- Q.Is treated southern pine as
strong as untreated southern pine? Can I use joist
tables for untreated southern pine lumber to size
responds: The standard CCA treatment process
does not weaken southern pine lumber, and span
tables for untreated southern pine can be used to
size treated joists provided the in-service
moisture content of the lumber will not exceed
19% for extended periods. When the moisture
content exceeds 19% for extended periods (on decks
built near grade, for example), allowable spans are
reduced by approximately 5%. Typically, outdoor
residential deck construction does not require the
use of wet service span reductions.
A complete span table for southern pine,
including information on wet-service conditions, is
available from the Southern Forest Products
Association (P.O. Box 641700, Kenner, LA 70064;
504/443-4464) for $2 plus shipping.
Jeff Easterling is with the Southern Forest
Products Association in Baton Rouge, La.