we’ve just gone through a swampy heat wave. So what better time to think about cold weather?
The epic winter of 2015 and its damaging ice dams have made this summer the busiest in decades for roof repairs. But it’s also an opportunity for homeowners to slash their heating bills and do something meaningful for the environment to boot.
The basics of ice dams are this: Snow lands on the roof and begins to melt. Water flows downhill to the gutter and meets more snow where it refreezes into a block of ice. That ice builds up and gets between roofing shingles causing damage. The ice in contact with the roof melts again, and with the gutter blocked by ice, the meltwater seeps underneath the shingles, causing leaks in the ceiling below.
For a lot of people, that means a new roof and maybe some electrical heating wires to melt the ice if it forms again. But that approach only treats the symptoms, not the cause of ice dams. The real fix is to thoroughly insulate the roof. Paul Eldrenkamp, a general contractor at the Newton-based remodeling company Byggmeister and an expert on energy retrofits, puts it this way: “A well insulated roof is like a good wool winter cap for your home’s head. Much of our heat escapes from the roof. Insulation helps with both energy bills and ice dams.”
The root cause of ice dams is heat transfer between interior spaces and the underside of the roof sheathing — the boards that sit below shingles. Most of that heat transfer is a result of warm air leaking through the attic. Traditionally, the way to try stopping that is by insulating the attic floor. But it doesn’t always work. For one, the most common attic insulation materials — fiberglass and cellulose — are not good at stopping air leaks. Also, we tend to have lots of big holes in our attic floors — such as pull-down stairs, recessed lights in the ceiling below, pipes and wires, ducts for heating and cooling. It’s time consuming to seal all those spaces, and can require homeowners to empty their attics for the insulation crew to be able to do a good job. That alone is enough to discourage people from getting the work done.
As an alternative, skip insulating the attic floor and go a step further — insulate the rafters. The weapon of choice is spray foam, which can adhere to the attic ceiling and create a thick layer of insulation. Think of it like whale blubber. The results: When snow accumulates on the roof, it doesn’t melt — it just sits there or blows off as nature takes its course.
If getting rid of ice dams forever isn’t motivation enough, a well-insulated attic has at least two other benefits.
First, proper insulation and air sealing (plugging up those little gaps that make you lose heat or cool air) can result in significantly lower energy bills. The federal Department of Energy estimates that 42 percent of energy expenses goes to heating spaces. Insulation can cut those costs by one third.
Second, curbing energy use also reduces your environmental footprint. Many eco-conscious consumers recycle and take public transportation, but energy waste is the real source of the excess greenhouse gas emissions that are causing climate change. A tightly insulated attic can make a big difference in a home’s lifetime energy use. Here in Massachusetts, we have one of the oldest housing stocks in the country. While our strong building code means new construction is super-energy efficient, many older homes still need modern insulation.
Don’t just fix or replace your roof — insulate it. You’ll save money on heating bills and do your part to slow global warming. As they say on “Game of Thrones,” winter is coming.
Ian Bowles is managing director of WindSail Capital Group, LLC and a former Massachusetts secretary for energy and the environment.