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Insulating a Metal Roof and Why It's Important

Insulating a Metal Roof and Why It’s Important

Insulating a Metal Roof and Why It's Important

Insulation exists to slow and reduce the transfer of heat through various surfaces. Modern roofs are almost always insulated, and metal roofs are no different. A well insulated metal roof keeps your heating bills down in the winter and your AC bills down in the summer. So how are metal roofs insulated? Do you have any options to choose from? Keep reading to learn the basics about insulating metal roofs.

Why Insulation Is Important

Metal makes a great roofing material for many reasons. It’s durable, recyclable, and relatively easy to install. It stands up well to the elements, from heavy snow to summer heat. The one minor drawback to metal roofing is that metal is a good conductor. In other words, it transfers heat well. Without insulation, a lot of the sun’s heat passes right through the roof, into your attic. Thankfully, insulation can counteract this effect.

With insulation, metal roofing can be as energy efficient as any other type of roofing. In the summer, the insulation will prevent heat from being transferred into your attic. This keeps the top floor of your home cooler and lowers your AC bills. In the winter, the insulation holds heat inside your home, keeping your top floor cozy and lowering your heating bills.

Without insulation, if the temperature outside drops, water will condense on the inside of the metal panels. Over time, this can lead to high humidity and mold growth in the attic. Insulation helps prevent this from happening since it keeps the temperature more consistent on either side of the metal panels.

Insulation is also a reason why modern metal roofs are not noisy. The insulation absorbs sound, so you don’t hear much when it’s raining or hailing outside. 

How Insulation Is Applied to Metal Roofs

If you have insulation added to your metal roof during installation — which is the norm — your roofer will start by putting down a layer of plywood decking. They’ll follow this with a layer of building paper, which will act as an extra barrier against moisture.

Next comes the insulation. Your roofer will place insulation over the entire roof surface. If using rigid insulation, they’ll use special tape to join the sheets of insulation together. This creates a continuous layer to reduce air leaks. Once the insulation is in place, your roofer will install the metal roof panels over it. 

Types of Insulation for Metal Roofs

There are three key types of insulation which can be used with metal roofing. Each has its own pros and cons.

Rigid Foam

Rigid foam insulation is a common option for new metal roofs. It can be cut to the exact size needed. It’s also easy to piece together to form a continuous barrier. Rigid foam insulation has a high R-value, so even a relatively thin layer does a good job of insulation your space. This type of insulation is affordably priced and does not require any specialized equipment to install.

Since rigid foam goes over the roof deck, it has to be installed with the roof. So, you can’t typically use rigid foam to insulate an existing roof.

Spray Foam

Spray foam insulation is a polyurethane product. It starts off as two liquids. When those liquids combine, they swell into a dense, foamy insulation product. 

If you’re having a new metal roof installed, your roofers will typically apply spray foam insulation between the roof deck and metal panels. On the other hand, if you’re insulating an existing metal roof, spray foam can be applied on the opposite side of the roof deck, inside your attic.

No matter which side it is applied on, the spray foam insulation settles into little divots and crevices, forming a consistent barrier. As such, it protects against air leaks and offers a higher degree of insulation than rigid foam.

A small downside to spray foam is that it requires special equipment to apply. It also tends to cost more than rigid foam insulation.

Fiberglass Batts

Sometimes people use fiberglass batt insulation with metal roofing. Fiberglass is inexpensive, easy to install, and can be added to an existing metal roof. 

Fiberglass batts cannot be placed over the roof deck. They have to be unrolled between the roof trusses, inside the attic. They also absorb moisture, which is an issue if condensation forms on the metal roof. Rigid foam and spray foam are far better choices for metal roof insulation in most cases.

Insulation is the key to quiet, energy-efficient metal roofing. Whether you’re having a new roof installed or want to add insulation to an existing roof, talk to your roofing contractor about your options. Contact Mark Kaufman Roofing if you’re looking for a roofer in the North Port, Florida area. Our experienced roofers will evaluate your needs and offer a comprehensive estimate.

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