How to Install an Exterior Door

When replacing an existing door with a new one, it’s essential to know how to correctly install it. Doing so will guarantee that the door fits and opens perfectly.

To begin, measure the door width and height. Take the smallest measurement from each side of the jamb and take three measurements simultaneously.

Measure the Door

When replacing a door, it’s essential to get an exact measurement. This will enable you to choose the appropriate size and ensure that it will fit perfectly into your home.

Measuring your current door is straightforward – simply measure its width and height. But to guarantee an exact measurement, take multiple measurements.

Width: Measure along the outside of the door from one side to another with a tape measure. Take the smallest figure as your width measurement.

Height: For interior doors, measure from the floor to the upper jamb; for exterior ones, measure from the sill to the upper jamb. Be sure to record these measurements along with the thickness of your door.

Thickness: For interior doors, measure from the edge of the panel to inside of the jamb; for exterior doors, measure all around (sides and top jamb included)).

Jamb Frame: Exterior doors feature a wooden frame constructed with top jambs, side jambs and the threshold. Measuring the width of an exterior door requires more precision than interior ones since you must factor in any trim pieces.

Rough Opening: Before installing the door, you must remove the molding that surrounds the rough opening in your wall. This area should be 2 inches wider than the width of the door and 2 1/2 inches higher than its height.

Once you’ve measured the rough opening for your new door, mark its location with a marker. This will enable you to keep track of your measurements and make any necessary changes before installation.

Remove the Old Door

Before installing an exterior door in your home, it is essential that you first take out the old one. Doing this will guarantee that the new door is installed at exactly the right height and width and give you a better idea of how much wood needs cutting for this task.

Prior to taking out the old door, it’s essential to mark its location for installation. Doing this makes the task simpler and ensures your new door fits securely within your home’s frame.

To mark the door for replacement, lay a protective pad on the floor and position it next to the existing one. Then use a combination square to line up the hinge layouts on both doors with their respective mortises.

Once you’ve marked the location of each door, cut a mortise for each hinge in the jamb. This is simply a shallow groove carved into the jamb to secure the hinge.

Once you’ve cut the mortise, replace the hinge in its jamb. Be sure to mark both screws that secure the hinge to the jamb and those holding the door to that same jamb.

With a circular saw, cut your new door to the proper height and width. Be mindful not to go too far off-center when cutting; otherwise, you could end up with a door that won’t open or close properly.

Once the new door has been cut to size, you can begin installing it in your home. It’s a quick weekend project that you can do yourself; just remember to take time to remove the old door and trim before getting started.

Dry Fit the New Door

Before installing your door, dry fit it into the opening to see how it will fit and make any necessary adjustments. This is especially crucial for large and heavy items like French doors, double doors, sliders or entry doors with sidelights.

If the door won’t fit, add shims behind the hinge-side jamb until it fits securely. Shims are strips of wood that can be placed between the frame and door to keep it from sagging or warping.

Once the jamb is secure, install the frame around it. Make sure there’s at least 1/8 inch clearance between the frame and door jamb edges; you may need to shim some wood for this, but cutting too tightly or completely removing it could lead to serious problems.

Once the frame is in place, screw in the hinges using a drill and centering bit. If needed, add additional screws at each hinge-side jamb for extra security.

Next, carefully carve out the hinge mortises (where hinges attach to doors). Tap with a hammer for an outline, and then make multiple shallow cuts as deep as the thickness of the hinge itself.

Repeat this process for the other side of the door. If your mortises are too shallow, trim away some wood at the bottom of each mortise.

Once the new door is in place, apply a bead of construction adhesive or sealant on the bottom of its rough opening. After it has dried, position a sill pan at this bottommost location – this will secure against your home’s exterior sheathing and protect the sill from water damage.

Install the Door Frame

When installing an exterior door, it’s essential that the new frame be level and plumb. This can be challenging for inexperienced builders; thus, taking your time and doing things correctly will guarantee success.

Additionally, you should prepare the opening for the door and ensure it’s ready for weatherproofing. To do this, level both the rough opening and sill (the section of floor under which it will rest). If necessary, insert spacer boards if needed.

Once the frame is in place, mark where your new door will go and decide what type of molding needs to be cut for it. You may need to trim away any siding or shingles that may be in the way.

Next, enlist the assistance of another person to help you install the door. Begin with the top hinge and slide it down part way until secure; then put in the bottom hinge. If you are not experienced, have someone hold the door in place while you open and close it several times to verify everything is in place correctly.

Repeat with all remaining hinges, adding more shims as necessary to get them properly aligned. Once everything is squared away, fasten through the shims into stud framing using longer hinge screws for extra support and securement.

Before installing casing and trim, fill the cavity between the jambs and frame with insulation. This will prevent your door from flexing or jumping when you nail on casing. You can use either a low-expansion foam formula designed specifically for doors and windows, or loose fiberglass or recycled cotton insulation.

Install the Door Hinges

When installing an exterior door, it’s essential to secure its hinges properly. Doing so will enable your door to open and close smoothly as well as provide added stability when closed.

Prior to selecting the ideal hinge type for your door, it’s essential to determine its correct type. Different hinges are rated according to various purposes and conditions such as weight of the door or exposure to weather elements.

The next step is to measure the correct thickness of your hinges. To do this, use a measuring tape and some patience.

Measure the distance from the center of the top hinge to that of the bottom hinge using a measuring tape. Be sure to include the length of each hinge’s knuckle as well.

Once you’ve taken all your measurements, place the hinges in their intended positions on both the jamb and door. Doing this makes it simpler to transfer the marks from the jamb to the door.

Once you’ve done that, it’s time to cut the mortise. A mortise is a shallow indentation where the hinge will rest flush with the jamb. Make sure not to cut this too deeply as that could cause the hinge to break and damage your door.

To cut a mortise, use a sharp chisel and hammer to tap it into the jamb from the side. Doing this will remove thin strips of wood, leaving your mortise less than 1/4-inch deep.

Once you’ve cut the mortise, it’s time to install the hinges into the jamb and secure them with screws. This step should only take a few minutes and requires minimal tools.


  1. What kind of exterior door should I choose?

When choosing an exterior door, consider the climate in your area, the level of security you need, and the style of your home. Common materials for exterior doors include wood, fiberglass, and steel.

  1. How do I measure for a new exterior door?

Measure the width and height of the opening where the new door will be installed, and add an additional 1/2 inch to both measurements to allow for the frame and any shimming that may be necessary.

  1. Do I need to remove the old door before installing a new one?

Yes, if you are replacing an old door, you will need to remove the old door and frame before you can install the new one.

  1. How do I install the door frame?

Position the frame in the opening, making sure it is level and plumb. Use shims to adjust the frame as needed, and then secure it in place with screws.

  1. How do I install the hinges?

Position the hinges on the edge of the door, making sure they are evenly spaced and centered. Use screws to attach the hinges to the door.

  1. How do I attach the door to the frame?

Position the door in the frame, making sure it is level and plumb. Use shims to adjust the door as needed, and then secure the hinges to the frame with screws.

  1. How do I install the door handle and lockset?

Position the handle and lockset on the door, making sure they are evenly spaced and centered. Use screws to attach the handle and lockset to the door.

  1. How do I install weatherstripping?

Install weatherstripping around the perimeter of the door frame, making sure it is snug and secure.

  1. What should I do if the door doesn’t fit perfectly in the opening?

Use shims to adjust the door and frame as needed to ensure proper operation.

  1. What kind of sealant should I use around the edges of the door frame?

Use a high-quality caulk or sealant that is designed for exterior use to seal out drafts and moisture.

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