UK building regulations require windows with sills below 1,100mm to limit the opening to no more than 100mm where children are present. Most parents discover this rule after a scare, not before. The child safety window lock market is crowded with cheap adhesive restrictors, cable locks and clip-on devices, but only a handful meet the regulatory threshold and provide genuine ventilation at the same time.
What Are the UK Window Safety Regulations for Child Protection?
Approved Document K of the Building Regulations sets the standard. Windows where the sill is below 1,100mm from finished floor level must include guarding or a restrictor that limits the opening to 100mm. This applies to new builds and major renovations.
The Housing Health and Safety Rating System (HHSRS) goes further for existing properties. Falls from windows are a Category 1 hazard. Local authorities can serve improvement notices on landlords and property managers who fail to mitigate the risk.
The 100mm figure is critical. A child’s torso cannot pass through a 100mm gap. Any window restrictor claiming child safety compliance must demonstrate it holds the opening at or below that threshold.
Why Most Cheap Window Restrictors Are Not Enough
Amazon UK lists dozens of child safety window locks from £4 to £22. BABYGO, Safelon, and BeeGo sell adhesive restrictors that stick to the frame. No drilling. No tools. Sounds ideal.
Three problems. First, adhesive fails in heat. A south-facing window in July generates enough warmth to weaken the bond. Second, adhesive restrictors have no structural rigidity. A child leaning against the window with body weight can shear the adhesive. Third, most adhesive locks restrict to a fixed width that the buyer cannot adjust.
Cable restrictors from Screwfix and B&Q at £6 to £44 are more robust. They screw into the frame and restrict via a steel cable. The cable limits the gap but offers no adjustability or rigidity. The fixed cable length means it cannot be locked at a chosen width, and the cable itself provides no structural resistance.
How MiniLatch® Meets the 100mm Child Safety Rule
MiniLatch® by LockLatch® has a nominal adjustable range of 4.5 to 8cm. The effective opening is narrower than that because the footplates usually mount to the middle of the frame rather than the very edge, reducing the practical gap by roughly 3-4cm. The result is a maximum effective opening well within the 100mm regulatory threshold.
For child safety, that tighter effective gap is precisely the point. The gap is wide enough for genuine airflow but physically too narrow for a child to pass through.
MiniLatch® started life as MonkeyLatch, developed for homeowners in KwaZulu-Natal dealing with vervet monkey incursions. The name changed when UK orders started arriving for cooler-weather ventilation and cat safety. The same engineering that stops a vervet monkey stops a toddler.
Does LockLatch® Also Comply With Child Safety Regulations?
Yes. Both LockLatch® and MiniLatch® comply with the 100mm child safety rule because of footplate geometry. The footplates usually mount to the middle of the frame rather than at the very edge, which reduces the practical opening by roughly 3-4cm below the nominal adjustable range. LockLatch® (9-17cm nominal) at its narrowest setting produces an effective opening within the 100mm threshold.
The choice between the two depends on ventilation needs. MiniLatch® provides less airflow but maximum child safety margin. LockLatch® at its narrowest setting meets the 100mm rule while allowing a slightly wider practical gap for better airflow.
What Locks Do Police Recommend for Windows?
UK police crime prevention officers generally recommend Secured by Design approved products. SBD categories cover closed-position window security. LockLatch® sits outside existing SBD categories because SBD does not currently have a category for open-position security devices.
That does not diminish its child safety credentials. SBD accreditation addresses burglary prevention, not fall prevention. The 100mm rule comes from Building Regulations, not police recommendations. Different standards for different risks.
Installation in a Family Home
MiniLatch® and LockLatch® both install in about 15 minutes per window. The fixing method uses one-way security screws on wood and steel frames, or pop rivets on uPVC and aluminium. Four small holes are drilled into the frame, then secured using either a screwdriver or a rivet gun depending on the frame type.
A lockable pin secured with a removable key holds the arm at the chosen width. The key means a child cannot adjust the setting. The arm is C304 stainless steel, rust-resistant with a lifetime guarantee and minimal maintenance requirements.
LockLatch® fits any window or door whatever the frame is made from and whichever way it opens. Casement, sash, sliding, top-hung. The same product works on every window type in the house.
For sash windows specifically, LockLatch® works in combination: either one LockLatch® plus a sash stop to lock the other sash closed, or two LockLatches (one on top sash, one on bottom) for cross-ventilation.
Both products ship from the UK distribution centre in Penley, near Wrexham. Shop LockLatch® now and see the full product range including MiniLatch®.
