2/4 or 4/4 refers to nominal rough-sawn thickness in inches. Read as
two-quarter or four-quarter. Means half-inch and one-inch respectively.
The number of finished sides is given as S2S, S3S, or S4S, meaning "surfaced 2
sides", "... 3 sides", etc. or sometimes just as S2, S3, or S4.
A 4/4 board is 1 inch thick in the rough, and when surfaced two (or more)
sides, will be 13/16" thick (if hardwood) or 3/4" thick (if softwood).
Doug Miller (alphageek at milmac dot com)
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