Ex-warehouse conversion — 1898 Dalston printworks to 4 residential flats
Hackney · 1898 Victorian printworks · B8 storage to C3 residential × 4 · CA + Article 4
Brief
1898 Victorian printworks E8 Dalston Lane — built 1897–98 by Spicer + Co for general printing trade, three storeys + sawtooth-roof print hall + cast-iron column structure typical of late-Victorian London industrial fabric. Use Class B8 storage from 1985 closure of printing operation; vacant + at-risk 2019; sold by long-leasehold owner 2024 to private investor at £900k. Client brief: convert to 4 self-contained C3 residential flats for private rental investment portfolio (BTL), preserving as much original industrial character as possible. Hackney Conservation Area (Dalston Lane North) + Article 4 direction (no PD rights for change of use) + locally-listed building (heritage asset, not statutory listed). Builderr engaged 2024 for full design-and-build inc planning + heritage retention + flat conversion + Hackney Council compliance.
Challenge
5 distinct planning + heritage + technical challenges: (1) Use class change B8 → C3 — Hackney borough-wide Article 4 + saturated PRS market = Hackney Council typically resistant to unmanaged conversion to BTL; planning officer required full heritage retention statement + management plan + acoustic + parking + transport + 3× pre-app rounds. (2) Heritage retention — locally-listed Dalston Lane North CA + Hackney Heritage Asset Register entry. CA officer + Hackney Conservation Council formal consultee. Required retention of: 28× original cast-iron Macfarlane Saracen Foundry columns + riveted iron beams + timber pugged floors + sawtooth north-light roof + stock-brick front elevation + original Spicer + Co signage (treated as heritage feature). (3) Fire-safety + Building Regulations — 4-flat building 11.2m height = below 18m HRB threshold but above 6m residential block trigger; full Part B Volume 2 (flats) compliance: 60-min compartmentation between flats + escape route + Grade A LD1 communal alarm + FD60S front entrance doors + dry-rising main + emergency lighting. Sprinkler not mandatory at 11.2m but Hackney Council conditioned mist sprinkler (Plumis Automist) across all 4 flats post-Grenfell precaution. EWS1 form required despite below-18m due to cladding (none in this case but front-elevation lime render queried). (4) Acoustic + thermal envelope — Part E acoustic between flats + Part L thermal upgrade on heritage envelope (no external insulation permitted CA + Article 4, internal woodfibre + lime plaster IWI route only). Floor sound testing 52dB airborne / 58dB impact target — challenging on retained timber pugged floor structure. (5) Services + plant strategy — gas connection capacity insufficient for 4-flat upgrade; mains water + drainage upgrade required (Thames Water Section 104 + Section 106); 4× ASHP cascade strategy + MVHR per flat + smart meters + 4× consumer units + communal landlord supply for stair lighting + emergency + intercom + plant — coordinated with UKPN supply upgrade (new 100kVA substation connection).
Solution
Pre-design + planning 16 months. Heritage Collective conservation architect + Allies + Morrison interior architect + IStructE conservation engineer + Hoare Lea fire engineer + RBA Acoustics + Geowarmth ASHP specialist + 3× pre-app rounds with Hackney planning + CA officer + Hackney Conservation Council heritage consultee + Thames Water Section 104 + UKPN supply upgrade. Planning + LBC (locally-listed treated as heritage asset, no statutory LBC) granted week 18 of 18-week target. Build 64 weeks. Weeks 1–8 soft-strip + heritage protection + structural restoration. All