External Staircases for London Victorian Terraces: Steel, Timber, and Stone Specifications

THE PRINCIPAL EXTERNAL STAIRCASE TYPES USED ON LONDON VICTORIAN TERRACES ARE:

STRAIGHT STEEL EXTERNAL STAIRCASE (THE MOST COMMON TYPE FOR REAR GARDEN STAIRCASES ON LONDON VICTORIAN TERRACES): A STRAIGHT-FLIGHT OR QUARTER-TURN STEEL STAIR WITH OPEN TREADS (PERFORATED CHEQUER PLATE OR OPEN STEEL BAR GRATING — SELF-DRAINING) IS THE STANDARD SPECIFICATION FOR A REAR GARDEN EXTERNAL STAIRCASE ON A LONDON VICTORIAN TERRACE. STEEL SPECIFICATION: STRUCTURAL STEEL STRINGERS (2 NO. 100X100X8MM RSA — RIGHT-ANGLE STEEL ANGLE — OR 150X75MM CHANNEL — S275 STEEL TO BS EN 10025) WITH WELDED STEEL TREAD CARRIERS. TREADS: BARE-METAL OPEN STEEL BAR GRATING (RECTAGRATING — BS EN 10025 S235 GALVANISED HOT-DIP) OR CHEQUER PLATE (5MM MILD STEEL HOT-DIP GALVANISED — SLIP-RESISTANT RAISED PATTERN) OR PROFILED STEEL TREAD (PERF-O GRIP OR GRIP-STRUT — SELF-DRAINING WITH RAISED GRIP PATTERN). FINISH: GALVANISED THEN POLYESTER POWDER-COATED (ANTHRACITE GREY RAL 7016 — THE MOST POPULAR COLOUR FOR EXTERNAL STEEL STAIRCASES ON LONDON VICTORIAN TERRACE REAR EXTENSIONS) OR EPOXY-PRIMED + TOP-COAT (FOR SITE PAINTING).

SPIRAL STAIRCASE (SPACE-EFFICIENT — SUITABLE WHERE REAR GARDEN FOOTPRINT IS TIGHT): A SPIRAL STAIRCASE (EITHER MODULAR KIT SPIRAL — ALBION DESIGN OF CIRENCESTER OR HAL-BAU GERMANY — OR BESPOKE FABRICATED STEEL SPIRAL) IS SUITABLE WHERE THE GARDEN FOOTPRINT AVAILABLE FOR THE STAIR IS VERY CONSTRAINED (A SPIRAL STAIR CAN FIT IN A 1200MM DIAMETER CIRCLE — SMALLER THAN A STRAIGHT FLIGHT FOR THE SAME RISE). ALBION DESIGN (CIRENCESTER — THE UK'S LEADING MODULAR SPIRAL STAIRCASE MANUFACTURER — AVAILABLE IN MILD STEEL HOT-DIP GALVANISED, STAINLESS STEEL, OR ALUMINIUM): CLASSICAL (72 STYLES — DECORATIVE BALUSTRADE), INDUSTRIAL (OPEN TREAD — SELF-DRAINING), OR CONTEMPORARY (GLASS BALUSTRADE). DIAMETER: 1200MM TO 2000MM — MINIMUM 1200MM FOR COMFORT (TREAD WIDTH AT CENTRE 500MM). PITCH: 25-45° RISE ANGLE.

TIMBER EXTERNAL STAIRCASE (LESS COMMON FOR LONDON VICTORIAN TERRACE REAR GARDENS — MOST APPROPRIATE WHERE A PAINTED TIMBER AESTHETIC IS DESIRED): HARDWOOD (BALAU BANGKIRAI OR IPE — NATURALLY DURABLE CLASS 1 HARDWOOD, NO TREATMENT REQUIRED) OR PRESSURE-TREATED SOFTWOOD (TANALISED UC4 — FOR GROUND-CONTACT MEMBERS). NOTE: TIMBER EXTERNAL STAIRS REQUIRE REGULAR MAINTENANCE (OIL OR RE-PAINT EVERY 2-4 YEARS) AND MUST BE DESIGNED WITH ADEQUATE FALL TO THE TREAD SURFACE (1:80 CROSS-FALL MINIMUM — PITCHED SLIGHTLY TO FRONT EDGE OF TREAD TO DRAIN RAINWATER) TO PREVENT WATER-POOLING AND ALGAE GROWTH (SLIP HAZARD).

