Brick Garden Walls for London Victorian Terraces: Construction, Pointing, and Repairs

THE MOST CRITICAL ASPECT OF A NEW BRICK GARDEN WALL ON A LONDON VICTORIAN TERRACE IS SELECTING A BRICK THAT MATCHES THE EXISTING PROPERTY CHARACTER — PARTICULARLY IN CONSERVATION AREAS WHERE VISUAL COMPATIBILITY IS A PLANNING REQUIREMENT.

LONDON STOCK BRICK (THE DOMINANT VICTORIAN-ERA BRICK OF INNER LONDON): LONDON STOCK BRICK (ALSO CALLED GREY STOCK, LONDON YELLOW STOCK, OR SUFFOLK YELLOW STOCK IN DIFFERENT PERIODS AND AREAS) IS A WIRE-CUT SOFT-MUD BRICK IN A DISTINCTIVE YELLOW-BUFF COLOUR (FIRED FROM KENT, ESSEX, AND SUFFOLK BRICK EARTH WITH CHALK AND CLINKER — THE CLINKER GIVES LONDON STOCK ITS CHARACTERISTIC SURFACE FIRE-MARKS AND COLOUR VARIATION). SPECIFICATION FOR NEW LONDON STOCK BRICK: IBSTOCK RECLAIMED LONDON STOCK (THE BEST MATCH FOR ORIGINAL VICTORIAN BRICK — IBSTOCK'S RECLAIMED STOCK USES ORIGINAL VICTORIAN KILNS AND CLAYS): 73MM FACE HEIGHT, 215MM LENGTH, 102MM WIDTH. IBSTOCK KENT YELLOW STOCK (MODERN ALTERNATIVE — MACHINE-MADE — SIMILAR COLOUR BUT LESS CHARACTER THAN RECLAIMED). FOR CONSERVATION AREAS AND LISTED BUILDINGS: RECLAIMED ORIGINAL LONDON STOCK BRICK (SOURCED FROM ARCHITECTURAL SALVAGE YARDS — LASSCO, BATTERSEA, OR MONGERS IN DISS — PRICED £0.50-2.00 EACH) IS THE MOST AUTHENTIC AND PLANNING-ACCEPTABLE OPTION — GENUINE OLD BRICKS WITH THE WEATHERING AND COLOUR VARIATION OF THE ORIGINAL VICTORIAN CONSTRUCTION.

HARD ENGINEERING BRICK (FOR WALL COURSES BELOW DAMP-PROOF COURSE LEVEL OR FOR HIGH-EXPOSURE APPLICATIONS): FOR THE LOWEST COURSES OF A BRICK GARDEN WALL (BELOW GROUND LEVEL AND IMMEDIATELY ABOVE GROUND — WHERE GROUND WATER, FROST, AND SALT ATTACK ARE MOST SEVERE): CLASS A ENGINEERING BRICK (IBSTOCK BLUE ENGINEERING — OR WIENERBERGER STAFFORDSHIRE BLUE — CLASS A TO BS EN 771-1 FLEXURAL STRENGTH > 7 N/MM² — WATER ABSORPTION < 4.5%): DENSE, HIGHLY FROST-RESISTANT — APPROPRIATE FOR RETAINING WALLS AND WALLS IN CONTACT WITH RETAINED EARTH OR DRAINAGE.

FLINT PANELS (FOR EAST KENT, SURREY, AND SOUTH LONDON VICTORIAN TERRACES WHERE FLINT WAS THE LOCAL WALLING MATERIAL): SOME LONDON VICTORIAN TERRACE BOUNDARY WALLS — PARTICULARLY IN SOUTH LONDON AND AREAS WITH HISTORIC ACCESS TO KENT FLINT — INCORPORATE FLINT PANELS (DRESSED OR KNAPPED FLINT NODULES SET IN LIME MORTAR). REPAIRS TO THESE WALLS: REQUIRE SOURCING MATCHING FLINT (FROM KENT FLINT MERCHANTS) AND LIME MORTAR MATCHING THE ORIGINAL.

THE CORRECT MORTAR SPECIFICATION FOR A BRICK GARDEN WALL ON A LONDON VICTORIAN TERRACE IS ONE OF THE MOST COMMONLY MISUNDERSTOOD ASPECTS OF EXTERNAL BRICKWORK — PARTICULARLY WHERE REPAIRS ARE CARRIED OUT BY BUILDERS UNFAMILIAR WITH HERITAGE MASONRY.

