Window pricing is driven by six main factors, each contributing meaningfully to the total: material (PVC is typically the most cost-effective; alu-clad timber the highest);
Window size (larger windows cost more, but cost per square metre often decreases with size);
Glazing specification (double or triple, coatings, gas fill, laminated or acoustic options);
Window type (picture windows are simpler than tilt-and-turn; bay windows are more complex than single casements);
Hardware specification (basic locks vs multi-point with high-rated cylinders);
and installation complexity (single replacement is straightforward; bay restoration or heritage work is more involved).
Understanding these factors helps you read quotes correctly and identify where to invest vs save. This guide does not list specific prices — those vary too much by region, supplier and project. Instead it explains what affects pricing so you can have informed conversations with installers.
Window pricing varies too much by region, installer, time of year, project scale, and specification for a national pricing guide to be useful. The same windows in similar properties can vary 30–50% between quotes from different installers, all of whom are competitive in their local markets. What matters is understanding what drives the cost so you can compare quotes intelligently and discuss specifications with installers from a position of knowledge.
Material is the single biggest driver of window cost. Each material has different manufacturing costs, different finishing requirements, and different inherent material costs.
Typically the most cost-effective material. PVC is extruded in standardised profiles, can be manufactured at scale, and the inherent material cost is moderate. Finishes (white as standard, foil-applied colours) are applied as part of the extrusion process. PVC frames typically cost 30–50% less than equivalent timber frames.
Mid-range material cost. Pine is widely available, easy to work, and has been used in joinery for centuries. The manufacturing is more labour-intensive than PVC extrusion, and the finishing (factory paint or stain) adds steps. Pine timber windows typically cost 30–60% more than PVC equivalents.
Higher material cost than pine because the hardwood itself is more expensive and harder to work. The denser timber is heavier and requires different cutting tooling. Meranti frames typically cost 15–25% more than equivalent pine frames.
Highest material cost of the four options. The composite construction (timber interior, aluminium exterior) involves two materials and the joinery to combine them. Both components contribute to cost. Alu-clad timber frames typically cost 80–120% more than PVC equivalents.
Relative material pricing
Larger windows cost more in absolute terms because they use more material, larger glazing units and more substantial hardware. But the cost per square metre typically falls as size increases because installation labour and fixed cost elements are spread over more area.
Small windows have high cost per square metre. The fixed elements (lock mechanism, hinges, sealing, installation labour) are similar to those of larger windows, but the glazed area is small. Bathroom and WC windows are typically in this category.
Most British residential windows fall in this range. The cost per square metre is moderate, and per-window pricing in this range varies mainly with material and specification rather than size.
Cost per square metre falls because the fixed elements are spread over more area. Per-window cost rises significantly because the materials and glazing involved are more substantial.
Specialist territory. Glazing units this size are heavy and require careful handling. Hardware must be specified for the load. Structural opening usually needs engineering attention. Per-square-metre cost can actually rise again because of these specialist requirements.
Glazing options range from basic double glazing to specialist high-performance units. Each step up in specification adds cost.
Two glass panes, sealed with inert gas (typically argon), basic low-E coating. The baseline for modern UK windows. Meets minimum Part L requirements.
Two panes with enhanced low-E coating, krypton or other premium gas fill, optimised pane separation. Adds 10–20% to glazing cost. Improves thermal performance noticeably.
Three panes with two gas-filled gaps. Heavier, thicker unit. Adds 20–40% to glazing cost over standard double glazing. Significant thermal improvement, particularly valuable in colder regions.
PVB interlayer between glass panes for safety and security. Adds 15–25% to glazing cost. Required by Building Regulations in some positions; valuable for security and acoustic improvement elsewhere.
Special coatings that reduce solar gain while preserving visible light. Adds 10–20% to glazing cost. Worthwhile for south and west-facing rooms with significant solar issues.
Laminated panes with sound-dampening interlayer, sometimes with different pane thicknesses. Adds 25–40% to glazing cost. Worthwhile near busy roads or noisy environments.
Coating that breaks down dirt under UV and rinses with rainwater. Adds 10–15% to glazing cost. Worthwhile for hard-to-clean positions (large picture windows, upper floors, roof windows).
Different window types have different manufacturing complexity. Simpler types (picture, basic casement) cost less than complex types (tilt-and-turn, sash, bay).
Hardware quality and security level significantly affect both cost and the long-term performance of the window.
Installation costs vary significantly with the complexity of the work.
Like-for-like replacement of existing windows in standard openings. The fastest, most cost-effective work. Each window typically takes 3–4 hours of installation time including removal of old window, fitting new window, and making good.
Where the new window size differs from the original, the opening must be modified — usually adding packing or, in more involved cases, adjusting the brickwork. Adds time and complication.
Replacing a complete bay window is substantially more work than replacing flat windows. The structural elements (sill, header, corner posts) often need attention, the lead or felt roof above may need attention, and the multiple glazed sections take more time to fit and align.
Listed buildings and conservation areas typically require specialist installers familiar with period work. The work itself takes longer, the materials are usually higher-cost timber, and the certification requirements are more involved. Heritage replacement typically costs significantly more than equivalent contemporary replacement.
FENSA or Certass registered installers include certification in their pricing. Non-registered installation requires separate Building Control approval, which adds cost and time. Always confirm whether quotes include certification.
Internal plastering, redecoration of disturbed wall areas, replacement of any damaged trim — these are sometimes included in quotes and sometimes not. Confirm in writing what is included.
Most installers include disposal of old windows in their pricing. Verify this — some quote it as an extra. Old windows are bulky waste and disposal at landfill or recycling has its own cost.
Light decoration (painting around new frame, touching up scuffs) is sometimes included; full redecoration of the room is not. If significant decoration will be needed, plan and budget for it separately.
Removal of curtains and blinds beforehand and refitting afterward may or may not be included. For installations with valuable curtain treatments, confirm who is responsible.
Heavy furniture near windows may need moving. Some installers handle this; some expect homeowners to clear access. Confirm in advance.