NATURAL STONE EXTERNAL STAIRCASE (CONSERVATION AREA PREMIUM — MATCHING THE EXISTING FLAGSTONE TERRACE): PORTLAND STONE, YORK SANDSTONE, OR INDIAN SANDSTONE STEPS (BULl-NOSED EDGE OR PENCIL-ROUND EDGE) ON STRUCTURAL STEEL STRINGER OR BLOCKWORK CHEEKS: SLIP RESISTANCE MUST BE ASSESSED — SOME NATURAL STONE (PARTICULARLY POLISHED GRANITE OR SMOOTH LIMESTONE) IS UNACCEPTABLY SLIPPERY WHEN WET. PENCIL-NOSED YORKSTONE IS GENERALLY ADEQUATE — SANDBLASTED OR THERMAL-FINISH GRANITE CAN BE SPECIFIED FOR HIGHER SLIP RESISTANCE.

EXTERNAL STAIRCASES ON LONDON VICTORIAN TERRACES ARE SUBJECT TO BUILDING REGULATIONS APPROVED DOCUMENT K (PROTECTION FROM FALLING, COLLISION, AND IMPACT) AND THE TECHNICAL GUIDANCE IN BS 5395 (STAIRS, LADDERS, AND WALKWAYS).

APPROVED DOCUMENT K — KEY REQUIREMENTS FOR EXTERNAL STAIRS IN DWELLINGS: RISE (R) AND GOING (G): FOR AN EXTERNAL STAIR IN A PRIVATE DWELLING (WHICH INCLUDES ALL EXTERNAL STAIRS ON LONDON VICTORIAN TERRACES WHERE THE STAIR IS NOT INTENDED FOR PUBLIC USE): RECOMMENDED RISE (R): 150-220MM. GOING (G): 220-300MM. THE 2R + G RULE (A STANDARD ERGONOMIC CHECK): SHOULD BE IN THE RANGE 550-700MM (2X RISE + GOING = 550-700MM). FOR A COMFORTABLE EXTERNAL STAIR THAT IS NOT TOO STEEP: A RISE OF 175MM AND GOING OF 280MM (2X175 + 280 = 630MM — WITHIN THE RANGE) IS THE TYPICAL DESIGN FOR A LONDON VICTORIAN TERRACE REAR STAIRCASE (PROVIDING A COMFORTABLE SLOPE AND ADEQUATE TREAD DEPTH).

HANDRAILS AND BALUSTRADES (APPROVED DOCUMENT K + BS EN 1991-1-1): HANDRAILS REQUIRED: WHENEVER THE STAIR HAS MORE THAN 2 RISERS (AND ALWAYS RECOMMENDED ON EXTERNAL STAIRS REGARDLESS OF THE NUMBER OF RISERS). HANDRAIL HEIGHT: 900MM MINIMUM (MEASURED VERTICALLY FROM THE PITCH LINE OF THE STAIR — I.E. FROM THE NOSING OF THE TREAD). HANDRAIL DESIGN: THE HANDRAIL MUST BE GRASPABLE — CIRCULAR SECTION 40-50MM DIAMETER (STANDARD HOLLOW STEEL TUBE 42.4MM OD — THE STANDARD STEEL HANDRAIL TUBE SECTION USED BY STEEL FABRICATORS IN LONDON) IS COMPLIANT. GUARD (BALUSTRADE) HEIGHT WHERE REQUIRED: 900MM ON STAIRS (MEASURED FROM NOSING), 1100MM ON LANDINGS AND FLAT SECTIONS.

