We are having a custom block home built in Florida. The windows & doors were installed last week. The plan indicate for 3/4" p.t. wood around all windows & doors opening. Looks like the builder made a mistake when he ordered the double entrance door because they put p.t. wood on one side of the door and used plywood on the other side. We asked the plywood be changed to p.t. wood but the builder refuses saying they put plywood around doors all the time and it is never a problem and that he can't do anything about it because the door will not fit if he was to follow the plan. Anyone frame exterior doors with plywood?
Plywood's stronger then real wood, but I would have use pressure treated plywood.
Only other way would be to use sill seal or at least a layer of tar paper or 6 mil. plastic between the concrete and the plywood.