A door that won't latch properly is frustrating — and often the culprit is a strike plate that's slightly out of alignment with the latch bolt. The good news is that in most cases this is a straightforward DIY fix requiring only basic tools and a bit of patience.
What Is a Strike Plate and Why Does It Matter?
The strike plate is the metal plate mortised (recessed) into your door frame. When the door closes, the latch bolt (the spring-loaded angled piece) clicks into the hole in the strike plate, holding the door shut. If the latch bolt doesn't line up with that hole — even by just a millimetre or two — the door will stick, bounce back, or refuse to latch at all.
Misalignment is common in NZ homes because our timber frames expand and contract with seasonal humidity changes, and older homes can settle over time.
Diagnosing the Problem
Before grabbing your tools, figure out exactly what's going wrong:
- Rub a lipstick or crayon on the end of the latch bolt, then close the door gently. The mark left on the strike plate shows where the latch is actually hitting.
- Check the gap around the door. If the door has dropped or the frame has swollen, the latch may be hitting above, below, or to the side of the strike plate opening.
- Look for shiny marks on the strike plate — these show where the latch is rubbing.
Common causes include:
- Seasonal timber swelling (especially in humid NZ summers)
- Loose hinge screws causing the door to sag
- House settlement shifting the frame
- A strike plate that was never quite right from installation
Tools and Materials You'll Need
- Flathead and Phillips screwdrivers
- Sharp wood chisel (12–25 mm)
- Mallet or hammer
- Drill with appropriate bits
- Pencil
- Metal file or rotary tool (optional)
- Longer screws (e.g. 75 mm timber screws for a more secure fix)
- Wood filler or matchsticks and PVA glue (for filling old screw holes)
Step-by-Step: Adjusting the Strike Plate
1. Tighten the Hinges First
Before touching the strike plate, check all hinge screws. A sagging door is often caused by loose hinge screws rather than a misaligned strike plate. Tighten them firmly — if the holes are stripped, remove the screws, pack the holes with matchsticks dipped in PVA glue, let it dry, then re-drive the screws.
2. Remove the Strike Plate
Unscrew the strike plate from the door frame and set it aside. You'll now see the mortise (the recess) cut into the frame.
3. Mark the New Position
Using the lipstick or crayon mark as your guide, determine which direction the strike plate needs to move — up, down, or sideways. Mark the new position lightly with a pencil.
4. Extend the Mortise
If the plate needs to move only 1–3 mm, you can often just file out the edge of the strike plate hole with a metal file to give the latch bolt more room. This is the quickest fix.
For larger adjustments:
- Use a sharp chisel to carefully extend the mortise in the frame in the direction needed.
- Work slowly and take thin shavings — you can always remove more timber but you can't put it back.
- Keep the recess depth consistent so the plate sits flush.
5. Reposition and Re-fix the Strike Plate
- Hold the strike plate in its new position and mark the new screw hole locations.
- If the new holes overlap the old ones, fill the old holes first (matchsticks and PVA, or a suitable wood filler) and allow to cure fully before drilling.
- Drill pilot holes to avoid splitting the frame timber.
- For added security, consider using longer 75 mm screws that reach through the frame into the structural framing behind — this is especially worthwhile on exterior doors.
- Screw the plate down firmly and check it sits flush.
6. Fill Any Gaps
If the old mortise is now partially exposed beside the repositioned plate, fill it neatly with wood filler, sand smooth, and touch up the paint.
7. Test the Latch
Close the door slowly and check the latch clicks in cleanly. The door should close with light pressure and the latch should spring back fully when released. Test the handle from both sides.
Tips for a Long-Lasting Fix
- Lubricate the latch bolt with a dry lubricant (graphite powder or a PTFE spray) to reduce friction and wear.
- If your door swells badly every summer, consider planing a small amount off the door edge — but note that significant planing of an exterior door may affect weatherproofing and could warrant a check against your home's weathertightness requirements under NZ Building Code Clause E2 (External Moisture).
- For older NZ villas and bungalows with significant settlement, the underlying cause (foundation movement) may need professional attention.
When to Call a Professional
Call a qualified locksmith if:
- The latch or lock mechanism itself is damaged or worn
- The door frame is significantly racked or twisted (a sign of structural movement)
- You're dealing with a high-security lock, deadbolt, or multi-point locking system — these require precise alignment and specialist knowledge
- The door is a fire door (these have specific compliance requirements under the NZ Building Code)
- You've tried adjusting the strike plate and the problem keeps returning
A licensed locksmith can also assess whether your door hardware meets current security standards. You can find qualified local locksmiths on tradedirectory.co.nz.
For any concerns about whether your door or frame work requires a building consent, check with your local council or refer to MBIE Building Performance — minor repairs generally fall under Schedule 1 exemptions, but it's always worth confirming.