SLIP RESISTANCE: THE CRITICAL SAFETY REQUIREMENT FOR EXTERNAL STAIRS IS SLIP RESISTANCE OF THE TREAD SURFACE — PARTICULARLY WHEN WET. BS 4592-3 (INDUSTRIAL-TYPE OPEN-BAR FLOORING) MINIMUM SLIP POTENTIAL: CHEQUER PLATE (5MM HOT-DIP GALVANISED) AND OPEN STEEL BAR GRATING (RECTAGRATING) BOTH ACHIEVE ADEQUATE SLIP RESISTANCE WHEN CLEAN — BUT CAN BECOME SLIPPERY WITH ALGAE OR LEAF DEBRIS. PROPRIETARY ANTI-SLIP TREAD NOSING SYSTEMS: GRADUS GR SERIES (ALUMINIUM BODY WITH CARBORUNDUM ANTI-SLIP INSERT — SILVER OR BLACK — BOLTED TO STEEL TREAD CARRIER): TESTED TO BS 7976-2 PENDULUM METHOD — MINIMUM PTV 36 (SLIP RISK LOW) ON WET SURFACE.

AN EXTERNAL STAIRCASE ON A LONDON VICTORIAN TERRACE MUST BE STRUCTURALLY FIXED AT THE TOP (TO THE HOUSE STRUCTURE OR REAR EXTENSION WALL) AND SUPPORTED AT THE BOTTOM (ON A FOUNDATION IN THE GARDEN).

TOP FIXING — TO THE HOUSE STRUCTURAL WALL OR REAR EXTENSION: STRINGER BOLTED TO THE WALL WITH M16 STAINLESS STEEL RESIN ANCHORS (HILTI HIT-RE 500 EPOXY OR FISCHER FIS V 360 S INTO THE EXISTING BRICK OR CONCRETE WALL — 150MM EMBEDMENT MINIMUM IN SOLID BRICK — AT 300MM CENTRES). STRUCTURAL ENGINEER: ANY EXTERNAL STAIR THAT TRANSFERS SIGNIFICANT LOADS TO THE HOUSE WALL OR REAR EXTENSION (PARTICULARLY WHERE THE HOUSE IS OLDER AND THE WALL CONDITION IS UNKNOWN) SHOULD HAVE A STRUCTURAL ENGINEER ASSESS THE FIX-POINT CAPACITY.

BOTTOM SUPPORT — FOUNDATION IN GARDEN: THE BOTTOM OF AN EXTERNAL STAIRCASE MUST BE SUPPORTED ON A FOUNDATION THAT PREVENTS SETTLEMENT (IN LONDON CLAY — WHICH IS SUBJECT TO SEASONAL MOVEMENT — THE FOUNDATION MUST ISOLATE THE STAIR STRUCTURE FROM THE CLAY SHRINK/SWELL CYCLE). OPTIONS: CONCRETE PAD FOUNDATION (MINIMUM 400X400X300MM DEEP — BELOW THE ROOT ACTION ZONE WHERE TREES ARE PRESENT): C20 CONCRETE, REBAR IF LOADED. GALVANISED POST BASE SOCKET (INSTALLED DURING CONCRETE POUR): ACCEPTS THE STEEL POST OR NEWEL POST OF THE STAIR STRUCTURE — ALLOWS ADJUSTMENT FOR LEVEL. ALTERNATIVELY, THE STAIR CAN BE DESIGNED AS A CANTILEVER FROM THE TOP FIXING, ELIMINATING THE NEED FOR A GROUND-LEVEL FOUNDATION — SUITABLE FOR SHORT FLIGHTS OF 4-5 RISERS.

DEFLECTION AND MOVEMENT: APPROVED DOCUMENT K DOES NOT SPECIFY A MAXIMUM DEFLECTION FOR EXTERNAL STAIRS, BUT THE STRUCTURAL ENGINEER'S DESIGN SHOULD ENSURE THAT DEFLECTION UNDER CHARACTERISTIC IMPOSED LOAD (2.0 KN/M² FOR STAIRS IN DWELLINGS — BS EN 1991-1-1) IS LESS THAN SPAN/360 — AND THAT THE STAIR DOES NOT FEEL SPRINGY OR DISCONCERTING WHEN USED.

EXTERNAL STAIRCASES ON LONDON VICTORIAN TERRACES — PARTICULARLY ON THE REAR ELEVATION WHERE THEY ARE VISIBLE FROM THE REAR GARDEN AND POTENTIALLY FROM ADJACENT NEIGHBOURS — MAY REQUIRE PLANNING PERMISSION IN LONDON CONSERVATION AREAS.

