Ask what a home extension costs in Maida Vale and the internet will hand you a tidy per-square-metre figure lifted from a national average. It is almost always answering a question that does not apply here. In W9 the useful question is not the rate. It is whether the law and your lease leave you any new floorspace to build in the first place.
That is not pedantry. Maida Vale is a district of grand cream-stucco terraces and broad red-brick mansion blocks laid out between the 1860s and the 1900s, most of it now inside a conservation area and a large share of it carved into leasehold flats. The open ground was spoken for long ago by the garden squares and the Regent's Canal, so back gardens here are shallow or absent. And a mansion flat, unlike a house, carries no permitted development right to extend at all.
So an honest guide to Maida Vale splits in two. The first half is what can actually be built between Warwick Avenue and the Kilburn end of the Maida Vale road. The second is what that work costs once it is permitted. The national benchmarks are not wrong, they simply describe a different job: an open suburban plot with a driveway, a skip on the drive and a crane over the fence. The Federation of Master Builders puts a single-storey extension at roughly £1,800 to £3,000 per square metre across the country. In W9 that figure barely covers reaching the starting line.
What follows is the real 2026 pricing, then the consent chain that fixes your start date, and the line items that quietly overrun W9 budgets.
A home extension cost in Maida Vale starts around £65,000 in 2026 for a small rear infill or closet-wing extension on a house. A full-width lower-ground rear extension runs £120,000 to £240,000, a mansard or additional-storey roof extension runs £170,000 to £330,000, and a single-storey basement scheme runs £330,000 to £700,000 and beyond. Per square metre that is £4,000 to £6,200 above ground and £6,200 to £9,500 for basement construction before fit-out. Those are Buildaway's own W9 quoting ranges. National guidance sits at roughly £1,800 to £3,000 per square metre. The gap is conservation constraint, freeholder consent, hand-carried structure, restricted hours and party wall exposure - not markup. And if you own a mansion flat rather than a house, the realistic answer is usually that you cannot extend outwards at all.
What Does a Home Extension in Maida Vale Cost in 2026?
A home extension cost in Maida Vale falls into four bands in 2026. A small rear infill or closet-wing extension runs £65,000 to £120,000. A full-width lower-ground rear extension runs £120,000 to £240,000. A mansard or additional-storey roof extension runs £170,000 to £330,000. A single-storey basement excavation runs £330,000 to £700,000 and beyond. Each band covers design, structure, envelope, services, finishes and VAT.
Maida Vale Home Extension Cost, by Project Type
Buildaway W9 quoting ranges, 2026 - bars scaled to the top of each range
Source: Buildaway 2026 quoting data for Maida Vale extension projects. Not drawn from any third-party cost index.
| Project type | What it includes | Maida Vale range | On site |
|---|---|---|---|
| Rear infill or closet-wing extension | Existing footprint plus 8–15 m² alongside the closet wing. New foundations, a structural opening, a glazed roof and a drainage diversion. | £65,000 – £120,000 | 12 – 18 weeks |
| Full-width lower-ground rear extension | 15–30 m² across the garden elevation. Steel goalpost, a lowered slab where the levels need it, garden glazing and a finished room. | £120,000 – £240,000 | 20 – 30 weeks |
| Mansard or additional-storey roof extension | 25–45 m² of new upper floor. Full scaffold and temporary roof, a slate and lead mansard, an extended stair and the fire and escape works. | £170,000 – £330,000 | 24 – 36 weeks |
| Basement scheme, single storey | 30–60 m² below the lowest floor. Sequenced underpinning, temporary works, tanking on twin pumps, a new lightwell and fit-out. | £330,000 – £700,000+ | 40 – 70 weeks |
Per square metre is the more useful comparison once you are weighing one direction of travel against another. The table below shows how the same project types price out per square metre of new floorspace in W9. As before, these are our own 2026 figures, not a published index.
| Work type | Maida Vale rate per m² | What drives the spread |
|---|---|---|
| Above-ground period extension | £4,000 – £6,200 | Stucco and heritage detailing, glazing, and how much structure is hand-carried |
| Mansard or roof extension | £4,600 – £6,800 | Scaffold duration, lead and slate detailing, fire and escape strategy |
| Basement construction, before fit-out | £6,200 – £9,500 | Depth, the canal-fed water table, and neighbouring foundations |
| Internal remodelling with structural openings | £2,300 – £3,600 | The realistic route in a flat: new structure and services, no new floorspace |
It also helps to think in proportion rather than in absolutes. ONS figures put the average City of Westminster property at £836,000 in May 2026, and flats and maisonettes at £743,000. Maida Vale's stucco houses trade well above that borough average, while its mansion flats cluster nearer to it. A fourth bedroom with an en suite is measured against what a comparable home fetches on the same avenue. That is why owners here extend rather than move. The stamp duty on trading up to a larger W9 house is usually the bigger cheque.
