Exterior Door Frame Installation

Run a level over the subsill (the flooring under the door sill). Also utilize the level to check the plumbness (vertical straightness) of the doorway's sides. If the sides are not plumb or the subsill is not level, extra shims will be required to compensate during installation.

Apply a thick line of caulk across the door subsill, about 1 inch from the inside edge. Extend this line of caulk up the sides of the doorway about 2 or 3 inches on either side. Apply a second line to the other side, about 1 inch from the outside edge.

Set the bottom of the door frame kit into the doorway, and tilt the door upward and into the doorway. Solidify the door by driving shims under the frame bottom with a rubber mallet. Remember that if you need to level the door sill to add the extra shims to one side or another.

Press on the door frame gently to test its stability. Solidify the door kit's grip further by driving shims between the doorway and the kit, putting all shims onto the hinge side of the door frame and focusing on the area behind the hinges. Also keep in mind that you need the door frame to be plumb, and you can straighten the door frame by driving shims to shift it.

Fasten the door frame by driving 16d finishing nails through the hinge side of the door frame, near where the hinges will go, and into the doorway, using a claw hammer. Do not drive the nails all the way in, as this is a temporary arrangement and you'll pull the nails out later.

Open and close the door and apply the level to the sill and door frame's sides again. If it works smoothly and is both level and plumb, continue with the installation. If not, pull the nails with a claw hammer and work with the shims and mallet again.

Close the door from the outside. Examine the space between the door and the weatherstripping on the door knob/lock side of the frame. The door should be in even contact with the weatherstripping, but if it is not, add more shims to the lock/knob side to even things out.

Close the door from the inside and check that there is a narrow, even gap of roughly 1/8 inch in the space on the inside between the door and the door frame. Add and subtract shims to the door knob/lock side of the frame if adjustments are necessary, putting an especially solid shim behind the area of the door knob and lock.

Fasten the door frame to the doorway by drilling holes and driving screws. Start with by driving screws through the shims behind the hinge areas, and continue to drive screws wherever it is recommended by the door kit manufacturer, but not through areas that lack a shim backing.

Pull the temporary finishing nails. Stuff low-expansion insulation into the space between the doorway and door frame, and then install the kit's trim as directed by the manufacturer.