Bifold and Sliding Doors for London Homes: Aluminium, Timber and uPVC 2025

ALUMINIUM BIFOLD DOORS ARE THE DOMINANT LARGE GLAZED OPENING SOLUTION FOR LONDON REAR EXTENSIONS IN 2025. THE KEY ADVANTAGE OF ALUMINIUM OVER TIMBER OR UPVC FOR BIFOLDS: STRENGTH ALLOWING VERY SLIM SIGHT LINES (DOWN TO 66-72MM BETWEEN PANES), POWDER-COAT FINISH IN ANY RAL COLOUR (RAL 7016 ANTHRACITE GREY IS THE MOST POPULAR FOR LONDON CONTEMPORARY KITCHENS), THERMAL BREAK WITHIN THE FRAME FOR PART L COMPLIANCE, AND LONG SERVICE LIFE WITH MINIMAL MAINTENANCE. KEY ALUMINIUM BIFOLD DOOR PRODUCTS SPECIFIED IN LONDON IN 2025: ORIGIN OB-49 BIFOLD — THE MOST SPECIFIED PREMIUM BIFOLD DOOR IN LONDON; THE ORIGIN OB-49 SYSTEM HAS A 107MM OUTER FRAME, 66MM SIGHTLINES BETWEEN PANELS, 50-YEAR POWDER-COAT GUARANTEE, THERMALLY BROKEN FRAME (U-VALUE TO 1.4 W/M²K WITH STANDARD GLAZING); AVAILABLE IN ANY RAL COLOUR (LEAD TIME 4-6 WEEKS FROM LONDON-BASED ORIGIN FABRICATORS). SMART ALITHERM 73 BIFOLD — A HIGHLY SPECIFIED ALTERNATIVE TO ORIGIN; WIDELY USED BY LONDON ARCHITECTURAL AND COMMERCIAL SPECIFICATION PROJECTS; 73MM OUTER FRAME. ALUK 58BF BIFOLD — A POPULAR MID-RANGE ALUMINIUM BIFOLD SYSTEM USED BY MANY LONDON WINDOW AND DOOR COMPANIES; 58MM FRAME, AVAILABLE IN STANDARD RAL COLOURS, COMPETITIVELY PRICED AGAINST ORIGIN. VELFAC 200 ALUMINIUM-CLAD TIMBER BIFOLD — A PREMIUM PRODUCT FOR LONDON CONSERVATION AREA AND HIGH-END APPLICATIONS; INTERNAL TIMBER, EXTERNAL ALUMINIUM; DANISH MANUFACTURE; U-VALUE 1.2-1.4 W/M²K.

LIFT-AND-SLIDE DOORS ARE AN ALTERNATIVE TO BIFOLDS FOR VERY LARGE LONDON EXTENSION OPENINGS WHERE THE PANEL COUNT IN A BIFOLD WOULD BE TOO HIGH (TYPICALLY ABOVE 4.5-5M WIDE). KEY PRODUCTS IN LONDON IN 2025: SCHUCO ASS 70.HI LIFT+SLIDE — THE MOST SPECIFIED PREMIUM LIFT-AND-SLIDE SYSTEM IN LONDON; HANDLES SINGLE PANELS UP TO 3.3M HIGH X 3M WIDE AND 400KG; USED IN HIGH-END LONDON ARCHITECTURAL PROJECTS WHERE FRAMELESS GLASS WALLS ARE SPECIFIED; U-VALUE FROM 0.8 W/M²K WITH TRIPLE GLAZING AND WARM EDGE SPACER BAR. SMART VISOGLIDE PLUS — A MORE ACCESSIBLE LIFT-AND-SLIDE SYSTEM FROM SMART (A MAINSTREAM UK ALUMINIUM SYSTEMS COMPANY); WIDELY INSTALLED BY LONDON WINDOW COMPANIES AS A PREMIUM SLIDING ALTERNATIVE AT LOWER COST THAN SCHUCO. CENTOR C4 FOLD-SLIDE — THE CENTOR SYSTEM (AUSTRALIAN) IS UNIQUELY ABLE TO FOLD BACK INTO A POCKET OR ALONGSIDE THE OPENING FOR A TRULY FLUSH THRESHOLD OPEN PLAN; SPECIFIED IN PREMIUM LONDON RESIDENTIAL PROJECTS WHERE THE THRESHOLD BETWEEN INSIDE AND OUTSIDE IS MEANT TO DISAPPEAR. FLAT THRESHOLD — ONE OF THE MOST IMPORTANT SPECIFICATION DETAILS FOR LONDON BIFOLD AND SLIDING DOORS IS THE THRESHOLD; A FLAT-FLUSH THRESHOLD WITH A 15MM MAX UPSTAND (BS 8213-1 REQUIREMENT) ALLOWS LEVEL ACCESS (PART M) AND DRAMATICALLY IMPROVES THE INSIDE-OUTSIDE CONNECTION; ORIGIN, SCHUCO AND SMART ALL OFFER THERMALLY BROKEN FLAT THRESHOLD OPTIONS.