PLANNING POSITION FOR EXTERNAL STAIRCASES: REAR EXTERNAL STAIRCASE (ON THE REAR ELEVATION OF A LONDON VICTORIAN TERRACE — NOT VISIBLE FROM THE STREET): CLASS A GPDO 2015 (EXTENSIONS AND ENLARGEMENTS) DOES NOT COVER AN EXTERNAL STAIRCASE. A REAR EXTERNAL STAIRCASE IS TECHNICALLY A MATERIAL CHANGE TO THE EXTERNAL APPEARANCE OF THE DWELLING AND COULD REQUIRE PLANNING PERMISSION IF IT MATERIALLY ALTERS THE REAR ELEVATION. HOWEVER: IN PRACTICE, A MODEST REAR EXTERNAL STAIR (NOT VISIBLE FROM THE STREET AND NOT MATERIALLY ALTERING THE PRINCIPAL ELEVATION CHARACTER) IS OFTEN TREATED AS DE MINIMIS BY LONDON BOROUGH PLANNING OFFICERS — PARTICULARLY WHERE THE STAIR IS COMPACT AND DESIGNED SYMPATHETICALLY. IN A LONDON CONSERVATION AREA: A REAR EXTERNAL STAIRCASE IS LESS LIKELY TO BE CONSIDERED DE MINIMIS — PARTICULARLY IF IT INVOLVES A LARGE OR VISUALLY PROMINENT STRUCTURE. A HOUSEHOLDER PLANNING APPLICATION IS ADVISABLE WHERE THE STAIR IS MORE THAN 1M WIDE OR PROJECTS MORE THAN 1M FROM THE REAR ELEVATION.

CONSERVATION AREA DESIGN GUIDANCE FOR REAR EXTERNAL STAIRCASES: USE SLENDER STEEL SECTIONS RATHER THAN HEAVY STRUCTURAL BEAMS. OPEN-TREAD DESIGN (OPEN STEEL BAR GRATING OR PERFORATED STEEL TREAD) REDUCES VISUAL BULK. DARK COLOUR (ANTHRACITE GREY RAL 7016 OR BLACK RAL 9005 POWDER COAT) HELPS THE STAIR RECEDE INTO THE BACKGROUND. MINIMAL HANDRAIL SECTION (42.4MM HOLLOW STEEL TUBE — AS SLIM AS STRUCTURALLY COMPLIANT). AVOID LARGE SOLID PLATFORMS OR LANDINGS THAT DOMINATE THE REAR GARDEN SPACE.

THE TWO MOST COMMON SPECIFICATION ROUTES FOR EXTERNAL STAIRCASES ON LONDON VICTORIAN TERRACES ARE: MODULAR SPIRAL STAIRCASE (FROM ALBION DESIGN OR HAL-BAU) FOR CONSTRAINED SPACES, AND BESPOKE STEEL STRAIGHT-FLIGHT FABRICATION (FROM A LONDON STEEL FABRICATOR) FOR LARGER GARDENS OR WHERE A STRAIGHT FLIGHT IS MORE PRACTICAL.

ALBION DESIGN SPIRAL STAIRCASE (MOST POPULAR MODULAR SPIRAL FOR LONDON VICTORIAN TERRACE REAR GARDENS): ALBION DESIGN (CIRENCESTER — ALBIONSPIRALS.CO.UK) — THE UK'S LEADING SUPPLIER OF DOMESTIC MODULAR SPIRAL STAIRCASES. MODELS SUITABLE FOR EXTERNAL USE (HOT-DIP GALVANISED OR STAINLESS STEEL): ALBION INDUSTRIAL SPIRAL (OPEN TREAD — GALVANISED STEEL — SELF-DRAINING — MINIMUM 1200MM DIAMETER): £800 TO £2,500 SUPPLY (FLAT-PACK KIT — SITE ASSEMBLED IN APPROXIMATELY 4-8 HOURS BY 2 PEOPLE). ALBION CONTEMPORARY SPIRAL (POWDER-COATED STEEL — GLASS BALUSTRADE OPTION — 1400-2000MM DIAMETER): £2,500 TO £8,000 SUPPLY.

