Re: pressure treated wood shrinkage
Dennis1946 .... Typically the treated lumber purchased for consumer use is high in moisture ... >19% and is considered green .... not the treating but the moisture content is high.
Personally I recommend to use a nail space when laying the new decking. This does 2 things ... allows water drainage .... allows expansion of the decking .
The lumber will eventually dry somewhat and will shrink .... how much depends on how wet the lumber is new and how much it has a chance to dry.
Hope this helps.
"" an ounce of perception -- a pound of obscure "