Loft Conversion Cost UK 2026: The Complete Price Guide

Most UK loft conversions in 2026 land somewhere between 20,000 pounds and 85,000 pounds fitted, with the national average for a standard rear dormer sitting at around 45,000 pounds to 50,000 pounds. The cheapest option is a Velux (rooflight) conversion, which leaves the roof shape alone. The most expensive is a mansard, which rebuilds the whole rear roof slope at 70 degrees and adds the most floor area.

Quick reference, fitted prices including VAT, UK 2026:

| Conversion type | Typical range | National average | Build time | |---|---|---|---| | Velux / rooflight | 20,000 - 35,000 | 27,500 | 4-6 weeks | | Rear dormer | 35,000 - 60,000 | 47,500 | 8-12 weeks | | L-shaped dormer | 45,000 - 65,000 | 55,000 | 10-14 weeks | | Hip-to-gable | 45,000 - 65,000 | 55,000 | 10-14 weeks | | Mansard | 55,000 - 85,000 | 67,500 | 12-16 weeks | | Mansard (inner London) | 100,000+ | 110,000 | 14-18 weeks |

These numbers assume a single bedroom plus en-suite finish to a normal residential standard, mid-range fittings, normal access and no significant party wall complications. Strip out the en-suite and you save roughly 6,000 to 9,000 pounds. Push the spec to luxury (custom joinery, underfloor heating, designer sanitaryware) and you add 10,000 to 20,000 pounds.

Sources for the headline ranges: Checkatrade Loft Conversion Cost Guide 2026, MyJobQuote UK Prices 2026, TradeMatch UK 2026 Pricing, MyBuildAlly Q1 2026 BCIS analysis, Which?/BCIS 2025.

The conversion type is the single biggest cost driver, ahead of region and ahead of size. Here is what each one actually costs in 2026 and why.

Velux (rooflight) loft conversion - 20,000 to 35,000 pounds

A Velux conversion keeps the existing roof structure intact. The builder strengthens the floor with steel or timber joists, runs a new staircase up, insulates between and under the rafters, and cuts in two to four rooflight windows. There is no external structure to build, no scaffold platform extension and no party wall agreement in most cases.

Sub-type variants:

• Two-window basic: 20,000 to 25,000 pounds. Single room, no en-suite.
• Four-window standard: 26,000 to 30,000 pounds. Bedroom plus shower room.
• Premium fit-out with electric blinds and en-suite: 30,000 to 35,000 pounds.

Why it costs what it costs: the cost floor is set by the staircase (3,000 to 5,000 pounds installed), the steels for the new floor (3,000 to 6,000 pounds), insulation (2,500 to 4,000 pounds) and the Velux windows themselves (around 1,000 pounds each fitted, see MyJobQuote). Labour is the other half. You need decent head height (2.2m at the apex, ideally 2.4m) for it to be worth doing.

Rear dormer loft conversion - 35,000 to 60,000 pounds

The rear dormer is the workhorse of UK loft conversions. The builder takes off the back roof slope, builds a flat-roof box that sits proud of the existing roofline, and gives you full standing headroom across most of the floor plate. Typical floor area is 18 to 25 m squared usable.

Sub-type variants:

• Box dormer (flat roof): 35,000 to 50,000 pounds. The standard option.
• Pitched-roof dormer: 42,000 to 58,000 pounds. Better looking, more roof work.
• Full-width dormer: 45,000 to 60,000 pounds. Maximum floor area, often needs planning approval rather than permitted development.

Why it costs what it costs: you are now building a structure (timber frame, EPDM rubber roof, zinc or render finish on the cheeks, dormer windows). That structure plus its fit-out is roughly 8,000 to 15,000 pounds on top of the base Velux cost. You also need more scaffolding, more building control inspections and usually a party wall agreement if you are terraced or semi-detached.

