How long does aluminium bifold installation take on-site?

Typical install: 1–2 days for a 3–5m bifold once the structural opening is prepared. Day 1: door arrives, frame fitted into opening, plumbed and squared, fixed; track and head support adjusted; first sash hung. Day 2: remaining sashes hung, gearing tested, hardware adjusted, weatherseal completed, internal trim and external cill fitted. Plumbing and adjustment continue intermittently for the next 2–3 weeks as the doors settle. Final adjustment visit at week 4–6 to fine-tune hinge and roller alignment after the building has dried and settled.

Are bifolds or sliding doors more popular for new London extensions?

Sliding doors (large-format sliding patio doors — Reynaers SL38, Schuco ASS 70.HI, IQ Slide) have grown rapidly since approximately 2020 and now exceed bifolds in many high-spec London extensions. The slim sightline (35–50mm slimline) and large unbroken pane sizes (2.5×2.5m typical per panel) give a more contemporary aesthetic. Cost: sliding doors cost 25–40% more than bifolds for the same opening — a 4m sliding door at £14,000–£20,000 vs a 4m bifold at £8,500–£14,500. Function: bifolds open the full opening (fully fold back to one side); sliding doors open only 50% (one half slides behind the fixed half), but provide a single continuous wall of glass when closed.

What aftercare do aluminium bifolds need?

Aluminium bifolds need minimal maintenance compared to timber. Annual maintenance: (1) Clean tracks (vacuum debris, wipe with damp cloth); (2) Lubricate rollers and hinges with silicone-based or PTFE spray (NOT WD-40 which attracts dust); (3) Check and adjust roller/hinge alignment if any binding develops; (4) Inspect weatherseals for damage. Every 5 years: replace weatherseal rubbers if compressed or torn; check hardware torque settings. Every 10 years: re-glaze if seal failure causes misting. Premium systems (Reynaers, Schuco) come with 10-year mechanical warranty and 10-year sealed unit warranty as standard.

Are corner bifolds (no corner post) worth the extra cost?

Often yes — they create a dramatic open-corner effect where two bifold walls meet without a structural post, opening to a 90-degree garden corner. Cost premium: £2,500–£4,500 over two standard bifolds of the same combined width. Engineering: requires a goalpost steel frame (steel beam spanning across both bifold openings on each side) and the load-bearing structure transfers to corner columns set back from the bifold itself. Visual: when closed, looks like a normal corner with frames meeting at 90°; when open, the entire corner of the room disappears. Suited to wide rear extensions (5–7m wide) with garden access on the corner. Lead time and complexity drive cost; not a routine spec but transformational visually.

Aluminium Bifold Doors Cost London 2026 | Builderr

Bifold door cost by system and opening size

London bifold pricing varies by manufacturer, sightline and configuration. 2026 supply and install prices for typical configurations: 3m opening, 3-panel, value system (Smart Systems Visofold 1000, AluK F82): £6,500–£8,500. 3m opening, premium (Reynaers CF 77, Schuco AS FD 75): £8,500–£11,500. 4m opening, 4-panel, value: £8,500–£11,000; premium £11,000–£14,500. 4.8m opening, 4-panel, value: £10,500–£13,500; premium (Reynaers SL or CF 77 with traffic door): £13,500–£17,500. 6m opening, 6-panel premium: £17,500–£22,500. The largest London residential bifolds (8m+ openings on heritage stately properties or large rear extensions): £25,000–£40,000. Variables that move price: traffic door (single panel that opens independently of the fold) — adds £400–£800; corner bifold (two bifold walls meeting at a corner without a corner post) — adds £2,500–£4,500; raised threshold vs flush threshold — flush threshold typically adds £350–£600 (preferred for level access into garden); coloured powder coat outside / different inside — adds £400–£900; double-glazed vs triple-glazed — TG adds £800–£1,400 per door.

