Industry-leading doors by Larnec DoorsLarnec Doors personal access door background

How to hang an external door

See all articlesPerson installing hinges on an external door
Personal Access Doors
September 28, 2022
minute read

Your DIY guide to installing an exterior door securely

Knowing how to install an exterior-facing door correctly is critical to workplace safety and security. Because of their ubiquity, people often take doors for granted and do not fully understand the demands they serve.

Judiciously choosing an appropriate door and installing it securely provides easy building access. It will also withstand the stresses of your worksite, harsh weather conditions, tampering by ill-willed parties and the rush of panicked staff during an emergency.

In this guide, we will teach you two key lessons:

  • The basics of installing an external door
  • How to install a steel Larnec personal access door

Larnec provide market-leading doors and accessories suitable for all Australian industries and private structures. Discover our range of pre-hung, quick installation personal access doors.

How to install an external door in 11 steps

For this DIY guide, we will assume that you are using a wooden door. Learning how to install a wooden door will allow you to learn basic principles that may not always come into play when installing the steel doors that Larnec manufactures.

Tools you need

  • Levels
  • Caulk gun
  • Polyurethane caulk
  • Hammer
  • Screwdriver
  • Nail set
  • Wood glue
  • Wood filler
  • Tape measure
  • Utility knife
  • Reciprocating saw or circular saw
  • Planer
  • Pry bar
  • Shims and small pieces of spare plywood
  • Fibreglass or expanding foam insulation

1. Measure your door frame

The first and most critical step is to determine the dimensions of your new door. If you are replacing an existing door, then the easiest way to find those dimensions is to measure the door you already have.

You will need to measure the existing frame if you do not have an old door to gather your measurements from. As a rule of thumb, a door must have a 2-3mm gap around the top and sides. The gap needed beneath the door will depend on the flooring you have. For example, you may have carpets or weather flashings to account for.

Round your measurements up to the nearest whole number. That way, you can trim each door edge to fit the frame perfectly. If you are ordering a steel door from Larnec, you must be specific with your measurements.

2. Select your replacement door

There are creative and practical considerations to selecting a replacement door. Of course, you will want to choose one that suits your desired aesthetic. But an exterior door needs to be robust enough to secure your home or workspace.

Our handy guide to choosing an external personal access door will teach you everything you need to know for this step.

3. Remove existing exterior trim and interior trim

You will now need to prep the wall by removing the door trims. Use a pry bar to loosen the trims. If you intend to keep and repurpose them, use a less invasive tool such as a utility knife or putty knife to scrape away the moulding and gently lift the trim away from the wall.

4. Remove the existing door jambs

If you do not plan to fit your replacement door to your existing door jamb, you will need to remove it. Using your reciprocating saw (or a handsaw, if you prefer), cut through the jambs and remove them.

5. Install the new door sill and door jamb

With the old door frame removed, you can now install a new one that better suits your needs.

Set your new sill in place, and adjust its height and level shims spread evenly apart. Hang a door in place to check that you are satisfied with the placement of the sill. Remember that the gap between the door and the sill must accommodate any flashings or carpet you may want.

Use your level to ensure the hinge jamb is plumb. If your door is wood, use this fitting as an opportunity to double-check its dimensions. Mark any door edge that needs to be trimmed, then do so with a plane.

At the end of this step, you should be satisfied that your new door fits perfectly into the door jamb.

6. Seal the jamb with caulk

When you are satisfied that your door jamb and sill are aligned, plumb and ready for your door, seal them with caulk. This will weatherproof the door opening.

Many Larnec doors (such as our ever-popular SENTRY 650.37 personal access door) come pre-fitted in a 4-sided jamb. This means you only have to install and seal the jamb, and your new external door is ready to use.

7. Place your external door into the opening

For the following steps, you will need the door to sit snugly in its final position.

Doors can be quite heavy. To safely place the door, set the bottom edge on the sill, and tilt the door back into position. Use casing nails to hold the door in position by tacking them in the jamb around the door. Only hammer them in halfway — they are only temporary.

Use your plumb and level to ensure the door is correctly positioned.

8. Shim the jambs to adjust them into their final position

You will now need to ensure that the jambs are plumb and in place.

Begin with the hinge-side jamb. Insert shims between the jamb and the door opening — make sure the shims are placed directly behind the hinges.

Next, place shims on the latch-side jamb. Now, both jambs should be plumb.

If the gap between the jamb and the door opening is too large for a few shims, first place in a thicker piece of plywood, then add your shims for minute adjustments.

When you are satisfied that the jambs are plumb and your door is sitting correctly, snap off any access wood from the shims. We recommend using a utility knife for an even cut. Then, nail the jamb to the door frame. Place the first nails near your shims to maintain the positioning you have just calibrated.

9. Screw in the door hinges

First, insert one screw into each hinge, and screw them in flush. The door should now be able to swing freely. Take this opportunity to check that the door and jambs are plumb and level and that there is a sufficient gap around each door edge.

When you’re satisfied, screw in the hinges completely.

10. Add insulation and patch holes

Fill in the gaps between the door jamb and the wall with fibreglass or expanding foam insulation.

Remove any remaining casing nails and fill in their holes with wood filler.

11. Install the door trims

This is the final step. Use wood glue to stick the trims back in place. You may then use nails to add further support.

Your external door is now installed. Bear in mind that installing a door is a complicated task and difficult to get right for inexperienced hands. If you find your project less than ideal, rest assured that you will improve with each effort.

Larnec external personal access doors are easy to install

Larnec personal access doors are effortless to install. All of our doors come pre-hung, and most come with 3- and 4-sided door jambs and internal trims. Because they are retrofitted, they can be installed quickly with no on-site drilling required — all you have to do is seal the jamb, and you’re done.

Installing Larnec steel doors is as simple as fitting their provided door jamb into the door frames.

Premium accessories to upgrade your newly installed external door

Larnec external PA doors are also compatible with a range of door accessories to improve their safety and security ratings. We can modify your exterior doors with:

  • J-mould weather flashings
  • Air-relief grilles
  • Viewing panels
  • Lockset upgrades
  • Panic bars
  • Threshold flashings

Larnec are Australia’s leading manufacturer of premium personal access doors. Contact our friendly team today to discuss your requirements and select the perfect PA door.


Are internal doors the same as external doors?

No. Internal and external doors are each designed to meet the different purposes for which they are built.

An exterior entry door is made of thicker layers of tougher materials than an interior door. Materials commonly used to build exterior doors include hardwood, metal and tempered glass.

An exterior-facing door must be temperature and weather-resistant, and strong enough to be modified with whatever accessories best suit that particular site. Common additions include panic bars, threshold plates and robust locksets.

Internal doors rarely need that level of sturdiness. They are designed to be lighter to open and close, and aesthetic considerations usually take precedence over security.

Does an external door need to be regulation compliant in Australia?

Yes. Every Australian state has its own regulations that businesses and property owners must adhere to.

For your convenience, we have explained these regulations here:

Related articles