Replacing or fitting a new door latch is one of the more approachable DIY joinery tasks for a NZ homeowner. With the right tools, a bit of patience, and careful measuring, most standard interior door latches can be installed in under an hour — no joiner required. Here's how to do it properly.
Understanding Your Latch Type
Before you buy anything, identify which type of latch your door uses (or needs):
- Tubular latch – The most common type in NZ homes. A cylindrical barrel that fits into a round hole bored through the door edge. Used with lever or knob handles.
- Mortise latch – A rectangular case that fits into a chiselled-out pocket (mortise) in the door edge. Often found in older NZ homes or on heavier doors.
- Deadlatch / privacy latch – Similar to a tubular latch but with a locking button, common for bathrooms and bedrooms.
Check your existing latch before purchasing a replacement. Note the backset (distance from the door edge to the centre of the handle hole — typically 44 mm or 57 mm in NZ) and the faceplate dimensions. Bring the old latch to your hardware store if you're unsure.
You'll find a good range of latches and door hardware at Bunnings or Mitre 10.
Tools and Materials You'll Need
- Tape measure and pencil
- Combination square
- Sharp wood chisel (25 mm works well for most faceplates)
- Mallet or hammer
- Drill with spade bits or hole saw (typically 54 mm for tubular latches)
- Flat-head and Phillips screwdrivers
- Sharp utility knife
- The new latch set (latch, handles, screws, and strike plate)
Step-by-Step: Installing a Tubular Latch
1. Mark the Handle Height
Standard door handle height in NZ is typically 900–1050 mm from the finished floor. Mark this centre point on both faces of the door and on the door edge.
2. Bore the Cross Hole
Using the template supplied with your latch (most quality latches include one), mark the centre of the cross hole on the door face. Use a hole saw or spade bit of the correct diameter (check the latch packaging — commonly 54 mm). Drill from one side until the pilot bit just breaks through, then finish from the other side to avoid tear-out.
3. Bore the Latch Hole
On the door edge, drill a hole to accept the latch barrel. This is usually 25–28 mm in diameter. Drill straight and level — a drill press or a guide helps here.
4. Chisel the Faceplate Recess
Insert the latch barrel, hold the faceplate flush against the door edge, and score around it with a utility knife. Remove the latch and chisel out a shallow recess so the faceplate sits perfectly flush with the door edge. Take your time — small, careful cuts are better than removing too much timber.
5. Fit the Latch and Handles
Insert the latch barrel and screw the faceplate in place. Thread the handle spindle through the latch mechanism and attach both handles according to the manufacturer's instructions. Most modern lever sets use a grub screw or clip system.
6. Fit the Strike Plate
Close the door and mark where the latch bolt meets the door frame. Use a chisel to mortise out a recess for the strike plate box and the plate itself, so it sits flush with the frame. Screw it firmly into the framing timber behind the lining — not just into the lining itself.
7. Test and Adjust
Open and close the door several times. The latch should engage smoothly and the door should close without rattling. If the latch doesn't align with the strike plate, adjust the strike plate position slightly or use a file to enlarge the opening.
Tips for a Professional Finish
- Sharp tools matter — a blunt chisel will tear the timber and leave a messy recess.
- If you're working on a hollow-core door, be careful not to drill too deep or in the wrong spot — the solid timber blocking inside is only in certain areas.
- For older NZ villas or bungalows with native timber doors (rimu, matai), take extra care chiselling as these timbers can be brittle. Pre-drilling screw holes prevents splitting.
- Always check that the door is hanging correctly before fitting a new latch — a twisted or sagging door will cause ongoing alignment problems.
Replacing a Mortise Latch
Mortise latches are more involved. If the existing mortise pocket is already cut, replacing the latch case is usually straightforward — remove the old handles and case, drop in the new one, and refit. However, if the new latch is a different size, you may need to extend the mortise with a chisel, which requires more skill. If in doubt, this is a good time to call a joiner.
When to Call a Professional
While latch installation is generally DIY-friendly, consider calling a qualified joiner (find one on tradedirectory.co.nz) if:
- The door frame or door itself is damaged, rotten, or significantly out of square
- You're fitting a mortise lock (as opposed to a simple latch) on an external door — security and weathertightness are important
- The door is a fire door (e.g., between an internal garage and the house) — fire doors have specific hardware requirements under the NZ Building Code and must be maintained correctly
- You're unsure whether your door hardware meets Healthy Homes Standards requirements for rental properties — check Tenancy Services for guidance
- The job involves external door locks where security is a priority
Note: Installing a door latch is not restricted electrical, gas, or plumbing work, so there are no licensing requirements for this task. However, always work safely — secure the door before drilling and keep chisels sharp and controlled.
