I think I'll be doing it the way you suggested.

When you say seal the joints ,  do you mean with tape?

tape will work,

but i use foam in a can ....get the pro style(reusable gun with control...less mess)
seal to floor,between sheets as you go.... 1/4" bead
also foam around outlet and switch boxes, penetrations, doors and windows

mac

thanks for the info - very helpful. the insulation boards I bought have a tongue and groove joint, so they provide a real good conection.

Once last question. Do I have to use pressure treated furring strips since they will not have any direct contact with the concrete block?

re: pressure treated strips

the only one required to be treated is where you have contact with masonry
(sometimes i use one along floor)

mac