Tue May 26
Alu-clad windows give you a timber interior with a powder-coated aluminium exterior – one frame that handles the warmth of wood and the toughness of metal. The result is a high-performance window that needs no repainting, insulates well, and works across contemporary new builds and heritage-sensitive projects alike.
What are Alu-clad windows?
An Alu-clad window has a solid timber frame on the inside and an aluminium shell on the outside. The aluminium cladding acts as a weather barrier, protecting the timber core from rain, UV and pollution without affecting the feel of the interior.
The concept was originally developed to extend the life of traditional timber windows. Modern versions go much further – precision-sealed construction, engineered drainage channels and thermal breaks that give the composite frame properties neither material achieves alone.
At TRC Contracts, our Alu-clad windows are manufactured and installed to the same exacting standards we apply to our heritage sash windows and timber casements – designed for projects where long-term performance matters.
Key benefits of Alu-clad windows
Low maintenance
The aluminium exterior requires no repainting. Occasional cleaning with soapy water is all that is needed to keep frames looking good. Annual oiling of hinges and moving parts keeps hardware in order. For clients managing large housing or education schemes, that reduction in lifecycle maintenance cost is a real operational advantage.
Thermal performance and U-values
Timber is a naturally low-conductivity material – it slows heat transfer between inside and out far better than aluminium alone. When combined with aluminium cladding and triple glazing, whole-window U-values can reach as low as 0.8 W/m²K, comfortably meeting Passivhaus thresholds. That directly translates to lower heating demand and year-round comfort.
Durability in exposed locations
The powder-coated aluminium shell resists warping, cracking and bending. It protects the timber beneath from driving rain, coastal salt air and UV degradation. Studies have shown that protecting a timber frame with aluminium cladding can extend its service life by over 20 years compared with an unclad softwood equivalent.
Design flexibility for contemporary and heritage projects
The exterior aluminium profile is available across the full RAL colour range. The interior timber – typically FSC-certified softwood or engineered hardwood – can be stained, painted or clear-lacquered to suit any interior scheme. You can specify different colours inside and out, giving architects a level of specification control rarely available with single-material systems.
Slim aluminium sight lines also allow more glazed area per opening, improving daylight and views without compromising weather performance.
Are Alu-clad windows suitable for heritage or listed buildings?
Yes. The timber interior is sympathetic to traditional interior character – the kind of natural texture and visual warmth needed to sit alongside lime plaster, stone flags or period joinery. The exterior profile can be designed to replicate the proportions of original windows while delivering modern air-tightness and thermal ratings.
TRC Contracts has over 30 years of experience supplying and fitting windows into conservation areas, listed buildings and sensitive heritage sites. Our bespoke window service means specification is tailored to the project, not pulled off a shelf.
Alu-clad windows FAQ
What is the difference between Alu-clad and aluminium windows?
An all-aluminium window has a metal frame throughout – inside and out. An Alu-clad window has a solid timber core clad in aluminium on the exterior only. The timber provides better natural insulation and a warmer interior aesthetic. The aluminium provides weather protection and eliminates external maintenance.
How long do Alu-clad windows last?
With correct installation and basic cleaning, Alu-clad timber windows are expected to last 50 to 60 years or more – significantly longer than uPVC and competitive with premium all-aluminium systems, while offering better thermal properties.
Do Alu-clad windows need painting?
No. The powder-coated aluminium exterior does not need painting, sanding or sealing. The interior timber may be refinished over time if you want to refresh the look, but it is fully protected from weather and does not require routine treatment.
Are Alu-clad windows energy efficient?
Yes. The timber frame acts as a natural thermal insulator, and when paired with triple glazing, these systems achieve U-values that meet or exceed Part L and Passivhaus requirements. They are well suited to new builds targeting high energy performance ratings.
Want to discuss Alu-clad windows for your project? Get in touch with TRC Contracts to talk through specification, supply or installation.
