Smart locks are designed to be installer-friendly, and many DIY installations go smoothly. But we regularly see a handful of mistakes that cause frustration, unexpected behaviour, or genuine concern that the lock itself is faulty.

In most cases, the lock is fine. This guide covers the three most common issues we see:

• The handle still opens the door even when the lock shows as locked
• Choosing the wrong hardware, latch, or backset for the door
• Poor door preparation — the one mistake that can actually damage the lock over time

For foundational measurement guidance before installation, see Chapter 02 — Measuring Your Door and How to measure your lock backset. For a full installation walkthrough, see Chapter 12 — Installation & Troubleshooting.

Last updated May 2026.

The 3 Most Common DIY Mistakes at a Glance

Mistake 1 — Handle Still Opens When the Lock Is “Locked”

The cause is the spindle or hub being set in the incorrect position during installation. Most smart locks use an adjustable internal spindle or hub system. If it is positioned incorrectly:

• The latch can retract while the lock is in locked mode
• The handle can still operate the latch mechanically
• The lock appears not to be locking
• The motor re-locks, but the mechanical connection was never disengaged

McGrath NX1 spindle example — the hub has three possible spindle positions. Selecting the wrong one allows the handle to retract the latch while the lock is in locked mode.

Mistake 2 — Choosing the Wrong Hardware or Backset

Another common issue is selecting the wrong configuration for the door. Examples include:

• Ordering a 60mm backset when the door is prepared for 70mm
• Choosing a tubular latch model when the door is prepared for a mortice lock body
• Installing on a door that is too thick or too thin for the supplied spindle length
• Purchasing a smart lock that does not match the existing hole pattern

The result is poor alignment, excess handle tension, visible gaps, or a lock that simply will not sit correctly on the door. In some cases the correct latch, lock body, or backset spacer will need to be ordered before the install can proceed.

Mistake 3 — Poor Door Preparation or Fitment

We regularly see cross-bore holes drilled slightly off-centre, holes not drilled square to the face of the door, mortice cavities cut unevenly, splintered or compressed timber, and misaligned strike plates.

For the correct hole sizing and door preparation specifications, see Chapter 02 — Measuring Your Door in the Buyer’s Guide.

Smart locks contain internal motors and gear assemblies. If the latch or bolt is under tension because the door preparation is not square or straight, the motor is forced to work harder than it is designed to. Over time this can:

• Drain batteries significantly faster than normal
• Cause delayed or sluggish locking and unlocking
• Create grinding or clicking noises during operation
• Lead to premature internal motor failure

Final Thought

In our experience, the majority of “faulty” smart locks are not faulty at all. They are installation-related — and most are completely fixable without any replacement parts.

Checking spindle orientation, confirming correct hardware selection, and ensuring proper door preparation will prevent nearly all of the issues described above. When in doubt, test off the door before drilling anything.

If you are using a TTLock-based lock (McGrath, Lockton, Austyle) and experiencing unexpected app notifications rather than a mechanical issue, see Tamper Alert on Smart Locks — phantom alerts are often a settings issue, not an installation problem. For the quick-reference FAQ entry on this topic, see Chapter 13 — Smart Lock FAQ.

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