Loft Conversion Hammersmith & Fulham: Costs, Planning and Vetted Specialists
Rear dormer, L-shaped dormer and mansard loft conversions across Hammersmith, Fulham, Shepherd’s Bush and Barons Court. Costs from £30,000, planning rules explained, and up to 3 matched quotes from vetted local specialists. Free, with no cold calls.
SIMPLE PROCESS
How do renovation quotes in London work with QuoteMyRenovation?
Four steps take you from the first idea to a finished project, paying as the work progresses.
Tell us about your project (3 minutes)
We match you with vetted builders (within 24 hours)
Compare your matched quotes (within 5 working days)
Pay as the work progresses (milestone payments)
What are you renovating?
Featured Renovation Partner
Our founding partner for kitchens, bathrooms, extensions and full refurbishments across Chelsea and south-west London.
For most families in Hammersmith and Fulham, moving to get an extra bedroom means leaving the street, the school and the neighbours they know. Converting the loft keeps all of that and adds a bedroom, often with its own shower room, at the top of the house.
The borough’s terraces are well suited to it. Many have a main roof with a rear outrigger behind it, which makes the L-shaped dormer the most popular choice in Fulham and Shepherd’s Bush. Where a street already has mansards, a mansard can add a full storey.
What decides the type of loft you can build is planning. Hammersmith & Fulham has 44 conservation areas, and loft conversions there don’t get Permitted Development rights. A mansard needs planning permission wherever you live.
This guide covers loft conversion costs in Hammersmith and Fulham, the types that suit local homes, Permitted Development and planning, conservation areas, Building Regulations, Party Wall notices, timings and how to find a vetted specialist.
Loft conversion costs in Hammersmith and Fulham
Loft conversion costs in Hammersmith and Fulham range from around £30,000 for a roof light conversion to £130,000 or more for a mansard with an en-suite. The type of conversion has the biggest effect on price, followed by the size of the roof, the specification and whether you add a bathroom.
The borough sits above the London average for building costs, mainly because of labour demand, scaffold and parking licences, and tight access on terrace streets. Parsons Green, Hurlingham and Brook Green, where specifications are usually higher, tend to run another 10-20% above these figures.
| Loft conversion type | Typical cost (Hammersmith & Fulham) | Parsons Green, Hurlingham & Brook Green |
|---|---|---|
| Roof light (Velux) conversion | £30,000-£50,000 | Add 10-20% |
| Rear dormer | £50,000-£75,000 | Add 10-20% |
| L-shaped dormer (main roof + outrigger) | £65,000-£95,000 | Add 10-20% |
| Hip-to-gable (end of terrace or semi) | £55,000-£80,000 | Add 10-20% |
| Mansard | £80,000-£130,000+ | Add 10-20% |
| Adding an en-suite shower room | Add £8,000-£15,000 | Add 10-20% |
These figures include scaffolding, steels, the dormer or mansard structure, insulation, a new staircase, fire protection, plastering, electrics and decoration. Professional fees for drawings, a structural engineer, Party Wall surveyors and Building Regulations usually add £4,000-£10,000.
Which loft conversion suits your Hammersmith or Fulham home?
Roof light conversion
The simplest and cheapest option. Roof lights are fitted into the existing roof slope, and the roof shape doesn’t change. It only works if there’s enough head height already, usually at least 2.2m from the top of the ceiling joists to the underside of the ridge, which many terraces don’t have.
Rear dormer
A box-shaped extension built out from the rear roof slope, giving full head height across most of the loft. A rear dormer usually creates one good-sized bedroom and a small shower room. Outside conservation areas, it can often be built under Permitted Development.
L-shaped dormer
The most popular loft conversion in Fulham, Hammersmith and Shepherd’s Bush. It combines a dormer on the main roof with a second dormer over the rear outrigger, joined in an L. It typically adds two bedrooms or a bedroom and a full bathroom. Whether it’s Permitted Development depends on the total volume added and whether the house is in a conservation area.
