Presuming the door is a 36 inch wide door the dimensions of your opening should be 37 inch wide by 81 inch tall.
Rough opening for prehung interior door.
Timely prefinished interior steel frame a opening width 1 1 4 b opening height 1 the rough opening would be 37 1 4 x 85 for a 3 0 x 7 0 door frame more info on timely rough openings.
The rough opening for a 36 inch pre hung door is is 38 5 inches by 82 inches.
The rough opening should be one inch wider than the frame and 3 4 of an inch higher than the door.
Reasons for door opening sizing when a pre hung door is being installed into an opening there have to be considerations for leveling the door and ensuring that it has an obstruction free swing.
The width of a door s rough opening is the width of the door plus 2 inches.
The width can vary from 12 to 48 inches.
Once the drywall is in the prehung door can be slipped in.
By placing the piece of wood at door height the doors have been properly framed.
Now all you need to know is how to properly frame your door rough opening.
Verify the rough opening is level and plumb c and d.
A pre hung door has a frame attached to.
The 2 inches accounts for a 3 4 inch jamb board on each side plus 1 2 inch.
The rough opening sill must not be crowned or sagged d.
So if you have a bedroom door that is 30 wide which is considered a 2 6 or 2 6 door just add 2 to the width and frame it 32 wide.
Compare the rough opening vs door size frame a door rough opening with images home improvement door rough opening sizes and charts caska compare the rough opening vs door size steel walk door rough opening size measuring instructions rough openings timely industries rough door opening for 32 inch homeadditionplus.
Rough opening for 32 inch door for example a two foot eight inch 32 by six feet eight inch high 80 prehung door would require a rough opening width of 34 inches and a height of 82 inches.
This is how the cripple is eliminated.
A piece of wood cut to the width of the door opening needs to be nailed at door height for drywall backing.
The exterior face of the rough opening must be in a single plane e with less than 1 8 twist from corner to corner.