Loft Conversion Builders in London
Add a bedroom, en-suite, or home office without moving house.
All Well Property Services provides professional loft conversions across South East London. Prices range from £45,000to £80,000. Typical build time: 6–10 weeks. All projects include a fixed-price contract, single project manager, and full Building Control sign-off. Call 020 3920 9617 for a free consultation.
What We Offer
Add a bedroom, en-suite, or home office without moving house. We build dormer, L-shaped, hip-to-gable, and mansard loft conversions. One team handles structural design, staircase build, and Building Regulations sign-off.
- ✓Dormer loft conversions
- ✓L-shaped loft conversions
- ✓Hip-to-gable conversions
- ✓Mansard conversions
- ✓En-suite bathroom installation
- ✓Velux and dormer windows
- ✓Staircase design and build
- ✓Building Regulations handled
Typical Investment
6–10 weeks | Fixed-price contracts
Dormer conversion
Most popular, flat-roof rear dormer
£45,000 – £60,000
L-shaped dormer
Maximum space on Victorian terraces
£55,000 – £70,000
Hip-to-gable conversion
Ideal for semi-detached properties
£55,000 – £75,000
Mansard conversion
Maximum headroom, usually needs planning
£65,000 – £85,000
Most clients in South London typically invest between £50,000 and £65,000 for a dormer loft conversion with en-suite.
Fixed-price contracts | No hidden costs | 6–10 week typical build
What Affects the Cost?
- •Roof structure and conversion type
- •En-suite bathroom inclusion (adds £5,000-£12,000)
- •Staircase complexity and existing layout
- •Party wall requirements (terraced/semi-detached)
- •Conservation area or planning requirements
Our loft conversion experience
Since 2020 we have built loft conversions across South London. Project mix covers hip-to-gable conversions on Edwardian and 1930s semis, rear dormer conversions on Victorian terraces, L-shaped dormers on wider terraces, and Mansard or roof-raise conversions where the existing roof has insufficient headroom. The boroughs we work in most often: Bromley, Beckenham, Anerley, Crystal Palace, Forest Hill, Sydenham, Lewisham, Dulwich in SE London; Balham, Tooting, Clapham in SW London. Property age varies — Edwardian semis and 1930s suburban properties have hipped roofs ideal for hip-to-gable conversions, while Victorian terraces typically suit rear dormers. The most common schedule variation is party wall agreements taking longer than 8 weeks, which we mitigate by serving notices early in the design stage.
Accreditations and standards for loft conversions
Fire safety is the highest-stakes requirement on loft conversions. Building Regulations Part B requires a protected escape route from the new loft floor down to the front door of the property. This means fire-rated doors (FD30 minimum) on every habitable room along the escape route, mains-wired smoke alarms on every floor (interlinked), and 30-minute fire resistance on the staircase walls. Our Building Control inspector signs off the fire safety provisions. Structural work is calculated by our chartered structural engineer. The new floor structure typically uses I-joists or sawn timber to support the floor loads (BS 5268 Part 2 timber design code, or the equivalent Eurocode 5 EN 1995). Steel beams are sized for the load and span. Where the existing roof structure can't accommodate the floor loads, we install ridge beams or replacement trusses. NICEIC electrical certification covers all new circuits to BS 7671. Insulation is designed to U-value 0.18 W/m²K for sloping roofs and walls (Building Regulations Part L). Party Wall Act 1996 applies to virtually all loft conversions on terraced or semi-detached properties.
How we deliver loft conversions
Single project manager runs the loft conversion from survey to handover. They serve party wall notices early, coordinate the structural engineer, schedule the scaffold and roof opening work to avoid weather delays, and manage the trade schedule across plastering, plumbing, electrics, joinery, and decoration. Fixed-price contracts cover everything: structural engineer calculations, party wall surveyor fees, scaffolding licences, FENSA registration for new windows, Building Control fees including the fire safety inspection, and any conservation area applications. The price doesn't change unless the specification does. Weather planning. We don't open up roof structures in heavy rain. Realistic loft conversion schedules assume one day in five may be unworkable for roof opening work, and we build that into the programme. Properties are protected with temporary scaffold covers and tarpaulin during the open-roof phase. We operate from Unit 1 Limes Avenue, Anerley, London SE20 8QR. Companies House number 12721034. 57 verified Google reviews averaging 4.5 out of 5 stars.