L-shaped dormer loft conversion - 45,000 to 65,000 pounds

The L-shaped is the Victorian terrace special. It combines a main rear dormer with a smaller side dormer over the outrigger (the kitchen or bathroom extension that sticks out the back). You get two bedrooms plus a bathroom out of one project on a property that normally only has loft space for one.

Sub-type variants:

• Two-bed L-shape standard: 45,000 to 55,000 pounds.
• Two-bed plus en-suite: 52,000 to 62,000 pounds.
• Premium specification: 60,000 to 65,000 pounds plus.

Why it costs what it costs: you are essentially building two dormers connected by a corner, with more complex roofing, an extra steel beam where the two structures meet and more floor area to fit out. Most popular in London, Manchester, Birmingham, Leeds and Newcastle terraces.

Hip-to-gable loft conversion - 45,000 to 65,000 pounds

Used on end-of-terrace and semi-detached houses with a hipped (sloped) end roof. The builder removes the hip, builds the gable end wall up vertically and then either fits Velux windows or adds a rear dormer on top. The vertical gable wall transforms the usable floor area.

Sub-type variants:

• Hip-to-gable only with Velux: 45,000 to 52,000 pounds.
• Hip-to-gable plus rear dormer: 55,000 to 65,000 pounds. Most common combination.
• Double hip-to-gable (detached): 60,000 to 75,000 pounds.

Why it costs what it costs: rebuilding the gable end in blockwork with proper tying and bracing is real structural work. Add the new roof tiles to match, lead flashings, scaffold for both elevations and you are 10,000 to 15,000 pounds above a standard rear dormer.

Mansard loft conversion - 55,000 to 85,000 pounds (London 100,000+)

The mansard rebuilds the entire rear roof slope at a 70 to 72 degree angle, with the new wall lined in matching brick or slate. It gives you the largest floor area of any conversion type and visually it can look like the property always had a top storey. Common in London period terraces, Bath, Edinburgh New Town and other conservation-sensitive areas.

Sub-type variants:

• Single-side mansard: 55,000 to 70,000 pounds.
• Double mansard (front and rear): 75,000 to 90,000 pounds.
• Inner London period property: 90,000 to 130,000 pounds. Higher labour rates, conservation specification, brick to match the existing facade.

Why it costs what it costs: a mansard is a roof replacement, not an extension. Almost every mansard needs full planning permission (it is not covered by permitted development), the structural calcs are heavier, the brick or slate finish costs significantly more than render or zinc, and the build runs 12 to 16 weeks.

For type-by-type sub-pages see /dormer-loft-conversion/, /mansard-loft-conversion/, /hip-to-gable-loft-conversion/ and /velux-loft-conversion/.

Where you live can swing the price by 30,000 pounds on the same job. London labour is roughly 30 to 40 percent more expensive than the North East. The table below is benchmarked against a standard rear dormer fitted to a normal residential standard, with mid-range fittings and en-suite included. Data cross-referenced from BCIS regional benchmarks (Q1 2026), Checkatrade, MyJobQuote and TradeMatch.

| Region | Rear dormer range | vs UK average | Notes | |---|---|---|---| | London (inner) | 55,000 - 80,000 | +30 to 45% | Conservation areas common, mansard often required | | London (outer) | 50,000 - 70,000 | +20 to 35% | Standard dormer still typical | | South East | 47,000 - 65,000 | +15 to 25% | Surrey, Kent, Sussex commuter belt | | East of England | 42,000 - 58,000 | +5 to 15% | Cambridge premium, rest closer to average | | South West | 38,000 - 55,000 | -5 to +10% | Bristol slightly higher than rural | | West Midlands | 38,000 - 53,000 | -5 to +5% | Birmingham at average, rest below | | East Midlands | 37,000 - 52,000 | -7 to +3% | Nottingham, Derby, Leicester | | North West | 37,000 - 52,000 | -7 to +3% | Manchester and Liverpool slightly above | | Yorkshire | 36,000 - 50,000 | -10 to 0% | Leeds, Sheffield, York | | North East | 35,000 - 48,000 | -12 to -5% | Newcastle, Sunderland, Durham - the cheapest mainland region | | Wales | 35,000 - 48,000 | -12 to -5% | Cardiff slightly higher than valleys | | Scotland | 38,000 - 53,000 | -5 to +5% | Edinburgh premium, Glasgow at average |

