How to Replace an Exterior Door

This fall, make a statement with an updated front door! Replacing an old exterior door with a newer model adds to curb appeal, improves your home insulation, and makes your yard more readily accessible. A beautiful and functional exterior door connects the indoor and outdoor spaces of your home and enables you to entertain guests inside and out.

Replacing an exterior door is simple enough to do-it-yourself and only takes a day using a pre-hung option. Once installed, you may consider finishing the door with stain or paint. Achieve carpenter-quality results when you follow these steps to replace an exterior door.

Steps to Replace an Exterior Door

1. Measure the Old Door

To ensure your new exterior door is the right size for the doorway opening, first measure the size of the old exterior door. Start by measuring the door width and length and rounding each number to the nearest inch. For example, a width measure of 35.75 inches would round up to 36 inches. The rounded measurement will determine the dimension of exterior door you need to order for the right fit.

Aside from the length and width of the door itself, you should also measure the width of the jamb, rough opening, and exterior opening. The door jamb is the upright portion of the woodwork surrounding the door, measured from the outer edge of one piece of trim to the outer edge of the other.

Next, measure the rough and exterior openings. In order to get the rough opening measurements, you’ll first need to remove the interior trim. You can use a crowbar to pry the trim off, using a putty knife to protect your interior wall as you go. Once a portion of the interior trim is off, measure the opening between framing members in the wall to find the width of the rough opening. Don’t forget to also measure the vertical distance between the sill and top of the door frame.

On the other side of the wall, the exterior opening should be measured around the perimeter of the exterior door casing and from the bottom of the sill to the top of the exterior door trim.

If you’re thinking about changing the style of exterior trim as you replace your door, consider using a wide and flat casing that fits well in the opening. Using a flat and wide casing allows you to add detail and style by attaching decorative molding directly over it.

2. Remove the Old Door

Once you have a replacement door ready to install, you can take the old exterior door out. Removing an exterior door requires a hammer and nail set to tap the pins of the door hinges out of place. You may want to lay a drop cloth underneath the door to protect your floors in case the door falls out of place as you tap at the hinge pins. With the pins sufficiently loosened, you should be able to swing the door open and lift it gently out of its hinges.

3. Pry Off Old Interior and Exterior Trim

You may have already removed your interior trim to get an accurate measurement of your exterior door’s rough opening. Pry off any remaining trim on the interior side of the door, using a putty knife to protect the wall from your tools. To get the exterior trim off, you’ll need to slice the caulked joint between the siding or masonry on the exterior and the trim along the door. Once you’ve cut through this, you should have no problem prying the exterior trim off with a crowbar.

4. Remove Door Jambs

Using a handsaw, you need to cut through the door jamb along the sides. This helps loosen the door jamb for removal.

5. Install the Sill

Before moving on, be sure to take a look at your subfloor and door frame. If either of these appear damaged or worn, you may consider making repairs. These portions of your doorway are structural and should be well maintained. If everything looks to be in good condition, you can prepare to install a new sill.

Install your new sill so that the door will open towards the inside of your home and manage to float over the flooring. If you have taller carpeting or a rug in this path, you may need to adjust the sill to sit a tad higher. Use a level to ensure that your sill is even with the floors in your home. Once you are ready to fix the sill in place, attach it with coated deck screws.

6. Install the Flashing Tape

To avoid water damage to the wood of the sill, you can apply flashing tape around the door rough opening, being sure to wrap up and around the sides of the door opening, too. With the sill installed you may want to check that the door will fit into the opening and that it stands plumb or straight up and down against the walls.

7. Apply Caulk

After you’ve checked to make sure your new exterior door will fit nicely, you can caulk along the sill. Most doorways require about two tubes of caulk to fully seal the sill, sides, and top of the door opening. Once you’ve finished caulking the opening, tip your new exterior door carefully into position.

8. Tack in the New Pre-Hung Door

Center the top of the door into the opening area and tack the door into place using galvanized casing nails. Double check that the door is plumb.

9. Shim Each Side of the Door Jamb

On the hinge side, shim at the same height as the hinges, adding wedges of wood to fill up any space between the framing of the door opening and new exterior door. As you shim, check periodically that the door is plumb. Next, continue shimming this time on the other side, also at the height of the hinges.

With all of your wedges in place, use a utility knife to cut along the shim. This will weaken the wood, allowing you to break it off neatly where it protrudes beyond the door frame. Be sure to secure the shims in place on each side by nailing through them and into the framing.

10. Insulate Surrounding the Door

Using expanding insulation foam, spray along the gaps between the door jamb and framing. Once the foam insulation is dry, you can fill any remaining gaps with fiberglass insulation strips.

11. Install Interior Trim

If the trim you pulled off of your old door is still in good condition, you can re-install the pieces to your new exterior door. Otherwise, add a new interior trim around the door, using a beveled transition piece between the sill and flooring.

12. Add Caulk Backer and Caulk

On the exterior, add caulk to the area where the trim and exterior siding meet. After you finish sealing around the door trim, you’ve successfully installed your new exterior door! For a finished look, remove the door to paint or stain as a separate project.

Replacing your exterior door with a new model can add personality to your home, improve insulation, and make outdoor areas more accessible. This simple do-it-yourself project creates a noticeable home transformation by changing the functionality of your space. An improved exterior door enhances the connection between the indoor and outdoor spaces of your home, so you can enjoy more of your home!

You can find everything you need to upgrade your home at Grayco Hardware & Home Center. Find my Grayco.