A few days ago, we showed pictures of various roofs with evidence of heat loss as demonstrated by strange snow melt patterns and icicles. Now, a few days later, I wanted to show what’s going on with couple of the homes.
First, the best performing roof still shows a remarkably even snow melt pattern. Remember, this roof assembly is well air-sealed and insulated to R-60. We do see a few small icicles on the left side of the roof. An important point is that it is impossible to completely eliminate icicles, even with a great insulation and air-sealing job. Outside temperatures, sun, and even depth of snow (since snow itself provides some insulation value) all are factors. You’ll also see a chuck of snow missing on the right. This actually didn’t melt off. A thin layer of melt water under the snow actually caused a section of snow to slide off the metal portion of the roof this morning.
This second shot, shows another house from the earlier pictures. This second house is on the same side of the street, facing the same direction, and just a couple hundred feet from the house shown above. Snow on the main part of the house continues to melt fairly quickly. The snow at the eaves of the two gable ends–not directly above the attic–is more than twice as deep as over the house showing the the house is a big contributor to the melt. The snow on the addition roof to the right is almost completely gone showing much higher heat loss from this part of the house–an issue that should have been much better addressed at the time of construction.
Again, you can’t completely eliminate heat loss or icicle formation. But with proper insulation and air-sealing you can greatly reduce the problem, save a lot of energy, and help your roof last longer. A good energy audit can show you the way. And energy-efficiency tax credits and state and utility incentives can often help pay for the improvements.