The Sealed guide to insulation

Which parts of the house need insulation? What materials are right for you? And who are the right contractors for the job?

Which parts of the house need insulation? What materials are right for you? And who are the right contractors for the job?

If you’re looking to make your home more comfortable and efficient, insulation is one of the most effective upgrades you can make. 

Insulation’s benefits are many. It helps reduce energy usage and keep your house cooler in summer and warmer in winter. And there are some lesser-known benefits as well. For instance, insulation can help keep your whole house quieter by dampening noise from the outside.

Choosing the best insulation for your home, however, can be a tricky task. It’s crucial that you choose the right materials, the right spots to insulate, and the right partners to help with the work. 

Feeling overwhelmed? Don’t sweat it. In this article we’ll give you the basics on insulation so you understand your options.

Why insulate? 

Insulation is one of the best ways to boost your home’s efficiency. That’s because insulation has what’s known as a high resistance value, or “R value.”

R value is a measure of how well a barrier or surface—like a window, wall, or layer of insulation—resists the flow of heat. Here’s one way to think about it. When you pour hot water into a paper cup, it can burn your hand. But if you pour hot water into a thermos, you won’t feel anything. That’s because the thermos has a higher R value than paper. 

If a building material has a high R value, it’ll be great at keeping the heat inside your house and the cold outside in winter. In summer, it’ll help keep the cool air inside and hold the balmy air outside. It also means your heating and cooling equipment have to work a lot less throughout the year.

If you worry your house is wasting energy on heating and cooling, some people will tell you that new windows are the best path to increasing your home’s efficiency. But even the priciest, most technologically advanced windows will only improve your R value by a few points. Properly installed insulation, however, can give you a boost in R value of up to 50 points.

That’s why we often caution Sealed customers against buying new windows unless absolutely necessary. Yes, new windows can make you more energy efficient, but insulation typically makes a far bigger impact on heating and cooling efficiency at a fraction of the cost.

Where to insulate?

The attic

We always recommend insulating your attic first. There are a number of reasons why.

Heat rises, so in winter the attic is the number one source of heat loss from your house. The warm air in your house is drawn up into the attic and out through the roof. 

In summer, as the hot sun beats down on your roof, an uninsulated attic can reach temperatures of up to 150 degrees. All that heat then radiates down through the floor of the attic, the ceiling of the second floor, and into the lower floors of your house. It’s one reason why many homeowners’ second floors feel like saunas in the summer. 

But it’s not all bad news with attics. While they are major sources of heat loss and heat gain, attics have one key advantage. They’re big and, often, unfinished and empty. That means there’s lots of room to apply thick layers of insulation. And it’s why attics offer the greatest potential for boosting your home’s R value with insulation.

Other areas of the house

  • Walls: This is the place many people think they should insulate first. Walls, however, offer much less space for insulation than attics, meaning there’s less potential to increase your home’s R value. We recommend insulating walls as a secondary measure after insulating the attic, or if you live in a very old home with totally uninsulated walls. 
  • Overhangs: If you have a room that’s built into an overhang, you likely experience ice cold winters and steaming summers. Adding insulation to the overhang can help stabilize your temperatures.
  • Garage ceiling and wall: Your garage is technically outside. So anyone with a bedroom over a garage or next to one knows that these can be some of the most uncomfortable rooms in a house. Insulating any ceiling or wall of the garage that borders a living space can prevent unwanted heat transfer with the rooms above and next to it.
  • Knee walls and secondary attics: Did you know your house might have more than one attic? It’s true. And these other attics, which sometimes appear to be little more than glorified closets, can also make a big impact on your home’s comfort. Insulation can help tame the temperatures in these hidden nooks and crannies throughout the house.

Know your insulation

There are many different types and brands of insulation available. Some are more efficient than others. And some are better suited than others to different types of applications and installations. Here’s a quick overview. 


This may be the one with which you’re most familiar. Often recognizable by a signature pink and yellow colors, it’s a great choice if you want to insulate areas like knee walls. It’s worth taking a few extra precautions when using fiberglass, though. It can be susceptible to moisture and it’s also a favorite snack of raccoons.

Spray foam

One of the newer insulation types, spray foam comes in two varieties: open cell and closed cell. Open cell is lighter, and less dense. It’s better for filling spaces with lots of little nooks and crannies. Closed cell is more dense, completely impermeable, and has a higher R value. But it’s more expensive and can be trickier to install.


Cellulose is a type of blown insulation made from shredded recycled newspaper. Before installation the paper is treated to make it fire retardant and pest-repellant. It can be blown in loose to insulate open areas like attic floors, or more densely for contained spaces such as garage ceilings.

Insulation and air sealing: a powerful combination

For all of its benefits, insulation is not a cure-all for homes experiencing energy waste and discomfort. To really solve these issues, you also need to consider insulation’s main partner in crime: air sealing

Insulation works like the down lining in a winter coat, helping lock in warmth, and air sealing is like a wind breaker, stopping excess airflow. If your house is heavily insulated but lacks proper air sealing, your insulation won’t have the same weather-stopping power. 

Plus, having a lot of insulation without proper air sealing can create secondary problems like mold and mildew buildup. Air sealing acts as a natural moisture barrier, and can prevent these problems as well. 

You’re not alone

As you can see, there’s a lot to consider when it comes to insulation. This is complicated work, and in our experience we’ve found it best to work with the experts. That’s why Sealed only partners with certified home performance contractors for insulation and air sealing. 

Fortunately, you don’t have to go through this process alone. We’ve helped hundreds of customers make smart decisions about upgrading their home’s insulation. And we’d be delighted to help you too. 

Want to learn more about insulation and how Sealed can help? Give one of our experts a call today at 888-985-7481.

February 24, 2020