WHY PORTLAND CEMENT MORTAR IS INAPPROPRIATE FOR MOST LONDON VICTORIAN TERRACE BRICK WALLS: ORIGINAL LONDON VICTORIAN TERRACE BRICK WALLS WERE BUILT WITH LIME-BASED MORTARS (A MIX OF HYDRAULIC LIME OR HOT-LIME PUTTY WITH SAND — SOFTER AND MORE FLEXIBLE THAN PORTLAND CEMENT MORTAR). WHEN PORTLAND CEMENT MORTAR IS USED TO REPOINT OR REBUILD A SOFT-FIRED LONDON STOCK BRICK WALL: THE MORTAR IS HARDER THAN THE BRICK (PORTLAND CEMENT MORTAR HAS A COMPRESSIVE STRENGTH OF 10-30 N/MM² — LONDON STOCK BRICK IS TYPICALLY 5-15 N/MM²). MOISTURE AND FROST MOVEMENT THAT WOULD PREVIOUSLY HAVE BEEN ACCOMMODATED BY CRACKING OF THE SOFTER MORTAR JOINTS IS NOW TRANSFERRED TO THE BRICK FACES — CAUSING SPALLING, DELAMINATION, AND ACCELERATED DETERIORATION OF THE BRICK FACE.

CORRECT MORTAR SPECIFICATION FOR LONDON VICTORIAN TERRACE BRICK GARDEN WALLS: NHL 3.5 HYDRAULIC LIME MORTAR (THE STANDARD SPECIFICATION FOR REPOINTING AND REBUILDING LONDON VICTORIAN STOCK BRICK WALLS): MIX: 1 PART NHL 3.5 (ST ASTIER NHL 3.5 — THE FRENCH NATURAL HYDRAULIC LIME WIDELY USED FOR HERITAGE BRICKWORK IN LONDON) : 2.5 PARTS SHARP WASHED SAND (TRADITIONAL BUILDING SAND — NOT SOFT BUILDING SAND — TYPICALLY 2-4MM AGGREGATE). CONSISTENCY: THE MIX SHOULD BE FIRM BUT NOT DRY — MORTAR SHOULD JUST HOLD ITS SHAPE WHEN SQUEEZED. COLOUR: NATURAL LIME MORTAR (GREY-BUFF TO BUFF — DEPENDING ON SAND COLOUR) — MATCH THE ORIGINAL MORTAR COLOUR BY TESTING ON A SMALL SECTION AND CHECKING THE DRY COLOUR AGAINST THE ORIGINAL.

NEW WALL MORTAR (WHERE A NEW WALL IS BEING BUILT IN MATCHING LONDON STOCK BRICK): FOR A NEW BOUNDARY WALL IN LONDON STOCK BRICK (TO MATCH EXISTING): NHL 3.5 MORTAR (AS ABOVE) — CONSISTENT WITH THE ORIGINAL MORTAR SPECIFICATION AND PROVIDING LONG-TERM COMPATIBILITY. AVOID M2 (1:1:6 CEMENT:LIME:SAND) CEMENT MORTAR — STILL TOO HARD FOR LONDON STOCK BRICK (COMPRESSIVE STRENGTH TOO HIGH).

THE STRUCTURAL DESIGN OF A BRICK GARDEN WALL — PARTICULARLY ONE EXCEEDING 1000MM IN HEIGHT — MUST ENSURE ADEQUATE STABILITY AGAINST LATERAL WIND LOADS AND AGAINST THE EFFECTS OF DIFFERENTIAL SETTLEMENT (PARTICULARLY IN LONDON CLAY, WHICH IS SUBJECT TO SEASONAL SHRINKAGE AND SWELLING).

STRUCTURAL GUIDANCE FOR BRICK GARDEN WALLS (BS 5628-1 — CODE OF PRACTICE FOR USE OF MASONRY): MINIMUM WALL THICKNESS FOR FREE-STANDING WALLS (BS 5628-1:2005 TABLE 1): UP TO 700MM HEIGHT: 90MM MINIMUM (SINGLE SKIN — BUT NOT RECOMMENDED FOR GARDEN WALLS DUE TO STABILITY CONCERNS). 700MM TO 1100MM: 102.5MM MINIMUM (HALF-BRICK — 102.5MM ACTUAL BRICK THICKNESS — ACCEPTABLE WITH ADEQUATE MORTAR JOINTS AND NO SEISMIC LOADING). 1100MM TO 1800MM: 215MM MINIMUM (FULL ONE-BRICK-LENGTH THICK WALL — THE STANDARD SPECIFICATION FOR LONDON VICTORIAN TERRACE BOUNDARY WALLS OF 1200-1800MM HEIGHT). OVER 1800MM: 215MM WITH INTEGRAL BRICK PIERS AT SPACING NOT EXCEEDING 3M (OR 327MM 1.5-BRICK WALL BETWEEN PIERS).

