Table of Contents
- How much does a loft conversion cost in Lewisham?
- Add-ons to budget for
- What's included in those prices (and what isn't)
- What drives loft conversion cost up — or down
- Planning permission & building regulations in Lewisham
- Timeline: how long does a loft conversion take?
- ROI: how much value can a loft conversion add in Lewisham?
- How to choose the right loft conversion company in Lewisham
- Budget-smart tips (without cutting corners)
- Example Buildaway packages (guide pricing)
- FAQs (Lewisham)
- Why Lewisham homeowners choose Buildaway
Lewisham (SE13) is one of South East London's most dynamic and diverse areas, undergoing rapid regeneration while still offering affordable family housing compared to its neighbours Greenwich and Blackheath. With excellent rail and DLR links from Lewisham Station (just 10 minutes to London Bridge), popular schools, and local green spaces like Hilly Fields Park, demand for property in Lewisham is strong. The housing stock includes Victorian and Edwardian terraces, 1930s semis, and modern apartments — with many homes perfectly suited for loft conversions to create extra living space without giving up valuable gardens.
Running out of room in Lewisham? A loft conversion can unlock the potential of unused roof space, adding a stylish bedroom, home office, or en-suite — while also boosting property value. This Lewisham-specific guide sets out 2025 cost ranges, what's included, what affects the price, planning and building regulations, timelines, ROI, and expert advice for choosing the right builder.
How much does a loft conversion cost in Lewisham?
Pricing below reflects South East London / Lewisham market rates for 2025 (labour + materials), including insulation, structural works, and compliant finishes.
| Conversion Type | Typical Total Range (2025) | Best For | What You Typically Get |
|---|---|---|---|
| Velux / Rooflight | £25,000 – £35,000+ | Quick, cost-effective extra room | Structural steels, joists, insulation, 1–2 rooflights, plaster/paint, electrics, heating tie-in |
| Rear Dormer (most popular) | £35,000 – £55,000+ | Full-height bedroom + en-suite potential | Everything in Velux plus dormer build, cladding/roofing, staircase, more daylight and usable floorspace |
| Hip-to-Gable (with or without dormer) | £50,000 – £65,000+ | 1930s semis and end-terraces in Lewisham | Extend hip to gable, extra steels, more usable area; often combined with rear dormer |
| Mansard | £60,000 – £80,000+ | Victorian terraces / conservation areas | Roof rebuild, mansard walls/windows, bespoke staircase, high insulation, maximum headroom and floorspace |
Add-ons to budget for:
- En-suite fit-out: £4,000 – £8,000+
- Juliet balcony / large glazing: £2,000 – £6,000+
- Bespoke staircase/joinery: £1,500 – £4,000+
What's included in those prices (and what isn't)
Included
- Survey, structural calcs, Building Control liaison
- Joists, steels, floor deck
- Roof alterations (Velux, dormer, hip-to-gable, mansard)
- Insulation to Part L regs
- Fire safety upgrades (alarms, FD30 doors, escape windows)
- Electrical circuits & heating tie-ins
- Plaster and joinery to ready-to-paint finish
- Standard staircase to Part K compliance
- Building Control inspections & certification
Exclusions
- Bathroom sanitaryware/tiling
- Premium bespoke finishes (stone tops, crittall glazing, fitted wardrobes)
- Planning fees and Party Wall surveyor fees
- Full re-roofing beyond loft works
- Decorating beyond basic paint
What drives loft conversion cost up — or down
Cost drivers
- Mansard builds vs. simple Velux/dormers
- Extra steelwork in older Victorian Lewisham terraces
- Bespoke staircase layouts in tight spaces
- En-suites with upgraded plumbing and tiling
- Juliet balconies and high-spec glazing
- Planning sensitivities near Conservation Areas like Brockley and Ladywell
- Restricted access or parking on narrow terraced roads
Ways to manage costs
- Stay within Permitted Development limits
- Align new plumbing above existing bathrooms
- Stick to standard staircase designs
- Focus spend on insulation/airtightness and visible finishes
Planning permission & building regulations in Lewisham
- Permitted Development (PD): Most Velux and some dormers qualify.
- Planning permission: Needed for mansards, front dormers, or homes in conservation areas (e.g., Brockley Conservation Area).
- Party Wall etc. Act 1996: Applies to most semis and terraces in SE13; budget £1,000–£2,000+ per neighbour.
Building Regulations:
- Part A – structure
- Part B – fire safety (alarms, escape routes, doors)
- Part K – staircase compliance
- Part L – insulation
- Part P – electrics
- Ventilation requirements for wet rooms
Timeline: how long does a loft conversion take?
- Pre-construction: 3–8 weeks
- Velux build: 4–6 weeks
- Rear Dormer: 6–8 weeks
- Hip-to-Gable / Mansard: 8–12+ weeks
- Snagging & sign-off: 1–2 weeks
ROI: how much value can a loft conversion add in Lewisham?
A loft conversion in Lewisham typically adds 10–20% to property value. With strong demand from families and professionals near rail/DLR links and parks like Hilly Fields, an extra bedroom and en-suite offers excellent ROI.
How to choose the right loft conversion company in Lewisham
- End-to-end capability: design, structure, build, finishing
- Transparent, itemised pricing
- Proven Building Control sign-offs & Part P certification
- Fire safety compliance built into scope
- 18-month Buildaway workmanship warranty
- Local experience across Lewisham, Ladywell, and Hither Green
Budget-smart tips (without cutting corners)
- Plan headroom early in Victorian terraces
- Design staircase first to optimise layout
- Keep plumbing stacked above existing services
- Spend on insulation & airtightness for comfort/energy savings
- Upgrade visible finishes like glazing, lighting, brassware
Example Buildaway packages (guide pricing)
- Velux Room-in-Roof — £27,500–£34,500
Includes steels, floor, rooflights, insulation, staircase, electrics, plaster finish. - Rear Dormer + En-suite Ready — £42,000–£56,000
Includes dormer, staircase, insulation upgrades, electrics/heating, plaster finish. En-suite fit-out typically +£4,000–£8,000. - Hip-to-Gable with Rear Dormer — £54,000–£68,000
Includes hip-to-gable extension, dormer, steels, staircase, full compliance, plaster finish.
(All guide prices include labour, materials, waste removal, and Building Control. Final quotes vary by survey, access, and specification.)
FAQs (Lewisham)
Do I need planning permission?
Not usually for Velux/rear dormers under PD; yes for mansards, front dormers, or conservation-sensitive areas.
Can I add an en-suite?
Yes — typically £4,000–£8,000+.
Will my roof need strengthening?
Yes, most Lewisham homes require new steels and joists.
Can we live at home during the build?
Yes, works are managed to maintain security/weatherproofing.
How do you handle fire safety?
Linked smoke alarms, FD30 fire doors, escape windows, protected stair routes.
What warranty do you provide?
Buildaway provides an 18-month workmanship warranty.
Why Lewisham homeowners choose Buildaway
Local expertise across SE13, Ladywell, Hither Green, and Brockley
Full Building Regs & Party Wall compliance
Transparent, line-item pricing with no hidden extras
Skilled in-house team with end-to-end accountability
18-month workmanship warranty and responsive aftercare
High-quality materials and finishes for a lasting investment