Preventing Ice Dams

Ice damsThere are many things about the winter that I enjoy.  The snow is pretty, Christmas lights are enjoyable to see, ice is great (as long as it’s not under my tires while I’m driving).  Icicles on my house, especially around the holidays, are also pretty…..pretty dangerous that is!   Icicles on your roof are a screaming symptom of what are known as ICE DAMS.

An ice dam is thick ridges of solid ice that build up along the eaves of your house. If they are left unattended, they can and will tear off your gutters, loosen your shingles, and cause water to back up and pour into your house.  Ice dams cause millions of dollars of damage every year.  Ice dams form with as little as 1 or 2 inches of snow accumulation on a roof.  They form along the roof’s lower edge usually above the overhang because the upper roof surface near the peak of your roof is at a temperature that is above freezing.  This happens because it is located directly above the living space and as most of us know, heat rises.  One of the key culprits to ice dam formation is poor insulation.  If the attic isn’t well insulated then the heat isn't staying in the living area of the home. It will escape through the roof and that is where your problems begin. Heat lost from homes helps melt the snow on the roof. Even well-constructed and designed roofs can have ice dams.

How an ice dam forms

  • Heat from the attic warms the roof but not the eaves
  • Heat melts the snow
  • Water runs down the roof to the eaves then re-freezes
  • This will happen several times as the temperature warms and cools
  • Over time the ice builds up and forms what is known as an ice dam

The more snow you have on your roof, the more it will trap indoor heat between the snow and the roof out of sight by you the homeowner until that first icicle shows up.  At that point it could be too late.  There could be a river of flowing melted snow that has been running down your roof for days.  Once the dam is big enough any newly melted snow will run down and be pushed back under the shingles and into your house.  Damage from ice dams can include:

  • Peeling paint- Wall paint (interior or exterior) most likely will not blister or peel at a time when ice dams are visible. This will happen long after ice and snow have disappeared for the season.  It is a good idea to pay close attention in the winter to avoid a repeated “Honey-Dew” list each year.
  • Damaged plaster – If moisture gets trapped within the wall cavity between the exterior and interior the result: smelly, rotting wall cavities. Structural framing can be compromised, metal fasteners may corrode, mold and mildew can form. The list of damage goes on.
  • Warped floors
  • Sagging/water stained ceilings
  • Soggy insulation - The more heat that is lost, the more ice dams that form, the more it leaks, the more the insulation gets damaged, etc.   As a result you pay more to heat and cool your house.
  • Dislodged roof shingles
  • Sagging ice-filled gutters

That’s a pretty big list of problems to have to tackle just as the weather begins to improve and you would like to start your outside projects.  If you would prefer to avoid ice dams, here are some tips on how to

Prevent them.

  • Set up a box fan in the attic to blow on the area where the water is actively leaking
  • Use a Roof Rake to pull the snow off the roof
  • Use a Calcium Chloride ice melter (loaded in a disgarded pair of panty hose) (HOW?)
  • Install ridge & soffit vents to circulate cold air
  • Cap the Attic Hatch
  • Ensure exhaust ducts are properly set to vent outside
  • Add or replace attic insulation, especially around lighting fixtures
  • Check chimney flashing for gaps
  • Caulk around wire| pipe | plumbing penetrations

Owning a home is a lot of work.  House guests are nice when they are invited.  Ice Dams are both a lot of work and an unwelcomed guest that we would all like to avoid  By taking the time to inspect your home regularly you will most likely be able to prevent ice dams and the costly damages they bring with them.

http://www.thisoldhouse.com/toh/photos/print/0,,20557572,00.html

http://bct.eco.umass.edu/publications/by-title/preventing-ice-dams/