With winter quickly approaching I thought it was time to discuss one of the problems that causes ice dams. Ice dams cause significant amounts of damage each year and most of them can be avoided if you understand the root cause. The following information should help you understand some of the causes of ice dams.
Proper vents are used to ensure proper ventilation from house ventilated eaves up to the ridge vent. Proper vents are typically made of styrofoam and come in many different shapes and sizes. The one shown in the picture is fairly representative of the ones sold today. The proper vent creates adequate air flow from the eaves up past the insulation material.
Blocked Proper Vents
Yesterday I went and looked at a house that’s having trouble with ice dams. The house is only a year old and the owner is quite frustrated at the poor performance. He asked that I come take a look at the house and see if I could identify any deficiencies that might be causing the ice dams.
Sure enough when I visited the house I was surprised to see a rather significant ice dam along the eave on the north side of the house. So I ended up going into the attic to inspect the insulation and ventilation. It only took me a minute to diagnose the problem that’s causing the ice dams.
The proper vent that was used during construction appears to be a very flimsy / cheap version that actually collapsed when the insulation was installed. Apparently the insulation crew stuffed the insulation so tight against the proper vent that the air flow was cut off. Basically this caused a very limited amount of air flow and thus the ice dams.
This is a perfect example of cheap materials and poor construction techniques creating a very serious problem. The house is just barely a year old and they have ice dams causing water damage. So if you’re having trouble with ice dams on a well insulated house it’s likely to be a lack of proper ventilation that’s causing the problem.