How to Install an Exterior Door Step by Step

Step by step

1. 1

   Prepare the opening and check the dimensions

   Clean the reveal of old foam, debris, and loose plaster. The rough opening should be about 1-2 cm (roughly half an inch) larger than the frame on each side, so the foam and leveling wedges can fit. Check the bottom edge of the opening with a spirit level, because the threshold alignment starts from there.

2. 2

   Prepare your tools and lighten the frame

   If the design allows it, take the door off its hinges - a lighter frame is easier to position. Get a long spirit level, installation wedges, a drill, anchors or frame screws, and low-expansion foam ready. For heavy steel doors, you'll need a second person anyway.

3. 3

   Set the frame plumb and level

   Place the frame in the opening and support it with wedges at the corners. Set it perfectly plumb and level, then check the diagonals, which should be equal. This is the most important moment of the whole job, because a tilted frame makes the door swing open on its own or refuse to close.

4. 4

   Fix the frame with anchors or frame screws

   Strap anchors screw onto the frame and get embedded in the wall, while frame screws pass through the frame profile straight into the wall. Fix at a minimum of three points on each side: near the top, in the middle, and near the bottom. Tighten evenly and without overdoing it, so you don't bow the profile.

5. 5

   Check how the door operates

   Hang the door and open and close it a few times. The gap around it should be even along the entire perimeter, and the door must not drift open or closed on its own. Make all corrections now, before you apply the foam.

6. 6

   Fill the gap with foam

   Use low-expansion foam, because regular foam can bow the frame inward and block the door from closing. Apply it in stages and leave the wedges and spreaders in place until it hardens - initially after a few hours, with full curing taking up to a day. Don't force-fill the entire gap, because a slight excess is easy to trim off after curing.

7. 7

   Seal the threshold and adjust the compression

   Seal the base under the threshold and keep the outward water drainage clear, so no puddle collects. Finally, adjust the hinges, often adjustable in three planes, and the strike plates so the door presses the seal evenly around the whole perimeter. Close the frame-to-wall joint from the outside with silicone.

Anchors or frame screws - what to fix the frame with

Strap anchors are metal flats screwed to the frame and embedded in the wall. They work well when you don't want to drill through the profile and a clean reveal finish matters. They do give a slightly less rigid mounting than frame screws.

Frame screws, meaning fixings that pass through the frame profile straight into the wall, hold the stiffest and are the typical choice for heavy steel doors. They require drilling the frame, so the holes need capping afterward. For concrete and solid brick, use long expansion plugs; for hollow blocks, fixings designed for hollow materials.

Insulated installation and a threshold without a thermal bridge

Insulated installation is a three-layer system in the gap: expanding or vapor-permeable tape on the outside, foam as insulation in the middle, and vapor-tight tape on the inside. This keeps water vapor from condensing in the joint and stops the joint from freezing through. For entry doors, it's a sensible addition, especially in a new, well-insulated house.

Pay attention to the threshold. An aluminum threshold with a thermal break limits heat loss at the bottom, and proper support and sealing protect the floor from water. Make sure water from outside has somewhere to drain and doesn't sit against the seal.

Cylinder, security class, and when to hand the job to a crew

Resistance depends not only on the lock but also on the cylinder. Choose a cylinder with a high security class - in the common rating scheme, class C is the highest - ideally certified and protected against snapping and drilling. The door itself has a separate burglary resistance class, marked RC, which you match to your needs.

Installing an exterior door is heavy work that demands precision, because a plumbing error ruins the lock's operation and the sealing. If you lack experience or the door was expensive, consider hiring a crew. Also check the warranty terms, because some manufacturers only honor it after installation by an authorized company, so doing the job yourself may void it.

Frequently asked questions