Ice Dams - The Cold, Hard Facts
For nearly four decades, we have dealt with Minnesota winters from the rooftop. We don’t settle in for long winter naps. Minnesota winters are legendary. Extreme winter conditions will challenge even the best-constructed buildings. We will share with you our knowledge & experience in dealing with ice dams. The good news is that you can “minimize” the elements that create roof ice to a point where the chance of roof leaks is near zero. Again, near zero. We are always careful with the word “eliminate” when dealing with ice dams.
Throughout the years we have removed roof ice from many building types that had excellent insulation. The steep slope structures were built with energy heeled trusses and a solid wind wash barrier @ the exterior wall. The low slope roofs were properly engineered to drain and not have ponding issues. There was excellent ventilation in the attic space that created a uniformed & correct airflow from bottom (the eave/overhang) to the top (the peak/ridge). There was a difference though. The buildings that engineered with the best insulation, ventilation and detailed roof installations have minimal ice. Minimal ice means minimal chance of leaks & resulting damage.
“Eliminate” ice dams? Very difficult.
There are three items that when constructed to the best possible finish can “minimize” the elements that create roof ice
1) Insulation - Not just the minimum.
Upgrade/add if your budget allows. An R-50 plus would be ideal. Be very detailed & complete at bypasses/penetrations and exterior wall/eave assemblies. Exterior wall plates and soffit chutes sprayed in with polyurethane foam (SPF). Excellent ROI.
2) Ventilation - A uniform & correct airflow.
A correct airflow is a straight line from eave/soffit to the ridge/peak or side to side as with gable end louvers. Attic spaces can be sectioned with poly sheeting to achieve a uniform airflow. Do not disturb firewalls when adding vents. Intake (eave) and Exhaust (peak) should be balanced. Do not mix and match vent types, airflow will not exhaust in a uniform manner.
3) The Roof System – Workmanship Excellence
Steep Slope - Additional ice shield at bathroom/dryer exhaust vents and roof sections under drip/drain lines. Detailed workmanship – underlayment (ice shield, felt & papers) should be complete to all perimeter edges before installing drip edge or gutter aprons. Turbine vents are excellent when a greater draw is needed from eave to peak.
Low Slope - Low slope/flat roofs should be engineered to eliminate ponding & drain properly. Get the vapor barrier right. The membrane should be complete at all perimeter and parapet assemblies. Insulation should be detailed & complete. A quality, detailed insulation assembly will not cost, it will pay.
If you are a DIY (insulation/ventilation), check with your local building official for required permits and inspections. In multi-family or commercial buildings, it is critical that items such as firewalls and clearance to combustibles be maintained or properly constructed. Please, always do it safely.
Removing Snow and Ice – Proactive or Reactive?
In a perfect world it would be ideal if you could completely clean every roof after every snowfall. Fortunately, this is not necessary. A mix of being proactive and reactive can keep everyone dry, on budget and avoid devastating/expensive insurance claims.
It is always best to promptly remove snow before it becomes ice. The man-hours required to clean snow from a roof section will always be less that it would to remove/channel an ice dam. Snow should be shoveled 4-8 feet back from the outside wall. Remove snow from valleys, drip/drain lines and bathroom/dryer exhaust vents. Be thorough with the snow removal. Exposed shingles will heat up (even in extreme cold) and allow the sun to do much of the work.
If your budget does not allow for continual (proactive) snow removal it is important to monitor the roofs for excessive snow and ice build-up. If/when there is ice damming or a leak call has occurred remember this:
Ice can be removed by Steam or by Hand. There are pros & cons to both methods. Remember - It’s not the tool; it’s the guy using it.
You do not need to remove all of the ice. You need to get the water to drain. Cut vertical channels (Steam or by Hand) in the ice dam. Drain channels should be cut a minimum of 1 foot wide. Do not remove ice from gutters. It is time consuming (costly) and unnecessary. Any melt/run-off will flow over the gutter.
Ice melt socks can be used to cut or maintain drain channels. Socks are excellent for flat roof scuppers/drains. Try to use socks minimally. If gutters are present aluminum will not rust but may scald if too much ice melt is used. If you need larger amounts of ice melt/socks, try to stay away from Calcium Chloride (CaCi). It works well but can be more corrosive. Try to use an ice melt that has Sodium Acetate (NAAC) or Calcium Magnesium Acetate (CMA).
Most important of all is only those who are experienced and properly insured should ever be on your roof. Please stay safe, warm and dry this winter.