Just FYI (and for easier searching i've named the thread with the appropriate keywords)
Here is a useful link i found that has a couple of great charts for calculating wood movement.
http://www.fpl.fs.fed.us/documnts/fp...tr113/ch12.pdf
Page 4 has the average moisture content for wood exposed to outdoor conditions listed by state and for each month!!!
Pages 16 and 17 have the coefficents for dimensional change for each type of wood.
To calculate wood movement you can multiply the width of the board (in inches) by the annual change in moisture content (high minus low). Then multiply that by the number from the chart.
Example:
You have a 30" wide table top of quartersawn (Q/S) white oak. You want to know how much movement to compensate for. You assume a 3 percent moisture content change per year (8% to 11%) based on the numbers on page 4.
11% minus 8% = 3
The coefficent for Q/S white oak is .00180
The width of the board is 30"
Now you plug this in to the equation.
Width x MC chg x Coefficient for dimensional change
30 x 3 x .00180 = .162
.162 = 2.58/16" (You could call this 5/32" or 3/16" to be on the safe side.)
V/R
Dan
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