Summary

French doors are a pair of fully-glazed hinged doors that swing open from a central meeting point, giving a wide, unobstructed opening without the sliding track or folding hardware of a patio slider or bifold. They remain the standard choice for period and traditional properties, and for anyone who wants a proper "opens like a door" feel rather than a track-and-wheel mechanism. Because they use ordinary door hinges rather than a proprietary sliding or folding system, French doors sit at the lower end of the patio-door price spectrum in supply cost — but the labour and detailing risk is different, not lower, and installers who price them like a slider lose money on the callback.

The two things that make French doors behave differently from sliders and bifolds, and which this guide focuses on: first, the meeting stile — the vertical edge where the two leaves meet when closed — has to be weathersealed and aligned precisely, or the pair whistles in wind and lets water through at the middle; second, French doors are genuinely hinged, so they sag, drop, and need packing/adjustment over their life in a way a sliding track does not. Get the hanging and hinge spec wrong and the comeback rate on French doors is higher than on any other patio door type.

This guide covers material and labour pricing across UPVC, aluminium, timber and composite, the structural-opening decision that also applies to sliders and bifolds (see patio doors pricing guide for the shared structural cost tables), hinge and locking specification, active/passive leaf configuration, threshold detailing, and a worked example for a standard 1,790mm × 2,090mm replacement. For the broader patio door category comparison (French vs slider vs bifold) see patio doors pricing guide; for bifold-specific structural and threshold detail see bifold door pricing guide.

Key Facts

Quick Reference Table — Typical Supply + Fit Pricing

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Configuration Width Material Price Range (Supply + Fit)
French door pair 1,190mm UPVC £1,200–£2,000
French door pair 1,490mm UPVC £1,300–£2,200
French door pair 1,790mm UPVC £1,400–£2,600
French door pair 1,790mm Aluminium £2,600–£4,200
French door pair 1,790mm Composite (timber core, alu-clad) £3,200–£5,500
French door pair 1,790mm Full hardwood (heritage/listed) £3,800–£7,500
French door pair 2,090mm Aluminium £3,200–£4,800
Side panel add-on (fixed sidelight, per panel) 500–900mm UPVC / Aluminium £350–£900
Toughened-to-laminated glazing upgrade — Any material +£80–£180 per leaf
Cost Component Typical Trade Cost Notes
UPVC pair 1,790mm supply only £600–£1,000 Mid-market fabricator
Aluminium pair 1,790mm supply only £1,600–£2,600 Trade price ex-VAT
Composite pair 1,790mm supply only £2,200–£3,800 Timber-core, aluminium-clad systems
Weather-bar / threshold kit £60–£150 Aluminium low-profile
Flush bolts (passive leaf, top+bottom) £25–£60 Or integrated shootbolt on multi-point kits
Steel lintel (new/widened opening only) £150–£450 Plus structural calc
FENSA / Certass certificate £25–£60 Per installation
Skip / waste disposal share £60–£120 Shared across a job, not door-specific

Detailed Guidance

Site survey — what to check that's specific to hinged doors

A slider or bifold survey focuses on track alignment and floor level; a French door survey needs additional checks because the doors swing:

FRENCH DOOR SURVEY CHECKLIST
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□ Existing opening width × height (brick-to-brick and frame-to-frame)
□ Swing direction confirmed with customer — in-swing or out-swing
□ Clear internal/external arc — furniture, steps, planting in the swing path
□ Structural opening / lintel condition (rust, sag, rot)
□ Cavity wall or solid wall construction
□ Threshold height, weather-bar clearance, DPC position
□ Meeting stile alignment on existing frame (if repairing rather than replacing)
□ Wind exposure — is this an exposed elevation? (affects out-swing viability)
□ Glazing critical locations — is any pane below 800mm or adjacent to a walking surface?
□ Trickle vent provision elsewhere in the room

Out-swing French doors need at least the door's own width of clear space outside, plus a level threshold approach — a door swinging out over an uneven patio or a single step is a safety and warranty problem. Where the external space doesn't allow out-swing, specify in-swing, which is also generally the better choice for weathersealing in exposed locations.

Hinges, sag, and why French doors need a different labour allowance

A sliding door runs on a track and rollers; it doesn't sag with time the way a hinged leaf does. French doors are held entirely on their hinges, and a 1,790mm × 2,090mm leaf in aluminium or timber can weigh 35–70kg. Under-specified hinges (2 per leaf, or lightweight butt hinges on a heavy composite leaf) lead to the classic French door fault: the door drops slightly at the lock side over 12–24 months, and the multi-point lock no longer engages cleanly.

