The Short Answer
On our estimates, uPVC French doors cost £1,300 to £2,200 fitted into an existing door opening; composite £2,000 to £2,800, timber £2,000 to £3,500 and aluminium £2,500 to £3,800. Fitting takes one to two days.
Turning a window into French doors means cutting the wall below the window down to the floor: about £2,200 to £3,700 in uPVC. If the doors are the same width as the window, the existing lintel can often stay; a wider or brand new opening needs new support, adding £1,300 to £2,500.
French door prices
| Job | Typical cost |
|---|---|
| uPVC French doors, existing opening | £1,300 to £2,200 |
| Composite French doors, existing opening | £2,000 to £2,800 |
| Timber French doors, existing opening | £2,000 to £3,500 |
| Aluminium French doors, existing opening | £2,500 to £3,800 |
| Converting a window (uPVC doors included) | £2,200 to £3,700 |
| New opening with lintel, before the doors | £1,300 to £2,500 |
| For comparison: uPVC sliding doors | £900 to £3,000 |
Turning a window into French doors
The Planning Portal's guidance is the key: if you reuse an opening without increasing the span of, or load on, the existing lintel, no further support is normally needed. Cutting a window down to the floor at the same width often fits that. Make the opening wider and the wall above needs new beams, with building regulations approval; the details are on bifold door costs.
French doors or sliding doors?
French doors open the full width of a modest opening and are usually a little cheaper than sliders in uPVC (£1,300 to £2,200 against £900 to £3,000, on our estimates). For a wide opening, sliders or bifolds suit better. Side panels and whether the doors open in or out are worth talking through with the fitter before ordering.
Regulations and planning
- Replacement French doors: safety glass, 1.4 W/m²K or the energy rating equivalent, and a competent person certificate (FENSA, CERTASS, Assure, Blue Flame, Certsure or NAPIT) or building control approval.
- A wider or new opening is a structural alteration and needs building regulations approval.
- Enlarged openings count towards the glazing limit of 25% of floor area before compensating measures are needed.
- Close to a boundary, doors may need fire resistance.
- Planning: not usually needed for doors of similar appearance; listed buildings and conservation areas need checking.
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Frequently asked questions
What is the average cost for French doors?
On our estimates, £1,300 to £2,200 for uPVC French doors fitted into an existing opening; aluminium £2,500 to £3,800.
How much are French doors fitted in the UK?
£1,300 to £2,200 in uPVC and £2,000 to £3,500 in timber, fitted into an existing opening, on our estimates.
Are French doors cheaper than patio doors?
In uPVC, usually a little: £1,300 to £2,200 against £900 to £3,000 for sliders, on our estimates.
How much does it cost to turn a window into French doors?
About £2,200 to £3,700 with uPVC doors, on our estimates, including cutting the wall down, a new threshold and making good. Keeping the same width can mean the existing lintel stays.
Do I need building regulations to put in French doors?
Replacing existing doors is certified by a registered installer. A wider or new opening is structural and needs building regulations approval.
How we priced thisView sources (6, 6 official)
Rules come from the legislation and official guidance, read at source. Prices are our estimates: we check them against trade price data, retailer shelf prices and specialists' price lists, then build them up from their parts so the totals add up. Below are the sources behind the page; the trade price guides we only compare against aren’t listed. Where sources disagreed, we've said so. More on our method.
- OfficialBuilding regulations: structural opening, Planning Portal. Checked 15 Oct 2026.
- OfficialDoors and windows: building regulations, Planning Portal. Checked 15 Oct 2026.
- OfficialApproved Document K: Protection from falling, collision and impact (2013 edition), Section 5, GOV.UK. Checked 15 Oct 2026.
- OfficialApproved Document L: Conservation of fuel and power, Volume 1 Dwellings (2021 edition incorporating 2023 amendments), GOV.UK. Checked 16 Oct 2026.
- OfficialThe Building Regulations 2010, Schedule 3: self-certification schemes (para 16, roof coverings), legislation.gov.uk. Checked 15 Oct 2026.
- OfficialDoors and windows: planning permission and building regulations, Planning Portal. Checked 15 Oct 2026.