The North East is consistently the cheapest mainland region in 2026. A standard rear dormer that lands at 52,000 pounds in outer London typically lands at 40,000 to 42,000 pounds in Newcastle, Sunderland or Gateshead. Labour rates are lower, material delivery is the same, and the local trade is competitive. If you are in Newcastle, our area pages cover specific neighbourhoods: /cities/newcastle/jesmond/, /cities/newcastle/gosforth/, /cities/newcastle/heaton/, /cities/newcastle/tynemouth/ and /cities/newcastle/whitley-bay/. A full city breakdown sits at /cities/newcastle/cost/.

For other major cities see /cities/london/, /cities/manchester/, /cities/birmingham/ and /cities/leeds/.

The shape and structure of your home dictate what type of conversion is realistic and what it will cost. A terrace and a detached house are different propositions even at the same square metres.

Terraced house

Typical conversion: rear dormer or L-shaped dormer. Typical cost: 35,000 to 60,000 pounds.

Terraces share at least one party wall, so you almost always need a Party Wall Award (legal cost 700 to 1,500 pounds per neighbour). Access is from the rear only, which can add 1,000 to 3,000 pounds to scaffolding if there is no side return. The flip side: the room shape is predictable and the dormer detailing is well understood by local trades, so quotes tend to be tighter.

Victorian and Edwardian terraces with an outrigger are perfect candidates for an L-shaped dormer, giving you two rooms out of one project.

Semi-detached house

Typical conversion: hip-to-gable plus rear dormer, or rear dormer only. Typical cost: 45,000 to 65,000 pounds.

Most UK semis have a hipped roof on the gable end. Building that hip up to a vertical gable transforms the loft from a triangular crawl space into a proper room. A hip-to-gable plus rear dormer gives you the floor area you need for a bedroom and en-suite. One party wall means one party wall agreement.

Detached house

Typical conversion: hip-to-gable both sides, or large rear dormer. Typical cost: 45,000 to 75,000 pounds.

No party wall issues, scaffold access on all sides, more permitted development allowance (50 cubic metres rather than 40). The catch is the size: detached lofts are usually bigger, which means more steels, more insulation and more fit-out. Bungalow conversions sit in this bracket and typically come in at 60,000 to 90,000 pounds because you are essentially adding a whole new floor (Checkatrade puts the bungalow average at 75,000 pounds, see source above).

Bungalow

Typical conversion: full first-floor conversion with dormers front and rear. Typical cost: 60,000 to 90,000 pounds.

Bungalows give you the biggest floor area uplift of any property type, often doubling the usable space. The trade-off is that you are essentially building a new storey: more steelwork, more roofing, more fit-out, and you almost always need planning permission rather than relying on permitted development.

Period and listed property

If the property is listed or sits in a conservation area, you can usually rule out permitted development. A mansard becomes the typical option, with conservation-grade brick or slate to match the existing facade. Budget 65,000 to 130,000 pounds depending on listing grade and location. See /blog/conservation-area-rules-uk/ for the planning detail.

