Why Your Roof Leaks After a Snowfall – and What Can Be Done

Why Your Roof Leaks After a Snowfall – and What Can Be Done
Ice and leaking in condo association roof after snowfall and thaw

One of the biggest cold-weather problems is ice damming, a specific challenge to the integrity of roofs. It’s important to know what causes ice damming and how it can be repaired, before you face an emergency situation.



An ice dam is a ridge of solid ice that commonly forms along the eaves of a roof. Dams can damage gutters, and cause water to back up under shingles and pour into your house. Products such as Ice & Water Shield and other similar treatments prevent most ice-related winter leaks; however, leaks can still occur on perfect roof installations. When ice damming conditions exist on roofs that have not leaked during rain, there is rarely a defect as will be explained. As a result, it rarely makes sense to send a repairman since there is nothing to fix.

On perfect shingle roof installations leaks still occur when large ice sheets and ice dams form during the winter. That is because shingle roofs are designed to keep out flowing water, not standing water. Standing water goes underneath shingles and through normal nail holes in felt. Luckily standing water only exists on shingle roofs under extreme conditions like Chicagoland is experiencing right now. Right now water is trapped under ice directly on top of shingle roofs.

Knowing this, code requires roofers to install ice damming membrane in the areas most likely to trap water under ice. The ice damming membrane can keep water out for approximately 48 hours. During that time the water usually refreezes or drains when it is warm. Ice damming membrane eliminates nearly 100 percent of leaks under average winter conditions. It fails when liquid water sits too long under ice. Also, water gets beyond the membrane when the ice sheets extend beyond the area it is installed.. Unfortunately there are no good construction solutions for this problem on shingle roofs. The only solution is to melt or remove the ice which would need to be redone each time extreme ice conditions occur.

During current conditions Associations must make difficult choices. Since no defect is likely repairmen can only remove the snow and spread salt on the ice which will stop the leaks. Knowing that ice will come again it is recommended that removal is only performed in limited situations. No decision making protocol is perfect so Association Boards must know the pros and cons of the ice removal decision. This guide may help.