01
What it is
A hip-to-gable loft conversion removes the sloping hipped section at the side of your roof and builds it up as a vertical brick gable end, recovering the triangle of internal volume a hipped roof steals from the loft.
Hip-to-Gable Loft Conversions in London
If your roof slopes in at the side as well as the front and back, that sloping hip is what's keeping your loft from becoming a room.
A hip-to-gable conversion replaces it with a vertical brick gable end, restoring the full-height volume a hipped roof takes away, and paired with a rear dormer it produces one of the most generous lofts you can build.
It's the natural choice for 1930s semi-detached and end-of-terrace houses, and on most of them planning permission isn't needed. We design and build hip-to-gable conversions across London with everything handled in-house, from feasibility through to final snagging.
- Planning
- Usually permitted development
- On site
- 10–12 weeks
- Best for
- 1930s semi-detached and end-of-terrace houses with hipped roofs
What you actually need to know
02
How long
Around 10–12 weeks on site, with the full process taking roughly 18–24 weeks from your first call to handover.
03
Planning
Usually permitted development on houses (Lawful Development Certificate and Building Control sign-off still required). Full planning applies to flats, conservation areas, and houses where permitted development rights have been removed.
04
One team, start to finish
A site manager you know by name. Weekly photo updates by WhatsApp. The same trade teams we've worked with for over seven years. No rotating subcontractors, no agency labour walking in and out.
Recent hip-to-gable conversions across London
Each project is labelled with the time on site, the final price and the council that covered it.
Kenilworth Avenue, Wimbledon SW19
Hip-to-gable with rear dormer adding a master bedroom and en-suite to a 1930s semi.
- Hip-to-Gable
- 11 weeks
- £66k
- Merton Council
Woodfield Avenue, Ealing W5
Hip-to-gable and rear dormer creating a double bedroom with walk-in shower room on a 1930s semi.
- Hip-to-Gable
- 12 weeks
- £71k
- Ealing Council
Creswick Road, Acton W3
Hip-to-gable conversion adding a guest bedroom and study nook to a 1930s end-of-terrace.
- Hip-to-Gable
- 10 weeks
- £59k
- Ealing Council
Braxted Park, Streatham SW16
Hip-to-gable with rear dormer, master bedroom and en-suite on a 1930s end-of-terrace.
- Hip-to-Gable
- 11 weeks
- £68k
- Lambeth Council
Nether Street, Finchley N3
Hip-to-gable adding a bright top-floor sitting room and shower room to a 1930s semi.
- Hip-to-Gable
- 10 weeks
- £62k
- Barnet Council
Marksbury Avenue, Richmond TW9
Hip-to-gable and rear dormer with premium en-suite and fitted wardrobes on a 1930s semi in Kew.
- Hip-to-Gable
- 12 weeks
- £72k
- Richmond Council
Is your house suitable for a hip-to-gable loft conversion?
Good fit if you have:
- A hipped roof, where the side of the roof slopes inwards as well as the front and back
- A semi-detached or end-of-terrace house (the free side is where the new gable goes)
- A 1920s or 1930s home, the classic outer-London suburban stock these roofs were built on
- An existing ridge height of 2.2m or more (we measure this at the survey)
- A side elevation that faces a garden or a neighbouring house rather than fronting the road on a corner plot
- Neighbours on your street who already have gable conversions, which is a strong planning signal
Probably not the right type if:
- Your house is a mid-terrace with party walls both sides. There's no hip to convert, and a Dormer conversion on the rear slope is the right starting point
- Your terrace has a rear back addition and you want two rooms out of the loft. An L-Shaped Dormer wraps over that back addition to add a bedroom and a full bathroom
- Your house sits in a conservation area where changing the shape of the roof is restricted. A Mansard is often the form planners will accept
- Your property is a flat or maisonette. Roof alterations there always need full planning, and a Velux conversion is usually the more realistic route
- You want more light rather than more floor space. A Velux conversion delivers that for far less money and disruption
Not sure which side of the line your roof falls on? Daniel will tell you straight at the free survey. book one here →
How does a hip-to-gable compare to other loft conversions?
| Type | Build time | Floor area added | Planning | Best for |
|---|---|---|---|---|
| Velux | 6–8 weeks | Smallest | Usually permitted development | Homes with enough existing headroom and a leaner budget |
| Dormer | 8–10 weeks | Large | Usually permitted development | Victorian and Edwardian terraces, 1930s semis |
| L-Shaped Dormer | 10–12 weeks | Largest (two rooms) | Often permitted development | Victorian terraces with a rear back addition |
| Hip-to-Gable | 10–12 weeks | Large | Usually permitted development | Semi-detached and end-of-terrace with hipped roofs |
| Mansard | 12–16 weeks | Largest single room | Planning permission required | Conservation areas, period properties needing maximum space |
Your hip-to-gable loft conversion, week by week
From your first call through to the day you move back in: a clear, predictable timeline that protects your home and your schedule.
- Week 0
Step 01
Free home survey
Daniel measures the ridge height, checks the flank wall the new gable will sit on, and tells you on the visit whether a hip-to-gable is the right call.
