You might think a roof is just a roof and that as long as it is constructed properly, that this should be enough. Think again. Different locales have considerably different weather patterns, and there is the range from excruciatingly hot to bitter cold. Considerations in these opposites make a difference in not only your own personal comfort, but your wallet, too, when it comes time to pay the utility bill.
The biggest thing to remember is that a roof is a system, not just something on top of your house. Roof systems require proper ventilation, insulation and water barriers. Without these three things in place, the best laid roof is destined to fail. This results in interior damage and costly repairs. Knowing the basics of a roof system is more than just picking the best shingle you can afford. Older homes especially suffer from poor design. When a roof is replaced, it is time to fix those issues to insure your roof and home don't suffer from the effects of an improperly installed roof. Here, we will discuss what it takes to install a roof properly, what is involved in the total roof system, and what to look for.
Although you are correct in assuming that insulation helps keep heat bills lower, it also is a big part of a roof system. The average family of four generates 2 to 4 gallons of water vapor a day through cooking, washing and doing laundry. Insulation installed correctly helps to keep this water vapor from entering the attic area. Water vapor in the attic leads to rot and decay of the infrastructure. Over time, this can lead to failure of the system. To be effective, the insulation must be integrated with a good attic ventilation system, including exhaust vents, baffles and intake vents. This system helps to keep the attic area dry.
Heat can be as damaging as cold if the ventilation system is not properly installed. It takes more than good insulation in an attic to keep cost down. Over a period of time on a hot summer day, heat becomes trapped in the attic, necessitating running air conditioners and fans to cool the interior. This heat buildup is damaging to shingles, causing them to deteriorate prematurely. The proper design includes baffles in the roof, properly spaced, and intake vents spaced regularly along the soffit. A ridge vent should run the length of the roof. Baffles prevent insulation from clogging the soffit vents, and help to prevent wind from washing through the insulation. They should be installed so that they are at least 4 inches above the insulation.
Ice dams on the roof can be very damaging, because they allow water to seep into the interior, damaging the attic floor. Water can leak down inside interior walls, compacting insulation and often leading to mold and mildew. They form when there are variations in the temperature of the roof. Upper portions of the roof are warmer than lower portions, so snow melts on upper levels and the water drains down to lower levels. When the water reaches the lower levels that are colder, an ice dam forms. When an ice dam forms, continuing water from melting snow is blocked from falling off the roof, and the pooled water will begin to seep through roofing materials and enter the attic.
What Causes Ice Dams
Ice dams form because the attic is not air tight. Heat rises through conduction to the upper portion of the roof, causing it to be warmer. It is the variation of heat through the roof system that causes dams to form. It can be rectified by insuring the attic is properly insulated. In many homes, heat ducts run in the ceilings. If not properly insulated, heat loss from these ducts also causes warm spots on a roof. Look at your roof in the winter. If you see bare spots on the roof above specific rooms of the house, you can bet that it is not properly insulated.
Fixing The Problem
Insure that insulation is adequate in the ceiling. Building codes describe the proper amount of insulation, but don't always result in enough insulation to prevent ice dams. Insure that your attic is as air tight as you can possibly make it.
Although a roof system is a complicated thing, it doesn't have to be rocket science. Making sure an attic is insulated properly, insuring that the attic is properly ventilated, and making sure a water barrier membrane is installed when a new roof is put on goes a long way towards a good roof system. The best plan of action is to inspect the roof frequently before problems arise.
Alden Smith is an award winning author and regular contributor to DoItYourself.com. He writes on a variety of subjects, and excels in research.