Ice Dams: The Cold, Hard Facts
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s a roofing contractor, I have dealt with winters from the rooftop for nearly four decades. Minnesota winters are legendary. Extreme winter conditions will challenge even the best-constructed buildings. 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. I am always careful with the word “eliminate” when dealing with ice dams.
3) The Roof System: Workmanship Excellence.
There are three items that when constructed to the best possible finish can minimize the elements that create roof ice:
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.
1) Insulation: Not just the minimum. Upgrade/add if your budget allows. An R-50 plus would be ideal. Be very detailed and complete at bypasses/penetrations and exterior wall/eave assemblies. Exterior wall plates and soffit chutes sprayed in with polyurethane foam (SPF). Excellent Return On Investment (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.
By G. Leonard West, LS West llc
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.
If you are a DIY (insulation/ventilation), check with your local building official for required permits and inspections. 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. Continued on page 18 November | December 2014
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