Casement windows are the most common window type in UK new builds and retrofits, yet their security when open is almost entirely ignored. The standard espagnolette handle locks the window shut. Open the window for air on a warm evening, and that lock does nothing. A casement window security lock that works in the open position is the missing piece, and fewer than one in ten UK homeowners know the option exists. LockLatch® was invented in South Africa, patented internationally (UK patent EP2989274, SA patent 2014/09494, USA patent 9,797,173), and ships with the security screws and pop rivets needed for installation in any UK casement.
Why Casement Windows Are Vulnerable When Open
A casement window hinges on one side and swings outward. When closed, the multipoint locking system engages along the full length of the frame. When open, the lock disengages completely. The window is held only by the friction stay, a mechanism designed to resist wind, not a person.
According to the English Housing Survey, the majority of homes built after 2000 use casement windows, the vast majority in uPVC. That is an enormous installed base of windows with no open-position security.
The night vent position, where the handle turns 90 degrees to hold the window at a narrow gap, provides minimal airflow and is not a security lock. The gap varies by manufacturer but is typically 10 to 15 millimetres. Barely enough to feel a breeze.
What Does a Casement Window Security Lock Look Like?
LockLatch® mounts to the window frame and the opening sash with a rigid C304 rust-resistant stainless steel arm. The arm adjusts to hold the casement window at any gap between 9 and 17 centimetres, wide enough for genuine airflow, narrow enough to deter entry.
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 window cannot be pushed further open, pulled shut, or removed from the device without the key. This converts an unsecured open casement into a locked-open one.
Crime prevention specialists describe the principle as target hardening. Most opportunistic intruders move on when they encounter resistance — they are testing handles and pushing windows, not carrying specialist tools. A locked-open casement that resists being pushed wider sends them to the next house.
Pets and Family Safety as Well as Security
UK pet owners are a significant share of the LockLatch® market because the same product solves several problems at once. A casement secured at 9-17cm provides a route for a small dog to come and go without the house being open. At the same setting, a cat cannot pass through. For families with children, 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 the very edge, reducing the effective opening and keeping it well within the 100mm regulatory threshold for child safety.
How Is This Different From a Window Restrictor?
Cable restrictors limit how far the window can open. They are primarily child safety devices. The cable prevents the window from exceeding a set distance, but the cable provides no adjustability or rigidity. A cable restrictor does not lock the window at a chosen width.
LockLatch® restricts the window AND fastens it open but locked at a predetermined gap. The rigid stainless steel arm holds the window firmly at the selected opening. That distinction matters. A cable flexes under pressure. A steel arm does not.
Can You Fit One to Any Casement Window?
Side-hung casements, top-hung casements, and awning windows all work. The U bolt allows easy positioning on the frame regardless of hinge location. Left-hand or right-hand opening makes no difference. The footplate positions adjust to suit the window geometry.
Timber and steel casements use one-way security screws. uPVC and aluminium casements use pop rivets. Both the security screws and the rivets are supplied with the product — there is no separate trip to a hardware shop. The installation method depends on the frame material, but the process is identical: four small holes, about 15 minutes per window, no tradesman required. Doing the install yourself matters more than it sounds — letting an unfamiliar tradesman into your home introduces its own security risk on a security product.
If the device is ever removed, holes can be covered with rubber grommets or filled with silicone for a clean finish.
What About Sash Windows and Sliding Windows?
Casement windows open outward on a hinge. Sash windows slide vertically. Sliding windows move horizontally. LockLatch® works on all three types, but the approach differs.
On sash windows, LockLatch® works in combination: either one LockLatch® plus a sash stop or jammer to lock the other sash closed, or two LockLatches (one on the top sash, one on the bottom) for cross-ventilation.
On sliding windows and doors, LockLatch® mounts to the frame and the sliding panel. The same 9 to 17 centimetre adjustable gap applies. The same 15-minute installation applies.
Battle-Hardened in South Africa, Refined for UK Homes
LockLatch® was invented 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.
Ordering and Worldwide Delivery
LockLatch® is made from C304 rust-resistant stainless steel requiring minimal maintenance. It carries a lifetime guarantee. Every unit ships with the one-way security screws and pop rivets needed for installation, plus the removable key for the locking pin.
LockLatch® ships worldwide from distribution centres in the UK and South Africa. 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. International orders ship 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 secure your casement windows in the open position.
