At Aluco, we don’t just replicate the look of steel windows — we push the detail into every component. One of the most striking features of classic steel windows is the “duplex” lock or surface-mounted rod locks, where a bottom handle engages at two locking points across the height of the opening sash.
Also launched as part of our Aluco Elite Window Collection at the Homebuilding and Renovating Show, this new period Duplex lock received a lot of attention for its wow-factor looks and how it authentically inbtroduced an entirely new level of period charm to modern steel-look windows.
A Brief History of Duplex & Surface Rod Locking in Steel Windows
In early steel window design (1910–1930s), windows commonly used rod and nose or surface-mounted rod locks, often with a visible top and bottom rod operated by a handle.
These mechanisms locked the window sash to the fixed frame, or mullion at two points. These two points at that time provided a sense of added security to a simple metal and single glazed window. Because the rods were internal to the frame, they were visible but robust — part of the aesthetic as well as the function.
The Steel Window Association notes that many modern steel window systems now include concealed multipoint locking, but these often lose the visual indicator of “locking points” that traditional rod systems gave. Even Historic England published a document emphasising that original steel windows were often riveted, had narrow profiles, external rods or nosing, and required regular maintenance to prevent corrosion.
bringing back the beauty of period locking
Before multipoint locking became common in aluminium and steel windows, locking at the furthest internal surface (i.e. as far from the outside edge as possible) was preferred to resist forced entry, similar to these period rods and handle. These were called “cockspur handles” and were used from the first generation ‘double glazing’ to around the 1990’s.
Modern multipoint locking systems are now widely used in windows, for steel or steel look. But for steel-window purists, that concealed hardware sacrifices the visual identity of historical steel windows.
This heritage context gives the new Aluco duplex lock real depth and visual beauty. This isn’t just about aesthetics. At Aluco, we do everything we can to echo the original engineering window locking philosophies of period metal windows.
The new Duplex Lock is not a cosmetic rod bolted on after the fact. This elegant piece of hardware is engineered for Aluco Elite profiles. It retains visual authenticity while keeping your windows closed and sealed.
why the aluco duplex window lock matters
There is no other brand in the UK in aluminium, offering this enhanced level of authenticity to your steel look windows.
Whether you call them industrial, Art-Deco, Soho-Style or heritage, only Aluco windows bring you as close as possible to steel windows without buying steel.
Other windows and doors marketed in a similar style are no more than an existing window with a transom, providing one choice of window handle. Aluco not only pioneered the monkey tail, pear drop and other styles, we now bring you what is arguably the most authentic period window locking system, replicating original metal windows with duplex locking.
Aluco. the authentic window
The new duplex lock takes Aluco Elite windows to another level of authenticity.
Purpose‑designed, fully integrated and tested, you can now recreate the visible top‑and‑bottom locking of true period steel windows.
Offered in antique brass, bronze and other period finishes, it’s more than just hardware – it’s a design feature in its own right.
For homeowners and architects wanting the unmistakable look and feel of heritage steel windows without the cost or limitations of steel, the Aluco duplex lock delivers a uniquely authentic detail you won’t find anywhere else.
Be the first to experience the new Duplex Lock by Aluco.
Our new Duplex lock is perfect for front-facing steel-look windows where locking visibility is a design statement. We hope Local authorities will love it for its historic look for period-style properties where authenticity is required, such as conservation areas. It’ll also be outstanding when you want the mechanical presence of lock rods and period hardware without the cost of real steel windows
Our new window hardware will be available soon. If you want to be among the first to view or specify it for your home or project, get in touch today.
Book a visit to our showroom or contact us for details of your nearest Aluco Approved Installer.
Frequently asked questions
What is the Aluco Duplex Lock
This is our modern solution to the iconic double locking that was a feature or original metal windows. A duplex lock uses a single handle to operate two locking points—at the top and bottom of the window—providing both heritage style and reliably closing your windows.
Why choose a duplex lock over a standard modern lock?
Unlike hidden espagnolette systems, or shoot-bolt locking, a duplex lock makes the locking rods visible, enhancing the authentic steel-look design with a genuine period feature. No other aluminium window in the UK provides this.
Is the Aluco duplex lock just for show?
Not at all. It’s fully engineered, integrated, and tested within the Aluco Elite system—delivering real and reliable window with classic style.
Can I choose the finish of the duplex handle and rods?
Yes. The handle and locking components are available in antique brass, bronze, and other period finishes to complement your interior design.
Where is the duplex lock best used?
It’s ideal for front-facing steel-look windows, period homes, and projects where visible hardware is part of the desired aesthetic.
