Best Metal Roofing Insulation Options
Insulating your metal roof will not only reduce the energy demands of your home but it will save the earth and reduce global warming. Metal roof insulation will keep your home warm in the winter, cool in the summer, and significantly reduce your utility costs. There are different types of metal roof insulations to choose from. The best choice for you will meet your insulation needs and fit your budget.
What is R-value?
You can generally compare roof insulation material performance using their R-value ratings. R-value is a measure of thermal resistance, or resistance to the flow of heat, of an insulator. In general, the larger the R-value, the more effective the insulating material is.
Three Types of Heat Loss or Gain
Buildings lose or gain heat from a combination of three basic ways: Conductive, convective, and radiant. Conductive heat loss is the least significant contributor to the total heat loss or gain of a building. Metal roofing is the most conductive roofing material, however, among the common roofing material choices. Conductive heat is what you experience standing barefoot on a warm concrete floor.
You are probably more famility with convective heat loss or gain, in which heat is transferred with the passing of air. Most thermal roofing insulations are designed to mitigate convective heat loss or gain. All roof insulations designed to mitigate convective heat loss or gains are vulnerable to losing their effectiveness by absorbing humidity. R-values given for convective heat loss or gain insulations are expressed per inch, so increasing the thickness of insulation increases the total R-value.
Radiant heat loss or gain is often overlooked but is still a significant contributor to the total heat gain or loss through the roof of a building. During the heating season 50 to 75 percent of heat loss through the roof is radiant heat loss. During the cooling season up to 93 percent of heat gain is radiant heat gain. Because R-value is a function of convective heat, radiant heat insulations are not given an R-value. Choosing a radiant barrier insulation material will significantly reduce the energy needs of your home. An insulation material incorporating radiant and convective barrier technologies is the best case scenario. What follows are your basic choices for metal roofing insulation materials.
- Fiberglass batt insulation is the itchy stuff most people are familiar with. It's your least expensive choice.
- Rigid board insulation is a more expensive option. It’s easy to work with and has a high R-value per inch.
- Bubble insulation is not reliable.
- Radiant barrier insulation can be used in conjunction with thermal insulation or independently.
- Spray foam is a large-scale version of what comes out of a can. Fire retardant can be added to the mixture.
Metal roofing insulation is a green solution to reducing your heating and cooling costs. Be mindful of any health hazards associated with the material you are considering. Check the manufacturer’s MSDS for known health concerns and protection.