You may have noticed that it is no longer possible to predict what the weather in the Pacific Northwest will be season to season. It used to be that ice dams on roofs were a rarity in the Willamette Valley, but now they may be something to worry about and certainly something to prevent. Pacific West Roofing has been around long enough to have seen our share of ice dams and we can work with you to prevent or repair damage from ice dams.  

What Causes an Ice Dam

An ice dam occurs when the upper areas of a frozen roof start to thaw while the lower areas are still frozen. Thawing occurs when heat collects in the attic warming the roof but not the eaves. Asphalt shingles are particularly susceptible to ice dams. The melting ice and snow flow down and refreeze along the eaves, as well as in the gutters, creating an ice dam. As that meltwater reaches the dam it pools leaving it likely to start leaking into your home through cracks and joints in the roofing materials. Even without the presence of an ice dam, the expansion and contraction of roofing materials as temperatures fluctuate can worsen any existing roof leaks or cause new leaks.

Another problem with melting and freezing water on roofs is icicles. Sure the look of icicles cascading from a roof makes for dramatic photos, but the extra weight they add to gutters and the roof can be damaging. Not to mention falling icicles can injure people and pets. The main reason icicles form is that water is not being directed through gutters and downspouts, most often because the gutters are clogged with leaves, needles, or other debris. Instead of running through the downspout, the water floods over the edges of the gutter and freezes. 

Any roof leak can cause damage ranging from a build-up of mold and mildew to rotting supports. 

How to Prevent Ice Dams

A simple way to prevent ice dams and icicles is to ensure your gutters are clear of debris. This prevents water from building up and freezing and also helps when spring thaw occurs and inevitably the rain returns. But it’s not just debris that’s the culprit. In the winter, snow and ice can build up in gutters and impede the flow of water. If you’re not comfortable on a ladder or on your roof, Pacific West Roofing is happy to come to your home to ensure the gutters are properly cleared and maintained

Keeping gutters free from ice and snow is easier if snow on the roof is kept to a minimum. Removing heavy snow loads from the roof reduces the chance of ice dams and roof collapse. 

Aside from gutter cleaning, the best way to minimize the risk of ice dams is to ensure your home has adequate insulation and a proper attic ventilation system. Your home should have enough insulation to prevent heat transfer from inside the home to the roof, and also have venting that keeps attic air cold enough to minimize freeze and thaw cycles. Air should flow under the eaves or soffit along the underside of the roof and out through the vents. In addition, any air leaks that might warm the underside of the roof should be sealed. Together, these systems slow or stop snow and ice from melting on your roof. 

If you live in an area where the chance of ice dams is greater, like in some of our higher elevations that are colder and get more snow and ice, there are options like modified rubber underlayments such as Ice and Watershield that can help. The downside is these shielding membranes need the heat of the sun to properly adhere to the roof deck, so they must be installed well before or after winter freezing. 

While it may be tempting to tackle snow and ice on the roof yourself with a shovel, hammer, or chisel, using these tools can damage roof shingles or even the roof structure itself. And salt might be another option but we all know the hazards salt poses to the environment and no one wants to kill off their shrubs and trees with salty runoff. Why not stay inside where it’s warm and dry and let the experts at Pacific West Roofing take care of your winter woes? Better yet, call us well before the first snow falls to inspect your roof and make sure it’s ready for another season of frozen precipitation. 


Find and Fix Roof Leaks for a Drier Winter


Beat Back the Weather with SBS Modified Asphalt Shingles

Portland Roofing Contractor Since 1980

CCB# 169414