Sliding doors vs French doors.

A French door is a pair of hinged leaves that meet at a centre rebate, typically opening outwards onto a garden or balcony. The geometry is centuries old. The closed-state reads as two doors with a visible meeting rail; the open-state pivots both leaves out of the way, with a clear opening that varies between roughly 60 and 90 percent of the aperture depending on hinge geometry.

A sliding door is a single uninterrupted plane of glass when closed (or two interlocking planes on multi-track systems), with one or more panels that slide laterally on a low-profile track when open. The closed-state reads as continuous glazing; the open-state always retains at least one panel in the run.

For most contemporary architecture in the UK — extensions, new-builds, garden-side elevations on modern houses — the closed-state aesthetic of a sliding door is what the brief wants. The plane of glass disappears into the elevation in a way a French door cannot, because the hinge stiles and the centre meeting rail of a French door are visible in elevation regardless of finish.

French doors are the right call when the architectural language is traditional, when the opening is narrow enough that panel-stack matters less than swing geometry, and on listed-building work where the planning officer reads the centre meeting rail as the historically appropriate detail. We supply sliding doors only — we are not the right manufacturer for a project that genuinely wants French doors, and we say so honestly.

On performance, properly thermally-broken aluminium French doors hit similar U-values to sliding doors of equivalent glass spec. Where French doors lose ground is at the centre meeting rail, which has more sealing surfaces than a sliding interlock and degrades faster over a 25-year life — the closed-state weather sealing on French doors is a real maintenance item where on a slider it largely is not.

When sliding makes sense over French doors. The elevation is wider than a standard pair of hinged doors can comfortably span; the closed reading wants to be a single plane of glass rather than a centre-mullion split; the threshold has to weather-seal a continuous opening rather than a stop-and-leaf interface. Sliding doors are the contemporary answer for rear extensions and full-elevation glass walls; French doors are the heritage-correct answer for period elevations and narrower openings.

When French doors make sense over sliding. The opening sits in a Victorian or Edwardian rear elevation where a pair of casement-style doors is consistent with the original fabric; the architectural register is heritage-led rather than contemporary; the elevation is narrow enough that hinged doors clear without an awkward swing arc into the room. Listed buildings and conservation-area projects often select French doors for consent reasons that have nothing to do with the technical brief.

Detail considerations. Sliding doors carry a continuous bottom track with a recessed weather seal; French doors carry a centre meeting stile with a head-and-foot seal that engages on the latch close. The continuous track is more weather-resistant in driving rain (BS EN 12208 Class E1200 vs typically Class E750 for hinged casements); the centre stile is more architecturally sympathetic on a heritage elevation.

Regulatory and material note. Maxlight does not manufacture timber-framed French doors. Where the brief specifies real timber casements, we recommend a heritage-specialist joinery rather than steering the project to an aluminium alternative the consent process will not accept. The BS EN 14351-1 product standard, BFRC rated U-values and Approved Document L 2025 limiting U-values apply to both routes; specification is the same conversation, even when the manufacturer is different.

The four trade-offs that matter, named explicitly with the reasons each system wins or loses on each.