Why does a W9 extension cost more than most of London?
A Maida Vale home extension sits above the wider home extension London figure, and the reasons belong to this postcode rather than to the trade. Consent often runs through a freeholder as well as the council. Conservation rules govern every visible surface. Westminster stops the working day at six. And on most Maida Vale streets there is no room for a crane, so structure arrives on shoulders.
- A second consent to satisfy. Where the home is a leasehold flat, planning permission is only half the job. The freeholder licenses the work separately, and the two processes rarely run to the same calendar.
- Conservation constraint on every visible surface. Stucco patched and painted to match, cornices and mouldings reinstated, lead rather than a modern flashing, natural slate rather than a substitute, and sash joinery rather than a system window. Each of those is a specification decided for you.
- Restricted hours. Westminster's Code of Construction Practice permits work 08:00 to 18:00 on weekdays and 08:00 to 13:00 on Saturday. Nothing on Sundays or bank holidays. There is no evening catch-up, so programmes stretch and preliminaries run longer.
- No crane, no compound. A steel goalpost is lifted in half a day on a suburban plot. On a Maida Vale terrace it is cut, carried and bolted together in place, often through the front door and down the hall.
- Kerbside economics. A Westminster skip licence costs £87 for up to two skips over one month. On the wider avenues it only works alongside a paid parking bay suspension.
- ULEZ, not the Congestion Charge. Maida Vale sits outside the Congestion Charge zone, so that daily charge does not bite here. But the London-wide Ultra Low Emission Zone still charges £12.50 a day for any non-compliant vehicle, and over a long build with deliveries and trades that adds up in the preliminaries.
- Party wall exposure on two sides. A terraced or mansion-block W9 property has neighbours to the left and right, and excavating next to their foundations triggers statutory notices and, usually, two surveyors.
- Specification. Owners extending in Maida Vale are not buying a utility room. They are buying a room that has to sit convincingly inside a stucco Victorian house. That is a different product from a suburban rear extension.
The day rates below show what those constraints look like in labour terms. They are Buildaway's own 2026 rates for W9 work, carrying the access, protection and hours premium specific to this part of Westminster rather than a general London uplift.
| Trade | W9 day rate, 2026 | Note |
|---|---|---|
| Groundworker | £250 – £330 | Higher still on hand-dig underpinning below the water table |
| Bricklaying gang, two-person | £500 – £680 | Stock brick and lime mortar run slower than blockwork |
| Carpenter or joiner | £310 – £410 | Period reinstatement, not off-the-shelf fixing |
| Structural steel erection, two-person | £680 – £930 | Half-day minimums; sections often cut down to be carried in |
| Roofer or leadworker | £310 – £410 | Specified lead and natural slate on any visible mansard |
| Plumber | £310 – £410 | Carrying heating and hot water into the new floorspace |
| Part P electrician | £300 – £380 | New circuits are notifiable and certified on completion |
| Plasterer | £280 – £360 | Lime plaster where the fabric is historic or listed |
| Labourer | £180 – £240 | A larger share of the programme, because everything moves by hand |
For the wider comparison, our guide to single-storey rear extension costs in London sets out what the same work costs once the Central London constraints fall away.
Where does the money end up?
On a typical Maida Vale extension, roughly a third of the budget is spent on enabling work and structure before anything resembles a room. Envelope and roof take about a fifth. Services and fit-out share about a third between them, and fees, consent and contingency take what is left. The shape is the reverse of a suburban extension, where structure is cheap and the fit-out dominates.
Where the Budget Goes on a Maida Vale Extension
Buildaway W9 project data, 2026 - indicative split on an above-ground extension
Source: Buildaway 2026 project data for Maida Vale and surrounding W9 extensions. Bars are scaled against the largest band, not against 100%.
The contingency line is worth defending. On a modern house, 5% is fine. On a Victorian stucco house nobody has actually seen the foundations. The drains predate any record drawing. The last few owners each altered the structure without paperwork. So we hold 7% to 10%, and we explain why. A contingency is not padding. It is the difference between an honest fixed price and a running tally of variations.
How does cost change across the W9 pockets?
Maida Vale is not one market but several, and each pocket prices differently because it holds different buildings. Little Venice is villa and canal-side terrace territory. The central avenues are the grand stucco and mansion-block heartland. The Kilburn edge is where the stock thins to smaller conversions and the numbers ease.
- Little Venice - Blomfield Road, Maida Avenue, Warwick Avenue, Clifton Gardens, Clifton Villas. Detached and semi-detached stucco villas, several of them listed, with the deepest gardens in the district. This is where a lower-ground or garden extension has the clearest run, and also where the canal-side conservation controls are strictest. Expect the top of our ranges and expect scrutiny of anything visible from the water.
