What You Need to Do Before You Start

Replacing a Larson storm door means removing the old frame and door unit from your exterior doorway, then installing a new one in its place. The job takes two to four hours and requires basic tools you likely already own — a drill, screwdriver, tape measure, and a level. You do not need to remove your main entry door or hire a contractor, though a second person makes the work easier.

Before you buy a replacement, measure your existing doorway opening from the inside of the frame. Measure the width at the top, middle, and bottom, and the height at the left, center, and right. Write down the smallest measurement in each direction — that is the actual opening size. Larson doors come in standard sizes, usually in 2-inch increments. If your opening is 32 inches wide by 80 inches tall, you need a 32x80 unit. Measure twice; buying the wrong size means returning it and starting over.

Key Takeaways

  • Measure your doorway opening from inside the existing frame at three points in each direction, then order the size that matches the smallest measurement.
  • Remove the old door by unscrewing the hinges from the frame, then unscrew the frame itself from the exterior wall and trim.
  • Install the new frame by setting it square and level in the opening, then screw it to the wall studs and trim using the pre-drilled holes in the frame.
  • Hang the new door by aligning the hinge pins with the frame hinges, then adjust the door so it closes smoothly without binding or gaps.

Removing the Old Door and Frame

Start by opening the old door fully and propping it open with a wedge or block so it cannot swing shut on you. Look at the hinges on the right side of the door (or left, depending on which way it swings). You will see three or four screws going through each hinge into the frame. Remove all of them using a drill or screwdriver. Once the hinges are loose, lift the door straight up and out of the frame. Set it aside — you do not need it anymore.

Next, look at the frame itself. On the outside of your house, you will see screws or nails holding the frame to the wall and to the trim around your main door. These are usually along the top and sides of the frame. Remove every screw you can see. If the frame was caulked to the trim or wall, use a utility knife to cut through the caulk so the frame comes free cleanly. Once all fasteners are out, pull the frame away from the opening. It should come out as one piece. If it is stuck, tap it gently from the inside with a rubber mallet.

Preparing the Opening for the New Frame

Once the old frame is out, look at what is left behind. You may see old caulk, weatherstripping, or small gaps where the frame sat. Use a utility knife and a paint scraper to remove any loose material, old caulk, or debris. Wipe the area clean with a damp cloth and let it dry completely. If there are large gaps or the trim is damaged, now is the time to repair or replace it — the new frame will sit on top of whatever is there.

Check that the opening is square by measuring diagonally from the top left corner to the bottom right corner, then from the top right to the bottom left. Both diagonal measurements should be the same. If they differ by more than a quarter inch, the opening is out of square. You can still install the door, but you may need to shim it (use thin wedges) to make it hang straight. Have shims on hand just in case.

Installing the New Frame

Unpack your new Larson door and lay it on a flat surface. Check that nothing is cracked or bent. The frame will come with pre-drilled holes along the sides and top where you will screw it to the wall. Set the frame into the opening from the outside, starting at the top. Have your helper hold it in place while you check that it is level and plumb (perfectly vertical). Use a level on the top of the frame and on both sides. Adjust the frame by tapping shims under the bottom corners until it is square and level.

Once the frame is positioned correctly, drill pilot holes through the pre-drilled frame holes into the wall studs behind. Use screws long enough to go through the frame and into the studs — usually 2.5 to 3 inches. Put one screw in the top center, then one on each side about a third of the way down. Check the level again. If it is still square, add the remaining screws. Do not overtighten — you want the frame snug but not crushed.

Hanging the New Door

The new Larson door comes with hinges already attached to the door itself. You will see the hinge pins sticking out. Open the frame and look at the hinge brackets mounted on the frame. They have slots or holes that line up with the hinge pins on the door. Lift the door and align the top hinge pin with the top bracket on the frame. Lower the door slowly, guiding the middle and bottom hinge pins into their brackets as you go. The door should hang freely once all three pins are seated.

Close the door gently and check the fit. The door should close smoothly without binding or rubbing. Look at the gap between the door and the frame on all four sides — it should be even, usually about an eighth of an inch. If the gap is uneven or the door binds, you can adjust it. Most Larson hinges have adjustment screws that let you move the door slightly left, right, up, or down. Loosen the adjustment screw, move the door, and tighten it again. Test the close and repeat until the fit is right.

Sealing and Finishing

Once the door hangs correctly, seal the gap between the frame and the wall with exterior caulk. Run a bead of caulk along the outside of the frame where it meets the trim and wall. Smooth it with a wet finger or caulk tool. Let the caulk dry according to the product instructions — usually 24 hours — before painting or exposing it to rain.

Check that the weatherstripping on the door closes tightly against the frame. Larson doors come with weatherstripping pre-installed, but if it is compressed or damaged, you can replace it. The stripping is usually held in place with adhesive or small screws. Peel off the old strip and stick on a new one, or unscrew the old one and screw on the new one. Make sure the door closes smoothly after you install new stripping.

Frequently Asked Questions

Do I need to remove my main entry door to install a storm door?

No. The storm door frame sits on the outside of your main door frame. You do not touch your main door at all. The only thing you remove is the old storm door and its frame.

What if my opening is not square?

Use shims — thin wooden wedges — under the bottom corners of the new frame to make it level and plumb. You may need to use more shims on one side than the other. Once the frame is square and level, screw it in place. The shims stay in the wall behind the frame.

Can I install a Larson door by myself, or do I need two people?

One person can do it, but a helper makes it much easier. Someone needs to hold the frame level and square while you drill and screw. If you are alone, use temporary braces or wedges to hold the frame in place while you work.

What size screws should I use to attach the frame to the wall?

Use exterior-grade screws that are long enough to go through the frame and at least 1.5 inches into the wall studs. Usually 2.5 to 3 inch screws work. Check your Larson door instructions — they often specify the screw size and type.

How long does it take to replace a storm door?

Most people finish in two to four hours, depending on how stuck the old frame is and whether the opening needs any repair. If you have never done it before, plan on the longer end of that range.