Patent ID: 8209927

Claim:
A fiber cement sheet comprising: cementitious matrix, reinforcing cellulose fibers distributed throughout the matrix, said reinforcing cellulose fibers comprise about 10% to 12% by weight, a low density additive, said low density additive comprising about 7% to 12% by weight, wherein the fiber cement sheet has a dry density less than 1.25 g/cm 3 , a thickness less than 0.7500 inches, and able to withstand uniform loads of 200 psf or greater and with an average deflection of less than 0.067 inches at 60 psf, able to withstand impact loads of 75 ft/lbs and a proof load of 400 pounds or greater following impact with a deflection of less than 0.108 inches under a 200 pound load after impact, and able to withstand concentrated static loads of 550 pounds or greater with a deflection of less than 0.108 inches under a 200 pound load when spaced on a span of 24 inches or less on center.