Aluminium vs vinyl windows: the full comparison for builders

Aluminium vs vinyl: what the comparison covers

The comparison only makes sense on equal terms: the same opening size, the same glass, the same installation. Where the two materials are placed on the same drawing, the differences that survive are the ones in this article. Two things frame everything that follows.

PVC-U, the material vinyl windows are made from, is a poor conductor of heat. Aluminium is a strong, light conductor that also conducts heat. That is why every opening line in the aluminium range is a thermal-break profile — 70–75 mm on the window lines — rather than a solid section. The comparison is really between PVC-U and thermally-broken aluminium.

Thermal performance: the PVC advantage is real, and it has a size

Vinyl does have a genuine advantage in raw frame conductivity. A solid PVC section transfers less heat than a solid metal section, and that is the reason the material is the default in cold climates with single-glazed heritage. The advantage shrinks fast once the comparison is fair: a thermal-break aluminium frame with a double-glazed unit is not being asked to compete against its weakest configuration.

And the frame is the smaller term. On any given opening, the difference between single glazing and an IGU, or between a standard IGU and a laminated or coated one, moves the performance figure more than the frame material does. The glass build is the first specification, and the frame material is the second.

Strength and span: where aluminium wins outright

Metal carries weight. A tilt-turn sash in the range runs to 1,400 × 2,100 mm on a 6–12 point lock; a single lift-and-slide leaf is rated to 300 kg; a bi-fold runs to an 8,000 mm clear opening with up to twelve metres unfolded. Those are openings the hardware and the frame are engineered for, not edges of a spec sheet.

Vinyl sashes of the same size are where the material starts to flex. In sustained hot climates, large vinyl sashes are the ones that warp, and the warp shows as a leaf that no longer seats the gasket. The limitation is not a defect of a bad product; it is what the material does at scale.

Finish: colour, UV and repair

The aluminium finish is a factory surface: anodised for the marine line, powder-coated to any RAL reference, or a wood-grain film over the metal. The colour is matched to the project before the order is cut, and the full RAL palette is available rather than a catalogue of ten colours.

Vinyl colour is baked into the material, which has one real merit: a chip does not expose a different colour underneath. The trade is the palette — a limited range of standard colours — and the fact that a vinyl frame cannot be refinished. Where the project wants a specific colour, a wood look, or a finish that has to survive salt air for decades, the factory metal finish is the route.

Maintenance and service life

Both materials are low-maintenance, and the honest answer on upkeep is that the gaskets and the hardware are the maintenance point on either one. The material difference shows up in what the frame itself does over the years: aluminium does not warp, does not melt and does not delaminate. Vinyl frames in sustained heat can warp or crack, and the UV exposure that fades a vinyl exterior is the same exposure an anodised metal surface is designed to take.

On the coast the difference is sharper. The marine line is anodised specifically for salt-air exposure, and the hardware is the same class of multi-point lock on either material. A vinyl window on a salt-air elevation is a gasket-and-fastener problem for life; a metal one is built for the exposure from the extrusion.

Cost: the honest answer

Per unit, on a standard residential opening, vinyl is usually the lower material cost. This is the point where the comparison is true and where it is also least useful, because the total cost of the opening is not dominated by the frame. The glass build and the hardware set carry most of the number on any non-trivial opening, and a detailed breakdown of how a quotation is built is in the pricing article.

Where the frame material does decide the cost is at the edges: large spans, heavy leaves, impact glazing, and the long service life of a building. A vinyl frame on a six-metre bi-fold is not a realistic specification, so the cost question on that opening is not vinyl versus aluminium but aluminium versus nothing.

Which one to specify, and when

The decision rules a builder can apply without opening a spec sheet:

• Standard residential openings, cost-led, single-glazed or standard IGU: vinyl is a legitimate choice, and it is the default on a large part of the market.
• Openings beyond about two metres wide, or leaves over 100 kg: aluminium. The hardware class is the difference.
• Bi-fold, lift-and-slide, pivot or any mechanism at scale: aluminium. The mechanism and the frame are engineered as one.
• Impact or cyclone specification: both materials exist in the impact market, and the aluminium line here is the 90 mm platform with a 0.38 mm PVB or SGP laminated core.
• Coastal elevations and any project that wants an anodised marine finish: aluminium.
• Multi-unit or commercial work where the hardware and the finish have to hold across the building: aluminium.
• A wood look without real wood: aluminium with the wood-grain finish.