Insulating: What is R-value?

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What is R-value? It's the key to understanding insulation.

The capacity of an insulating material to resist heat flow various parts of your home and vary by region. Check is called its R-value. The higher the material’s R-value, with your local utility company or read the insulation the better it insulates. Recommended R-values differ for manufacturer’s literature.



Type

R-value per inch

Cost

Pros / Cons

Fiberglass

R-3.0 to R-3.8

Low

Pros: Easy-to-install batts press into place; made in standard stud and joist widths; available with Kraft paper facing attached.

Cons: Can be irritating to installer’s skin and lungs; susceptible to air gaps during installation.

Loose fill

R-2.2 to R-4.0

Low

Pros: Better coverage in irregular spaces and over trusses; can be poured or blown into walls.

Cons: Messy to work with; quality can vary; lower R-value; can shift or settle; may need to rent insulation blower.

Extruded foam

R-5.2

High

Pros: High compressive strength; great performance underground.

Cons: Cover with drywall or other fireproof material.

Expanded foam

R-3.8 to R-4.3

medium

Pros: Lowest cost among foams.

Cons: Not for underground. Cover with drywall or fireproof material.

Sprayed urethane foam

R-6.0 to R-7.3

High

Pros: Makes a tough, seamless thermal and vapor barrier; covers irregular surfaces adds structural strength.

Cons: Must be professionally applied. Very expensive. Cover with drywall or other fireproof material.


Hint: Easier fiberglass cutting -- For easier cutting, temporarily flatten unruly fiber glass insulation with a piece of scrap plywood. Just cut a 1-1/2-in-wide slot in the center of a 16 x 30-in, board, use the slot as a straightedge and get a clean cut every time.

Next: Installing fiberglass batts

Prev: Introduction to Insulating: Do it right to save money, stay warm

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