What Are My Roof Insulation Options in Portland?

Articles | Insulation
July 24, 2022

Insulation. You depend on it, whether you realize it or not. It’s the element of your home that keeps heat in during the winter and keeps it out during the summer. It’s not just about comfort, either. Your energy bill depends on having effective roof insulation because, without it, heat will simply convect into the outside world through your rooftop and dissipate. This will force your heater to cycle back on continuously, burning through more and more fuel and eventually driving your energy bill up to unmanageable levels.

The people of Portland, Oregon, depend on well-insulated roofs. This is because Portland has a climate that can vary greatly depending on the time of year. The roof insulation Portland homes need should provide an excellent barrier to heat energy, and there are several material options to choose from. Here, we’ll discuss the pros and cons of each one.

What Makes For Good Insulation Material?

Some materials are better for insulation than others. That is obvious, but exactly which materials are the best has long been a matter of scientific study. The effectiveness of insulation material is measured in what’s known as R-value: this is a measurement of how well a material can resist the transfer of heat.

The second law of thermodynamics means that heat energy is always trying to transfer from one place to the next. There’s no way to completely stop this transfer, but you can slow it down tremendously with the right material. This material should be found throughout the home but particularly below the roof. After all, heat energy naturally travels upward, so a great deal of heat is lost through the roof of a home.

Materials that work best for insulation should have a rigid molecular structure. It’s the movement of molecules that leads to the transfer of heat, so the more rigid the composition, the better it is at preventing the transfer of heat energy. We’ll discuss a few such materials in this article.

Equally important for effective insulation is building it up in many layers. These layers trap air, which in turn can hold the heat energy and prevent it from immediately dissipating. This is why jackets work to keep us warmer. They provide an added layer of warm air that traps heat energy. Of course, with regard to air conditioning, this works in reverse as well. Heat energy cannot penetrate through effective insulation, even on a hot day.


One of the most common types of insulation is batt insulation, or batting. You’ve probably seen it before, anytime you’ve looked into an attic or behind a layer of drywall. It’s usually made up of fiberglass wool. Why fiberglass? Well, as a type of glass, fiberglass has extremely rigid molecules, which is part of the criteria we’ve previously mentioned.

There are plenty of benefits to batt insulation, with the biggest one (for most homeowners) being its relatively low cost. You can purchase large rolls of fiberglass insulation for very little money. This means you can add many layers of it quite easily. It can be purchased at several different R-values, depending on your need.

The biggest downside of batting is that it’s generally installed in between the structure of your roof, meaning that any area it doesn’t cover can quickly become a weak point in your insulation. Even a small area that doesn’t receive coverage can quickly drive your energy bill up. You can largely avoid this problem by ensuring that proper installation is done, by a highly trained professional from an experienced company.

Spray Foam

Spray foam insulation is exactly what it sounds like: it’s a type of insulation that can be sprayed into place. It’s generally made up of a two-part chemical composition (usually methylene diphenyl diisocyanate and some type of catalyst) and can be easily used to fill nooks and crannies.

This sets it apart from batt insulation right away. While batting has a hard time filling every hole and crack, spray foam can more easily get into small areas that other types of installation cannot. Unlike other insulation types, it’s also waterproof. The insulation Portland homeowners need should be able to resist water since there’s so much rain there.

There are several downsides to spray foam insulation too. It’s expensive, and putting enough of it into place to provide effective insulation requires many layers. This renders it cost-prohibitive for some homeowners. Also, while it’s waterproof, if the installation is done incorrectly, cavities can form where water will pool, leading to water damage. Once again, this problem can be avoided with proper professional installation.

Loose Fill Insulation

Loose fill insulation is unique among insulation types because it can be used in areas that can’t easily have other insulation materials installed there. It’s made up of small particles of some type of insulation material—usually cellulose or glass wool—and it can be blown into place using a large hose. In doing so, it can fill up cracks, crevices, and cavities in a way similar to spray foam.

Depending on the material you choose to use, loose-fill insulation can be either expensive or inexpensive. Somewhat predictably, the R-value of the material is better with the higher-priced options. The material does have a few downsides: it’s extremely messy to install, blasting dust everywhere, which means it’s not practical for every space. It also tends to settle over time, potentially forcing you to have another installation performed.

Insulation Boards

The final option we’ll list for Portland homeowners is foam board insulation. This is made up of, of course, thick sheets of high-quality foam (such as expanded polystyrene) and can be installed in between the rafters of a roof. This makes it the best insulation option for covering structural elements, as spray foam and loose-fill insulation can’t be allowed to cover wiring and related structures.

Insulation boards can simply be screwed into place, making installation easy. This method does have a few downsides of its own, however. While the installation is easy, the boards must be cut into place very carefully in order to fit in every necessary area, and this can take a great deal of extra time. This makes it more difficult to install in certain areas.

Ultimately, the proper installation is probably more important than the material itself. That’s why you should contact the professionals at Interstate Roofing to discuss your options for installing insulation with your roof with them. Whatever material you choose to use for your home, they will be able to install it for you in a safe, effective, and clean manner at the same time they install your roof.