PIERS: A BRICK PIER (PROJECTING SECTION OF BRICKWORK AT INTERVALS ALONG THE WALL — TYPICALLY 340X340MM OR 440X440MM IN PLAN — BUILT INTO THE BONDING OF THE WALL) DRAMATICALLY INCREASES THE LATERAL STABILITY OF A BRICK GARDEN WALL. FOR A 215MM WALL BETWEEN 1800MM AND 2700MM HEIGHT: MAXIMUM PIER SPACING 3000MM. PIER SIZE: 340X340MM (1.5-BRICK X 1.5-BRICK) MINIMUM. FOR A 102.5MM WALL BETWEEN 1100MM AND 1800MM: MAXIMUM PIER SPACING 1500MM (PILASTER PIER). FOUNDATIONS: A BRICK GARDEN WALL FOUNDATION IN LONDON CLAY: CONCRETE STRIP FOUNDATION (C20 CONCRETE — 600MM WIDE X 300MM DEEP FOR A 215MM WALL). FOUNDATION DEPTH: MINIMUM 450MM BELOW FINISHED GROUND LEVEL IN LONDON CLAY — DEEPER WHERE TREES ARE WITHIN 2X THE WALL HEIGHT (TO AVOID TREE ROOT DISRUPTION AND CLAY SHRINKAGE UNDER THE FOUNDATION).

RETAINING WALLS: WHERE THE BRICK WALL RETAINS A HEIGHT DIFFERENCE IN GROUND LEVEL (E.G. A FRONT GARDEN BOUNDARY WALL RETAINING A RAISED FRONT GARDEN ABOVE PAVEMENT LEVEL), THE WALL MUST BE DESIGNED AS A RETAINING STRUCTURE — WHICH REQUIRES: STRUCTURAL ENGINEERING INPUT (LATERAL EARTH PRESSURE CALCULATION — TYPICALLY REQUIRING A 215MM-350MM THICK WALL FOR RETAINED HEIGHTS OF 600-1200MM). DRAINAGE BEHIND THE WALL (WEEPHOLES — 75MM DIAMETER HOLES THROUGH THE WALL AT 1500MM CENTRES — ABOVE PAVEMENT LEVEL — TO RELIEVE HYDROSTATIC PRESSURE).

THE COPING OR CAPPING ON A BRICK GARDEN WALL — THE TOP COURSE OR CAP THAT PROTECTS THE WALL FROM RAIN PENETRATION AT THE HEAD — IS ONE OF THE MOST IMPORTANT DETAILS FOR LONG-TERM WALL DURABILITY.

BRICK-ON-EDGE COPING (THE MOST COMMON COPING FOR LONDON VICTORIAN TERRACE BOUNDARY WALLS): ORIGINAL LONDON VICTORIAN TERRACE BOUNDARY WALLS TYPICALLY HAVE A BRICK-ON-EDGE COPING — BRICKS LAID VERTICALLY (ON THEIR EDGE, NOT ON THEIR BED) WITH A SMALL OVERHANG EACH SIDE AND A CREASING TILE COURSE BELOW (CREASING TILES — THIN RED CLAY TILES — LAID AS A WEATHERED COURSE BELOW THE BRICK-ON-EDGE COPING, PROJECTING 25-50MM ON EACH SIDE, ACTING AS A DRIP DETAIL). SPECIFICATION: USE THE SAME LONDON STOCK BRICK AS THE WALL (RECLAIMED OR IBSTOCK LONDON STOCK). CREASING TILES: ROSEMARY OR TRADITIONAL RED CLAY CREASING TILES — 10MM THICK, LAID IN TWO COURSES IN NHL 3.5 LIME MORTAR.

