Ever wonder why there is build-up of ice on one roof and the house right next door barely has any? Is it really a big deal if houses have ice dams and icicles, I mean, they look cool, right? To be clear, ice dams are not good, they cause damage and can lead to costly repairs. And if one house has them and another doesn’t, that means one of the homes needs some work to make it more efficient and avoid those pretty ice sculptures.
So what causes ice dams anyway? There are a few different reasons ice dams form on houses but the good news is that there are ways to resolve them!
The most common cause of ice dams is when one part of the roof gets warmer than another. The heat escapes through the roof, the snow melts at the pitch of the roof and starts to run down. As the water hits the cold exterior at the base of the roof it refreezes and begins to build up. The ice dam can start to lift the shingles as it grows allowing water inside. Ice and water inside leads to leakage and that could mean mold, along with ceiling and wall damage.
Why would one part of the roof be warmer than another, you ask? Well, poor insulation will allow heat to escape, improper venting and sealing of the roof, and having a heating source in the attic are all common causes.
Insulating with insulation between R-30 and R-40 should do the trick, but you will want to be aware of how your attic is vented. Believe it or not, ventilation is beneficial, even if a little heat gets through. The ventilation of outside air keeps those areas from warming up and allowing water to leak into the house or building.
If you have cathedral ceilings you need to be aware of heated air escaping through recessed lights. It can cause condensation and ice dams. Plumbing stacks and chimneys can do the same thing because they all breech the insulation. Caulking and expanding spray foams can help create a barrier to prevent heat escape.
One cause that has no solution is the thickness of the snowfall. If only we could get the snow to fall in an even layer. When the snow is thinner at one part of the roof then the sun will heat it up quicker and it will melt first and ice dams can begin to develop. The solution for this one is the same as above, proper insulation and ventilation. Waterproof roof membrane is also highly recommended.
So, next time you consult with a roofing and insulation professional, you now understand what they should be recommending and can ask questions about what they are going to install to make sure that your house doesn’t become dammed.
Oh, and fixing these issues can also help keep your home cool in the summer too!