Some of you guys are scary-psychic !Only if the walls below are balloon framed and no bottom/top plates exists.
Actually....I have too much room...have to build one wall out 3 1/2" [exterior balloon]....and another wall needs 1" [interior, non-load bearing, wet wall]unless you are talking about new construction, you probably don't have room to put anything on the studs. Most bathrooms I've seen have a RO so close to the actual length of a tub that if you put drywall or cbu on the wall you would not be able to slide the tub into the alcove.
It mostly depends on the code and the inspector or how good you want to be. But anytime you run into a situation where fire can spread, for example, the basement through the subfloor cut out for the drain, into a wall cavity, up the wall cavity, to a "false ceiling or soffit" built above the tub and go unrestricted for the most part into an attic space, there is a high degree of probability if the inspector is worth his weight - you will be fire stopping it.
Balloon framing is the simplest example. Soffits over cabinets in kitchens is another. Usually where there are multiple ceiling heights coming together on a common framed wall, holes cut in plates or anywhere fire can spread from one floor to another, etc.
Nope..free standing SFH.celtic,
if it is a common wall to another dwelling unit or apartment then 5/8 type x drywall is required behind the tub to provide the fire wall.
batt insulation shoved in the stud and joist bay will meet the fireblocking requirement in your situation and meet energy requirements if it is an exterior wall. your welcome:thumbup:Nope..free standing SFH.
However....there is a multi-family row-type house we own that is going to need some major help.
I will stick to my own trade [electrical] for that job.
TY Catspaw :thumbsup: