Insulation R-value

What It Means

R-value is the rating for how strongly a material resists heat moving through it, and it's how insulation is compared and sold. A higher R-value means the insulation does a better job of keeping heat in during winter and out during summer. According to ENERGY STAR, a product's R-value depends on what it's made of, how thick it is and how dense it is, and when insulation is installed in layers, the R-valuesPersonal valuesThe principles and qualities a person holds most important, such as honesty, family or creativity, which guide their choices and how they judge events. See more of the layers add together.

How It Sounds at Home

• "The attic only has about R-19 in it."
• "We're blowing in more to get the R-value up."
• "Check the R number on the bag."

The Breakdown

How to use R-values when you plan insulation

1. Look up ENERGY STAR's "Recommended Home Insulation R-Values" for your climate zone. The right level depends on climate, and ceilings and attics usually call for a higher R-value than walls and floors.
2. Find out what you already have: the type of insulation and how thick it is, since both change its R-value. Buhata's suggestion is to ask a home energy auditor or insulation contractor if you can't tell.
3. Add the layers. ENERGY STAR says the R-values of layers in a multi-layer installation add together, so an existing R-19 plus a new R-30 layer gives R-49 in total (example numbers).
4. Compare that total with the recommendation for your zone and part of the house.
5. Leave room for the new layer. Squeezing insulation into a space too small for it means it won't reach its rated R-value.

Try it today. Look up your climate zone on ENERGY STAR's page and note the recommended level for your attic, the place where the number usually runs highest.

Good to Know

ENERGY STAR says it's more economical to install recommended insulation levels while a house is being built than to add them later, which makes a remodel or new build the time to get it right. Compressed insulation loses some of its rated R-value, so fit matters as much as the number on the package. Buhata's suggestion for attic or wall work: ask your city or county about building codes and permits, and hire a licensed contractorLicensed contractorA contractor who holds the license your state or local government requires for the kind of work being done, which you can check before you hire. See more for any job you aren't sure about.

Related Terms and Categories

• Attic ventilation

  The flow of outside air through an attic, in at vents under the eaves and out near the peak, that carries moisture out and keeps the attic cold in winter.

• Weatherstripping

  Strips of material fitted around doors and windows that open and close, sealing the gaps where air leaks in and out.

• Caulking

  Sealing cracks and gaps between parts of a house that don't move, such as around window and door frames, with a flexible filler called caulk.

• Pipe insulation

  Foam or fiberglass sleeves and wraps fitted around water pipes to cut heat loss from hot water lines and help keep exposed pipes from freezing.

• Seasonal home maintenance

  Home upkeep sorted by time of year, so each job lands when the weather suits it and before the system it protects is needed most.

• Home inspection

  A professional look at a home's condition, usually before buying, that reports which systems and parts need repair or may need replacing soon.

Home maintenance and repairs