What Is Aluclad? Timber Inside, Aluminium Outside

Start with the timber. The core is engineered Scandinavian softwood: knot-free laminations bonded so the grain directions oppose each other, which is why the section stays straight in a way solid timber does not. This is the structural frame — it carries the glass, it carries the hardware, and it does the majority of the insulating.

The aluminium is not structural. It is a thin, profiled, powder-coated skin that sits proud of the timber on clips, with a deliberate ventilated gap behind it. That gap matters more than anything else in the construction: it lets moisture escape rather than sit trapped against the wood, and it lets the aluminium expand and contract in the sun without dragging the timber with it.

Structural frame

Engineered Scandinavian timber, laminated for stability

External cladding

Powder-coated aluminium on clips, ventilated behind

Whole-window U-value

From 1.2 W/m²K double, from 0.8 W/m²K triple

External maintenance

Washing down only — no repainting cycle

Internal maintenance

Occasional re-finishing, indoors, after many years

Timber is a better insulator than aluminium by a wide margin, which is why an aluclad frame carrying triple glazing reaches whole-window figures a thermally broken aluminium system generally cannot. In practical terms, the frame is not the weak point of the wall.

Security follows the same logic. A solid timber door leaf with a bonded aluminium skin is a substantial object; tested to PAS 24 with triple-point locking, it behaves accordingly. The difference is audible the first time the door closes.

The external face needs washing, in the same way any coated frame does — twice a year in a normal setting, more often close to a road or the coast. There is no repainting cycle, and the powder coating is the same technology used on architectural aluminium curtain walling.

Internally, the timber is factory finished. In a normal domestic environment it will need attention after many years rather than a few, and when it does, the work happens indoors, in the dry, on a face that has never been rained on. That is a fundamentally different proposition to standing on a ladder in October.

• Wash external cladding with warm water and a mild detergent — never solvents or abrasives.
• Keep drainage slots at the cill clear; a blocked slot is the most common cause of a nuisance leak.
• Lubricate hinges and locking gear annually with a light machine oil.
• Check internal timber in rooms with high humidity — bathrooms, utility rooms — more often than elsewhere.
• Adjust hinges rather than living with a rubbing sash; every function on the system is adjustable.

It is a premium specification and it should be spent where it shows. On a rear elevation with a tight budget, or where the internal reveal will be plastered up to the frame and barely seen, thermally broken aluminium or a good timber-look uPVC will serve the house better and free money for glass.

Aluclad timber sections are also deeper than an equivalent aluminium system. Where the brief is genuinely the slimmest possible sightline — a minimal-frame slider across a whole rear elevation — aluminium wins on that specific criterion and we will say so.