Sliding Door Calculator

Indicative 2026 UK cost guides put a basic 2-panel uPVC sliding patio door from about £850 fitted, with aluminium sliding doors typically £1,800-£4,500 supply and install for 2-3 panel systems. Mainstream aluminium sliders are supplied at around £250-£450/m², while premium slimline systems run £800-£1,400/m² before fitting. Installation into an existing opening is usually a single day’s work (this calculator defaults to £600 fitting labour), but forming or widening the opening adds structural work — a new lintel and knock-through — on top of the door price. Enter your own quote in the Custom Price and Installation Cost fields for an accurate total.

The main types are inline sliding (panels slide behind each other on tracks), lift and slide (panels lift off seals before sliding for better weather performance), and pocket sliding (panels slide into a wall cavity). Inline is most common and affordable. Lift and slide offers the best weather sealing.

Under Approved Document L 2021 (Table 4.2), a replacement door with more than 60% glazing must achieve a whole-door U-value of 1.4 W/m²K or better. The new-build notional spec is 1.2 W/m²K. Quality aluminium sliding doors with argon-filled double glazing and low-E coating typically run 1.2-1.6 W/m²K, and triple glazing 0.8-1.2 W/m²K — so a double-glazed door is not automatically below the 1.4 limit. Always check the door’s certified Uw on its CE/UKCA label rather than assuming it passes. Enter that figure in the calculator’s Certified U-value field for an accurate compliance check.

Individual panels are typically 800-2000mm wide. Inline sliding doors commonly span 2-4m total. Lift and slide systems can span up to 6m or more with larger panels. The structural opening and lintel must support the weight across the full span.

Modern sliding doors with multi-point locking systems are very secure. Lift and slide doors are particularly secure as the panel drops onto the track when locked. Both sliding and bi-fold doors can achieve PAS 24 security ratings. Laminated glass further improves security.

Yes. Standard upstand thresholds are typically 20-30mm high. For accessible (Part M) entrances, Approved Document M limits the threshold to a maximum of 15mm high, with any upstand over 5mm chamfered or pencil-rounded — a low or flush threshold meets this. Flush thresholds require careful drainage detailing to prevent water ingress. A low or flush threshold option commonly adds in the order of £200-400 to a door (indicative — varies by system and supplier).

Most UK sliding patio doors are sold in standard widths of 1600mm, 1800mm, 2100mm and 2400mm for a 2-panel set (one fixed pane, one sliding pane), with wider multi-panel openings common from about 2400mm up to 7500mm for 3-panel and 4500mm or more for 4-panel systems as extra sliding panels are added. Height is almost always a standard 2100mm to suit typical UK ceiling and lintel heights, though options from 2000-2500mm exist. This calculator’s Opening Width field accepts 1500-8000mm and Opening Height 1800-3000mm (default 2100mm) to cover everything from a small utility slider to a wide multi-panel garden opening. Always measure the structural opening (brick to brick), not the old frame, as made-to-measure doors are manufactured to that size.

This calculator’s £600 Installation Cost default covers a typical single day’s fitting into an opening that already exists at the right size. Forming a brand new opening or widening one adds structural work on top of the door price: typically £800-£2,500 for a lintel or steel beam and £1,000-£3,000 for the knock-through, making good and disposal, depending on wall construction and span. Enter your fitting-only quote in the Advanced Options Installation Cost field, then price the structural opening separately with our Structural Opening Calculator or Lintel Sizing Calculator.

French doors are usually the cheapest option, from about £750 fitted for a basic uPVC pair, because a hinged pair needs simpler hardware than sliding gear. Inline sliding doors sit in the middle: this calculator’s own default uPVC 2-panel supply rate is £560/m² (the £800/m² aluminium base rate times the 0.7 uPVC frame factor). Bi-fold doors typically cost the most, roughly £1,650-£8,500+ fitted, and lift & slide systems sit in the same top tier (this calculator prices lift & slide at £1,200/m² against £800/m² for inline), because of their multi-panel running gear and hardware. Sliding doors give the widest clear view when closed; bi-folds open the widest full-width aperture; French doors suit narrower openings and the tightest budget. Compare the figures for your own opening with our Bi-Fold Door Calculator and French Door Calculator.