Like HowStuffWorks on Facebook!

What types of insulation can help keep your house warm?

There are many materials you can use to insulate your home. Fiberglass insulation is noncombustible and doesn't retain moisture. Fiberglass insulation is a cost-effective, energy-saving product that improves energy efficiency and reduces the fossil fuel combustion necessary to heat and cool a building. Cellulose insulation - another option -- is made mostly of shredded newspaper. Although it's treated to be fire retardant, it's not fireproof. Because it absorbs and retains moisture, it takes three times as much cellulose to be as efficient as fiberglass.

Polyisocyanurate is made of plastic that contains a low-conductivity gas. Over time, gas may leak out and let air in, lowering performance. Polyisocyanurate insulation can be installed in liquid form, as a rigid board or laminated insulation panel, or sprayed as foam. Liquid foam can mold to any surface and also costs less than installing foam boards.

Expanded polystyrene (EPS) is composed of small plastic beads that are fused together and typically made into concrete blocks. Molded expanded polystyrene (MEPS) insulation is difficult to control in its form of small foam beads. Extruded polystyrene (XPS) is made of a molten material that is pressed into sheets. It is resistant to moisture, mildew, corrosion and rot.

Polyurethane foam is a plastic that is sprayed in liquid form and then expands. It's effective at both high and low temperatures. Radiant barriers are reflective surfaces that reduce heat loss in winter and heat gain in summer. While they can block 90 to 97 percent of radiant heat, they don't provide much thermal insulation. Reflective insulation is made of metallic foil. It provides a radiant barrier, as well as insulation. A professional should install it because it conducts electricity.

Cotton insulation from recycled clothing is treated with Boron, which is nontoxic and pest- and fire-repellant. In addition to insulating well, it also dampens sound. Finally, mineral wool comes in loose-fill and blanket form and is made of 75 percent recycled materials.