Cutting in a Door Opening
?When cutting in a door opening, it important that you measure the wall area to see that you have adequate room for the door and casing. For instance, a typical pre-hung 3068 door with WP442 casing is 5” wider than the nominal opening. You should also check with the manufacturer to determine the height of the door. Some manufacturers use full height doors with a clearance space below. Some undercut the door and maintain the nominal height. Also exterior doors may add height for thresholds and for rabbeted jambs and headers, which required more height for rough openings. Also do not be fooled by measuring an existing door or depending on the size of the door that you ordered for the same project two years ago. I had to replace a door that I had installed for a customer when he had a break in. The manufacturer had raised the height of the door unit almost 2”. Check both sides of the wall for space and note any outlets in the area.
Once you have determined that he door can fit properly in the space, Mark the rough opening. I use a level to mark one jamb and the header. I measure my rough opening width from the first jamb mark create the second jamb mark. I also verify that mark checking for plumb.
Next, if the wall is drywall or wood, I use a reciprocating saw (Sawzall) to cut the opening. I place a 12” blade in the saw facing backward. This allows me to lay the saw flat against the wall surface and cut with minimal penetration. I saw the opening and then use? a pry bar to remove the wall finish. Once removed, I take a speed square and mark the inside of the opposite wall surface for cutting. I cut the opposite site and remove the surface. I cut the exiting studs into at the header height. By tapping them sideways, with a hammer or a sledge hammer, I can remove them from the wall. Care must be exercised to remove the studs within the new header. Any wires or pipes found in the opening must be relocated before the framing can be placed.
Once the opening is clear, I measure for the header from stud to stud of the remaining studs in the wall. This is usually slightly less than 48” if the wall studs were 16” oc. I cut about a 30 degree angle on each end making a parallelogram, one angle off the top side and one angle off the bottom. This allows me to brace the door from stud to stud and the angle allows me to insert it into the wall cavity and position it. I also cut a couple of studs or lay down lumber to build the header to full height under the double plate above. I screw it to the existing studs with a screw gun and 3” screws. If the wall is to be refinished around the door, I run some drywall screws through the wall surface to hold the header in position. If the wall is not to be refinished, I restrict the screws to the area around the opening that will be covered with the casing. I then place a double stud at each jamb fitted tight to the header. I screw the studs to the wall surface at the casing area, as well as to the header and the bottom plate.
Once the rough framing is in place, you can infill the wall trench in the floor with the appropriate floor finish. Don’t forget the framing inspection, if required. To set the door, it will also be necessary to mark and cut the existing base to the casing. I use again a sawzall with a fine toothed 12” blade mounted backward. This way I can place the tip at the floor and slowly star cutting the marked line. I can usually hang a pre-hung door with or without applied casing in the opening.
For exterior doors cut in to brick veneer, I use a concrete saw to cut the veneer. The brick will have to be toothed out and the brick re-laid to the brick mould. ?An alternate is to use an additional piece of trim to cover the exposed holes from cutting through the brick. Also a brick lintel will be required to hold the brick in place.