Can I use UPVC sashes in a London Conservation Area?

Generally no — almost every London CA appraisal restricts window replacements to original material (timber) + original detailing. Even where UPVC is technically allowed, planning officers strongly resist + Article 4 directions remove PD rights to install. Slim-DG timber is the CA-acceptable route. UPVC may be enforced against in CAs/Article 4 areas — risk of removal order.

How long does bespoke heritage joinery take?

Survey + spec 2–3 weeks; workshop drawings + sample approval 2 weeks; manufacture 10–18 weeks (tier 1) or 6–10 weeks (tier 2); on-site fitting 3–6 weeks. Total 17–29 weeks for a 14-sash project. Order at planning consent — do not wait for site mobilisation, or risk significant programme delay. Many tier 1 workshops at 22+ week lead by 2026.

Does LBC allow window replacement at all on Grade II buildings?

Yes but limited — Historic England guidance prefers in-situ repair (~70–80% of LBC cases). Replacement permitted where original is beyond economic repair, with like-for-like specification: same timber, same profile, same horn detail, same glazing pattern. Slim-DG accepted by most LPAs (Westminster, Camden, K&C published policies). New timber sash to LBC spec £1,800–£2,800 per unit.

Heritage Joinery Cost London 2026 | Builderr

How Much Does Heritage Joinery Cost in London?

Bespoke heritage joinery in London: timber sash windows £1,400–£2,800 per unit (Mumford & Wood, Ventrolla, Sash Window Workshop); panelled internal doors £1,800–£3,400 per leaf; staircases £8,500–£32,000 depending on geometry; skirting + architrave £180–£340 per linear metre fitted. Premium for matched profiles, slim-DG glazing, hand-cut mortice-and-tenon. CA + LBC works specifies + samples required pre-order.

Per-element rates + workshop tiers

London joinery workshop tiers 2026: (1) Tier 1 conservation specialists — Mumford & Wood, Ventrolla, Hicks Joinery, Aitken & Howard — £85–£140/hr workshop + £450–£780/m³ FSC oak/idigbo. Sash windows £1,800–£2,800 supply + fit per unit with Histoglass slim-DG, brass weights + parting beads. Panelled doors £2,400–£3,400 per leaf with mortice-and-tenon, raised + fielded panels, brass furniture. Run-in-situ cornice replication £180–£420/m by Pavilion Plaster + Hayles & Howe. (2) Tier 2 quality workshops — Patchett Joinery, Westbury, John Sankey — £65–£95/hr + standard pre-treated softwood. Sashes £1,400–£2,000 per unit; doors £1,800–£2,600. (3) Tier 3 generalist — local joiners + UPVC conversions — £45–£65/hr, sashes £900–£1,400 (rarely accepted in CA/LBC). Bespoke staircases: straight flight £8,500–£14,000; quarter-turn £12,000–£18,500; helical/spiral £22,000–£32,000+ depending on hardwood + balustrade. Skirting + architrave: machine-profiled match £85–£140/m fitted; hand-cut historical profile £180–£340/m. Lead times: tier 1 14–22 weeks; tier 2 8–14 weeks; tier 3 4–8 weeks.

CA + LBC requirements + cost drivers

Conservation Area + Listed Building Consent dictate joinery spec — and budget. CA controls: 6-over-6 vs 4-over-4 sash configuration per CA appraisal; glazing bar profile (Lambs-tongue, ovolo, gothic); slim-DG (4–11mm units) accepted in most CAs but check; horn detail (Victorian/Edwardian profile); colour (off-white, Farrow & Ball Down Pipe, Pointing standard). LBC controls (Grade II/II*/I): typically demands in-situ repair over replacement under Historic England + Society for the Protection of Ancient Buildings (SPAB) guidance — joinery surveyor scope decisions sash-by-sash. Restoration premium: in-situ sash overhaul (deboxing, cord/weight replacement, draught-strip, slim-DG retrofit) £950–£1,650 per unit — cheaper than replacement + LBC-compliant. Cost drivers: (1) timber species — accoya 30–45% premium over softwood, 100-year service life vs 60; (2) glazing — single-glazed standard, slim-DG +£280–£420/unit, double-glazed +£140/unit (Energy Saving Trust recommended for non-CA); (3) ironmongery — solid brass £85–£280/door vs nickel-plated £35–£85; (4) finish — site-applied vs factory water-based microporous +£140–£280/unit; (5) sash horns + run-through glazing bars (no joint visible) +25–40% on standard. London VAT: 0% on Grade I/II* LBC qualifying repair work; 20% on standard.