Just got some prices for POSIs: there are two prices; one for treated joists, and the other for -errrm- untreated joists.
First: why do you need to treat joists? They can't misbehave, or be rude, and so
Is it worth it? The price difference is £100+ for quite a few
The architects notes specify treatment for the wall plate for the joists, but doesn't mention treatment for the joists themselves.