- Central Maida Vale - Randolph Avenue, Sutherland Avenue, Elgin Avenue, Delaware Road, the Maida Vale road itself. Broad red-brick and stucco mansion blocks and stucco terraces. Little scope for outward extension on the flats, strong demand for internal remodelling, roof space and lower-ground work on the houses. Cost is driven by freeholder consent and by working within a shared block.
- The Kilburn fringe - Shirland Road, Chippenham Road, the streets toward W9's northern edge. Smaller Victorian terraces and period conversions, more of them in single ownership. Extension is more often achievable here, and the heritage and consent layer is a smaller share of the total price.
If your property sits just beyond these pockets, the same team and the same approach cover the rest of the borough. St John's Wood raises much the same questions a few streets east, where large villas and mansion blocks meet the same Westminster rulebook.
Can You Actually Extend a Property in Maida Vale?
For a large share of Maida Vale homes the answer is no, at least not outwards. Permitted development rights apply to a dwellinghouse. A flat is not a dwellinghouse, so a mansion-block flat has no route to extend. Houses have rights on paper, but conservation area status strips most of them away. What remains is a planning application, freeholder consent where the home is leasehold, and a clear-eyed look at where space actually exists.
Why a mansion flat has no right to extend
Schedule 2, Part 1 of the General Permitted Development Order, which grants the familiar rights to extend, is written for dwellinghouses. Flats and maisonettes are excluded from it entirely. That single line of law decides the outcome for most of Elgin Avenue, the mansion blocks along the Maida Vale road and the porticoed conversions off Randolph Avenue. Any enlargement of a flat needs full planning permission and freeholder consent, and in practice the agreement of the leaseholders whose light, structure, demised space or amenity is affected. GOV.UK guidance on planning permission is the starting point, but your lease is what actually governs you.
Houses fare better, though not by much. A conservation area is article 2(3) land in planning language. On that land, side extensions fall outside permitted development, and so do rear extensions of more than one storey. The larger home extension route is unavailable, and the upward extension right introduced in 2020 does not apply. Maida Vale's coverage is broad: most of the district lies within the Maida Vale conservation area, with the canal streets inside the separate Little Venice conservation area, both maintained by Westminster.
What Maida Vale owners build instead
So a Maida Vale home extension is nearly always one of five things. A rear infill beside the closet wing. A lower-ground extension into a shallow garden. A mansard or extra storey where the roofline can carry it. A basement dug beneath the existing footprint. Or, for flats, an internal remodelling that wins usable space without adding a single square metre.
| Property type | Where you find it | What is realistically possible | Dominant constraint |
|---|---|---|---|
| Stucco villa | Blomfield Road, Maida Avenue, Clifton Gardens, Clifton Villas | Closet-wing infill, lower-ground extension, basement, occasional mansard | Listed status and canal-side conservation control |
| Victorian or Edwardian mansion flat | Elgin Avenue, the Maida Vale road, Delaware Road, Sutherland Avenue | Internal reconfiguration, lateral conversion, terrace enclosure, top-floor roof space | No permitted development rights; the lease and other leaseholders |
| Stucco terrace house | Randolph Avenue, Warrington Crescent, Warwick Avenue | Lower-ground extension, basement, mansard, rear infill | Conservation control and party walls on two sides |
| Period conversion | Shirland Road, Chippenham Road, the Kilburn-edge streets | Internal remodelling; rear infill where the demise allows | Undocumented earlier structural work |
| Upper flat above commercial | Formosa Street, Clifton Road, Sutherland Avenue parade | Roof extension where the terrace allows, internal remodelling | A trading business below setting hours and noise limits |
| Modern apartment | Post-war blocks along the Maida Vale road and Maida Vale fringe | Internal remodelling in almost every case | Managing agent, warranty and building safety conditions |
If you own a flat and extension is closed to you, the money is usually better spent on the space you already have. Our guide to kitchen renovation costs in Maida Vale covers that route. Where the property is a house with roof space, a loft conversion in Maida Vale is often the cheaper way to the same bedroom.
What Consents Does a Maida Vale Home Extension Need?
A Maida Vale home extension usually needs several consents, not one. Planning permission from Westminster. Listed building consent, where the building is listed. A licence for alterations from the freeholder, where the home is a leasehold flat. And building regulations approval. Party wall notices sit alongside them. Each runs on its own clock, so the order you tackle them in decides your start date.
Who holds the freehold of your building?
Maida Vale is not estate land in the way Marylebone is. There is no single great landlord licensing every alteration across the district. Freeholds are split between private landlords, long-term investors and resident management companies, and a good number of the houses are simply owned freehold by the people living in them.
That sounds like freedom, and for a freehold house it broadly is. But most of Maida Vale's homes are flats inside larger blocks and converted terraces, and there the freeholder still controls what you may do to the structure and the shared fabric.
