Table may be used for other species and grades of wood by adjusting the spans as follows:

*For the these grades and species the span may be increased by the following percentages:

• Douglas fir or larch, select structural: increase 20%
• Douglas fir or larch, #1: increase 10%
• Southern pine, select structural: increase 18%
• Southern Pine, #1: increase 7%
• Calif. redwood, clear select structural: increase 36%
• Calif. Redwood, select structural: increase 18%
• Calif. redwood, #1: increase 36%
• Western cedar, select structural: increase 2%

*For the these grades and species the span may be decreased by the following percentages:

• Southern pine, #2: decrease 2%
• Calif. redwood #2: decrease 2%
• Western cedar, #1: decrease 6%
• Western cedar #2: decrease 14%
• Hemlock or fir, #1: decrease 2%
• Hemlock or fir #2: decrease 11%
• Spruce, #1: decrease 9%
• Spruce #2: decrease 16%

Source: Add-On Solar Greenhouses & Sunspaces by Andrew M. Shapiro

 

 -Reload Sundance Supply Site