PRECAST CONCRETE COPING (LESS SYMPATHETIC BUT MORE WEATHERPROOF): MARSHALLS STANDARD COPING (200MM WIDE X 75MM HIGH — CHAMFERED WEATHERING TOP — PRECAST CONCRETE): GREY OR BUFF — LAID ON A CONTINUOUS BED OF NHL 3.5 LIME MORTAR (DO NOT USE DRY-PACK POINTING — ALL JOINTS MUST BE FILLED TO PREVENT WATER INGRESS THROUGH THE COPING BED). NOT APPROPRIATE IN CONSERVATION AREAS WHERE BRICK-ON-EDGE IS THE HISTORICALLY CORRECT DETAIL.

ENGINEERING BRICK COPING (WIENERBERGER STAFFORDSHIRE BLUE — THE MOST DURABLE COPING FOR HIGH-EXPOSURE LONDON GARDEN WALLS — E.G. FACING THE STREET OR ON A RETAINING WALL SUBJECT TO ROAD SALT): ENGINEERING BRICK-ON-EDGE COPING (BLUE ENGINEERING BRICK — CLASS A): HARDER, DENSER, AND MORE FROST-RESISTANT THAN LONDON STOCK — APPROPRIATE WHERE HIGH EXPOSURE IS ANTICIPATED (NORTH-FACING WALL, ADJACENT TO A CARRIAGEWAY WHERE SALT SPRAY AND SPLASH IS A RISK).

DPC IN BRICK GARDEN WALLS: A DAMP-PROOF COURSE (DPC) SHOULD BE INCORPORATED IN A BRICK GARDEN WALL AT: APPROXIMATELY 150MM ABOVE FINISHED GROUND LEVEL (TO PREVENT GROUND MOISTURE RISING UP THE WALL). STANDARD SPECIFICATION: 2-COURSE ENGINEERING BRICK DPC (USING WIENERBERGER STAFFORDSHIRE BLUE OR IBSTOCK BLUE ENGINEERING BRICK — WATER ABSORPTION < 4.5% — AS THE DPC COURSE): MORE DURABLE AND PERIOD-SYMPATHETIC THAN A MODERN FLEXIBLE DPC MEMBRANE IN AN EXPOSED BRICK GARDEN WALL.

BRICK GARDEN WALLS IN LONDON ARE SUBJECT TO PLANNING RULES UNDER THE TCPA 1990 AND GPDO 2015 — WITH IMPORTANT DISTINCTIONS BETWEEN FRONT BOUNDARY WALLS AND REAR/SIDE GARDEN WALLS.

GPDO 2015 PERMITTED DEVELOPMENT FOR GARDEN WALLS AND FENCES: WALLS AND FENCES ON OR ADJACENT TO THE BOUNDARY WITH A HIGHWAY (FRONT BOUNDARY WALL ON A LONDON VICTORIAN TERRACE): MAXIMUM PERMITTED DEVELOPMENT HEIGHT: 1M (1000MM). A FRONT BOUNDARY WALL EXCEEDING 1M IN HEIGHT REQUIRES PLANNING PERMISSION — REGARDLESS OF CONSERVATION AREA STATUS. WALLS AND FENCES NOT ON THE HIGHWAY BOUNDARY (REAR GARDEN WALLS, SIDE BOUNDARY WALLS NOT ON A HIGHWAY): MAXIMUM PERMITTED DEVELOPMENT HEIGHT: 2M (2000MM). A REAR GARDEN WALL OR SIDE BOUNDARY WALL NOT ADJOINING A HIGHWAY CAN BE UP TO 2M HIGH AS PERMITTED DEVELOPMENT.

CONSERVATION AREAS — SPECIAL CONSIDERATIONS: IN A LONDON CONSERVATION AREA WHERE AN ARTICLE 4 DIRECTION REMOVES PD RIGHTS FOR GATES, WALLS, AND FENCES: ANY NEW BOUNDARY WALL (REGARDLESS OF HEIGHT) REQUIRES PLANNING PERMISSION. DEMOLITION OF AN ORIGINAL VICTORIAN FRONT BOUNDARY WALL IN A LONDON CONSERVATION AREA: ALSO REQUIRES PLANNING PERMISSION (CONSERVATION AREA CONSENT UNDER TCPA 1990 SECTION 196D — DEMOLITION OF BUILDINGS OR STRUCTURES IN CONSERVATION AREAS — NOW SUBJECT TO PLANNING PERMISSION UNDER THE ENTERPRISE AND REGULATORY REFORM ACT 2013). PLANNING OFFICERS IN LONDON CONSERVATION AREAS TYPICALLY: RESIST REPLACEMENT OF ORIGINAL BRICK BOUNDARY WALLS WITH MODERN BLOCK, RENDERED WALLS, OR TIMBER FENCES. STRONGLY SUPPORT REPAIR AND REINSTATEMENT OF ORIGINAL BRICK BOUNDARY WALLS WHERE THEY HAVE BEEN PREVIOUSLY DEMOLISHED.