BESPOKE STEEL STRAIGHT-FLIGHT EXTERNAL STAIRCASE (FABRICATED BY A LONDON STEEL FABRICATOR — E.G. METALCRAFT, SOUTHWARK METALWORKS, LONDON IRONWORKS): MATERIALS: 2 NO. 100X100X8MM RSA STRINGERS (S275 STEEL — BS EN 10025) + 1100X250X5MM OPEN BAR GRATING TREADS (RECTAGRATING BS EN 10025 S235 HOT-DIP GALVANISED AFTER FABRICATION) + 42.4MM OD HOLLOW STEEL HANDRAIL TUBE WITH STEEL NEWELS AT 1000MM CENTRES + INTERMEDIATE VERTICAL BALUSTER INFILL AT 100MM CENTRES. FINISH: HOT-DIP GALVANISED AFTER FABRICATION (BS EN ISO 1461 — MINIMUM 45 MICRONS ZINC COATING) + POLYESTER POWDER COAT ANTHRACITE GREY RAL 7016 (APPLIED OVER GALVANISED PRIMER — DURASEAL POWDER SYSTEMS). TYPICAL STAIR FOR 5 RISERS (RISE 175MM EACH — TOTAL RISE 875MM — GOING 280MM EACH — OVERALL PLAN DIMENSION APPROXIMATELY 1400MM LONG X 900MM WIDE): FABRICATION AND HOT-DIP GALVANISING: £1,200 TO £2,500. POWDER COAT: £400 TO £800. DELIVERY AND INSTALLATION (BOLTED TO WALL + CONCRETE PAD FOUNDATION): £400 TO £800. TOTAL BESPOKE 5-RISE STRAIGHT STAIR: £2,000 TO £4,100.

EXTERNAL STAIRCASE COSTS FOR LONDON VICTORIAN TERRACES RANGE FROM APPROXIMATELY £800 (SIMPLE MODULAR SPIRAL KIT — DIY ASSEMBLED) TO £10,000+ (BESPOKE ARCHITECTURAL STEEL STAIR WITH GLASS BALUSTRADE — PROFESSIONALLY INSTALLED).

ALBION INDUSTRIAL SPIRAL STAIRCASE (1200MM DIAMETER — OPEN TREAD — GALVANISED — DIY ASSEMBLY): SUPPLY: £800 TO £1,500. PROFESSIONAL ASSEMBLY AND INSTALLATION (INCLUDING CONCRETE PAD BASE): £400 TO £800. TOTAL: £1,200 TO £2,300.

ALBION CONTEMPORARY SPIRAL (1600MM DIAMETER — POWDER-COATED ANTHRACITE — GLASS BALUSTRADE): SUPPLY: £4,000 TO £8,000. PROFESSIONAL INSTALLATION: £800 TO £1,500. TOTAL: £4,800 TO £9,500.

BESPOKE STEEL STRAIGHT-FLIGHT STAIR (5 RISERS — 175MM RISE — 900MM WIDE — OPEN BAR GRATING TREADS — HOT-DIP GALVANISED + ANTHRACITE POWDER COAT): FABRICATION + GALVANISING + POWDER COAT: £1,600 TO £3,300. INSTALLATION (BOLTED TO WALL, CONCRETE PAD): £400 TO £800. TOTAL: £2,000 TO £4,100.

BESPOKE STEEL STRAIGHT-FLIGHT STAIR (10 RISERS — 175MM RISE — 900MM WIDE): FABRICATION + GALVANISING + POWDER COAT: £2,500 TO £5,500. INSTALLATION: £600 TO £1,200. TOTAL: £3,100 TO £6,700.

TIMBER EXTERNAL STAIR (HARDWOOD IPE — 5 RISERS): £1,800 TO £3,500 SUPPLY AND INSTALL.

NATURAL STONE STAIR (YORKSTONE STEPS ON STEEL STRINGERS — 5 RISERS — SUPPLY AND INSTALL): £2,500 TO £5,000.

PLANNING APPLICATION (IF REQUIRED IN LONDON CONSERVATION AREA): £258 HOUSEHOLDER FEE + APPROX £300-500 PLANNING DRAWINGS BY ARCHITECT OR TECHNICIAN.