Fluid Window: Minimal Aluminium Casement Windows with Concealed Hinges

The hinges are concealed within the frame, creating a sleek, flat sash profile so the window reads as a flush plane from both sides and the elevation keeps a consistent rhythm across multiple openings. The strength of the aluminium frame allows exceptionally thin frames and larger glass areas than vinyl or wood. Outward opening preserves internal floor space and keeps external elevations clean. Handles are colour-matched, with a designer range where a more expressive detail is wanted.

The slim sash format takes side-hung leaves to 750mm by 1500mm at 35kg, and top-hung to 1200mm by 1500mm at 50kg. The heavy duty format extends that to 750mm by 1750mm at 42kg side hung, and 1800mm by 1800mm at 100kg top hung. Both take 23–44mm glazing, so a single elevation can mix formats without the glass specification changing.

The thermally broken frame achieves a whole-window U-value of 1.0 W/m²K, with acoustic insulation to 45dB — high enough for urban and roadside elevations. A lower U-value indicates better insulation. Modern aluminium systems use thermal breaks to reduce heat transfer, unlike older aluminium windows that were known for poor insulation. Weather performance is Class 4 air permeability, Class E1200 water tightness and Class CE 2400 wind resistance. A 45dB rating is the figure to check where a window faces a busy road. The 23–44mm glazing range also supports double and triple glazing, including double glazing options, for better thermal and acoustic insulation and less heat loss.

The system is PAS 24 and RC2 compliant, which covers most local authority and insurer requirements for new dwellings. Glazing at or near floor level is toughened or laminated safety glass under Approved Document K and BS 6262-4, and laminated glass can be specified where enhanced security or acoustic performance is required.

Configurations run from a single side-hung or top-hung leaf through fixed lights to combinations — fixed plus side hung, fixed plus side hung plus top hung, two side hung plus one top hung, and larger multi-window arrangements, with the right opening configuration shaped by the window style and each window opening. Vent options such as trickle vents can also be specified to support airflow even when the windows are closed. Because every format shares the same sightline and hardware, a mixed arrangement still reads as one window.

Finishes cover the full RAL range, including popular colours such as Anthracite Grey and other grey tones, alongside anodised surfaces and wood-effect powder coated options, so windows can be matched to sliding doors, steel-look framing or structural glazing elsewhere on the same building, while quality powder-coated or anodised finishes help protect high-quality aluminium against corrosion, rust, fading and harsh weather conditions. Powder coating also creates a smooth, durable barrier. Handle finishes are colour matched, in standard classic RAL or textured RAL, to suit the overall style.

We design, engineer, fabricate and install in-house, overseeing how the windows manufacture from specification to finishing so they stay coordinated with the doors and structural glazing on the same elevation rather than sourced separately and made to fit. That in-house process gives tighter quality control and supports long-term durability. Performance is evidenced rather than estimated. See the Fluid Window at Ashmead Barn, Keepers Cottage, Sea Breeze and Beulah Walk, or see one at our Watford showroom.

Architects — where a consistent window rhythm across an elevation matters and visible hardware would break it. Request CAD details and evidenced performance data.

Homeowners — for a whole-house window replacement or new windows that suit both replacements and new builds, where the windows should match the doors rather than compete with them.

Developers — where one window system has to cover every opening on a scheme without changing sightline or finish, helping meet customers expectations for consistency and finish.