Price for 3 hinges minimum per leaf on standard heights, rising to 4 on doors over 2.1m or on heavy timber/composite leaves. Where the door is being reused (renovation of an existing frame) rather than replaced entirely, budget labour time to true up hinges, re-pack the frame, and re-align the strike plates — this is a common "repair not replace" job that's priced very differently from a full supply-and-fit.

The meeting stile — the single most callback-prone detail

Where the two leaves close together in the middle, there's no continuous frame member behind the seal the way there is at the outer jambs. This is the meeting stile (sometimes called the astragal on timber doors where a planted timber bar covers the joint). Two failure modes dominate:

Always inspect and quote for meeting-stile alignment as a distinct line item on renovation/repair jobs — it's rarely a five-minute adjustment.

Threshold and weather-bar detailing

Unlike a level-access slider, French doors nearly always use a raised aluminium weather-bar at the sill — typically 15–25mm upstand. This is both a weathersealing feature (the bar sheds water outward and gives the door bottom seal something to compress against) and, on older or heritage-style doors, a trip hazard that needs to be flagged to elderly or mobility-restricted customers.

Where a level-access threshold is specifically requested (increasingly common for accessibility), French doors are a poor fit — the swinging leaves and a flush sill combine badly for weatherproofing. Recommend a slider or bifold instead, or specify a drained channel threshold at a significant cost premium (£350–£700, similar to the flush threshold detail on bifolds — see bifold door pricing guide).

Locking specification and security

Multi-point espagnolette locking is now standard even on budget UPVC French doors — typically 3 hooks/rollers on the active leaf engaging into keeps on the frame, plus a mortice deadlock or additional hook at the handle position. The passive leaf is secured independently, usually with flush bolts (manual, top and bottom) on budget doors or an integrated shootbolt operated by a lever on premium systems — always specify which, since flush bolts require the customer to remember to bolt the passive leaf every time, which is a common source of "my French doors aren't secure" complaints after the event.

For PAS 24:2022 compliance, specify laminated glass in the lock-stile glazing pane, reinforced hinge screws (resisting hinge-bolt attack), and a cylinder or lock mechanism tested to the standard's attack resistance requirements. PAS 24 is not mandatory on replacement doors in an existing dwelling but is increasingly the customer's default expectation and a genuine selling point over a cheaper non-compliant import.

Materials and where the margin sits

Worked example — 1,790mm × 2,090mm aluminium French door pair, like-for-like replacement

Frequently Asked Questions

Are French doors cheaper than bifolds or sliders?

Generally yes for the supply cost at equivalent width, because the hardware is simpler — ordinary hinges and a multi-point lock rather than a proprietary sliding or folding track system. But the labour risk (hinge sag, meeting stile alignment) is higher per linear metre than a slider, and French doors don't scale to the very wide openings (3m+) that bifolds and lift-and-slide doors handle well. For openings up to about 2.1m where the customer wants a traditional door feel rather than a "wall that opens," French doors are usually the most cost-effective choice.

Do French doors need a steel lintel?

Only if the opening is being created or widened. A like-for-like replacement into an existing opening reuses the existing lintel — inspect it for rust (steel), sag, or rot (timber) before quoting, and flag replacement separately if needed. See patio doors pricing guide for the shared structural-opening cost table that applies across all patio door types.

Should I recommend in-swing or out-swing?

In-swing is the safer default for most UK replacements — it avoids the wind-driven rain exposure at the meeting stile that out-swing doors face on exposed elevations, and it doesn't require a fully clear, level external space for the swing arc. Recommend out-swing only where the customer specifically wants to preserve internal floor space (common in small kitchen-diners) and the external area is level, clear, and reasonably sheltered.

Why do my customer's French doors keep sticking or the lock won't engage a year after installation?

The most common cause is hinge sag — the leaf has dropped fractionally at the lock side, throwing the multi-point lock hooks out of alignment with their keeps. This is normal wear on a hinged door under its own weight and is fixed by adjusting the hinges (most modern hinges have a small adjustment screw) rather than by forcing the lock or re-cutting the keep. Flag this as a routine annual-check item to customers at handover — it heads off a warranty callback.

Can I fit French doors into an opening designed for a single door?

Only with a widened structural opening — French doors need at least 1.1–1.2m clear width for the narrowest stock pair, and most customers want 1.5m or more. Converting a single doorway to French doors is structural work under Part A, not a simple swap, and should be quoted and line-itemed as such.

Regulations & Standards