A new exterior door will provide your house with safety, style, and energy savings, plus it adds resale value. Exterior front doors made of fiberglass, wood, or steel are solid additions to your home that will last for years.
Do-it-yourselfers with considerable home improvement experience can install their own exterior door. With an assistant and with careful prep work, an exterior door can be installed in one day.
Before You Begin
Pre-hung doors do not come with doorknobs or deadbolts. You'll need to supply those. If the door does not already come pre-bored for a deadbolt, it's strongly recommended that you add this feature to your door order. Deadbolts make it far more difficult for intruders to break into your home through the front door.
Best Time to Install an Exterior Door
Installing an exterior door can be a race against time and the weather. Your goal is to complete the installation within one day. If the project spans more than a day, you'll need to block the open doorway at night with plywood—not secure and not weatherproof.
Ideally, you should install your exterior door during a time of year when the daylight is longer and the weather is drier and warmer. Late spring through late summer in most areas affords you an ample amount of comfortable working time.
Codes and Permitting
In many areas, replacing doors without altering the structure will not require a permit. Always double-check with your local permitting authority, though. If your home is part of a homeowner's association, you'll likely need to clear the type and style of door with the HOA board.
Pre-hung doors are very heavy: 120 pounds or more. Not only that, they are bulky and unwieldy. You must have an assistant when moving and installing an exterior pre-hung door. Door units can be hazardous in the dry-fit stage when they are on edge but still not attached to the house. Make sure that one person always has a hand on the door.
Equipment / Tools
- Tape measure
- Bubble level
- Power nailer
- Cordless drill
- Reciprocating saw
- Oscillating multi-tool
- Caulking gun
- Electric miter saw
- Putty knife
- Pre-hung exterior door
- Low-expansion foam insulation, can
- Sill pan kit
- Exterior-grade screws
- Interior door trim kit
- Exterior-grade caulk
Measure Door Opening
With the prybar, remove the door's inner casing trim. Use the tape measure to measure the height of the door's rough opening. Measure both the left and the right sides. Measure the width at the top, middle, and bottom. Note these measurements for ordering the door.
Verify Door Opening Square
Run the tape measure diagonally from the top-left down to the bottom-right. Similarly, run it in the other direction (top-right to bottom-left). If both measurements are the same, the door opening is square.
With the bubble level, make sure that the vertical sides are plumb and that the header (top) and threshold (floor) are level.
Most rough openings need to be 1/2-inch taller and 1-inch wider than the exterior door unit. Purchase the door before removing the existing door.
All pre-hung doors come with specific handing: either left- or right-handed. The door swing direction cannot be reversed, so be sure to buy a door with the correct handing.
Prepare Door Opening
With the pry bar, remove exterior trim and any insulation tucked into the spaces around the door. With a cordless drill, remove the existing door from the hinges. Remove the hinges from the door jamb. Unscrew the existing door sill. Use the reciprocating saw to cut any nails that might be holding the existing door frame to the studs on each side.
Dry-Fit Door in Opening
Place the door unit in the opening and center it. By measuring, make sure that the door, when swung open, will clear the top of the finished floor inside the house. Test the door sill for level.
Do not open the door, as it may tip out of balance and fall. Keep the restraining shipment brackets in place for now.
Trace Around Door Trim
The new door's exterior trim, which typically comes pre-attached to the door unit, may fit perfectly into place where the previous molding had been. If not, use a pencil to trace on the siding around the molding.
Cut Siding (Optional)
If necessary, use an oscillating multi-tool to cut the pencil outline that you made on the siding. Remove the waste material.
Create Sill Pan
With the assistant, remove the door unit and set it aside safely. Piece together the three sections of sill pan in the door frame. Two pieces should be at each side, with the third piece in the middle.
Add Sill Pan
Caulk the three pieces of sill pan together, then let the caulk harden. Set the assembled sill pan aside.
Add three parallel beads of caulk to the floor. Set the sill pan in it. Caulk the back and the seams of the sill pan.
Set Door in Place
Add caulk to the back of the door's pre-attached outside trim. With the assistant, set the door unit back in place.
On the inside of the house, add a couple of shims at the top of the door frame to hold the door in place and in plumb. Use the bubble level to verify plumb. Gently tap the shims into place as far as is needed in order to tilt the door from left to right to bring it into plumb. Place shims at each hinge, about 1-inch above.
The door lock side of the unit should have a gap of about 1/8-inch. This gap should be consistent from top to bottom. Double up two shims from front to back to create a flat spacer. Place this spacer in the gap on the lock side of the door unit.
After first making pilot holes, drive and countersink exterior screws at each of the three hinge locations through the door casing.
On the door lock side, add screws above and below the strike plate and at the top and bottom. Screw the strike plate into place.
Remove the door's restraining shipment brackets and test the opening and closing of the door. Along the bottom, the door should fit the sill plate tightly but should have enough give that the door opens easily. If necessary, adjust the sill plate's adjustable cap up or down with a Phillips screwdriver.
Cut off Shims
Remove the exposed sections of shims by scoring them with a utility knife and then snapping them off or by cutting them with the oscillating multi-tool.
Add Foam Insulation
Apply minimally expanding foam insulation in the gap between the door unit and the door frame. After the foam has expanded and dried, slice away any excess foam with a putty knife.
Add Interior Trim
Cut three pieces of interior trim on the electric miter saw. Place the three pieces on the house interior, securing the pieces with finish nails or with the cordless nailer.
Add Doorknob and Deadbolt
Add the doorknob to the door. If the door is bored for a deadbolt, add this as well.
On the house exterior, add caulk around the trim.
Tips for Installing Exterior Doors
- Start the project as early as possible in the morning to give yourself as much time as possible to work on this one-day project.
- To avoid running out to the hardware store and slowing down the process, make sure that you have all tools and materials on hand before you start.
- Identify an alternative way to get in and out of the house when dry fitting and installing the exterior door, since you will not be able to pass through that door for periods of time.
When to Call a Professional
If the door frame is unusually sized or requires significant repair work, call a door installation company or a contractor.
Along with precision, speed is important. If you cannot remove the existing door and install the new door in one day, call a professional. French doors, double doors, sliders, and entry doors with sidelights are large, heavy, and have unique installation requirements. These also should be installed by professionals.