Metal Roof Insulation is becoming a hot topic in the building construction industry as metal roofs become more prevalent on residential homes. It used to be that these roofs were only found on architect-designed homes, but today they are more widely used. Different metal roof manufacturers and building experts have differing opinions on insulating metal roofs. Some say you should always insulate a metal roof and others say it is unnecessary.
In an ideal building situation, metal roof insulation is probably unnecessary because Attic Blown-in Insulation|insulation would be handled by soffit and roof vents in the attic. However, when ideal situations aren't met, insulation may make sense with a metal roof.
Spray Foam Metal Roof Insulation
The most common type of metal roof insulation available on the market is spray foam insulation. Advanced Insulation and MBCI, are two of the largest metal roofing manufacturers. The companies both sell an open-cell foam that is fairly cost effective. However, closed cell foam is often a better choice because it gets twice the R-value per inch. Furthermore, closed-cell foam is a vapor retarder and open-cell is more vapor-permeable. A vapor retarder prevents water from condensing when it makes contact with the metal roof.
Water condensation is one concern with insulating metal roofs. Corrosion is another. The foam can sometimes cause the metal to corrode. Only the roofing manufacturer can tell you if corrosion or condensation will be problems. They can also tell you if insulating the roof will violate the warranty. You can't rely on your roofing contractor's opinion only. In order to protect your roof's warranty, you must check with the manufacturer.
One reason it may make sense to insulate a metal roof is to help fight global warming. Global warming is linked with, among other things, melting polar caps, animal extinction and drastic changes in temperature. A well insulated roof can reduce energy requirements for a home. This not only helps with heating bills, but it also helps the environment. Plus, many spray foam insulations are made from recycled content so they are environmentally sensitive from cradle-to-cradle.
Fiberglass is a very common insulation material for metal roofs. Unfaced fiberglass insulation can be placed directly on an existing roof surface. Or, it can be installed directly under the metal panel. Fiberglass insulation causes a metal roof to expand and contract.
Metal Roofing Facts
Here are some other important facts about metal roofs.
- Metal roofs are no noisier than other roofs because the attic and insulation provide a sound barrier.
- Metal roofs are not struck by lightning any more than standard roofs.
- Metal roofs have a similar life span to conventional roofs and usually come with 30 year warrantees.
- Metal roofs are impervious to termites, rot and mildew.
- Metal roofs conduct heat quickly from the sun.
- Metal roofs cost more than conventional roofs.
- Metal roofs, like conventional roofs, can be installed over an existing roof.
- Metal roofs are durable, lightweight, easy to install, easy to maintain and weathertight.
When installing anything on a roof, make sure to check your local building codes and pull any necessary permits. Beware of wind lift codes too. Keep in mind, if you plan to insulate the roof yourself, metal roofs are very slippery and therefore dangerous.
Check with an expert before insulating your metal roof and again, be sure to follow the manufacturer's guidleines. A properly insulated metal roof can garner great rewards both financially and environmentally.