A hip-to-gable loft conversion is the highest-value way to convert a house with a hipped roof, such as a 1930s semi, an end-of-terrace or a chalet bungalow. It squares off the sloping “hip” end into a vertical gable wall, unlocking a full second floor’s worth of head height and space, and it is usually paired with a rear dormer for a large master bedroom. We design and build them across West London and Surrey, planning managed, building control signed off, at a fixed price agreed in writing before we start.
A hip-to-gable loft conversion takes the sloping “hip” end of a roof, the part that slopes inward on the side, and builds it straight up into a vertical “gable” wall. The roof ridge is then extended out to meet it. That single change turns the cramped, sloping corner of the loft into full-height usable space.
It is the go-to conversion for houses with a hipped roof, which describes most 1930s and 1950s semis, end-of-terrace homes and chalet bungalows. Because it involves more structural work than a simple dormer (a new gable wall built up and a steel to carry the roof), it costs a little more, but it also delivers the most space. That is why it is almost always paired with a rear dormer to create a proper master bedroom with an en suite.
We build every hip-to-gable end to end, from structural design and planning to the finished, decorated room, under one fixed-price contract. For the wider picture, see our loft conversion service and the full types of loft conversion guide.
They squared off the hip on our 1930s semi and added a rear dormer, and the loft went from unusable to a proper master bedroom with an en suite…
Hip-to-gable works on any house with a hipped roof, one that slopes inward on the side as well as the front and back. Here are the four types we convert most. Not sure? Book a free survey and we’ll confirm in 45 minutes.
The classic hip-to-gable candidate. These semis have a hipped roof with a sloping side that wastes loft space. Squaring it off, usually with a rear dormer, creates a full master suite. Our most common job across West London and Surrey.
An end-of-terrace has one exposed hip end at the side. Converting it to a gable unlocks floor area that a mid-terrace simply cannot access, which is why end-of-terrace homes get noticeably more space from a loft conversion.
Chalet bungalows and bungalows with hipped roofs are ideal for hip-to-gable. Squaring off the hip turns a low, awkward roof into a genuine first floor, effectively adding a whole storey of living space above.
Detached houses often have a hip on both sides. A double hip-to-gable squares off both, so the whole loft becomes full-height, room enough for two bedrooms plus a bathroom. The biggest hip-to-gable layout we build.
Use this as a starting point. Every roof is different, so we confirm the design and planning route on the free survey.
| Your Property | Best Approach | Why |
|---|---|---|
| 1930s / 1950s semi (hipped roof) | Hip-to-gable + rear dormer | The highest-value conversion on this house type, adds a true second-floor suite. |
| End-of-terrace | Hip-to-gable (+ dormer) | Squaring the one exposed hip unlocks space a mid-terrace can’t reach. |
| Chalet bungalow | Full hip-to-gable conversion | Turns a low hipped roof into a genuine first floor of living space. |
| Detached (hips both sides) | Double hip-to-gable + dormer | Squaring both hips gives the maximum floor area, often two bedrooms. |
| Mid-terrace (no hip) | Rear dormer or mansard instead | No exposed hip to convert, so a dormer or mansard is the route. |
| Conservation area property | Planning-led, sympathetic design | Needs full planning and materials in keeping; we handle the heritage detail. |
A hip-to-gable involves more structural work than a plain dormer, so it sits at the upper end of loft conversion prices, and London is higher again than the UK average. The ranges below are for London in 2026 and include structural work, insulation, electrics and standard finishes. Every price includes VAT — no surprise 20% at the end. For a full breakdown see our loft conversion cost guide.
| Conversion | Typical London Cost | Build Time | Planning |
|---|---|---|---|
| Hip-to-gable (bedroom) | £55,000 – £75,000 | 8–12 weeks | Usually PD |
| Hip-to-gable + rear dormer | £70,000 – £95,000 | 10–14 weeks | Usually PD |
| Hip-to-gable + dormer + en suite | £80,000 – £105,000 | 12–16 weeks | Usually PD |
| Double hip-to-gable (detached) | £85,000 – £120,000 | 14–18 weeks | Usually PD |
| En suite bathroom (add-on) | £8,000 – £18,000 | +2–3 weeks | Included in build |
Indicative London ranges for 2026, including VAT, structural calcs and building control. For independent benchmarks see Checkatrade (~£2,000/m² for hip-to-gable) or Architecture for London. Try our free calculator for a tailored estimate.
