Installing a new door frame is fairly straightforward. However, fitting the frame into an opening can be more of a challenge. Buyers should consider what type of frame would work best for the application, as well as which installation technique will be used. Part of the difficulty in this task comes in sizing the frame properly so that it will fit into the opening and allow the door to operate as intended. By taking careful measurements and choosing the right frame, you'll greatly improve your chances of successfully installing a new door frame.
Measure the size of the rough opening to determine the height and width. Perform these measurements at two different points, as the walls may not be square. If the measurements are not the same, use the smaller of the two when selecting your frame.
Select steel masonry frames that are 11.2 cm (4 1/2 inches) smaller than the opening of the width and 5.6 cm (2 1/4 inches) shorter than the height. The 11.2 cm (4 1/2 inch) difference in width will allow 5 cm (2 inches) on either side to accommodate a standard frame, as well as 6 mm (1/4 inch) of clearance on either side for installation. The 5.6 cm (2 1/4 inches) height difference allows for a 5 cm (2 inch) frame header as well as a 6 mm (1/4 inch) of clearance space at the top of the frame.
Choose steel drywall frames that are 2.5 cm (1 inch) smaller than the opening in both width and height. This is because a steel drywall frame is designed to wrap around the wall, so not as much space is needed to accommodate the frame.
Purchase wood frame or pre-hung units that are 2.5 cm (1 inch) smaller than the opening in width and height. These wood frames can be installed in masonry or drywall, and are designed to butt against the framing on either side of the opening. Wood frames are much thinner than metal frames, so less space is needed than what is required for butted masonry walls.
Use a tape measure to measure the wall thickness. If the frame will be butted against the wall, the jambs should be the same thickness of the wall. If the frame will be wrapped around the wall, the jambs should be 2.5 cm (1 inch) larger than the wall. For instance, a 12.2 cm (4 7/8 inch) wall will require a 12.2 cm (4 7/8 inch) butted frame or a 14.7 (5 7/8 inch) wrapped frame.
Fitting the frame
Cut wood frames to size as needed based on the sizing requirements in the first section of this article. Most wood frames are equipped with extra-long jambs to provide some flexibility to installers. Use a saw to cut these jambs to the right length. Take extra care not to cut them too short.
Install the frame in the opening. Use wooden shims to level the jambs and header of both metal and wood frames. Place shims between the wall and the jambs or under the legs of the jambs as needed.
Fit metal plasterboard frames using the integral compression anchors. These anchors are designed to be adjusted with an Allen key once the frame is installed. Turn the anchors until the frame is tight to the drywall on either side. Add shims under or behind the jambs as needed to complete the installation.
Fill any gaps or extra space around the frame with batt insulation. Cover these gaps with casing or trim to create the desired finish.