Smart locks UK security ratings 2026

The UK security standard that matters most for a smart lock is Sold Secure Diamond or PAS 24

If you are replacing a front-door lock with a smart version, the first question is not about app features but about security ratings. Unlike a traditional deadbolt, a smart lock’s electronic components are not tested by the same British Standard (BS 3621) that covers mechanical locks (GOV.UK, Approved Document Q, 2026). The two relevant tests are Sold Secure (Diamond, Gold, Silver) for physical attack resistance and PAS 24 for enhanced security on doorsets.

Sold Secure is an independent testing body that rates a lock’s resistance to physical attack, such as drilling, picking, and brute-force attempts. PAS 24 is a British Standard that tests the entire doorset (lock, hinges, frame) against forced entry. A smart lock must carry at least one of these ratings to meet most UK home-insurance conditions (GOV.UK, Building Regulations 2010, as amended 2026).

Without a Sold Secure or PAS 24 rating, a smart lock may be rejected by your insurer in the event of a claim. The key difference from a mechanical lock is that the electronic components are not covered by BS 3621, so the physical attack resistance is the only part tested under these standards.

Quick numbers what the 2026 smart lock ratings mean in practice

These figures come from Sold Secure testing methodology (MCS Certified, 2026) and insurance criteria from the British Insurance Brokers’ Association (BIBA) guidance note (BIBA, 2026). A Diamond-rated lock typically withstands a sustained physical attack for over ten minutes, while an unrated lock may fail in under two minutes.

How a smart lock’s electronic vulnerabilities change the risk

A smart lock’s motor and wireless module can be bypassed by a relay attack or forced firmware update, even if the physical lock is Sold Secure Diamond. The 2026 threat is not brute force but signal interception (Bluetooth or Wi-Fi relay), and no existing UK security rating tests electronics (NCSC, Smart security devices, 2026).

The National Cyber Security Centre (NCSC) advises that smart locks should be treated as connected devices with the same vulnerabilities as any IoT gadget. Which? tested several smart locks in 2026 and found that models without two-factor authentication could be unlocked remotely if the app password was compromised (Which?, 2026).

The physical security rating (Sold Secure or PAS 24) addresses only the mechanical attack surface. For electronic vulnerabilities, the homeowner must rely on the manufacturer’s security updates and their own network setup.

The direct answer is a smart lock secure enough for a UK home in 2026?

Yes, if the lock carries Sold Secure Gold or Diamond and the homeowner takes three specific steps: use a separate Wi-Fi network for smart devices, disable remote unlock, and enable two-factor authentication on the app. This combination meets the minimum insurance requirement (Sold Secure Gold) and addresses the NCSC’s main electronic vulnerability (NCSC, 2026).

Sold Secure Gold locks are accepted by most UK home insurers, including Aviva, Direct Line, and LV=, according to BIBA guidance (BIBA, 2026). The separate Wi-Fi network prevents a compromised smart speaker or thermostat from being used as a gateway into the lock. Disabling remote unlock removes the relay attack vector, and two-factor authentication prevents password theft from granting access.

A smart lock that meets these criteria is as secure as a mechanical deadbolt for physical attack, but the electronic risk is managed, not eliminated.

Eligibility and installer verification MCS, TrustMark, and the only certification that matters for insurance

For a smart lock, the installer does not need MCS (that is for renewables) or Gas Safe (that is for gas). The relevant registrations are TrustMark (for all home-improvement trades) and, if the lock is wired or involves door-structure alteration, NICEIC or NAPIT (for electrical work) (GOV.UK, TrustMark scheme rules, 2026).

The lock’s rating, not the installer’s certification, determines insurance acceptance. However, a TrustMark-registered installer is required for any warranty claim on the door itself. If the smart lock replaces a full cylinder and the door is composite, the door manufacturer may void the warranty if a non-registered installer fits the lock (TrustMark, 2026).

For a retrofit smart lock that clips over the existing deadbolt, no electrical certification is needed. For a full replacement that involves wiring into the door frame, the electrical work must comply with Part P of the Building Regulations, which requires certification by a NICEIC or NAPIT registered electrician (GOV.UK, Approved Document P, 2026).

What a smart lock’s U-value has to do with door security (and why it matters for your energy bill)

A smart lock that replaces a full door cylinder can degrade the door’s thermal performance if the lock body is not insulated. A typical U-value for a modern composite door is 1.2 W/m²K (Energy Saving Trust, 2026). An uninsulated smart lock body can add 0.3–0.5 W/m²K to that value, effectively increasing heat loss through the door by up to 40% at the lock point.

The 2026 Part L of the Building Regulations (conservation of fuel and power) requires any replacement door to have a U-value no worse than the original (DESNZ, Part L 2026 compliance guide). If a smart lock reduces the door’s overall U-value, the installation may not comply with Building Regulations.

Manufacturers such as Yale and Ultion now offer insulated lock bodies specifically built to maintain the door’s thermal performance. Check the product specification for “thermal break” or “insulated body” to avoid a cold spot around the lock.

The trade-off mechanical deadbolt vs. smart lock for a UK front door

A BS 3621 mechanical deadbolt (Sold Secure Diamond, no electronics, no app, no relay risk) costs £30–£80 for the lock alone. A Sold Secure Gold smart lock costs £150–£400 for the lock plus £200–£500 for a professional fit by a TrustMark-registered installer (Which? door lock buying guide, 2026).

The mechanical lock has zero electronic vulnerabilities and is accepted by every UK insurer. The smart lock adds convenience (keyless entry, remote monitoring, temporary codes for tradespeople) but introduces relay risk and requires ongoing firmware updates. The cost difference is roughly £300–£800 more for a smart lock, depending on the model and installation complexity.

For a home where the door is already secure and the homeowner is comfortable with the electronic trade-offs, a Sold Secure Gold smart lock is a reasonable upgrade. For a home where maximum security is the only priority, a BS 3621 mechanical deadbolt remains the lower-cost, lower-risk option.

How to check your existing door is compatible before buying a smart lock

Not all UK doors can accept a smart lock. Timber doors with a 57mm backset and 44mm thickness are standard; composite doors with a 70mm backset are common but may require a specific lock type (GGF door dimension guide, 2026).

Take three measurements before buying: backset (distance from the edge of the door to the centre of the keyhole), door thickness, and cylinder length. The lock must match the door’s existing mortice (the recess cut into the door edge). If the door is a composite model from Solidor or Rockdoor, check the manufacturer’s compatibility sheet to confirm which smart lock models are approved (Solidor, 2026 specifications).

For retrofit smart locks that clip over the existing deadbolt, compatibility is usually broader, but the lock must still fit the door thickness and backset. If the door is a uPVC or aluminium type, the lock mechanism may be integrated into the door frame, which means a full replacement smart lock may not be possible without replacing the entire doorset.

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