How Thick Is R30 Ceiling Insulation?

R30 insulation measures 9.


R30 insulation keeps your home warm in the winter.R30 insulation keeps your home warm in the winter.
5 inches thick and comes in widths to accommodate 16-inch or 24-inch joist spacing. Most batts have a a light, corrugated backing board on one side for a vapor barrier.

Fiberglass batts are manufactured to be resistant to mold. However, direct contact with water will result in the promotion of mold.


R30 insulation is used for attics and crawl spaces where 2-foot-by-10-foot joists are installed.


R30 batts are designed to be wedged between rafters to prevent thermal leaks. Measure the joist spacing before buying the batts to determine whether 16-inch or 24-inch spacing is needed. You can trim the batts with a standard utility knife.


One benefit of installing R30 batts is reduced heating and cooling costs. Another benefit is preventing frozen plumbing lines in winter.


Avoid placement of batts within 3 inches of recessed lighting unless the fixtures are rated for direct contact with insulation.

About the Author

David Miller is a Kentucky-based freelance writer who has written on a variety of subjects for eHow. He has also written content for many websites and small businesses. He has a background in the technology sector which he still pursues and enjoys.