We took the budget for a standard 47,500 pound rear dormer on a three-bed semi in the Midlands and broke it down line by line. Use this to sanity-check any quote you receive.

| Line item | Typical cost | Share of total | |---|---|---| | Structural steelwork (RSJs, floor joists, padstones) | 4,500 | 9.5% | | Dormer construction (frame, roof, cheeks, EPDM) | 8,500 | 18% | | Staircase (oak or painted softwood, balustrade) | 3,500 | 7.5% | | Windows (two dormer + one Velux on the roof slope) | 2,800 | 6% | | Insulation (between rafters, party walls, floor) | 2,400 | 5% | | First fix (plumbing, electrics, heating runs) | 3,500 | 7.5% | | Plasterboard and plastering | 3,200 | 7% | | En-suite (shower, WC, basin, tiling, extractor) | 4,800 | 10% | | Second fix and decoration (paint, flooring, skirting, ironmongery) | 4,200 | 9% | | Scaffolding (8 to 12 weeks hire) | 2,800 | 6% | | Architectural drawings and structural calcs | 1,500 | 3% | | Building Regulations application and inspections | 750 | 1.5% | | Party wall surveyor (one neighbour) | 1,200 | 2.5% | | Contingency (allowed for in quote) | 3,800 | 8% | | Total | 47,450 | 100% |

Labour vs materials split: roughly 45 percent labour, 35 percent materials, 10 percent fixtures and fittings, 5 percent planning and statutory, 5 percent contingency. This tracks the BCIS split that Which? publishes from the Building Cost Information Service data.

Where quotes lie to you: if a builder gives you a number more than 15 percent below the rest of the market, the most common omission is the en-suite, the steelwork allowance, or the scaffolding. Always insist on an itemised fixed-price written quote, which is what we provide at UK Loft Conversion as standard.

Loft conversion costs are best understood as fitted prices because the fixed costs (staircase, steels, planning, scaffolding) dominate small projects. That said, per-m-squared rates are useful for comparing one quote to another when the floor areas differ.

2026 UK per-m-squared rates, fitted with normal residential specification:

| Conversion type | Per m squared (low) | Per m squared (typical) | Per m squared (high) | |---|---|---|---| | Velux | 900 | 1,100 | 1,400 | | Rear dormer | 1,500 | 1,750 | 2,100 | | L-shaped dormer | 1,700 | 1,900 | 2,200 | | Hip-to-gable | 1,800 | 2,050 | 2,400 | | Mansard | 2,000 | 2,250 | 2,700 |

These line up with Checkatrade's published rates (1,670 per m squared dormer, 2,170 mansard) and MyJobQuote's typical range of 1,200 to 1,800. London adds 25 to 40 percent on top.

Important caveat: anyone quoting you on pure per-m-squared without seeing the property is guessing. Two identical sized lofts can differ by 8,000 pounds because one needs a hip-to-gable rebuild and the other just needs Velux windows. The per-m-squared number is a sanity check, not a quoting tool.

The headline quote is rarely the final number. Here are the costs that catch homeowners out, in rough order of how often they show up.

Building Regulations application fees: 500 to 900 pounds. This is separate from any planning application. Every loft conversion needs Building Regs approval regardless of whether you need planning permission. Local authority fees vary by region.

Planning application (if needed): 258 pounds in England (2026 fee). Most dormers and Velux conversions on houses fall under permitted development, but conservation areas, Article 4 directions, flats and mansards always need planning. Allow eight to twelve weeks for a decision once the application is valid.

Party Wall surveyor: 700 to 1,500 pounds per neighbour. Required for terraces and semis where the work affects a shared wall. If a neighbour disputes, you can be looking at 2,000 to 4,000 pounds per side.

Architectural drawings and structural calculations: 1,200 to 2,500 pounds. Sometimes bundled into the builder's quote, sometimes separate. For mansards and listed buildings, add a heritage consultant if required.

Asbestos survey: 300 to 600 pounds. Only relevant in properties built before 2000 with original artex ceilings or insulation. Removal if found is 800 to 2,000 pounds.

Bat or wildlife survey: 400 to 900 pounds. Required if there is any evidence of bat roosting (legally protected). Adds time as well as cost: surveys can only be done May to September.

Electrical consumer unit upgrade: 700 to 1,500 pounds. Older homes often need a new consumer unit to take the extra load.

