Bi-Fold Doors Installation Guide

Bi-fold doors have become the defining feature of modern home extensions in London, transforming how families connect indoor and outdoor spaces. These multi-panel doors fold back concertina-style, opening up to 90% of the width and creating seamless transitions to gardens. Whether you're planning a kitchen extension, conservatory replacement, or orangery, understanding bi-fold door options, specifications, and installation requirements will help you choose the right system for your property. This guide covers everything North London homeowners need to know about bi-fold doors.

How Bi-Fold Doors Work

Bi-fold doors consist of multiple panels (typically 2-8 panels) connected by hinges. The panels fold and stack to one or both sides when opened. Key components include:

• Panels: Individual door sections, typically 600-1200mm wide
• Track System: Top or bottom-hung mechanism allowing smooth operation
• Hinges: Connect panels allowing folding action
• Running Gear: Wheels/rollers enabling panels to slide
• Locking System: Multi-point locks for security
• Traffic Door: One panel can open independently like a normal door
• Threshold: Floor track (or low threshold for accessibility)

Materials: Aluminium vs. UPVC vs. Timber

Aluminium Bi-Fold Doors: Most popular choice (80%+ of installations):

• Slim Frames: Narrow sightlines maximise glass area and views
• Strength: Supports large panels with minimal framework
• Durability: Won't warp, rot, or require painting
• Low Maintenance: Occasional cleaning only
• Powder-Coated Finish: Wide colour range, long-lasting
• Thermal Performance: Thermally-broken frames prevent cold transfer
• Cost: £1,200-£2,000+ per metre width for quality systems

UPVC Bi-Fold Doors: Budget option:

• Lower Cost: £800-£1,400 per metre width
• Good Insulation: Multi-chambered profiles
• Chunkier Frames: Less elegant than aluminium
• Limited Colours: Mainly white or woodgrain effect
• Can Warp: Large panels prone to distortion in heat
• Shorter Lifespan: 15-20 years vs. 30+ for aluminium

Timber Bi-Fold Doors: Premium traditional option:

• Beautiful Appearance: Natural wood aesthetics
• Suits Period Properties: Better for conservation areas
• High Maintenance: Regular painting/staining required
• Can Swell/Warp: Affected by moisture
• Premium Pricing: £2,000-£3,500+ per metre width
• Thermal Performance: Good with proper glazing

For most North London extensions, quality aluminium doors offer the best balance of performance, aesthetics, and value.

Configuration Options

Panel Count and Arrangement:

• 3-Panel: Suitable for 2.1-3m openings
• 4-Panel: Most common, fits 2.8-4.2m openings
• 5-Panel: For 3.5-5m openings
• 6+ Panels: Wide orangeries or large extensions

Folding Arrangements:

• Fold to One Side: Most common, all panels stack to left or right
• Fold to Both Sides: Central opening with panels stacking each side
• Fold Outward or Inward: Outward folding more common

Traffic Door: One panel opens independently like a standard door:

• Convenient for quick garden access without opening all panels
• Can be any panel, but typically at one end
• Essential for daily use
• Usually included in quality systems

Glazing Specifications

Double Glazing: Standard for most installations:

• U-values of 1.2-1.6 W/m²K
• Argon gas-filled for better insulation
• Low-E coating reduces heat loss
• 24mm total thickness typical

Triple Glazing: Premium option:

• U-values of 0.8-1.0 W/m²K
• Better thermal and acoustic performance
• Heavier (requires robust hardware)
• More expensive (£200-£400 extra per door)

Safety Glass: Essential considerations:

• Toughened glass standard for safety
• Laminated glass for enhanced security and acoustic performance
• Building regulations require safety glazing in certain locations

Solar Control Glazing: For south-facing installations:

• Special coatings reflect solar radiation
• Prevents overheating in summer
• Reduces furniture fading
• Slight tint usually unnoticeable

Threshold Options

Standard Threshold: 60-70mm upstand:

• Most weatherproof option
• Drainage channels integrated
• Step over required
• Not wheelchair accessible

Low Threshold: 20-25mm upstand:

• Easier access, better for elderly/children
• More seamless indoor-outdoor transition
• Requires careful drainage design
• Slight step still present

Level Threshold: Completely flush:

• Wheelchair accessible, fully accessible design
• Seamless transition to garden
• Requires extensive drainage planning
• More expensive and complex installation
• May require building floor up or paving down

Installation Requirements

Structural Opening: Must be properly prepared:

• Steel lintel or beam supports load above
• Structural engineer calculations for beam size
• Opening must be square, level, and plumb
• Proper damp-proof course around opening
• Cavity closing/tray installation for weatherproofing

Subframe vs. Direct Fix:

• Subframe: Wooden or PVC frame installed first, doors fix to this. Allows adjustments, easier installation
• Direct Fix: Doors fixed directly to opening. Neater finish, requires perfect opening

Drainage: Critical for performance:

• Bottom track must drain water away
• External paving should fall away from threshold
• Drainage channels integrated into threshold
• Weep holes must remain clear

Security Features

Quality bi-fold doors include comprehensive security:

• Multi-Point Locking: Locks at top, middle, and bottom of panels
• Shoot Bolt Locks: Extending bolts secure into top and bottom tracks
• Anti-Lift Devices: Prevent panels being lifted off tracks
• Internal Beading: Glass secured from inside, can't be removed externally
• Laminated Glass: Holds together if broken, delays intruders
• Secure by Design: Police-approved systems available

Good bi-fold doors meet PAS 24 security standards and achieve high insurance ratings.

Operating Mechanisms

Top-Hung: Panels hang from top track:

• Smoother operation, less effort required
• No bottom track to trip over
• Better for level thresholds
• More expensive (£200-£400 premium)
• Requires robust top support

Bottom-Rolling: Panels run on bottom track:

• More common and economical
• Bottom track visible
• Still provides smooth operation if quality system
• Track can collect debris requiring cleaning

Costs of Bi-Fold Doors

Budget UPVC (per metre width): £800-£1,200

• Basic white UPVC
• Standard double glazing
• Bottom-rolling
• Basic hardware

Mid-Range Aluminium: £1,200-£1,800 per metre

• Quality aluminium frames
• Good glazing and hardware
• RAL colours available
• Standard warranty

Premium Aluminium: £1,800-£2,500+ per metre

• Slim sightline frames
• Triple glazing
• Top-hung option
• Flush thresholds
• Extended warranties

Typical Installation Examples:

• 3m wide 4-panel system (mid-range): £3,600-£5,400
• 4m wide 5-panel system (mid-range): £4,800-£7,200
• 5m wide 6-panel system (premium): £9,000-£12,500

Prices include doors, hardware, glazing, and installation but not structural opening preparation.

Choosing Quality Systems

Reputable manufacturers include:

• Origin: Premium UK brand, excellent quality, slim frames
• Smart Systems: High-quality aluminium, good value
• Schuco: German engineering, premium specification
• Reynaers: Belgian brand, commercial-grade quality
• Sunflex: Specialist in large openings

Avoid very cheap systems from unknown brands—bi-fold doors are used daily and cheap versions fail quickly.

Maintenance and Care

Proper maintenance ensures longevity:

• Clean tracks monthly, remove debris and dirt
• Lubricate hinges and running gear annually
• Wash frames and glass regularly
• Check drainage holes remain clear
• Adjust doors if alignment changes
• Inspect seals annually, replace if damaged

Quality aluminium bi-fold doors should last 30+ years with minimal maintenance.