Mansard
A mansard replaces the rear roof slope, and sometimes the front, with an almost vertical wall and a flat top. It adds the most space of any loft conversion and is common in the borough where a street already has them. A mansard always needs planning permission. Some older terraces, particularly towards West Kensington and Barons Court, have a hidden “butterfly” roof behind a front parapet, and a mansard is usually the only practical way to convert them.
Hip-to-gable
Changes a sloping side roof into a vertical gable wall to make room for a staircase and more floor space. It only applies to end-of-terrace and semi-detached houses, which are less common in the borough, and is often combined with a rear dormer.
Planning permission for loft conversions in Hammersmith & Fulham
Usually Permitted Development (outside conservation areas)
- Up to 40 m³ of extra roof space for a terraced house, or 50 m³ for a semi-detached or detached house
- No extension beyond the front roof slope facing a road
- Nothing higher than the highest part of the existing roof
- Dormers set back at least 20cm from the eaves, where possible
- Materials similar in appearance to the existing house
- Side-facing windows obscure-glazed and fixed shut below 1.7m
- No balconies, verandas or raised platforms
- If you rely on Permitted Development, apply for a Lawful Development Certificate. It confirms the conversion is lawful and avoids delays when you sell.
When you need planning permission
- Any loft conversion in a conservation area where Permitted Development rights for roof extensions don’t apply
- Any mansard, wherever you live
- Conversions that go over the 40m³ or 50m³ volume limits
- Any change to the front roof slope facing a road
- Flats and maisonettes, which have no householder Permitted Development rights
- Properties where an Article 4 Direction has removed roof extension rights
- Listed buildings, which also need Listed Building Consent
- Roof terraces and balconies
BUILDING REGULATIONS
All loft conversions, including Permitted Development ones, require Building Regulations approval. A Building Control officer will inspect insulation, fire safety (escape routes, fire doors), structural integrity (floor joists, steelwork), and the staircase. Budget £700-£1,200 for Building Regulations fees. This is managed through your local authority or an Approved Inspector.
Mansards in Hammersmith and Fulham
The council judges each mansard on its design and on the street around it. Where neighbouring houses already have mansards, approval is much more likely, because the roofline has already changed. On an unbroken roofline, especially in a conservation area, approval is harder. A pre-application enquiry with the council’s planning team before you commission full drawings is worth the time.
Loft conversions in Hammersmith & Fulham conservation areas
The borough has 44 conservation areas, including Parsons Green, Walham Green, Hurlingham, Barons Court, Hammersmith Grove, Moore Park, Olympia and Avonmore, The Mall and Shepherds Bush. In all of them, a loft conversion that changes the roof needs planning permission.
That doesn’t mean you can’t convert. Rear dormers and mansards that follow existing patterns on the street are regularly approved. The council looks at how visible the roof is from the street and from public spaces, whether it keeps the character of the terrace, and the materials, usually natural slate and timber windows. A good designer will look at what neighbours have had approved before drawing yours.
Building Regulations for loft conversions
Every loft conversion needs Building Regulations approval, even if it doesn’t need planning permission. The main checks are:
- Structure: steel beams and new floor joists, designed by a structural engineer
- Fire safety: a protected escape route down through the house, fire doors onto the stairs and mains-powered, interlinked smoke alarms
- Staircase: a fixed staircase with at least 2m head height, reduced to 1.9m at the centre and 1.8m at the edge where there’s a sloping ceiling
- Insulation: the roof and dormer walls must meet current energy standards
- Sound insulation between the new floor and the rooms below
Budget £800-£1,500 for Building Regulations fees.
Party Wall notices for loft conversions in a terrace
Most loft conversions in the borough’s terraces need steel beams bearing on, or cut into, the party walls, and many raise the party wall to form a dormer cheek or a mansard wall. Under the Party Wall etc. Act 1996, that needs 2 months’ notice to both neighbours.
If they agree in writing within 14 days, you can go ahead. If not, surveyors prepare a party wall award, typically costing £900-£1,800 per neighbour. On streets where lofts are common, most neighbours agree, especially if you speak to them before the formal notice arrives.
