Manufacturing + visual + technical differences
Handmade brick manufacturing: clay hand-thrown into wooden moulds dusted with sand or coal-dust, surface texture from hand-pressing + sand release, dimensions vary ±3–5mm (length 215mm nominal but ±5mm common), faces show 'creases' + 'kiss marks' from clay contact + slight colour variation in single batch from kiln position. Fired in lower-temperature kilns (~950–1050°C) producing softer brick with higher water absorption (12–22% by weight) + lower compressive strength (15–40 N/mm² typical). Best for: pre-1919 match, Conservation Area extensions, premium new-build period-style. Premium UK makers — Bulmer Brick + Tile (Suffolk, 1880-founded, Royal Warrant holder), HG Matthews (Buckinghamshire, organic + traditional methods), Coleford Brick + Tile (Forest of Dean), York Handmade, Charnwood, W H Collier (Marks Tey). Lead 8–16 weeks. Cost £2.40–£4.80/brick. Machine-made: clay extruded continuous column then wire-cut into bricks, or pressed in steel moulds. Dimensions tight ±1.5mm, uniform colour single batch, faces smooth or textured per finish (smooth, rumbled, dragfaced, sandfaced). Fired 1050–1150°C, harder denser brick, water absorption 6–14%, compressive 30–80 N/mm². Best for: post-1919 match, structural reliability, fast supply, budget projects. Ibstock 'London Stock' range — closest machine match to period brick but visibly uniform side-by-side. Wienerberger, Forterra Tradesman, Michelmersh, Hanson. Lead 1–4 weeks normally, can be longer for specialist colours. Cost £0.80–£1.60/brick. Technical considerations: handmade higher absorption better suits lime mortar + breathable wall construction (matched performance); machine-made lower absorption suits cement mortar + modern cavity walls. Mixing eras risky — handmade extension on machine-made original house works (rustic + period-feeling), but machine-made extension on handmade Victorian house reads wrong + LPA often refuses.
Selection by project type + planning + cost
Project type guidance: (1) Victorian/Edwardian terrace rear extension in CA: handmade or salvaged reclaimed required, machine-made typically refused by planning condition. Add £4,800–£12,000 to 22m² side-return budget over machine-made spec. (2) Post-war (1920s–1960s) semi-detached side extension: machine-made London Yellow Stock acceptable + matches original. £0.80–£1.60/brick. (3) Modern detached extension or new build: machine-made standard, choice of finish + colour, £0.80–£1.60/brick. (4) Listed building LBC works: handmade specified almost always, sometimes hot-fired in traditional kiln for genuine match (Bulmer Brick + Tile offers this for Grade I/II*). Premium £4.80–£8.50/brick. (5) Heritage repair (decayed brick replacement): salvaged reclaimed first choice (Cawarden, Lassco), handmade backup. £1.80–£4.80/brick. Cost impact example: 22m² side-return ~4,200 bricks: machine £3,360–£6,720 vs handmade £10,080–£20,160 — £6,700–£13,400 differential on a £75–£95k extension = 7–18%. Decision drivers: planning condition wording, CA appraisal text, heritage context + neighbouring brickwork, budget bracket, client design preference. Builderr default on pre-1919 Victorian/Edwardian + every CA-located extension: handmade or salvaged reclaimed quoted unless owner opts to value-engineer machine-made with planning + CA risk acknowledged in writing.