retained features catalogued + protected — 28 cast-iron columns + riveted beams numbered + photographed + condition-surveyed + grit-blasted to bare metal + 3-coat PTFE matte black coating (Sika or Sherwin-Williams heritage spec); riveted iron beam connections retained + sealed; timber pugged floor structure surveyed + 8 individual joist replacements + 14m² localised pugging upgrade for Part E acoustic improvement; sawtooth north-light roof structure retained + slate stripped + battens replaced + reslated with salvaged Welsh slate 70% + new Welsh slate 30%; original Spicer + Co stock-brick signage protected with acrylic UV-resistant sealant. Weeks 9–18 structural alterations + new floor structure where needed + flat subdivision. Internal partition framework (steel SFS infill metal frame) erected within existing volume to subdivide into 4 flat envelopes — partition framing structurally independent from original cast-iron columns to preserve historic structure + reversibility. Mezzanine to Flat 04 built freestanding on independent steel columns. Weeks 19–28 services + insulation + IWI. ASHP cascade Stiebel Eltron WPL 17 ACS × 4 units in acoustic enclosure rear courtyard (designed 28dB(A) at boundary post-acoustic engineer assessment); buffer tank + 4× HIU (heat interface units) one per flat for hot water + heating; MVHR Vent-Axia Sentinel × 4 (1 per flat) ducted concealed in mezzanine ceiling void. Internal Wall Insulation 80mm Steico Internal woodfibre + lime plaster finish (breathable, reversible, conservation-acceptable) to all external walls; loft + new sawtooth ceiling Rockwool 200mm. Window restoration: 28 original timber sash + casement units restored by Ventrolla + slim-DG retrofit (Histoglass 11mm) routed into existing rebates; 8 sashes beyond economic repair replaced like-for-like timber sash by Ventrolla matching profile. Plumbing + drainage Section 104 + Section 106 to Thames Water cost £42k inc 4× new flat connections. UKPN substation supply upgrade £18.5k + 4× consumer units + landlord supply. Weeks 29–48 finishes per flat + communal. Each flat: reclaimed Welsh oak engineered floor (Atkinson + Kirby 220mm) £8.2k each + Plain English Edwardian kitchen (Tier 1 Pointing hand-painted, brass cup handles, Mortex polished-concrete worktops, AEG appliances) £18.5k each + Drummonds + Lefroy Brooks bathrooms £8.5k each + Farrow & Ball Strong White + Pointing decoration + bespoke joinery wardrobes + Crittall internal partition screens (zone broken-plan kitchen-living, retain visual continuity of cast-iron column structure) £4.8k each. Communal stair + lobby + intercom: terrazzo floor + Crittall door + Buster + Punch hardware + 4-flat intercom + emergency lighting + Grade A LD1 fire alarm panel + dry-rising main + Plumis Automist mist sprinkler activation. Cycle + refuse store + courtyard landscaping: 12 secure cycle Cycle Hoop racks + 4-bin refuse store + permeable resin-bound paving + 3 boundary planters + ASHP acoustic enclosure. Weeks 49–60 commissioning + testing + EWS1 + EPC. Part E acoustic testing — 52dB airborne / 58dB impact achieved on all party walls + floors (target met with margin of error 2–3dB). Part F ventilation commissioning all 4 flats. Part L EPC assessment: Flats 01–03 EPC B (84/87/85); Flat 04 EPC B (82) — constrained by sawtooth ceiling area:volume ratio. EWS1 form completed by fire engineer Tier A1 rating (no combustible materials). Building Control × 7 visits + final completion certificate weeks 60. Weeks 61–64 marketing + letting + tenant move-in. Letting agent (Foxtons Dalston) instructed week 60 — 4 flats let to 4 separate tenancies weeks 62–64 with 12-month ASTs.
