Understanding Metal Roof Over Shingle Insulation



Insulation is an important factor to consider when it comes to installing a metal or shingle roof. Surprisingly, it’s a conversation that doesn’t take place enough. It’s such a crucial element because it helps determine how well your roofing material conserves energy. Both shingle and metal roofs are constantly exposed to the sun. Therefore, you can expect both materials to reflect, absorb and release heat. Yet, the rate at which each roofing materials do that can help homeowners determine whether its the best fit for they’re homes.

Huntsville AL is known for its warm weather. In fact, during the summer months, the average temperature is at least ninety-one degrees. Considering a roofing materials insulation properties is essential for keeping your home cool.

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Metal Roof Insulation

Metal roof insulation addresses two major goals; stabilizing the interior temperature and help to prevent material from collecting under the roofing material. Yes, providing a layer of insulation under a metal roof is imperative because metal is naturally a better heat conductor than wood. Quality insulation helps a home retain heat in the winter and keep cool when the temperature dips.

In addition, to controlling heat flow, aiding in preventing condensation insulation will also help control the noise. Metal roofing materials can be noisy specifically when it rains, hail or there is heavy snowfall.  When searching for the right insulation for a metal roof you’ll have to consider the R-value of the material. The R-value measures the thermal resistance of a specific material. The higher the R-value rating is the more effective it will be. The best metal roof insulation options include:


Fiberglass Batts – Fiberglass batts is perhaps the simplest and cheapest ways to insulate a metal roof. Fiberglass consists of fine thread-like pieces mixed with other synthetic materials that are tightly woven together to form a thick insulating pad. The great thing about fiberglass is that it’s a very versatile material which means it can be cut into any width or lengths to cover a surface. Fiberglass insulation should be done by a professional because the shards of glass can be dangerous to work with for a novice.

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Rigid Board – Rigid board insulation can be used anywhere within a dwelling including the foundation. The rigid boards are made from panels of polyurethane and polystyrene, The thicker the material is the higher the R-value. These boards are placed right under a metal roof panel and have to be fitted together. The joints should be sealed or caulked to provide the maximum thermal resistance.


Spray Foam – Spray foam is the most popular insulation method for the metal roof because it’s highly effective. It’s effective at preventing condensation and rodent infestation. This is a form of polyurethane insulation which R-value is determined by the inches. Spray foam is very easy to work with since it can be used to insulate a new or old new metal roof without any disruptions. This insulation method does cost more than fiberglass.


Shingle Roof Insulation

Insulating a shingle roof provides the same benefits of providing insulation for a metal roofing material. It helps retain energy efficiently in your home which ultimately leads to major cost reductions and comfortability. Typically, when insulating a shingle roof homeowners also opt to seal and insulate the attic as well. Extending such efforts to the attic space is imperative because it helps prevent moisture buildup, keeps warm air from escaping in the winter and your home from overheating in the summer.

Before insulating a shingle roof it’s important to make sure the attic is well-ventilated. A poorly ventilated attic cause the shingles problems to crack and melt. It can compromise the health of your shingle roof and shorten its lifespan. Therefore before attempting to insulate your roof, you’ll need to inspect the attic space.

Insulation methods that are offered for metal roofs are also available for shingle roof insulation projects. This includes; spray foam, fiberglass batts, and rigid board insulation. However, here are some additional insulating methods that a professional roofer can implement to make your home more energy efficient:

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Cellulose – Cellulose is the oldest type of insulation material that has been used in homes for several decades. It’s composed of recycled denim. Although it’s the most traditional form of insulation some experts feel that it works best for the attic space rather than the roof. It is fairly inexpensive.


Structural Insulated Panels – SIPs are prefabricated insulated panels that can be used on walls, ceilings and importantly roofing structures. What makes this insulation material different is that it provides more uniform and superior insulation than other construction methods. It’s known for reducing energy consumption by 12-14% making it highly effective. Structural insulated panels have a very high R-value and they can be customized to match the unique dimensions of a  particular roof.


Open Cell Spray Foam – Open-cell spray foam is an additional effective insulation material. It has an R-value of 3.5 per inch. Therefore, it’s great at stopping the movement of air. This means that cold air is will not seep into your home and cooler air will be retained during the summer. The biggest disadvantage of this insulation material is that it requires a moisture barrier because it does allow water vapor to pass through.


Understanding Metal Roof vs Shingle Insulation

Technically, there is no difference in the insulation value of a metal or shingle roof. While metal roofs are efficient at its ability to resist heat transfer it is exposed and absorbs just as much heat as a shingle roof. Shingle roofs weight twice as much as a metal roof which means that it accumulates twice as much heat. Since a metal roof is exposed to just as much heat it runs the risk of transferring such energy to your home which can increases energy bills. That’s why it’s is essential for both roofing types to be well insulated.  Insulating a metal or shingle roof is an investment. If you’re spending money air conditioning and heating your home than it’s well worth it.