How exactly does insulation work? Homes have to have insulation to help with temperature control. A house without insulation cannot pass inspection in this day and age. So, what does the insulation do?
South Central Services installs spray foam, blown-in cellulose, and batt insulation. Our team is passionate about the role of insulation in a home. By the end of this article, you’ll understand how insulation keeps a home cool!
Homes Need Some Material To Keep Out Heat.
In the summer, we want our homes to be cool. The outdoor temperatures are much higher than we could enjoy living and working in. Without an insulation material, there would be practically no barrier between your home environment and the temperatures outside.
While the building materials in your wall and roof assemblies are technically a barrier, they cannot effectively stop heat without insulation.
Insulation Materials Have A High R-Value.
What makes insulation materials special is their R-value. R-value stands for resistance value, and it describes how well a material resists conductive heat transfer.
The higher a material’s R-value, the better it resists heat!
Anything can have an R-value. Metal has a low R-value, making it an ideal cookware material. When cloth is layered, it has a higher R-value, helping it work as a hot pad for a hot pan.
All Insulation Blocks Conductive Heat.
High R-value is something every insulation has in common. A material that cannot block conductive heat transfer will not work well as an insulator.
Conductive heat transfer is direct heat transfer. You can think of a stovetop and the heat that transfers to the pan. When a pan sits on a burner, the pan conducts heat from the burner. Conductive heat transfer is direct and travels through solid materials.
The Best Insulations Block Heat Through The Air.
If you want an insulation with excellent performance, you need an air-seal. Heat does transfer through conduction, but it also travels with radiation and convection.
If we return to our stovetop and look at the oven beneath it, we see convection heat. When you put a baking tray of cookies into the oven, the cookies are baked by hot air.
Standing back from the oven, you can feel heat radiating from the stovetop when the burner is on.
While every insulation product will block conduction heat, not all insulations can stop convection or radiant heat.
Budget Insulations Can Be Paired With An Air-Sealing Tool.
More affordable insulations like fiberglass batt and blown-in cellulose cannot block radiant or convection heat on their own. Both batt and blown-in insulations allow air to pass through them.
A separate air-sealing product can maximize the performance of these insulations. Before installing batt or blown-in, areas of air leakage can be sealed up with caulking, can foam, and covers. Preventing air leakage means preventing heat transfer through that air leakage.
When our team insulates an attic with blown-in cellulose, we always air-seal any leaks and penetrations first. We also offer a hybrid system for exterior walls, which combines an air-seal with fiberglass batt.
The use of a separate air-seal will drive up the cost of these insulations. However, even with air-sealing, both batt and blown-in can be quite affordable.
Insulations Like Spray Foam Can Air-Seal On Their Own.
Spray foam insulation is a more expensive option than batt or blown-in. Unlike more budget-friendly insulations, spray foam can air-seal.
When insulating with spray foam, there’s no need for a separate air-sealing product. Spray foam is spray-applied and seals up any leaks, gaps, cracks, or penetrations on its own.
Spray foam is versatile and can be installed almost anywhere. It’s an excellent option for irregular surfaces like stone. As a general rule, spray foam is regarded as premium because of its longevity, versatility, and superior performance.
In Summer, Attic Insulation Is Most Important.
When it comes to keeping the heat out, your attic insulation plays a key role. Summertime means bright sunlight beating against your roof. The heat outside transfers into your attic. That hot attic air presses into your living space without effective insulation and air-sealing upstairs.
Whether you choose spray foam or a budget product with a separate air-seal, you need effective attic insulation to stay cool.
Budget products like blown-in cellulose can be installed on the attic floor. The separate air-seal beneath the blown-in prevents hot attic air from leaking into the rooms below. The same can be achieved with closed cell spray foam on the floor.
An alternative to attic floor insulation is encapsulation. Encapsulation uses open cell or closed cell spray foam on the underside of the roof and the attic gables. By putting the insulation layer just below the roof, the attic air stays cooler.
Encapsulation is a good option when there is ductwork upstairs, or the space needs to be temperature-controlled. With an encapsulated attic, neither the conductive heat from the roof assembly nor any air leaks in the envelope can heat the upstairs.
In either case, the result is a cooler home in the summer.
The Bottom Line About How Insulation Works In The Summer
All homes need insulation. Every insulation has an R-value that demonstrates a resistance to convection heat transfer. You should also invest in an air-seal to keep a home as cool as possible in summer. Depending on your choice of insulation, the air-seal will either be included or separate.
By air-sealing, your insulation package can also resist conduction and radiant heat transfer through the air. This is seen most prevalently in the attic. Without insulation, your attic absorbs and transfers immense amounts of heat in your home. With effective insulation upstairs, your whole home stays cooler.
Now that you know how insulation keeps your home cool, your next step is to:
- Compare attic insulation options
- Estimate the cost of an attic insulation upgrade
- Learn more about how heat travels in your home
Disclaimer: While we strive to publish information accurate to building science, local building codes and standards supersede our recommendations.
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