This time of year I often get asked whether a metal roof can help someone avoid wintertime ice dams and the resulting damage to their roofs and homes. Generally, the answer to that question is “yes” but there are several things to keep in mind.
First, any time you re-roof your home, it is an opportunity to install an ice and water shield type of membrane around the bottom edge of the roof. Required by code in many places, this rubber or asphaltic membrane will help guard against water intrusion inside of your home if ice damming occurs. However, it does not help keep your shingles from being damaged.
Next, if you have interior damages from ice damming but in the spring your shingles look okay, that does not mean they do not need to be replaced. Some ice damage can be small cracks which, though barely visible, leave your roof extremely vulnerable to water intrusion and further damage.
Third, metal roofs due to their smooth surface and heat handling characteristics, tend to shed snow quickly. This helps avoid ice damming.
The interlocking nature of most metal panels also helps avoid problems due to ice dams.
Finally, if your home is prone to ice dams, when you re-roof is the time to see if you can increase your attic ventilation as well. Keeping your attic at a similar temperature to the outside will go a long way in keeping ice dams from occurring.
With so many architectural challenges by poor designs, dormers, gables, cathedral ceilings, getting to a cold roof via ventilation can be difficult and extremely costly. Your article does not address a basic fact of Mother Nature… THE SUN. What do you do about radiant heat from the sun everyday? Most homes will see some sun exposure during the day. That heat melts snow and creates moisture on the roof, typically following the slope to the eaves and valleys. Then the temperature drops and the melt refreeze. If this happens over a couple of days… ICE DAM! Even on a metal roof keeping valleys, eaves and gutters clear can only be achieved by keeping the refreeze from occurring by keeping the melt liquefied and allowing it to get off the roof and then too the ground. There are products out on the market that can prevent ice dams and keep them from forming. Checkout http://www.thermaltechusa.com and see them in action.
Comment by Darin Rohead — February 11, 2010 @ 4:07 pm
Thanks Darin. You are absolutely correct. I think you guys have great products and I have recommended them before and will in the future as well.
Comment by toddmiller — February 11, 2010 @ 7:03 pm
WE have a 33 year old two story home in Minnesota. the roof on our home needs replacing and we are wondering about a metal roof. The roof line is steep and an area attaching the house to the garage that collects a fair amount of snow. Would a metal roof be a good choice for this application? I love the looks of metal, the stability of metal and the fact that the life span may be longer for a metal verses asphalt roof. Looking forward to your reply!
Comment by Kathie Teslaw — April 2, 2011 @ 4:51 pm
A metal roof is a good choice I feel for almost any home and roof design. However, it is still improtant to think about details and the exact roof being done.
It sounds like you have a “blind valley” area that catches snow. I have the same thing where the garage attaches to my house. This area won;t change much with metal. In fact, some snowguards above the area may help hold the snow and prevent it from converging and packing quite to hard in this area. I would also suggest looking at increasing attic ventilation in the area (which may be very difficult) and perhaps some sort of heating system to help melt the compacted snow.
I hope this helps.
Comment by toddmiller — April 3, 2011 @ 6:16 am
We have a low slope roof. Last winter we had severe interior and roof damage due to ice dams, and are now considering a metal roof. With a metal roof do we still have to have rain gutters/eaves troughs? Do we need to take any measures, such as heating the lower portion of the roof? We already had a waterproof membrane under the current shingles, and it still leaked in. Also, what sort of cost are we looking at for metal roofing?
Comment by Jack Johnson — September 24, 2011 @ 12:57 pm
Metal roofing will be 2 – 3 times the cost of traditional shingles. Most metal roofing customers are homeowners who intend to stay in their home through at least one re-roofing cycle.
Metal roofing does not eliminate ice dams. Its smooth surface can help and the way that the panels interlock can reduce damage from ice dams but there is nothing magical about metal that eliminates ice dams. Many folks give out false information about this fact.
Ice dams are most often the result of inadequate ventilation and insulation in the attic. Addressing those things is the most sure way to end ice dams.
There are a couple of articles here on my site which I have written about this subject.
Comment by toddmiller — September 25, 2011 @ 6:51 am