your average Douglas fir weighs 35 lbs per cubic foot witch equals 2.005208 lbs. per linear foot for 2x6 so a 16 footer would weigh approx 32.083 lbs. (answer from Pocket Refe … rence third edition, Thomas J. Glover) math done by me. 5.5 x 1.5=8.25 c.i. per linear inch x 12=99 c.i. per foot x 16 feet = 1585 cubic inches divided by 1728 (12x12x12) =.9166666667 x 35 lbs =32.0833333345 lbs. per 16 feet.