I would consider the addition a screened in porch requiring only what the owner wishes to add in way of devices and lighting. I've wired many a new home lately and even though the screen porch could easily be wired to habitable room standards, they weren't required by any inspectors.
#79063 - 11/21/0109:33 AMRe: Screen Room a 'Habitable Room' ?
It is getting skylights too at some point. This one will have a 6' section of electric baseboard heat and the wall common with the house will be sheetrocked as if it was an interior wall. As finished, it has 3 recessed lights, a ceiling fan, 6 interior receptacles and 1 exterior receptacle (all GFCI protected) and a set of floodlights at the rear peak.
It will have the comforts and conveniences necessary when the room is in use. It will still be separated from the house by an exterior set of doors with weatherstripping, will only be heated when in use, and it is sitting upon a wooden-framed deck.
Because of all the windows it was a challenge to find locations where the owner would agree to having (wiremold box) receptacles. There was no question as to them wanting power out there, but the amount of outlets and locations was a point of conjecture.
An installation like this is clearly not of the same construction as the rest of the house and could be removed at any time without compromising the integrity of the house itself. (If the common wall was left with the vinyl siding (inside)) Does this have to strictly meet the requirements of the NEC for habitable rooms? Or, can they have what they want in this room?
#79064 - 11/21/0110:49 AMRe: Screen Room a 'Habitable Room' ?