INSTALLING BIFOLD OR LARGE SLIDING DOORS IN A LONDON REAR EXTENSION OR GROUND FLOOR REAR WALL ALWAYS REQUIRES A STRUCTURAL STEEL LINTEL TO CARRY THE LOAD OF THE STRUCTURE ABOVE THE OPENING. THE CORRECT STEEL SIZE MUST BE SPECIFIED BY A STRUCTURAL ENGINEER AND DEPENDS ON: SPAN OF THE OPENING (WIDTH OF THE BIFOLD OR SLIDING DOOR), LOAD ABOVE (WHETHER THERE IS A FIRST FLOOR ROOM, A FLAT ROOF, OR JUST A PITCHED ROOF STRUCTURE ABOVE), MATERIAL OF THE WALLS BEING SUPPORTED (BRICK, BLOCK, STONE), AND PAD STONE SPECIFICATION (THE BEARING PLATE EACH END OF THE STEEL). MOST COMMONLY INSTALLED STEELS FOR LONDON RESIDENTIAL BIFOLD OPENINGS (INDICATIVE, ALWAYS CONFIRM WITH STRUCTURAL ENGINEER): 3M OPENING: UB 203X133X25 S275 (THE MOST COMMON LONDON RESIDENTIAL BIFOLD STEEL SIZE); 4M OPENING: UB 254X146X31 S275; 5M OPENING: UB 305X127X37 OR UB 305X165X40 S275. PADSTONES — END BEARINGS FOR THE STEEL MUST BE SOLID BLOCKWORK OR ENGINEERING BRICK PADSTONES (MINIMUM 215X215X102MM DENSE AGGREGATE BLOCK UNDER EACH END). TEMPORARY SUPPORT — ACROW PROPS (GROUNDFORCE SHORCO OR SIMILAR) MUST SUPPORT THE EXISTING STRUCTURE DURING THE STEEL INSTALLATION.

PLANNING: INSTALLING BIFOLD OR LARGE SLIDING DOORS IN A NEW REAR EXTENSION FOLLOWS THE SAME PERMITTED DEVELOPMENT RULES AS THE EXTENSION ITSELF. FOR REPLACEMENT OF AN EXISTING REAR DOOR OR WINDOW OPENING WITH A BIFOLD/SLIDING DOOR IN THE MAIN HOUSE REAR ELEVATION: THIS IS GENERALLY PERMITTED DEVELOPMENT (LIKE-FOR-LIKE ENLARGEMENT OF AN EXISTING OPENING OR ADDITION OF AN OPENING IN THE REAR) BUT IN LONDON CONSERVATION AREAS WITH ARTICLE 4 DIRECTIONS, CHANGES TO THE REAR ELEVATION ARE CONTROLLED AND MAY REQUIRE PLANNING PERMISSION. LISTED BUILDINGS REQUIRE LISTED BUILDING CONSENT FOR ANY DOOR REPLACEMENT OR ENLARGEMENT. PART L (CONSERVATION OF FUEL AND POWER): ALL NEW GLAZED DOORS IN LONDON BUILDING REGULATIONS WORK MUST MEET A MINIMUM U-VALUE OF 1.4 W/M²K (FOR REPLACEMENTS) OR 1.6 W/M²K (FOR NEW EXTENSIONS, TO COMPENSATE FOR INCREASED GLAZED AREA); THERMALLY BROKEN FRAMES WITH LOW-E ARGON-FILLED DOUBLE GLAZING TYPICALLY ACHIEVE 1.2-1.4 W/M²K; TRIPLE GLAZING ACHIEVES 0.6-0.8 W/M²K BUT ADDS 15-30% TO DOOR COST AND IS ONLY NECESSARY FOR PASSIVHAUS OR HIGH-PERFORMANCE LONDON PROJECTS.

LONDON BIFOLD AND LARGE SLIDING DOOR COSTS IN 2025 (SUPPLY ONLY PRICES FROM FABRICATOR; ADD 20-30% FOR INSTALLATION): ALUMINIUM BIFOLD (3-PANEL, 2400MM HIGH X 2700MM WIDE, ORIGIN OB-49, ANTHRACITE GREY, DOUBLE GLAZED, PER UNIT SUPPLY) — £3,200-£5,000; 4-PANEL (3600MM WIDE) — £4,500-£7,000; 5-PANEL (4500MM WIDE) — £6,000-£9,500; ALUK OR SMART EQUIVALENT (SAME SIZES) — 15-25% LESS THAN ORIGIN; VELFAC 200 BIFOLD (3-PANEL, SAME DIMENSIONS) — £5,500-£8,500; SCHUCO ASS 70 LIFT-AND-SLIDE (3M WIDE SINGLE TRACK, 2.4M HIGH, SUPPLY ONLY) — £6,000-£10,000. INSTALLATION (STRUCTURAL STEEL SUPPLY AND FIT, LINTEL INSTALL, DOOR INSTALLATION BY WINDOW COMPANY) — £1,500-£3,500 FOR A STANDARD LONDON RESIDENTIAL BIFOLD INSTALLATION (EXCLUDING STRUCTURAL ENGINEER FEES £350-£700).