You may be insulating your home wrong. Here’s what to know.

Insulation is key to keeping your home toasty in the winter without driving up your utility bills.

Improving insulation can help with sealing air leaks — and could save you up to 20% on your heating and cooling costs, according to the Energy Department. But the benefits depend on how properly the insulation is done.

“You could use the wrong material and the wrong approach,” said Christian Kaltreider, a buildings research engineer with the Pacific Northwest National Laboratory. “Whether that material and that approach are appropriate are highly dependent on what climate you are in.”

Here’s what you need to know.

What is the purpose of insulation?

Insulation primarily controls how heat flows in and out of a building, Kaltreider said. “It’s trying to keep heat in or heat out to keep the interior comfortable.”

But certain types of insulation can also help with controlling the flow of air, vapor and water. If properly done, some insulation can control all four elements.

Just adding insulation, however, can increase the risk that moisture could build up within your walls, he said. Improper insulation could hinder a wall’s ability to dry out by blocking the flow of vapor. Because insulation reduces the amount of heat flowing through the wall, the trapped vapor can get cold enough to create condensation. Moisture inside your walls could lead to mold or cause building materials to deteriorate.

“Properly applying the right materials in the right place is vital, especially for vapor control,” Kaltreider said. “The colder you get or the hotter you get, the more challenging and important that can be.”

What are the different types of insulation?

There are two ways to insulate a building: cavity or continuous insulation.

Cavity insulation is used in spaces between the wood studs that frame most traditional homes. These spaces are often packed with fiberglass batts — pink and yellow rolls of fluffy material. Batts can also be made of mineral wool. Other types of insulation include loose-fill products made from fiberglass or cellulose that are blown or injected into the gaps.

But while materials such as fiberglass batts are insulating, they’re not airtight, said Keith A. Simon, vice president of design phase services at Salas O’Brien, an engineering firm. He likened this type of insulation to wearing a big wool sweater on a blustery winter day.

“The wind just cuts right through you and you’re freezing cold,” said Simon, who is an expert in building enclosure technology. “You have plenty of insulation, but it’s not airtight, and so it doesn’t work. So, same thing with houses. You have to have both. You have to have insulating value, but you also need airtightness to be not just high-performance in terms of energy efficiency, but also comfortable.”

Spray foam insulation, which is airtight and in some cases can help control vapor, “is a very significant upgrade in performance over fiberglass batts and other common types of cavity insulation,” Simon said.

But if you’re aiming for better insulation, he and other experts suggest considering continuous insulation, which involves covering your home with insulating material rather than just applying it in the spaces between studs.

When insulation is placed between studs, heat can escape through the wood, a problem known as thermal bridging. Continuous insulation, which often uses rigid foam boards that are installed on the exterior side of walls, can greatly reduce or almost eliminate that heat loss, experts said.

Continuous insulation can also be made from mineral wool and wood fiber, said Janna Alampi, principal architect and owner of EPICx Studio, an architecture and building enclosure consulting firm in Iowa.

Homes that are properly insulated using this method could not only have low energy bills and reduce moisture problems, but they could also help avoid the huge temperature swings that might happen during power outages by locking in warm or cool air and helping to keep indoor spaces comfortable, Alampi said. Existing homes can be retrofitted with continuous insulation, she said.

“If you just use cavity insulation, you’re not going to get these benefits,” Alampi said. But, she added, changes to your insulation will likely impact your heating and cooling system. Improving your insulation means you don’t need as much heating and cooling and you could reduce the size of your system, she said.

How do you pick the right insulation?

The first rule of thumb is to follow your local building code, which typically has insulation requirements, Kaltreider said.

Online tools also are available to help you learn more about what type of insulation is best suited for your home, he said. One of these resources allows you to virtually build different types of walls with various kinds of insulation and show you how well they could control the flow of heat and what your mold risk and moisture content might be.

It’s also important to keep in mind that different types of insulation can have varying environmental and health risks. Some spray foam products, for instance, use blowing agents containing chemicals that have high global warming potential, and the manufacturing process can be energy intensive, Simon said.

Research into alternative bio-based insulation materials is ongoing, he added.

If you’re interested in creating a high-performance energy-efficient home, Simon encouraged thoroughly vetting the professionals with whom you choose to work.

“You want to hold your architect or designer or contractor’s feet to the fire and make sure you’re getting a high-performance building holistically,” he said. “There’s no easy solution. It’s not just insulation.”