[RyanD]

When they sell doors and they list the size 32x80, 32x78 is that the actual door size or is that the framing too? How big should the rough opening be?

 

[jomama45]

That nominal dimension is the door size, actually the interior of jambs. The door is usually 1/4" to 3/8" smaller in width than the 32". The rough opening is generally 2" to 2.5" bigger both ways.

 

[II Weeks]

1/4" to 3/8" smaller

are you sure about that?

the R.O. is 2" wider and higher than the door size.

so a 32X80 has an R.O. of 34X82 ( 82 might go higher depending on finish floor)

 

[jomama45]

II Weeks, I agree with what you're saying, but I meant a good way to measure an existing door is to measure the actual door slab, which in this situation should be about 31 5/8" to 31 3/4", which = 32" prehung. It seems people get lost sometimes & think they have an odd size because the door doesn't actually = 32".