Most window locks on the UK market do one thing: hold the window shut. That leaves homeowners with a choice between safer ventilation and fresh air, particularly in summer when indoor temperatures regularly exceed 25 degrees. One category of product solves this by locking the window in the open position, and the search for an open window security lock has grown steadily as more people discover that the option exists. LockLatch® was invented in South Africa, patented internationally (UK patent EP2989274, SA patent 2014/09494, USA patent 9,797,173), and proven across more than two decades in one of the world’s most demanding home-security environments before reaching the UK market.
Why Would Anyone Lock a Window Open?
The logic sounds counterintuitive until you think it through. A closed and locked window is secure but provides zero airflow. An open and unlocked window provides airflow but is an invitation. The standard UK insurance position is straightforward: when the premises are unoccupied, all windows and doors must be closed and locked. LockLatch® does not change that rule. It changes what happens when you are at home, want fresh air, and need a way to keep windows open safely without compromising the security of the rest of the house.
An open window security lock restricts how far the window can open and then locks it at that gap. The window stays open for safer ventilation, but nobody can push it further or climb through. This is fundamentally different from a cable restrictor, which limits the opening distance but offers no adjustability or rigidity. Cable restrictors flex. A rigid stainless steel arm does not.
How Does an Open Window Security Lock Work?
LockLatch® is a C304 rust-resistant stainless steel device with a U bolt for easy positioning on the frame. The arm adjusts to hold the window at any gap between 9 and 17 centimetres. A locking pin drops into the barrel of the lock in any of the four holes, and the lock is lockable with a removable key.
The device fits any window or door whatever the frame is made from and whichever way it opens. Casement, sash, sliding, top-hung, awning. Timber, uPVC, aluminium, steel. Four small holes are drilled into the frame, then secured using either a screwdriver or a rivet gun depending on the frame type. One-way security screws for wood and steel frames, pop rivets for uPVC and aluminium. The entire process takes about 15 minutes per window.
The effective opening is slightly narrower than the nominal 9 to 17 centimetre range because the footplates usually mount to the middle of the frame rather than the very edge, which can reduce the usable gap by 3 to 4 centimetres. For UK homes wanting safer ventilation while occupied, this works in the homeowner’s favour.
Battle-Hardened in South Africa, Refined for the UK
LockLatch® was designed in South Africa, where break-in rates per capita are among the highest in the world and where homes need to balance security against extreme summer heat. For more than two decades, South African homeowners have used LockLatch® to keep windows open at night for cross-ventilation while the family sleeps, knowing the window cannot be pushed wider from outside.
The product that arrived in the UK is the same one that survived 20-plus years of real-world testing in that environment. The C304 stainless steel arm, the lockable pin, the four-hole mount, the adjustable gap range — all refined under conditions far more demanding than the average UK street. The international patents (UK EP2989274, SA 2014/09494, USA 9,797,173) protect a design that has been quietly proven before being brought to a wider market.
Target Hardening: Why Burglars Move On
Crime prevention specialists describe a concept called target hardening. The principle is that most opportunistic intruders move on when they encounter resistance. They are not carrying specialist tools. They are testing handles, pushing windows and looking for the easiest way in.
A lockable pin secures the LockLatch® arm in position. The window cannot be pushed further open without removing the device, and the device cannot be removed without the key. That level of resistance is enough to send an opportunistic intruder to the next house. This is not a claim about defeating a determined attack. It is a claim about target hardening: changing the risk profile of an open window from easy to difficult, and inviting the chancer to move on.
A Real-World UK Example
Claire from Hungerford in the UK contacted LockLatch® after a break-in at her property. The intruder attempted to enter through her patio sliding door, which was secured with a LockLatch®. Rather than defeat the lock, the intruder broke through the window pane itself and cut himself in the process. He was caught, charged and sentenced.
Claire’s insurance company was Admiral Platinum cover. When the assessor inspected the patio door, they accepted the LockLatch® as a secure lock and treated the door as locked for the purposes of the claim. The police and crime scene officers attending the scene also commented on the device positively. Claire’s words: “because if someone wants in to a house… they’re going to get in eventually, just not through a LockLatch®.”
The story illustrates the target-hardening principle in practice. The LockLatch® held. The intruder moved to a route that left forensic evidence, which led to identification, prosecution and a conviction.
What About Closed Window Security?
LockLatch® does not replace the standard window lock. The existing handle, espagnolette or multipoint lock on a closed window provides closed-position security. What LockLatch® provides is security in the open position, which no standard window fitting addresses. These are two different problems requiring two different solutions, and they work alongside each other rather than replacing each other.
For unoccupied premises, the standard UK insurance position applies: close and lock all windows and doors. For occupied premises wanting safer ventilation, pet access or child safety, LockLatch® is what closes the gap.
How Does This Compare to Other Solutions?
Cable restrictors are the most common alternative. They limit opening distance but offer no adjustability or rigidity. The cable limits the gap but does not lock the window at a specific width, and the cable itself provides no structural resistance to being pushed.
Window stays and friction hinges provide some resistance but are not designed as security devices. They hold the window in position against wind, not against a person.
Security mesh screens cover the entire window opening. They are effective but expensive, permanent and alter the appearance of the building. They also reduce airflow and natural light.
LockLatch® sits between these options. It restricts the window AND fastens it open but locked at a predetermined gap. It is adjustable, removable, and made from C304 rust-resistant stainless steel with a lifetime guarantee.
Installation, Removal and Worldwide Delivery
Four small holes are drilled into the frame, then secured using either a screwdriver or a rivet gun depending on the frame type. If the device is ever removed, the holes can be covered with rubber grommets when the product is taken off, or filled with wood filler or silicone for a permanent finish.
LockLatch® ships from distribution centres in South Africa and the UK. The UK distribution centre is in Penley, near Wrexham, with delivery across England, Scotland, Wales and Northern Ireland typically taking two to four working days via Royal Mail or courier. Beyond the UK and South Africa, LockLatch® ships worldwide via Royal Mail and international couriers — customers in Europe, North America, Australia, New Zealand and the rest of the world receive the same product, the same lifetime guarantee and the same C304 rust-resistant stainless steel construction.
Shop LockLatch® now and lock your windows open safely this summer.