Boiler upgrade: 2,500 to 4,500 pounds. If your existing boiler cannot heat the new room, you may need a system upgrade or a separate heating zone.

Rewiring nearby circuits to current Part P standards: 800 to 2,500 pounds. When the electrician opens up ceilings on the floor below to run cables, anything non-compliant gets flagged.

Decoration of the floor below: 1,500 to 3,500 pounds. The new staircase opening tears into the ceiling of the floor below. Painting and snagging there is rarely in the loft quote.

Furniture and fittings: 3,000 to 12,000 pounds. Beds, wardrobes, blinds, lights, curtains. Not part of any builder's quote but a real cost.

Contingency: 10 percent of contract value, minimum. Which? recommends no less than 10 percent. We agree. Old houses hide surprises in the roof structure that nobody can see until the slates come off.

The maths on building versus moving has shifted hard in favour of building since stamp duty thresholds tightened and average UK house prices climbed past 290,000 pounds.

Worked example: a 350,000 pound three-bed semi in the Midlands. Family wants a fourth bedroom and a second bathroom.

Option A - move to a four-bed at 430,000 pounds:

• Stamp duty: 9,000 pounds
• Estate agent fees on the sale: 3,500 pounds
• Conveyancing both sides: 2,400 pounds
• Surveys and searches: 1,000 pounds
• Removals: 1,500 pounds
• Mortgage product fees: 1,000 pounds
• Carpets, curtains, immediate updates to the new house: 5,000 pounds
• Top-up borrowing on the difference: 80,000 pounds plus all the above transaction costs
• Total acquisition cost over the asking price gap: roughly 23,400 pounds in friction.

Option B - L-shaped dormer at 55,000 pounds:

• All-in build cost: 55,000 pounds
• Likely uplift to property value: 15 to 25 percent of 350,000 = 52,500 to 87,500 pounds
• Net position after the build: minus 2,500 pounds to plus 32,500 pounds (i.e. break-even to 32k uplift, before considering the value of staying put)
• No stamp duty, no estate agents, no schools change, no moving.

On that example, building beats moving every time. The case flips only when the property is already at the top of its street's value ceiling - in those situations a conversion may not recover its cost on sale. For a detailed look at the value uplift maths see /blog/loft-conversion-roi-uk-2026/.

Rules of thumb for ROI:

• 15 to 25 percent uplift on existing property value is the typical range across the UK.
• London and the South East consistently recover the full cost of the build, often more.
• North East, Yorkshire, Wales and parts of Scotland may not fully recover a top-spec build on sale, but you still get the space to live in for years before you sell.
• Two-bed becomes three-bed: biggest jump in marketability. Three becomes four: still strong. Four becomes five: diminishing returns.
• En-suite added: roughly half the en-suite cost back in valuation. Worth doing for liveability, less so for pure resale.

Loft conversions are typically funded from one of three sources: savings, a mortgage further advance against the equity in the property, or a personal home improvement loan.

Savings. The cleanest option. No interest, no application, no monthly outflow once the build is done. Most of the homeowners we survey for fixed-price quotes fund the bulk of the project from cash and use the build as a way to put existing equity to work.

Mortgage further advance. Going back to your existing mortgage lender to borrow more against the property, typically on the same rate or a slightly different product. Application takes two to six weeks. You need a recent valuation. Best suited if you have 30 percent plus equity already.

Remortgaging. Moving to a new lender and increasing the loan in the process. Worth it if your current rate is uncompetitive. Builds in additional legal and valuation costs (around 1,500 pounds).

Personal loan. Unsecured borrowing, faster to arrange, smaller amounts only (most lenders cap personal loans at 25,000 to 50,000 pounds). Quicker but typically more expensive per month than secured borrowing.

