Hi:
I am building a home with a closed attic system and planned R8 ducting it seem the HVAC contractor has installed R4 by mistake. I know that R4 is less expensive. I am trying to figure out how critical this will be to my efficiency. I am planning to have the HVAC contractor change out the ducting but will take a delay. So I guess I am asking whether this change out is necessary or not, since the ducting is in a semi conditioned space anyway.

Thanks,

I would get by with R6 but R 4 should never have been a thought. R4 was out lawed years ago. Is this a reliable contractor or what. R8 is the law now adays but not all places are pushing it yet by next year all inspevctors should be on board with this.