Setting a New Door in a Old House

Remove the old door and doorframe from the location where you are putting the new door. Run a reciprocating saw around the perimeter of the old doorframe, between it and the rough opening, to cut any nails that are holding it in place. Pull the entire assembly out of the rough opening.

Clean up the inside face of the rough opening by pulling out old nails and screws and removing any bits of plaster or other material.

Place the new door and doorframe into the old rough opening. Secure the new doorframe with cedar shims. Place a pair of shims between the outer face of the doorframe and the inner face of the rough opening, pushing one shim in from the inside of the house and one shim in from the outside of the house so that they overlap. Press them together until they are tight. Do this with three or four pairs of shims on each side and two pairs of shims on top of the doorframe.

Check the level of the doorframe by holding a four-foot level against its inside face. Adjust the level by loosening shims on one side of the door and tightening them on the other. When the doorframe is level and plumb, secure it by driving nails through the inside face of the doorframe, through the pairs of shims and into the face of the rough opening.

Trim the shims so they are flush with the edges of the doorframe by scoring them with a sharp utility knife and snapping them off.

Insulate around the doorframe by filling the gap between it and the rough opening with low-expansion spray foam insulation.

Apply finish trim to the inside and outside faces of the doorframe.