Insulation is one of those things you forget about but can’t live without—at least not comfortably. Your home has or should have, insulation strategically installed in the walls, floors, attic, and elsewhere for several reasons. First, it keeps the house cool in summer and warm in winter by preventing heat from escaping or entering your home. Second, it lowers your electric and heating bills, since your furnace or air conditioner isn’t working as hard to replace the heat or cool air they generate.

Insulation is a silent worker, and you need to ensure you find the most skilled and reputable contractor to install it. To help, here are the different types of insulation material, why they’re used, and which ones might be best for your home.

Blanket Batts and Rolls

Blanket batts and rolls might be the first thing you think of when you think of insulation. These are those rolls of fiberglass (and sometimes other materials, such as sheep wool, mineral wool, or cotton) that you see at the hardware store. Blanket batts and rolls are sized to fit between the studs, rafters, and joists behind the walls and in your attic. They’re easily cut and installed for DIY projects, and they provide a fair measure of insulation—but they only protect the area in which they’re installed.

Spray Foam

This is fairly self-explanatory: spray foam is a brand of liquid polyurethane that’s sprayed into the walls. The foam expands, seeking out and filling cracks and gaps, and then slowly hardens, locking in and keeping out heat. The foam comes in two formats: open-cell and closed-cell, with closed-cell foam providing the most insulation. It’s not cheap, and it can shrink and let in water. You’ll need to pick a professional contractor to apply spray foam properly.

Blown-In Insulation

Blown-in insulation is another one where the process is in the name. A device is used to blow the insulation into the necessary area. The material usually consists of fiberglass, Rockwool, or recycled cardboard and newspaper. With paper, water and adhesive may be added to ensure the insulation sticks, as well as chlorine and other chemicals to prevent mold and pests. Blown-in insulation also keeps noise levels down. Again, it’s best to hire an expert to apply it, and it requires extra time to dry.

Foam Board

The last of the different types of insulation material that can be used to ensure your home isn’t underinsulated is foam board. Foam board insulation is made of polystyrene, and it’s easily cut and trimmed to fit your space and around obstacles such as pipes. Foam board is thinner than blanket batts and rolls, but it provides even more protective value. It’s best for unfinished walls and low-sloping roofs, and it can be easily installed, but there are some concerns about its health and safety aspects.