WOOD 120 Lumber volumes, measurements and sizes 1

2 Lumber volume In sawmilling, lumber is most often measured by the “board foot” or “fbm” (foot board measure). 1fbm = 1 foot x 1 foot x 1 inch

3 Foot Board Measure 12 inches 1 inch Board foot = 12 inches wide, 12 inches long, 1 inch thick = 144 in 3 = 1/12 ft 3

Foot Board Measure How many board feet in an eight foot long two by four? 4

5 Lumber volume In softwood sawmills Softwood lumber price is quoted in dollars per thousand board feet ( $ / Mfbm). Sawmill shift production is given in 100’s of thousand board feet. Sawmill capacity is given in million board feet (MMfbm).

Softwood 6 Largest BC sawmill production capacity 600 MMfbm Average BC sawmill capacity approx MMfbm Price of softwood lumber ≈ $350 /Mfbm

Softwood vs. Hardwood 7 Price of softwood lumber (e.g., SPF) $350 /Mfbm $0.35 / board foot Price of hardwood lumber (e.g. sugar maple) $5 / board foot (for regular lumber) $30 / board foot (for figured lumber)

8 Lumber Recovery Factor (LRF) Definition: LRF is the volume of green/rough sawn lumber that is produced out of a given input volume of logs. The units of LRF are board feet per cubic meter. LRF typically ranges between 200 to 300 board feet per cubic meter.

9 Lumber Recovery Factor (LRF) LRF depends on: Qualityof logs Size of logs Equipment used in a mill Recovery % fbm/m 3 (Theoretical 100% recovery = 423 board feet)

Impact of log size on LRF 10 (Top diameter, nominal 2” production) (Wood Products Online Expo)

Fibre Recovery (sawmill) 11 Lumber55% Chips25% Sawdust10% Shavings 5% Shrinkage 5% Lumber Chips Shavings Shrinkage Sawdust

Processed lumber Raw material Energy Incinerated or for other processes recovery landfill 38% 41% 52% 36%11% 25%23% 11% 23%16%23% Utilization of harvested wood in North America (Dovetail Partners 2012)

13 British Columbia Sawmill Lumber Recovery Factors BC Mills +17% Leading Mills Average LRF (bf/m ) (BC Ministry of Forests, 2005)

14 Softwood lumber sizes Nominal size (inches) Actual size (inches)

Lumber – target size 15 Minimum dimension required to achieve desired final size given unavoidable reductions in size during manufacture.

16 Planer allowance Top head Bottom head Final thickness Top head planer allowance Bottom head planer allowance

Shrinkage allowance Lodgepole pine Maximum potential shrinkage (30%mc to 0% mc) Tangential 6.8% Radial 4.7% After drying to 15% mc (target max. is 19%mc) Tangential 3.4% Radial 2.4% Assume higher possible shrinkage value Possibility of over-drying (therefore excess shrinkage) 17

18 Target Size Minimum dimension required to achieve desired final size given unavoidable reductions in size during manufacture.

Lumber sizes Actual size – real size of lumber (1.5 x 3.5) Target size – minimum size that rough lumber can be cut to achieve required actual size (1.9 x 3.9) Nominal size – traditional green size from which the name is derived (2 x 4) 19

Effect of sawing variability on target size frequency Average thickness (in.) Target size componentMill AMill B Final size1.50 in.1.50 in. Planing allowance in in. Shrinkage3%3% Total process standard deviation0.015 in in. Rough green target size1.72 in.1.80 in. Mill A Mill B