Is Roof Venting Necessary for Ice Dam Prevention

Roof and Ridge Vents Serve a Purpose

One of the most common ideas in ice dam prevention is that roof ventilation is required. The idea is that if the attic is cool the snow will not melt. So roof venting pulls in 'cool' air from the soffits or eaves and that pushes the warmer air out of the attic through a ridge vent or roof vents. The basic mechanics is passive drafting or hot air being displaced by cooler air. The theory is correct - you can even see this in a chimney when you start a fire. Once the chimney is warmed, the drafting takes place. The reason this works so well in a chimney is that there is enough of a difference of temperature and there is a difference in height. (This is why when chimneys don't draft well, height is often added as a remedy)

Okay - so we get the basics. If the attic is kept as cold as the outside air, then no snow melt and no ice dams. How is that best accomplished - this keeping the attic cold. Some insist roof ventilation does this. I have argued in various forums on the subject that roof Ice dam prevention through proper air sealing and insulationventilation does very little. The best method is to keep the warm conditioned air in the living space through proper vapor barriers, air sealing, and the appropriate level of insulation. If this is done well, then little or no conditioned air escapes. Notice the picture to the right. It shows a roof with snow covering the entire surface. Not even the ridge or any ventilation is exposed. This is not a picture taken right after a snow either. It was taken the date of the posting and has had snow on it for over a month. And, yes, someone is living there and the heat is on. This is just an example of how a home can be properly constructed to prevent ice dams. And, ventilation is not playing a role as it has been covered by the snow. This roof is ventilated, though. That is important for summertime moisture and heat management.

What about older homes that can't achieve the proper levels of insulation and air sealing?

We often visit older homes where it is just not possible to get the level of protection as seen in the picture above. Building codes have been improved and construction techniques have followed suit. For those customers, ice dams can and do cause problems. Water can leak in causing drywall damage, rot and mold. On the outside, icicles and the dripping on front walks and stairs is a liability. We are here to help. Our ice dam prevention systems can permanently solve those issues - water infiltration from ice dams and the constant drip/freeze cycles. Our ice dam prevention products are designed to function flawlessly and not be an eyesore on your roof. You won't see zig zag heat cables as part of what we do for ice damming. Visit our ice dam products page for more information on how we do it.

We would be happy to meet with you for an in home estimate. We will walk you through the solution to your ice dam problem and design a system that can effectively eliminate your ice dam problem and your worries. Please Contact Us to set up an appointment.