| Type of insulation |
R-value per inch |
Where to use |
Need to know |
| Cellulose
Made from 75% to 85% recycled newsprint that’s treated with a nontoxic borate flame retardant.Available either as a loose-fill product that’s blown or packed into spaces, or as a spray-on product that’s mixed with a binder so that it will adhere in vertical applications. |
3.0 to 3.8 |
Attics and uninsulated existing walls (loose-fill). Some home improvement stores rent cellulose blowers for DIY installation of loose-fill cellulose in attics.Unfinished wall cavities (sprayed). To install loose-fill cellulose in uninsulated closed walls, an insulation contractor can drill holes along the top of the wall and blow in the cellulose. |
Unlike loose-fill cellulose, sprayed-in cellulose insulation requires professional installation. The contractor must take care not to exceed the manufacturer’s recommended moisture level.May cost less than fiberglass, but installation may be more. |
| Cotton
Made from 85% textile scrap (primarily denim scrap) treated with nontoxic flame retardants.Comes in rolls or batts (pre-cut 4 ft. or 8 ft. lengths). |
3.0 to 3.7 |
Attics, unfinished walls. |
Easy to work with and nontoxic to handle.Installers don’t need to wear protective gear.Batts cost 50% more than fiberglass batts, but installation costs are about the same. |
| Fiberglass
Made from spun glass fibers. Some products contain as much as 40% recycled glass, often from post-consumer bottles.Available as loose-fill or in rolls or batts (pre-cut 4 ft. or 8 ft. lengths). |
2.2 to 4.2 |
Attics (batts or loose fill); walls and floors (batts). |
The most common and generally least expensive type of insulation.Choose no-added formaldehyde products.Professional installation recommended for loose-fill fiberglass insulation. |
| Spray-in-place foam
Spray-in-place foam insulation is like a larger, professional version of the small spray-foam tubes sold at hardware stores. When sprayed under pressure into cavities, it expands greatly in volume, forming a tight seal.Some products are made with a small amount of pre-consumer recycled chemicals. |
3.4 to 6.8 |
Unfinished attics and floors; wall cavities (new or existing) |
Requires professional installation.Most are made from petrochemicals, but cement and soybean-based spray foams are also available.No longer made with ozone-depleting HCFC blowing agents.
Expensive compared to other types of insulation but provides high R-value and superior air sealing. |
| Foam Board
Sold as rigid foam sheets.Some products are made with up to 10% recycled plastic bottles. |
3.6 to 6.5 |
Unfinished walls, foundation walls, floors, ceilings |
Relatively high insulating value.When installed on interior surfaces, must be faced with gypsum board or other building-code-approved fire resistant material.Ask for foam boards made without ozone-depleting HCFC blowing agents. |
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