Usually not. A hip-to-gable is normally permitted development, and helpfully the eaves set-back rule that applies to dormers does not apply to the hip-to-gable part of the roof. We confirm the route at the survey and, where it’s permitted development, file a Lawful Development Certificate. Full guidance is on the Planning Portal, and we cover it in our loft conversion planning permission guide.
Every hip-to-gable must be signed off under Building Regulations, covering head height, fire safety, structure, stairs and insulation. That sign-off is in our price, along with everything below.
Every hip-to-gable follows the same six stages, so you always know what happens next, with no surprises in scope, timing or cost.
Our project manager checks the roof, confirms head height and whether a single or double hip-to-gable suits the house. Around 45 minutes, no obligation.
We prepare drawings and structural calculations, handle the Lawful Development or full planning application, and serve any party wall notices.
Once design is signed off, you get a written contract covering every element. The agreed price does not change unless you request a change.
Scaffolding, the new gable wall built up, steel beams, floor joists, the roof extended and any rear dormer formed. Building control inspects at key stages.
Insulation, staircase, first-fix electrics and plumbing, then plasterboard and plastering. The room is wired, plumbed and insulated before finishing.
Building control issues the completion certificate. We walk through with you, fix any snags and hand over your written workmanship guarantee.
Because a hip-to-gable adds a genuine second-floor room rather than just tidying up the existing loft, it is one of the strongest value-adding conversions there is. According to 2025 Nationwide research, a loft conversion adding a large double bedroom and bathroom can add up to 24% to the value of a three-bedroom home, typically more than the build cost, and without the stamp duty and upheaval of moving.
Most loft disputes come from the same warning signs at quoting stage. Watch for these before you sign, ours included.
A hip-to-gable needs a new gable wall and steel to carry the roof. Without proper calculations before the quote, the price is guesswork that grows mid-build.
On a semi the gable is built off the party wall, so the Party Wall Act applies. A builder who ignores it can leave you exposed to a neighbour dispute mid-project.
A “labour and materials” quote lets every variation become an extra. A proper fixed-price contract caps your risk. Ours is locked in writing before work starts.
Building Regulations sign-off is non-negotiable. An unsigned loft causes serious problems when you sell, and is technically illegal.
Anything above 10–15% before materials arrive is a cash-flow red flag. Payments should be staged against completed work.
Check Companies House and ask for recent local jobs. We’re on Google and Checkatrade with a real Hayes address you can verify.
From our Hayes base we cover West London, South-West London and Surrey, areas full of the 1930s semis that suit a hip-to-gable. We know each council’s planning approach, which saves weeks at design stage.
Our home patch, wall-to-wall with 1930s and 1950s hipped-roof semis, so hip-to-gable plus rear dormer is our single most common job here. See our Hayes page.
A mix of Victorian terraces and Edwardian and 1930s semis. The semis take a hip-to-gable well; conservation pockets need a planning-led design.
Heavy on 1930s semi-detached stock with hipped roofs. Hounslow processes permitted development quickly, so hip-to-gable jobs move fast.
Inter-war semis alongside conservation areas. We square hips off where permitted and design sympathetically where planning is needed. See our Richmond page.
Suburban 1930s semis with hipped roofs and good gardens, ideal for a hip-to-gable plus dormer that adds a full master suite.
The Surrey commuter belt is full of larger detached and semi-detached homes with hipped roofs, well suited to single and double hip-to-gable conversions.
Our project manager will visit, check whether your roof suits a single or double hip-to-gable, and tell you exactly what it would cost, all fixed in writing. Or get an instant estimate with our free calculator.
Contact us today to discuss your project and receive a no-obligation quote.