Loft conversions in each part of the borough
Fulham and Parsons Green (SW6)
Fulham’s Victorian and Edwardian terraces almost all have rear outriggers, so the L-shaped dormer is the most common conversion. Around Parsons Green and Hurlingham, several streets are in conservation areas, so expect a planning application and slate-faced dormers. Many clients here add an en-suite shower room.
Hammersmith, Brook Green and Ravenscourt Park (W6)
W6 has a mix of terraces and larger semi-detached houses, so rear dormers, L-shaped dormers and hip-to-gable conversions all appear. Brook Green and the streets around Ravenscourt Park have higher specifications and more conservation area controls.
Shepherd's Bush and White City (W12)
W12’s smaller Victorian terraces suit rear and L-shaped dormers. More of these streets sit outside conservation areas, so Permitted Development often applies, and costs are closer to the London average.
Barons Court and West Kensington (W14)
W14 has taller terraces, butterfly roofs behind parapets and many converted flats. A mansard is often the only practical option. Top-floor flats need planning permission and the freeholder’s consent, and may need to buy the roof space from the freeholder.
How long does a loft conversion take in Hammersmith?
- Roof light conversion: 4-6 weeks on site
- Rear dormer: 8-10 weeks on site
- L-shaped dormer: 10-12 weeks on site
- Mansard: 12-16 weeks on site
- Design, Party Wall notice and Building Regulations: allow 2-4 months before work starts
- Planning permission, if needed: add 8-13 weeks before work starts
Most of the work happens from scaffolding outside, so you can usually stay at home until the final few weeks, when the staircase is cut through to the floor below.
How to pay for your loft conversion
Every QuoteMyRenovation builder agrees to milestone payments. A typical loft schedule is a 10% deposit, then payments when the scaffold is up and the steels are in, when the dormer or roof structure is built and watertight, when the staircase and first fix are complete, when insulation and plastering are done, and when second fix and any en-suite are finished. We hold back a 5% retention until any snags are fixed, and we check in with you before each payment. See how milestone payments workÂ
How to find a vetted loft conversion specialist in Hammersmith and Fulham
Loft conversions are specialist work. The builder needs to handle structural steel, roofing, fire safety and a staircase in a working family home. When you compare quotes, ask each specialist:
- How many L-shaped dormers or mansards have you built in SW6, W6 or W12?
- Is the structural engineer included, and who designs the steels?
- Who handles the Party Wall notices, and is the surveyor’s fee included?
- Who arranges the scaffold licence and parking suspension?
- How will you protect the rest of the house when you open up the stairs?
- Will you provide a programme of works with milestone payment dates?
QuoteMyRenovation matches Hammersmith and Fulham homeowners with vetted local loft conversion specialists who read your brief before deciding to quote. You get up to 3 matched quotes from specialists who know what you need, with no cold calls. It’s free to use.
BOOK NOW: Loft Conversion Hammersmith
News
From our blog
Sign up to receive the latest updates and news
COMMON QUESTIONS
Frequently Asked Questions About Loft Conversion Hammersmith
Questions homeowners ask us most often before submitting their brief.
How much does a loft conversion cost in Hammersmith and Fulham?
Do I need planning permission for a loft conversion in Hammersmith?
Can I build a mansard in a Fulham conservation area?
Should I choose an L-shaped dormer or a mansard?
Do I need a Party Wall agreement for a loft conversion?
How long does a loft conversion take in Hammersmith?
How should I pay for a loft conversion?
FREE · NO OBLIGATION · NO COLD CALLS
Submit your brief and receive up to 3 matched quotes from vetted loft conversion specialists covering Hammersmith and Fulham, from Parsons Green and Sands End to Brook Green, Ravenscourt Park and Shepherd's Bush. It's free, with no obligation. QuoteMyRenovation is London's renovation marketplace, connecting Hammersmith and Fulham homeowners with vetted local builders since 2024.
London’s renovation quote marketplace. Connecting homeowners with vetted renovation specialists across London boroughs.
Services
Company
- About us
- How it works
- Milestone Payments
- FAQ
- Contact Us
- For Builders
- Privacy policy
- Terms of service