Replacing a broken internal door handle and latch set is one of the more satisfying DIY jobs around the home — it's achievable for most homeowners with basic tools, a bit of patience, and the right replacement hardware. In most cases you can have a new handle fitted and working within 30–60 minutes.
What You'll Need
Before you start, gather the following tools and materials:
- Flathead and Phillips-head screwdrivers
- Tape measure
- Pencil
- Sharp chisel (if adjusting the latch mortise)
- Utility knife
- Replacement door handle and latch set (see sizing notes below)
- Optional: cordless drill with hole saw attachment (if enlarging or redrilling)
Choosing the Right Replacement Handle Set
Not all handle sets are the same size, so measuring before you buy is essential.
Key measurements to take:
- Backset – the distance from the edge of the door to the centre of the handle spindle hole. Common sizes in NZ are 60 mm and 70 mm.
- Door thickness – most standard internal doors are 35 mm or 40 mm thick.
- Spindle hole diameter – typically 54 mm or 60 mm.
- Latch faceplate width and length – measure the existing mortise (the rectangular recess in the door edge).
If you're replacing like-for-like, take the old latch set to your hardware store to match it up. Bunnings (https://www.bunnings.co.nz) and Mitre 10 (https://www.mitre10.co.nz) both carry a good range of internal door hardware, and PlaceMakers (https://www.placemakers.co.nz) is worth checking for trade-quality options.
Step-by-Step: Removing the Old Handle and Latch
1. Remove the door handles
Look for a small grub screw or a slot on the rose plate (the circular cover around the handle). On lever handles, there's often a small hole in the neck of the lever — insert a thin screwdriver or pin to release it. Once released, pull the lever off. Remove the rose plates to expose the through-bolts or screws holding the two handle halves together.
2. Unscrew and separate the handle assembly
Unscrew the bolts or screws connecting the two handle halves through the door. Both sides should now pull free.
3. Remove the latch
Open the door and unscrew the two screws on the latch faceplate on the door edge. Slide the latch body out of the mortise.
4. Remove the strike plate
Unscrew the strike plate from the door frame (jamb). Keep it handy to compare with your new one.
Step-by-Step: Fitting the New Handle and Latch Set
1. Fit the new latch
Slide the new latch body into the mortise with the angled face of the latch bolt pointing in the direction the door closes. If the new faceplate is a slightly different size, use a sharp chisel to carefully pare back the mortise edges for a flush fit. Screw the faceplate in firmly.
2. Fit the handle assembly
Feed the square spindle through the latch body's spindle hole. Attach both handle halves, ensuring the spindle engages correctly. Tighten the through-bolts evenly so the handles sit flush and operate smoothly without binding.
3. Fit the rose plates and secure levers
Snap or screw the rose plates into place. Reattach the levers and tighten any grub screws.
4. Fit or adjust the strike plate
Close the door slowly and mark where the latch bolt meets the frame. If the new strike plate lines up with the existing mortise in the frame, screw it in place. If it's slightly out of alignment, you may need to chisel the frame mortise slightly or use a strike plate with an elongated opening.
5. Test the operation
Open and close the door several times. The latch should engage cleanly and the handles should return to position without sticking. Check that the door latches securely from both sides.
Tips for a Neat Finish
- If the old rose plates left paint marks or scuffs, a slightly larger rose plate on the new set will cover them.
- Use the correct screw length — screws that are too long can split the door stile.
- If the door has swollen or dropped over time, the latch alignment issue may be a door-fitting problem rather than a hardware problem. Check whether the door closes squarely in the frame first.
- For heritage or older NZ homes with non-standard door thicknesses or mortise sizes, specialist hardware suppliers may be needed.
When to Call a Professional
While replacing a handle and latch is generally DIY-friendly, there are situations where it's worth calling a qualified handyman:
- The door frame or jamb is damaged, rotten, or out of square — this may indicate a structural or moisture issue worth investigating.
- You need to install a deadbolt or lockset for external security — while not legally restricted work, a locksmith or experienced handyman will ensure correct installation.
- The door itself needs rehinging, planing, or significant adjustment.
- You're working on a fire door (common in multi-unit dwellings or commercial spaces) — fire doors have specific hardware requirements under the NZ Building Code and must not be modified without checking compliance requirements with MBIE Building Performance.
Replacing internal door hardware does not require a building consent under Schedule 1 of the Building Act, but if you're ever unsure whether your project needs consent, check with your local council.
You can find experienced local handymen on tradedirectory.co.nz who can tackle this job quickly and ensure everything is fitted correctly.
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