PARTY FENCE WALLS (WALLS ON THE BOUNDARY BETWEEN TWO PROPERTIES): A BOUNDARY WALL ON THE DIVIDING LINE BETWEEN TWO LONDON VICTORIAN TERRACE REAR GARDENS IS A PARTY FENCE WALL (DEFINED IN THE PARTY WALL ACT 1996). RAISING OR REBUILDING A PARTY FENCE WALL IN LONDON: REQUIRES A PARTY WALL NOTICE UNDER SECTION 2 OF THE PARTY WALL ACT 1996 (A STRUCTURE NOTICE OR PARTY STRUCTURE NOTICE) IF THE WORKS INVOLVE: REBUILDING THE PARTY WALL. RAISING THE HEIGHT OF THE PARTY WALL. UNDERPINNING THE PARTY WALL. OWNERS ON BOTH SIDES HAVE RIGHTS UNDER THE ACT — IF CONSENT IS NOT REACHED, A SURVEYOR PROCESS IS REQUIRED.

BRICK GARDEN WALL REPAIR AND NEW CONSTRUCTION COSTS IN LONDON RANGE FROM A SIMPLE REPOINTING JOB (£15-25/M² FOR A HERITAGE BRICKLAYER WITH LIME MORTAR) TO A FULL NEW BRICK BOUNDARY WALL IN RECLAIMED LONDON STOCK (£300-600/M LENGTH FOR A 1500MM HIGH WALL).

REPOINTING — GARDEN WALL (LONDON VICTORIAN TERRACE — EXISTING BRICK IN GOOD CONDITION, MORTAR JOINTS FAILED — NHL 3.5 LIME MORTAR): RAKING OUT OLD MORTAR (ANGLE GRINDER WITH RAKING WHEEL OR COLD CHISEL — MINIMUM 15MM DEPTH): £8 TO £15/M² LABOUR. RELINING/REPOINTING (NHL 3.5 LIME MORTAR — TUCK-POINTED FLUSH FINISH): £10 TO £18/M² LABOUR + £3-6/M² MATERIALS. TOTAL REPOINTING: £21 TO £39/M² (FRONT ELEVATION — SCAFFOLD ACCESS ADD £15-25/M²).

COPING REPLACEMENT (EXISTING COPING FAILED OR MISSING — BRICK-ON-EDGE WITH CREASING TILES — 1M RUN): REMOVE OLD COPING: £15 TO £30/M. NEW CREASING TILES (2 COURSES — ROSEMARY CLAY): £12 TO £25/M SUPPLY AND LAY. NEW BRICK-ON-EDGE COPING (IBSTOCK LONDON STOCK — SUPPLIED AND LAID IN NHL 3.5): £25 TO £50/M SUPPLY AND LAY. TOTAL COPING REPLACEMENT: £52 TO £105/M.

NEW BRICK BOUNDARY WALL (RECLAIMED LONDON STOCK BRICK — 215MM THICK — NHL 3.5 MORTAR — 1500MM HIGH — WITH BRICK-ON-EDGE COPING — LONDON): FOUNDATIONS (CONCRETE STRIP 600X300MM — EXCAVATION AND POUR): £50-100/M. BRICKWORK (215MM THICK — 1500MM HEIGHT ABOVE GROUND — APPROX 135 BRICKS/M LENGTH AT 215MM THICKNESS): BRICK SUPPLY (RECLAIMED LONDON STOCK — £0.80-1.50/BRICK): £108 TO £202/M. LABOUR (HERITAGE BRICKLAYER — NHL 3.5 LIME MORTAR — LONDON RATE): £120 TO £200/M. CREASING TILES AND BRICK-ON-EDGE COPING: £52 TO £105/M. TOTAL NEW WALL: £330 TO £607/M LENGTH (EXCLUDING SCAFFOLD AND PLANNING WHERE REQUIRED).