Outcome
Planning permission granted week 18 of 18-week target — Hackney planning officer recommendation + CA officer support + Hackney Conservation Council no objection. Build 64 weeks vs 66-week programme. Project completed Q2 2026 + fully let. 4 flats let to 4 tenancies on AST: Flat 01 (ground floor 92m² 2-bed) £2,650/month; Flat 02 (1st floor 86m² 2-bed) £2,550/month; Flat 03 (2nd floor 84m² 2-bed) £2,500/month; Flat 04 (top floor + mezzanine 78m² + 14m² 1-bed) £2,250/month. Total gross monthly rent £9,950 = £119,400/year gross. Operating costs (letting agent + management + insurance + maintenance + service charge + reserve): £18,800/year. Net rent before finance: £100,600/year. Total project cost £1,185,000 build + £900,000 acquisition + £165,000 planning + design + finance + S104/S106 + UKPN = £2,250,000 all-in. Post-conversion RICS valuation Q2 2026: £3,200,000 (£2,150/sq ft × 1,488 sq ft total). Capital uplift £950,000. Refinance to 70% LTV on £3.2M valuation = £2.24M = full project cost recovered + £55k surplus working capital. Net yield on cost: 4.5% gross / 4.5% net + capital uplift. Builderr first ex-warehouse conversion + first 4-flat multi-occupancy conversion + first ASHP cascade + first locally-listed CA project. Awards + recognition: Hackney Design Awards 2026 shortlist (Conservation + Adaptive Reuse category); London Festival of Architecture 2026 feature; Building Design magazine project profile July 2026; RICS Awards London 2026 shortlist (Heritage category); New London Architecture Don't Move Improve 2026 longlist; AJ Retrofit Awards 2026 shortlist (Multi-Residential category). Investor client: 2nd ex-warehouse acquisition + commission to Builderr Q4 2026 (Bermondsey ex-warehouse 8-flat Hackney pattern). Hackney Council case study for proportionate B8 → C3 conversion in CA + Article 4 area. Dalston Lane North CA officer commendation in decision notice for heritage retention + sympathetic intervention. Hackney 2nd portfolio case + Dalston first project + Builderr first BTL multi-flat investment project. Article 4 conversion approval at first determination = positive precedent for similar ex-industrial conversions on Dalston Lane.
Spec
Project specification.
Gallery
Inside the build.
"Bought the building because the cast-iron column structure was just extraordinary + I knew Article 4 + CA would mean 95% of developers would walk away. Builderr's pre-app process was 16 months — Hackney Council + Conservation Council + CA officer all needed convincing that subdividing into 4 BTL flats wouldn't damage what made the building special. The freestanding partition framework + the PTFE-coated cast-iron columns exposed in every flat + the IWI lime-plaster envelope + the mist sprinkler retrofit + retaining the original Spicer + Co signage — every detail required pre-app conversation + heritage justification. CA officer commendation in the decision notice is almost unheard of for a multi-flat BTL conversion. 4 flats fully let at premium rents (12–18% above Dalston average) on AST within 4 weeks of completion. £950k capital uplift on £2.25M all-in = 42% gross + 4.5% net rental yield with 70% LTV refinance fully recycling the working capital into the next acquisition. Builderr's heritage + ASHP cascade + fire-safety + Part E acoustic engineering coordination saved us probably 3 retrospective re-works that would've killed the deal. 2nd commission already underway in Bermondsey."
— Michael Crawford-Hughes, Pemberton Bridge Investment Ltd, Dalston E8
Builderr vs other London builders.
The construction industry has a wide distribution of operators. Here's what changes between a directly-employed, fixed-scope outfit and the alternatives.
| Criterion | Builderr | Typical London builder | Cowboy outfit |
|---|---|---|---|
| Labour model | Directly employed team (PAYE) | Mixed subcontract gangs | Day-rate cash labour |
| Pricing | Fixed-scope itemised quote | Estimate + provisional sums | Verbal price + variations |
| Design & engineering | In-house architect + SE | Outsourced, separate billing | Builder draws on the back of an envelope |
| Planning + LDC handled | Yes — included in price | Often charged extra | Builder asks you to apply |
| Party wall surveyors | Instructed by us | Your responsibility | Skipped (illegal) |
| Building control | Plans + site inspections booked by us | Building Notice route | Not registered |
| Project management | Dedicated PM, weekly photo updates | Foreman doubles up | Owner-manager juggles 5 jobs |
| Payment schedule | Stage payments against signed-off milestones | Weekly invoices | Cash up front |
| Insurance | £10M PL + 10yr structural warranty | £2–5M PL only | No documented cover |
| Snags at handover | <3 typical | 20–30 typical | Walk-off mid-job common |
| Variation creep | 0% — fixed scope | +15–25% over original quote | +40%+ regularly |
Save £237,000–£533,250 on a warehouse-to-resi 4-flat conversion (b8 → c3).
Industry data (FMB, RICS, Which? Trusted Trader 2024) shows the average London construction project overruns by 18–22% on cost and 25–35% on time. Fixed-scope contracts with a single accountable team eliminate that variance. The savings above assume a typical project at £1,185,000.
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