4-Way® Floor Deck

Homasote 4-way Floor Decking is a structural, noise-deadening subfloor and insulating, carpet underlayment made from multiple plies of Homasote® structural building board permanently bonded under extreme pressure with a water-resistant glue, trimmed to size and shaped with tongue-and-groove to form floor decking panels. 4-Way is used as a structural sub-flooring in low-rise condominium and apartment developments, motels, nursing homes, professional buildings and private homes, especially where noise control is a prime consideration.



  1. Laboratory tested for acoustical ratings using ISO, R140 and HUD test methods
  2. Resilient surface provides in-place, wall-to-wall underlayment that will protect carpeting and prolong life beyond the ability of concrete or hardwood surfaces
  3. Moisture-resistant and protected against termites, rot and fungi
  4. Annular thread nails, (3" long, 9 ga., annular threaded shank, 3/8" head), are used for glue-nail application
  5. Adequately supports uniform live loads up to 100 lbs./sq. ft. based on a maximum deflection of 1/360 of the span

Sizes & Weights (nominal)

Panel thickness Size Weight Joists
1-11/32" 4' x 8' 3.0 lb./sq. ft. 16" o.c.
1-3/4" 4' x 8' 4.1 lb./sq. ft. 24" o.c.

NOTE: Finished T&G on long edges and square on ends. Estimate 32 panels (4' x 8') per 1000 sq. ft. of floor.

Typical Physical Properties

Density: 26-28 lb./ft.3
Tensile, parallel to surface (min.): 450-700 psi
Transverse, MOR (min.): 750-1000 psi
Stiffness, MOE (min.): 86,000 psi
Hardness, Janka Ball (min.): 230 lb.
Water absorption by volume (max.):
  2 hrs. immersion
Expansion from 50%-90%
relative humidity (max.):
R-Value (1-11/32"): 3.27
R-Value (1-3/4"): 4.46
Flame Spread: Class III (or C)

Other Test Data

1 Hour Full-Scale Fire Performance, Tested in Accordance with ASTM E119-98 by Southwest Research Institute, Project No. 01-2271-001; 1-3/4" 4-Way.

1 Hour Full-Scale Fire Performance, Tested in Accordance with ASTM E119 by Factory Mutual Corp., Project No. 16738.40; 1-11/32" 4-Way.

NAHB Research Foundation, Glue-nail Structural Tests, March, 1971.
S.B. Barnes & Assoc., Horizontal Diaphragm Test, 1972
Fire rated: 1 hr. (per Factory Mutual Test)
Design F.C.: 77 1 hr.(S/N 16738-40)

Code Compliance

FHA Materials Release 1150c