- Weeks 1–3
Step 02
Fixed-price proposal
Design drawings, structural approach and a fully itemised fixed-price proposal, with every cost on its own line. A 15% deposit secures your build slot.
- Weeks 4–8
Step 03
Drawings, planning and party wall
Lawful Development Certificate, structural calculations, Building Control and the party wall notice, plus brick samples matched to your existing flank wall before work starts.
- Weeks 9–20
Step 04
Build on site
The hip comes off in week 2 and the new gable rises straight away. The roof extends over it, the rear dormer follows, and finishes wrap by week 12. Weekly photo updates by WhatsApp.
- Week 21+
Step 05
Handover and 5% retention release
Final walk-around, completion certificate and written guarantees. 5% of the contract is held in retention until you've signed off the snagging.
Hip-to-gable loft conversion questions, answered
How much does a hip-to-gable loft conversion cost in London?
A hip-to-gable loft conversion in London typically costs £58,000 to £72,000, VAT included. The lower end covers the new brick gable end, a modest rear dormer and a double bedroom with standard finishes.
The mid-range adds an en-suite shower room. The upper end gets you a larger dormer, a premium en-suite, engineered wood floors and fitted joinery.
Every quote is itemised line by line, with no provisional sums.
What is a hip-to-gable loft conversion?
On a hipped roof, the side of the roof slopes inwards as well as the front and back, which cuts the usable loft space down to a narrow wedge.
A hip-to-gable conversion strips off that sloping hip and builds the side wall straight up in brick to ridge level, creating a vertical gable end.
That restores full-height volume right across the loft, and in almost every case we add a rear dormer at the same time to maximise the floor area, giving you a proper double bedroom where a hipped roof alone could barely fit a staircase.
Do I need planning permission for a hip-to-gable conversion?
Usually not on a house. Hip-to-gable conversions normally fall under permitted development, so we apply for a Lawful Development Certificate instead, which typically takes 6 to 8 weeks.
The combined volume of the gable and any rear dormer must stay within your allowance (50 cubic metres on a semi-detached house), materials must be similar in appearance to the existing house, and any side windows need obscure glazing.
Corner plots where the side elevation fronts the road need a closer look, and full planning applies to flats, conservation areas, and houses with permitted development rights removed. We confirm which route applies at the free survey and handle the whole application either way.
How long does a hip-to-gable conversion take to build?
Around 10 to 12 weeks on site.
The hipped roof section comes off in week 2 and the new gable brickwork goes up immediately under temporary weatherproofing, steels and the new floor follow in weeks 4 to 5, the roof is extended and the rear dormer made watertight by weeks 6 to 7, and finishes wrap in weeks 10 to 12.
Add the design, certificate and party wall stage beforehand and the full journey from first call to handover is roughly 18 to 24 weeks.
Can a hip-to-gable be combined with a rear dormer?
Almost always, and we recommend it on nearly every project. The gable on its own restores headroom at the side of the loft but adds relatively little floor area.
Building a rear dormer at the same time pushes the back of the roof out as well, and together they create the largest space most semis can achieve, typically 20 to 28 square metres.
Because both are built under one scaffold in one programme, the combined cost is far lower than doing them separately, and on most houses the pair still sits within the permitted development volume allowance.
Will the new gable match my existing brickwork?
This is where hip-to-gable jobs are won or lost, so we take it seriously.
During the design stage we match brick samples against your existing flank wall, using weathered or reclaimed bricks where a modern brick would stand out, and we match the mortar colour and joint style as well.
The extended roof over the gable is finished in slates or tiles to match the originals. If your house is rendered or pebbledashed, we finish the new gable the same way so the conversion reads as part of the original house.
Other loft conversion types we build
Dormer
Adds the most usable headroom and floor space. The most popular choice for Victorian and Edwardian terraces across South London.
About Dormer conversionsL-Shaped Dormer
Two dormers joined in an L over the rear and side return. Adds two rooms, typically a bedroom and a generous bathroom.
About L-Shaped Dormer conversionsMansard
A full new storey behind a steep rear wall. The highest spec, the biggest space, often required in conservation areas.
About Mansard conversionsVelux / Rooflight
The simplest, fastest, lowest-cost option. It works inside the existing roof with skylight windows, often without planning permission.
About Velux / Rooflight conversionsHip-to-gable loft conversions across London
Hip-to-gable conversions belong to the 1930s semi-detached streets that ring the capital: Wimbledon and Streatham south of the river, Ealing and Acton in the west, and the avenues around Finchley in the north.
If your street is lined with hipped roofs, the chances are we've already built on a house like yours.
Tap an area below to see what's possible on your roof.
Ready to square off that hipped roof?
Tell us your postcode and a bit about your roof.
Daniel will come out, measure up, and confirm whether a hip-to-gable is the right move for your house.
If it is, a fully itemised fixed-price proposal lands within 7 days of the visit. If another type would serve you better, he'll say so and point you in the right direction.
- Free home survey, usually within 5 working days
- Itemised fixed-price proposal within 7 days of the survey
- 15% deposit only after you sign · 5% retention held until snagging is signed off
- VAT included in every figure
Prefer to talk? Call Daniel on 07414 648 263.