Leveler to make sure that everything stays level (you’ll have difficulty opening your new door if it’s at an angle). Caulk to fix the insulation and framing in place. Hammer and nails, nail set, screwdriver (depends on the nails holding your old door in place) to remove the old door and put on the new door. Tape measure or ruler to measure the old and new doors and frames. Insulation to make it so those winter winds don’t start whipping around your door. Wood shims to hold the door at the right level, if needed.

Wood doors tend to have a nicer look, but they aren’t as weather-resistant as fiberglass or steel doors. Steel doors also tend to be the least expensive, while wood and fiberglass tend to be around the same price depending on the style of the door.

To check the width you’ll need to measure across the top middle and bottom from stud to stud of the old door. The stud is basically the side of the door. The smallest number is the rough estimate for the width. For door height you’re going to need to measure the middle, and both sides of the door from the top of the door to the floor. The smallest number is again going to be your rough estimate. Measure the width of the doorjamb. Check the measurements of the old door against the measurements of the new door you’re considering. If they match up closely, then you’re good to go. If not, you’re going to need to consider a new door.

For most hinges you should be able to insert a nail set into the hole at the bottom of the hinge pin and strike it upward with a hammer. Keep driving the pin upward (with the hammer) until it comes out. Score the caulking between molding and wall in order to break the seal. With a pry bar and hammer, carefully remove molding. Pry away the doorjamb, framing, and the threshold. Now you can scrape away the old caulking.

Be sure that the rough opening and the subsill (the section of the floor under which the sill will rest) is level. If needed, use shims or a beveled board to level it. If the door needs to clear an especially high floor, like a thick carpet, a spacer board may be needed.

You particularly want to check that the hinge side is level.

This weather-proofs the door opening.

You may want to enlist a friend to help you lift and place the door depending on its weight. Be sure that the door is centered in the opening, and assure that the frame fits snugly into place at the bottom of the opening.

Arrange the shims and the frame assembly, on the hinge side of the door, until it is plumb in both directions. Ultimately, there should be a continuous gap of about 1/8 inch (0. 3175cm) between the edge of the door and the jamb.

Verify, from the outside, that there is even contact between the door front and the weatherstripping on the section of the frame opposite of the hinge jamb. If necessary, make adjustments by moving the jamb in or out, at the top or the bottom. Inspect the edges of the inside face of the door. Be sure that there is a continuous gap of 1/8 inch (0. 3175cm) between the door edges and the jamb, all the way around the door.

Place a solid shim behind the site of the lock strike. Verify occasionally that the door assembly is remaining properly adjusted. Install the lock strike, putting the screws through the shim.

Fill holes left by the screws with wood filler and allow to dry. Wear gloves, because you do not want to get caulk on your hands.