Who makes doors and windows?

Most doors and windows sold in the UK are manufactured by a handful of large national producers, including Everest, Anglian, Safestyle, and specialist brands like Rationel and Velfac, according to the Glass and Glazing Federation (GGF, 2026).

The answer depends on whether you want standard off-the-shelf products or bespoke joinery. National manufacturers dominate the replacement market, while local joinery workshops and timber merchants supply custom-made timber doors and windows. Double-glazing units themselves are typically sourced from specialist sealed-unit manufacturers, not the same companies that make the frames.

National manufacturers supply most replacement windows

Companies like Everest, Anglian, and Safestyle manufacture their own uPVC and aluminium frames in UK factories. Everest operates a manufacturing facility in Derby, producing bespoke windows and doors for nationwide installation (Everest, 2026). Anglian’s main production site is in Norwich, making both uPVC and timber composite products. These firms hold British Fenestration Rating Council (BFRC) ratings, which you can check via the BFRC database. Their products typically carry a 10-year insurance-backed guarantee.

Timber doors and windows come from specialist joinery firms

If you want timber windows or doors, national joinery brands like Rationel (Danish, but UK-distributed) and Velfac (a subsidiary of Velux) are common choices. Alternatively, local joinery workshops make bespoke hardwood or softwood windows to order. The Wood Window Alliance certifies timber windows that meet PAS 24 security standards. For listed buildings, you may need a specialist conservation joinery firm approved by your local planning authority, check their list of recommended suppliers.

Double-glazed sealed units come from separate manufacturers

The glass panes inside doors and windows are made by dedicated sealed-unit manufacturers, not the frame makers. Major sealed-unit producers include Pilkington, Saint-Gobain, and Thermoseal Group. These firms supply glass units to installers and national brands. The Energy Saving Trust notes that a standard double-glazed unit (4-16-4mm with low-e coating) has a U-value around 1.2 W/m²K (Energy Saving Trust, 2026). Always check that your glass unit carries a British Standards Kitemark or a UKCA mark for compliance with Building Regulations Part L.

A worked example

Glazing is standard-rated for VAT at 20%. The zero rate for energy-saving materials covers insulation, heat pumps and solar panels; HMRC names secondary and double glazing as excluded (VAT Notice 708/6). The Energy Saving Trust estimates that upgrading from single glazing to A-rated double glazing saves a typical semi-detached home around £195 per year on heating bills. This gives a simple payback period of approximately 33 years on the upfront cost. However, the real value comes from the improved comfort, reduced condensation, and a potential uplift in the home’s Energy Performance Certificate (EPC) rating, which can increase the property’s resale value. If you are eligible for the ECO4 scheme, you may receive full or partial funding for the replacement, bringing the payback period down to zero. Always verify installer certification through the Competent Person Scheme or FENSA to guarantee the work meets Building Regulations.

What homeowners often get wrong

The most common mistake is assuming that the company installing your windows also manufactures the glass sealed units inside them. This misconception leads to poor warranty claims and missed opportunities for better performance. Here are three specific errors to avoid.

1. Believing the installer makes the glass Most national frame manufacturers like Everest and Anglian do not make the double-glazing sealed units. Those are supplied by specialist firms such as Pilkington or Saint-Gobain. If a sealed unit fails within its warranty, you must contact the glass manufacturer, not the door company.
2. Ignoring the Energy Performance Certificate rating Homeowners often focus on the frame material and colour but overlook the BFRC rating. An A-rated window saves roughly £100 more per year than a C-rated one on a semi-detached house. Choosing a lower rating can waste over £2,500 in heating costs over a decade.
3. Assuming all grants cover the same work The ECO4 scheme funds energy-efficiency improvements for low-income households, but it only covers windows that fail a thermal efficiency test. The BUS grant (£7,500) does not cover windows at all. Applying for the wrong grant can delay your project by months.

Quick reference

• Everest, Anglian, and Safestyle manufacture their own uPVC and aluminium frames in UK factories in Derby, Norwich, and Yorkshire respectively.
• Timber windows and doors come from specialist brands like Rationel, Velfac, or local joinery workshops, not from the national uPVC producers.
• The BUS grant (£7,500) covers heat pumps only and does not fund window or door replacements under any circumstances.
• Replacing single glazing with A-rated double glazing in a typical semi-detached home saves roughly 4,500 kWh of gas per year according to the Energy Saving Trust.
• All replacement window installations must comply with Building Regulations and be certified by a Competent Person Scheme such as FENSA or Certass.