Installing a door

Exterior doors rot or warp, interior doors get scratched up by cats and dogs or kicked in by vandals.  Whatever the reason, here are some basics for door installation.  

Layout subfloor
Items needed:

Level
Hammer
Finishing Nails
Caulk
Wood Putty
Reciprocating Saw or hacksaw
Miter box and saw
Trim
Door

Safety Suggestions and Tips
Wear safety glasses 
Always make sure doors are square and plumb.
Level of difficulty


Time Required:
 2 hours

Steps

Remove molding
Remove molding

Step 1:

The first step should always be to cut or score the caulk or paint inside and out along the trim.  This will keep the paint and/or drywall from tearing away.

Tearout the threshold
Tearout the threshold

Step 2:

Remove the trim, inside and out, with a flatbar and hammer. Once removed, you should be able to see nails that go through the doorjamb to the stud framing of the wall. They are easily taken care of with a reciprocating saw (Sawzall) or a hacksaw blade.  If the whole door is trash, introduce the prybar.  You should also take the threshold up as well.  The threshold may be screwed or nailed down so take care not to rip out screws with a prybar.

Inspect framing
Inspect framing

Step 3:

When you are as close to the original opening as possible, sweep things clean and inspect for any water or insect damage. If the framing and the floor below the threshold are in good condition, place your new door into position.  It may need to be "padded out on one side, both sides, or a little from above. There should be about 3/8" to a 1/2" gap on both sides and up to an inch on top. It is not uncommon to have to cut some  wood to the appropriate size to make a smaller door fit the opening.


Plan ahead

Step 4:

The jamb on interior doors is a type of tongue and groove that comes apart and slides back together easily.  If you are installing an interior door, pull the trim from the door.  This is usually held in place by shipping nails.  Exterior doors do not usually come with trim.

Use shims to position door
Use shims to position door

Step 5:

Pull the door out, remove the shipping nails and place a bead of caulk (for outside doors) under the area where the threshold will go. Slide the door back into the opening and use shims from the inside and out overlapping each other.  You should use a couple of sets of shims on each side.  

Keep door level and plumb
Keep door level and plumb

Step 6:

Make sure that you keep a level on hand to ensure the door is plumb.  Don't use any nails until the shims are holding the door exactly how it has to be. There should be at least an 1/8" all the way around between the door and the jamb The door frame should also be flush with both sides of the wall.

Secure door
Secure door

Step 6:

Nail (or screw) through the middle of the jamb to the stud wall and above to the header. It will disturb the set of the door less if you nail through the shims first.  Set the nails slightly so that the doorstop (the thin strip of wood that stops the door in the middle of the jamb) will cover the nails or so that they can be filled with painter's putty.

Check square
Check square

Step 6:

The door should now be able to swing freely from open to closed position without brushing against the jamb. If this is NOT the case, you can use your hammer with a wood block to make some minor adjustments. After it is secure, the rest is simple trim work. Use finishing nails and clean cuts with accurate measurements to frame the sides and top of your door inside and out.  I always advise using just a little construction adhesive or caulk behind trim work to help the little nails. If there are gaps in your trim work, caulk them with paintable caulk if it is to be painted, sandable wood filler if it is to be stained.