Wednesday, January 24, 2007
Icicles on the Roof - Equals a Poorly Insulated Home
I took these pictures yesterday morning, two days after a five inch snow fall. Temperatures have not been above freezing since. Many older homes are "cooking" the snow off their roofs and making icicles and ice dams.
Remember these are Cape Cod homes. In a Cape Cod the second floor rooms are built under the roof. They have a:
1. lower vertical wall, called the knee wall (with a craw space between the knee wall and the roof),
2. an upper angled wall (angled at the same pitch as the roof) and
3. a flat ceiling (with a small true attic above it).
The home in the first picture has a warm attic. Most likely, there is not enough insulation above the flat ceiling in the attic area. Note, the large beautiful icicles.
The second Cape Cod does not have enough insulation between the angled upper wall and the roof. This is common because the space is typically only six inches wide and also should allow air flow between the crawl space and the attic. Sadly this is not easy to fix (everything else that I mention here is relatively easy to fix). Meanwhile the attic looks pretty well insulated.
This house looks pretty good. But note the one area where the snow is melting just to the right of the chimney. In a Cape Cod the crawl space is often used for storage, either by building shelving units into the crawl space or by putting little entry hatches in the knee wall that allow people to store "stuff" in the crawlspace. If either the built-in storage units or the entry hatches are not air tight they will leak warm air and cause snow melt above them.
Also, note in the third picture that snow is melting from around the chimney. This means that inside-the-home air is running up the chimney chase and melting snow around the chimney.
Heat rises. So warm air is pressing against a Cape Cod's second floor ceiling with more "pressure" than anywhere else in the home. The ceiling and the walls need to be air tight.
All these houses were built in about 1950. It could be that for those fifty years they would have been 20% more efficient with better insulated and tighter second floor areas. That 20% heat losses would have heated the homes for about 10 years.
So look at your roof, after a snow or a frost, and see how it is doing. If you have icicles or is melting some areas before others it probably needs work and is wasting you money and wasting the planet's natural gas.
To get a better idea where the air leaks are, get a blower door test. In Wisconsin contact Focus on Energy to line one up (www.focusonenergy.com).
This is something real that you can do to reduce global warming and your energy bill. And everyone that lives in your house in the future will benefit as well.