole, a roof rake is used to remove snow from roofing systems and this can prevent ice damming if done consistently. When using a roof rake, care must be taken not to break the roof shingles that become brittle in cold weather. This simple but effective solution is only prudent for single story homes, as this process can be carried out while standing safely on the ground. Roof rakes cannot reach two- and three-story roofing systems from the ground and operating this device from a ladder is unreasonably dangerous.

Heat Cables

Heat cables are high-resistance wires that can be mounted on the roof edge in a zigzag pattern and then plugged into an outdoor GFCI receptacle. This solution is ideally deployed in areas where ice dams regularly occur, and other prevention methods have failed. This method requires that meltwater be routed away to avoid refreezing in the gutters and along the roof edge. This is usually accomplished by routing the heat cable through the downspout to keep it clear of ice and flowing freely.

What to Do if You Have an Ice Dam

While the preventative methods listed above can be effective, sometimes ice damming is inevitable. Ice dams may consistently form at the foot of roof valleys because of snow drifts on the roofing system. Despite keeping a temperature balanced attic, some sections of the roof may be impossible to keep cold. Additionally, wet heavy snows and consistent lingering snow storms may lead to ice damning because of natural daily freeze-thaw cycles.

Steam Removal

Steam removal of ice dams is an expensive undertaking that first requires the roofing professional remove excess snow from the roof. Next, ice is melted away using commercial steaming equipment that heats water and dispenses it under pressure. This process melts the ice away without damaging roofing shingles.

Water Mitigation Service

Ice dams are frozen ridges that form during winter months at the edge of your roof and prevent melting snow from draining off. If left untreated, ice dams can block gutters, loosen shingles, and result in water infiltration. Water damage and the need for water mitigation at this juncture are inevitable.