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Install external bi-fold doors.
Aluminium, uPVC or hardwood bi-folds — measured, manufactured and fitted with full glazing seal.
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Costs, timelines, pitfalls and the right questions to ask before any doors starts on external Bi-Fold Doors.
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Top tips
Hiring a doors, without the regret.
Four moves that separate a smooth job from a nightmare.
Track levelling drift
If the substrate settles 2mm the leaves bind. Use installers who level on a stainless sub-frame, not directly to subfloor.
Roller wear
Cheap nylon rollers fail in 5–7 years on heavy leaves. Specify stainless or ball-bearing rollers.
Cold bridging at threshold
Flush thresholds need careful detail or you'll get condensation pooling in winter.
Wind load
Wide bi-folds (4+ leaves) over 3m height need TS 008 glass spec or they bow in a gale.
Costs & timeline
Know what it costs. Know when it ends.
Indicative UK ranges and what affects price.
Cost range
By job type
Inc. VAT · 2026
Source: NMT quotes
Source: NMT quotes
uPVC 3-leaf 2.4m, supplyCheapest material, bulky frames
£2.4k–£3.8k
Aluminium 3-leaf 3m, supplyUK market standard
£3.8k–£6.5k
Aluminium 5-leaf 4.8m, supplyOrigin, Smart, Schueco
£6.5k–£11k
Timber bi-fold, supplyEngineered oak, hardwood
£5k–£9k
Installation labour2 days, two-three fitters
£700–£1.5k
Structural opening / new lintelBuilding Regs notifiable
£1.2k–£3.5k
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Quote spread is typically ± 18% — always get 3 quotes.
At a glance
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Bi-fold doors fold concertina-style to one or both ends, giving the widest unbroken garden opening possible. They are the natural choice for kitchen-diner extensions opening to the patio. Expect £3,500–£15,000 fitted in the UK depending on width, material, and glass specification.
What Does the Work Involve?
A bi-fold installation starts with the structural opening — most existing French-door or window openings need widening, which means a new steel lintel, building-regs approval, and brickwork make-good. The track and frame come as a single matched unit; the leaves arrive separately, are hung on top-running rollers (or bottom-rolling on heavy aluminium units), and slid onto the track. The multi-point lock is on the master leaf. Threshold options range from full weather-bar (60mm step) to flush-fit floor-finish (20–25mm step) for the contemporary look.
Typical Costs
| Item | Low (£) | High (£) | Notes |
|---|---|---|---|
| uPVC 3-leaf 2.4m, supply | 2,400 | 3,800 | Cheapest material, bulky frames |
| Aluminium 3-leaf 3m, supply | 3,800 | 6,500 | UK market standard |
| Aluminium 5-leaf 4.8m, supply | 6,500 | 11,000 | Origin, Smart, Schueco |
| Timber bi-fold, supply | 5,000 | 9,000 | Engineered oak, hardwood |
| Installation labour | 700 | 1,500 | 2 days, two-three fitters |
| Structural opening / new lintel | 1,200 | 3,500 | Building Regs notifiable |
| Flush threshold detail | 200 | 500 | Floor finish flush both sides |
How Long Does It Take?
Structural opening (lintel + brickwork) takes 3–5 days. Bi-fold install on a prepared opening takes 1–2 days for 3–5 leaves. Bespoke RAL colours add 8–12 weeks to lead time; stock colours (white, anthracite, black) are 4–6 weeks.
DIY or Professional?
Professional only. The structural lintel needs building-control sign-off, and the bi-fold track must be levelled within 1mm over the full width or the leaves drag. Heavy aluminium leaves (40–60 kg each) need two fitters to lift safely.
Choosing the Right Tradesperson
FENSA or Certass registered. Ask which brand — Origin, Smart Systems, Schueco, Reynaers and SunFlex are the UK premium tier. Ask the U-value of the complete unit — aim for 1.2 W/m²K or lower. Insist on Yale, ERA or AvocetHardware locking. Get the warranty in writing — 20 years on Origin, 10 years on most others.
UK Regulations
New or enlarged opening needs Building Regs approval — lintel calculations, structural steel sizing, and DPC continuity all need to be signed off. The doors themselves must achieve U-value ≤1.4 W/m²K (Part L) and PAS 24:2022 if part of a new dwelling (Part Q). Glazing within 800mm of finished floor level must be safety glass. FENSA/Certass self-certifies the door installation but not the structural work.
Common Problems
- Track levelling drift: If the substrate settles 2mm the leaves bind. Use installers who level on a stainless sub-frame, not directly to subfloor.
- Roller wear: Cheap nylon rollers fail in 5–7 years on heavy leaves. Specify stainless or ball-bearing rollers.
- Cold bridging at threshold: Flush thresholds need careful detail or you'll get condensation pooling in winter.
- Wind load: Wide bi-folds (4+ leaves) over 3m height need TS 008 glass spec or they bow in a gale.
Frequently Asked Questions
How wide can a bi-fold door go?
Most UK manufacturers offer up to 6 metres on a single track. Wider openings (8m+) usually use two pairs of bi-folds on opposing tracks.
Bi-fold vs sliding doors?
Bi-folds open 90% of the aperture. Sliders open only 50% (or 67% on 3-pane systems). Sliders give bigger panes of glass when closed; bi-folds give wider clear opening when open. Sliders are usually cheaper per metre.
Which material is best?
Aluminium dominates the UK bi-fold market for good reason — thinnest sightlines (only 40–80mm of frame visible per joint), best thermal performance, longest warranty. uPVC bi-folds have bulky frames; timber needs more maintenance.
Are bi-fold doors secure?
Yes — quality bi-folds have multi-point locking, anti-lift devices, and PAS 24:2022 certification. Specify a 3-star Sold Secure cylinder for the master leaf.
Can the track be flush with the floor?
Yes — flush-fit thresholds give a near-seamless inside/outside floor finish. The trade-off is reduced weatherproofing in extreme conditions, so most installers recommend a covered or recessed external area.
Do bi-folds need planning permission?
No, replacing existing French doors with bi-folds is permitted development. Enlarging the structural opening may need approval in conservation areas. Listed buildings always need consent.
This guide was written with AI assistance and is intended for general information only. Prices are estimates based on UK averages and may vary by region. Always get at least three quotes and consult a qualified professional before starting any work.
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