Things You'll Need
Steel measuring tape
Pair of trestles
Hand-held circular saw
Self-centering hinge drill bit
Installing a bathroom door can be challenging. Doors are unwieldy. If the hinges are attached incorrectly, the door will lean one way or the other. Consequently, the door will tend to open or close by itself and it may scrape the floor in the half-open position. Additionally, without enough clearance between the door and the door jamb, the door will either jam shut or be impossible to close when the wood swells because of bathroom heat and humidity.
Measure the door opening with a steel measuring tape. The standard door size is 36 inches by 80 inches. Factory-manufactured doors allow 1/8 inch of clearance on either side; however, door height depends on the type of floor covering installed. Consequently, doors must be trimmed to allow for a top clearance of 1/8 inch and a floor clearance of 1/4 inch.
Lay the door on a pair of sturdy trestles or saw horses. Use a steel measuring tape and carpenter's pencil to mark the finished height on either side of the door. This must be the door opening height minus 3/8 inch. Mark the cut line with a straight-edge by joining the two pencil marks on the side of the door.
Measure the distance from the cutting edge of a hand-held circular saw blade to the side of the saw base plate. Transfer this measurement to the door above the cut line. Clamp a straight-edge along this line with a pair of C clamps to act as a saw fence.
Trim the bottom of the door with the circular saw, keeping the side of the base plate firmly against the straight edge while doing so. Sand the bottom smooth with a piece of 120-grit sandpaper wrapped around a sanding block. Paint the exposed bottom door surface with a paintbrush and the enamel paint you intend to use once the door has been fitted. Allow the paint to dry overnight.
Place two wooden wedges in the door opening a hand's width from the door jambs. With the help of a friend, stand the door on both wedges. Position the door flush with the door stop on the inside of the door jamb. Tap the wedges either way with a hammer until you have and even clearance of 1/4 inch between the bottom of the door and the floor. Check the gaps. There should be a 1/8-inch clearance between the sides and the top of the door.
Lay the door back on the trestles. Decide which way the door will open. The hinges should normally be on your right-hand side when entering the bathroom, provided interior fitting permit this configuration; however, a door in the corner of a room should open parallel to the adjacent wall. Draw a line on the edge of the door 6 inches from the top and bottom corners with a pencil and carpenter's square to mark the upper and lower hinge positions.
Open a hinge and hold it in position with the upper edge touching the line, and the hinge knuckle flush against the corner edge of the door. Mark the outline of the hinge with a sharp pencil. Carefully chisel out a mortise the same depth as the thickness of the hinge plate with a 3/4-inch chisel. Repeat with the lower hinge edge against the line. Test-fit the hinges to ensure that they fit flush with the door edge surface and that the hinge knuckles rest flush against the corner of the door. If you have cut the mortise too deep, shim the hinge level with the surface with thin cardboard cut to the size of the hinge. Double-check the alignment with a carpenter's square.
Hold the upper hinge in place and use a cordless drill/driver to drill four hinge pilot holes with a self-centering hinge drill bit. Repeat with the lower hinge and use a screwdriver bit to attach both hinges to the door with the screws provided with the hinges.
Stand the door in the half-open position against the door jamb. Place the wedges under the door and maneuver it into place so that the hinge knuckles fit flush against the corner of the door jamb. Adjust the wedges to lift the door an even 1/4 inch above the floor. Open both hinges and lay them flush against the inner face of the door jamb. Mark their outline with a sharp pencil.
Stand the door out of the way against the wall. Chisel out two hinge mortises on the door jamb, using a spare hinge as a guide. The hinge must fit flush with the door jamb surface and the hinge knuckles must fit flush against the door jamb corner.
Maneuver the door into place. Stand the door in the half-open position and lift it with the wedges until the hinges fit snugly into the mortises while maintaining 1/4 inch of floor clearance. Drill single pilot holes through the upper screw holes of each hinge with the self-centering hinge drill bit. Use a screwdriver bit to firmly attach the door to the door jamb with two screws.
Remove the wedges. Open and close the door gently. Stop at various positions to check for stability. Adjust if necessary by tapping the wedges either way with a hammer. Close the door and check all clearances. Drill the remaining pilot holes and screw the door firmly into place. Open and close the door several times to check the door action.
Wear safety glasses and heavy workman’s gloves when using power tools.
Never cut toward any part of your body or hands while using a chisel.