A note on staging payments. Most reputable loft conversion firms work to a stage payment schedule: deposit on signing (usually 5 to 10 percent), then progress payments at completion of structural, weathertight, first fix, second fix and final sign-off. We do not ask for the full balance up front and you should never pay one that does. If a builder asks for more than 25 percent before steels are in, walk away.

Build time is closely tied to type. Here is what to expect on site from skip-arrival to handover.

| Conversion type | On-site duration | Total timeline including planning | |---|---|---| | Velux | 4 to 6 weeks | 8 to 12 weeks | | Rear dormer | 8 to 12 weeks | 14 to 22 weeks | | L-shaped dormer | 10 to 14 weeks | 16 to 26 weeks | | Hip-to-gable | 10 to 14 weeks | 18 to 28 weeks | | Mansard | 12 to 16 weeks | 22 to 34 weeks |

The planning leg is the variable. Permitted development jobs can start within four to six weeks of signing if drawings are already done. Full planning takes eight to twelve weeks for a decision once the council has validated the application, plus another two to four weeks for Building Control to review structural drawings. Add it all up and a mansard in a conservation area can easily run nine months end-to-end. For the full breakdown see /blog/how-long-does-loft-conversion-take/.

Most importantly: you can stay in the house for almost the entire build. Scaffolding goes up, the roof opens for around two days under temporary cover, and the staircase opening is the only week where dust upstairs is unavoidable. We have done hundreds of conversions where the homeowner barely changed their routine.

After running fixed-price quotes nationwide, we see the same expensive mistakes again and again. Avoiding these saves typical homeowners 5,000 to 15,000 pounds on a project.

Skipping the survey. Builders who quote off photos or a quick chat almost always under-quote, then bill for variations. Insist on a free home survey with measurements taken on site.

Ignoring head height. If the apex of your existing roof is below 2.2 metres, a Velux conversion will not give you usable standing room. A dormer becomes the only realistic option, which moves the price up by 20,000 pounds. Better to know on day one.

Assuming permitted development covers everything. It usually does, but Article 4 directions, conservation areas, listed buildings and flats are all exceptions. A 258 pound planning application beats the demolition order you get for building without permission.

Specifying the en-suite late. Plumbing runs and structural opening positions change if you add a bathroom mid-build. Decide early, lock the layout, save 2,000 to 4,000 pounds in rework.

Choosing the cheapest quote. A 38,000 pound dormer that should cost 47,000 pounds will hit you for 12,000 pounds in variations and end up at 50,000 pounds for a worse spec. Look for the middle of the range with a fully itemised written quote and a 10-year structural guarantee.

Skipping the contingency. Old roofs hide surprises (rotten purlins, undersized rafters, asbestos artex, no sarking felt). 10 percent contingency is not optional, it is engineering reality.

Not budgeting for the floor below. Staircases tear up ceilings. Decoration, sometimes a small bedroom remodel, often a new landing carpet. Allow 2,000 to 4,000 pounds.

More failure modes covered in /blog/loft-conversion-mistakes-to-avoid/.

We are a UK-wide loft conversion specialist with vetted local operators across England, Wales and Scotland. Our standard package includes:

• Free home survey with full measurements and feasibility report, normally within 5 working days of enquiry.
• Fixed-price written quote with every line item itemised. The price you sign is the price you pay, variations only if you change the spec.
• 10-year structural guarantee on all steelwork, roof structure and dormer construction.
• Full project management from drawings through Building Control sign-off. One point of contact start to finish.
• Stage payment schedule with no large up-front deposit. Pay as the build progresses.
• All trades vetted with current insurance, CSCS cards and Gas Safe / NICEIC certification where relevant.
• Building Regs handled in-house. We submit drawings, book inspections and deal with the local authority on your behalf.

If you want a fixed-price quote on your own roof, the fastest route is to request a free home survey. We will measure up, confirm what type of conversion suits the property, talk you through the spec and have a written quote back to you within five working days. There is no obligation to proceed.