Type of Material

R-value per inch

Other Characteristics

Fiberglass, mineral wool

Inexpensive. R-value eroded by air currents, compression. If flooded, must replace. Noncombustible.

- batts, rolls (low-high density)

2.9 - 4.3

Kraft paper good seasonal vapor retarder. Suitable for do-it-yourselfer.

- loose fill, “Blown In Blanket”

2.3 – 3.1

Good coverage (BIB for walls, roof).

Cellulose

Less air movement & erosion of R-value. Sound absorbing. Increases moisture buffer capacity of wall. Borate fire retardant, may deter insects, fungi. If flooded, must replace.

- loose fill

3.4 - 3.7

Good coverage. Can settle & lose R-value.

- damp spray

3.5 – 3.8

Good coverage, performance. Doesn’t settle. Let dry before installing drywall.

Rigid foam boards

As sheathing, good seasonal vapor retarder and reduces thermal bridging. If sealed, can provide exterior air barrier. Preferred for steel framing, masonry construction. Can withstand flooding.

- expanded polystyrene (EPS, “beadboard”)

4.0

Semi-permeable without skin. Least expesive type of rigid foam. Available foil-faced (for radiant barrier).

- extruded polystyrene (XPS)

5.0

Stronger than others. Low permeability; impermeable with skin.

- polyisocyanurate (ISO board)

5.6 – 6.5

More R-value in less space. Typcially foil-faced; provides vapor barrier & radiant barrier (good for brick veneer).

Spray foam

Excellent air barrier, seals penetrations. Uniquely well suited for insulating unvented attics, band joists, gaps in thermal/air barrier envelopes.

- closed cell, high density (urethanes)

5.6 – 6.3

New types have no CFCs. Cures to semi-rigid, adds strength, floodproof. Semi-permeable. Can withstand flooding.

- open cell, low density (polyicynene)

3.6

Stays flexible. Permeable. Can absorb water but dry quickly.

Radiant barriers

varies with use

Requires min. ¾” min. air space. Most effective under roof deck. Other insulation still needed; blocks only radiant heat, not conduction.

Autoclaved aerated concrete (AAC)

1.1 – 1.4

Provides structure & thermal mass benefit. Noncombustible.