Sightline, glass area and visual considerations

Sightline (the frame width visible when the door is closed and viewed from inside) is the dominant visual quality factor for aluminium bifolds. Premium systems offer narrower sightlines because internal hardware is engineered to fit within thinner profiles. Comparison (sightline at meeting stiles when closed): Reynaers CF 77: 99mm. Schuco AS FD 75: 105mm. AluK F82: 116mm. Smart Systems Visofold 1000: 122mm. Origin OB-49 (popular high-spec): 117mm. The visual impact at a 4.8m bifold wall: Reynaers CF 77 shows approximately 9% frame and 91% glass; Smart Visofold shows approximately 13% frame and 87% glass — a meaningful difference for clients wanting maximum garden views. Glass spec: standard double-glazed argon-filled low-e 28mm sealed unit is the dominant spec — U-value 1.0–1.2 W/m²K at the glass centre. Triple-glazed 44mm unit: U-value 0.6–0.8 W/m²K at glass centre, £800–£1,400 per door upgrade. Acoustic glass (6.4mm laminated outer, 6mm inner): adds 4–6 dB STC reduction, £150–£250 per door upgrade for road-facing applications. Solar control glass (SunGuard or Pilkington Suncool): reduces solar gain by 50–60%, recommended for south or west-facing bifolds in heavily glazed rooms (helps avoid summer overheating), adds £200–£400 per door.

U-values and Part L compliance

Aluminium bifold door U-values (whole-door including frame and glass): standard double-glaze 1.3–1.6 W/m²K (Reynaers CF 77, Schuco AS FD 75, AluK F82); high-performance double-glaze with warm-edge spacer 1.2–1.4; triple-glaze 0.8–1.0 W/m²K. Building Regulations Part L 2025 compliance: replacement doors in an existing dwelling 1.4 W/m²K (whole door) — most premium aluminium bifolds compliant as standard. New extensions: the bifold contributes to the overall extension fabric U-value calculation; in a typical 25–35m² London rear extension with a 4.8m bifold (glass area approx 8.5m²), the bifold dominates the heat-loss area — selecting a 1.2 W/m²K bifold rather than 1.5 W/m²K can save 1.5–2.5% on whole-house annual heat demand. Builderr's standard spec for new extensions: Reynaers CF 77 or Schuco AS FD 75 at 1.2–1.4 W/m²K — meets Part L with margin and outperforms most value systems while maintaining acceptable budget. Triple glaze (0.8 W/m²K) is recommended where the extension faces north or where MVHR/Passivhaus-style detailing is being deployed.

Installation, threshold and waterproofing detail

Bifold installation quality drives long-term satisfaction more than door spec. Critical site detail: (1) Threshold — flush threshold (no upstand from finished internal floor to external paving) is the dominant London spec for new extensions. Achieved by setting the bifold sill 50–80mm below the internal screed level with a falls-to-drain paving design externally. Flush threshold requires careful waterproofing detail (Bauder bituminous DPC, Schluter Kerdi or similar) and external drainage channel (ACO HepLine or similar) to catch wind-driven rain. Cost of flush threshold detail: £600–£1,400 for the threshold zone (channel, DPC, weep design) over and above the standard upstand detail. (2) Lintel — bifold openings typically require a steel lintel; for openings 4m+ a 203×133 UC or 203×203 UC may be required (structural engineer specification). Lintel + padstones + structural calc: £600–£1,600 for the lintel zone. (3) Track support — the head of the bifold must be supported on a rigid lintel; deflection of more than 3mm under load can cause panel binding and prevent operation. The structural engineer specifies the lintel deflection limit (typically span/360 + 3mm hardware reserve). (4) Adjustment — premium bifolds have multi-axis adjustment hinges (Reynaers, Schuco, Origin); value systems have limited adjustment. Over 1–2 years after install, panel sag from glass/frame weight requires re-adjustment — premium systems re-adjust easily; value systems may require door removal and shim packing.

How Much Do Aluminium Bifold Doors Cost in London (Detailed Spec Guide)?