Free tools for planning your project
No email required. Get instant estimates and planning answers before you book a consultation.
Loft Cost Calculator
Estimate the cost of your loft conversion based on type (dormer, mansard, hip-to-gable), intended use, and location in South East London.
Best Month
See historic rainfall and temperature for your postcode every month, plus the best window for external work. Live data from the Open-Meteo archive (Met Office and ECMWF).
Listed Check
Check whether your property is a listed building or sits inside a conservation area, and what that means for renovation work. Live data from Planning.data.gov.uk and Historic England.
Planning Risk
Traffic-light check of every planning restriction at your postcode: listed buildings, conservation areas, Article 4 directions, Tree Preservation Orders, flood zones. Live data from Planning.data.gov.uk.
Recent Loft Conversions Projects
Loft Conversions across South East London
What Our Customers Say
“All Well managed our project from start to finish. The fixed-price contract meant no surprises, and the result is stunning.”
Verified Customer
“Professional team, clean site, and they handled all the paperwork. Would recommend to anyone.”
Verified Customer
“Great communication throughout. They kept to the timeline and budget exactly as quoted.”
Verified Customer
Accredited & Certified
Frequently Asked Questions
- What types of loft conversion are there?
- The four main types of loft conversion are dormer, L-shaped, hip-to-gable, and mansard. A dormer (from £45,000) adds a flat-roofed box to the rear slope and is the most popular choice for terraced houses across Lewisham, Bromley, and Greenwich. An L-shaped dormer (from £55,000) extends across the rear and side of the roof, maximising floor space on Victorian terraces — typically creating 25-35 square metres of usable space. Hip-to-gable (from £55,000) extends the sloped side of a roof to a vertical wall, ideal for semi-detached properties common in areas like Eltham and Beckenham. A mansard conversion (from £65,000) replaces the entire roof slope with a near-vertical wall at 72 degrees, creating maximum headroom but usually requiring planning permission under local authority design guidelines. We assess your roof structure and head height during the free survey — you need a minimum of 2.2 metres from joist to ridge — and recommend the best option for your property type and budget.
- Do I need planning permission for a loft conversion?
- Most dormer and hip-to-gable conversions in London fall under permitted development rights and do not require a planning application, provided they stay within volume limits set by the General Permitted Development Order — 40 cubic metres for terraced houses or 50 cubic metres for detached and semi-detached properties. The dormer must not extend higher than the existing roof ridge, front-facing dormers are not permitted, and external materials should match the existing house. Mansard conversions almost always need full planning permission because they change the overall roof profile and massing. Properties in conservation areas — including parts of Dulwich, Blackheath, and Charlton — face additional restrictions: rear dormers may still be permitted but side-facing dormers and roof alterations visible from the street typically require approval. We handle all planning checks, pre-application enquiries, and formal applications as part of our service, and we apply for a Lawful Development Certificate to give you written proof of compliance.
- Do I need a party wall agreement for a loft conversion?
- If your loft conversion involves any structural work on or within 3 metres of a shared wall with a neighbour — which is the case for most terraced and semi-detached properties in South London — you will need a party wall agreement under the Party Wall etc. Act 1996. You must serve a formal notice on your adjoining neighbour at least two months before structural work begins. If they consent in writing within 14 days, no surveyor is needed and the process costs nothing beyond the notice itself. If they dissent or do not respond within 14 days, both parties must appoint a surveyor (or agree on a single agreed surveyor) to draw up a legally binding Party Wall Award documenting the condition of both properties. The process typically costs £700-£1,500 per neighbour depending on surveyor fees in your borough and takes 4-8 weeks. We guide you through every step, prepare the notice documents, and can recommend experienced RICS-accredited party wall surveyors local to your area.
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