So the practical question is not which estate owns you, but whether you hold your home freehold or leasehold. A freehold house answers to the council and the party wall surveyors. A leasehold flat answers to those and to the freeholder as well, and it is usually the freeholder's consent that fixes when work can begin.
What triggers a licence for alterations?
Essentially everything an extension involves, if you are leasehold. Structural change triggers it. So does altering the appearance of the building. So does installing plant, and a ventilation or air source unit counts as plant. In a flat, even a new hard floor finish can trigger it, because those finishes carry impact noise to the flat below.
Approval times vary widely, because there is no single estate process. A well-run resident management company can turn a clean application round in weeks; an absentee freeholder's managing agent can take far longer. In every case the clock only starts on a properly complete application, with drawings, a specification and a method statement. An incomplete pack does not start the count. It simply sits.
That single gap is the most common reason a Maida Vale home extension slips by a month or two. It is also entirely avoidable.
Which statutory consents apply?
- Planning permission. Assume you need it. The householder fee in England is £548 from 1 April 2026, and fees rise with CPI each April. Flats use a full application instead. Your scheme is judged against Westminster's City Plan 2019–2040, in the version adopted on 21 January 2026.
- Basements need permission, always. Westminster's city-wide Article 4 direction came into force on 31 July 2016. It removes permitted development rights for basement work across the city. Policy then limits a residential basement to one storey below the lowest original floor, and to no more than half the garden. You will also need a structural methodology statement, ground water and drainage evidence, and a construction management plan.
- Listed building consent. Listing is common on the Little Venice villas along Blomfield Road and Maida Avenue, and on the stucco terraces around Warwick Avenue. Historic England is blunt about the risk. Unauthorised work to a listed building is a criminal offence under section 9 of the Planning (Listed Buildings and Conservation Areas) Act 1990. It carries up to two years in prison or an unlimited fine. Both the person doing the work and whoever ordered it commit the offence.
- Conservation area control. Most of Maida Vale lies within the Maida Vale conservation area, with the canal streets falling inside the separate Little Venice conservation area. Westminster publishes audits and maps for each one. Read them before an architect draws anything.
- Party Wall etc. Act 1996. A party structure notice needs two months' notice. An excavation notice under section 6 needs one month. On a terrace you usually serve both neighbours. Each can appoint their own surveyor, at your cost.
- Building Regulations. Part A covers the new structure. Part B covers escape and fire on any new storey. Part C covers ground moisture and waterproofing. Part F, K and L cover ventilation, safety and thermal elements, and Part P covers the new circuits. Since April 2024 the private route to building control is a Registered Building Control Approver.
- Community Infrastructure Levy. A scheme comes into charge at 100 m² of new floorspace, or where it creates a dwelling. An extension to your own home can claim the residential extension exemption. But it must be claimed and granted first, and a commencement notice served, before work starts. Westminster sits in Mayoral CIL band 1 alongside its own charging schedule.
- Working hours. Westminster's Code of Construction Practice permits 08:00 to 18:00 on weekdays, and 08:00 to 13:00 on Saturday. Nothing on Sundays or bank holidays. Noisy work outside those hours needs consent under section 61 of the Control of Pollution Act, applied for at least 28 days ahead. A revised Code was published on 10 March 2026 and applies from 1 June 2026.
How Long Does a Maida Vale Home Extension Take?
Allow ten to eighteen months from first call to handover for an above-ground home extension, and eighteen to thirty months where a basement is involved. On site the work is twelve to eighteen weeks for a rear infill, and twenty to thirty weeks for a full-width lower-ground extension. A mansard takes twenty-four to thirty-six weeks, a basement forty to seventy. Consent, not construction, is the pacing item.
What Are the Hidden Costs of a W9 Home Extension?
The costs that catch Maida Vale homeowners out are rarely the bricks. They are the consent layer, the access layer and the neighbour layer. A quote built on a national per-square-metre rate never contains them. Below are the twelve that turn up most often on W9 projects, with the impact we typically see.
| Line item | Why it applies in Maida Vale | Typical impact |
|---|---|---|
| Freeholder licence deposit | Held by the freeholder against damage on a leasehold flat, returned after completion | Into five figures, out of your cash flow for the whole build |
| Legal costs, both sides | Your solicitor plus the freeholder's costs of granting the licence | £3,000 – £8,000 |
| Party wall surveyors | Two neighbours, each entitled to their own surveyor at your cost | £2,500 – £6,000 per adjoining owner |
| Heritage consultant and design team | Listed and conservation work needs a heritage statement and robust drawings | 8 – 12% of construction cost across the full design team |
| Community Infrastructure Levy | Triggered at 100 m² unless the exemption is claimed before work starts | Avoidable in most cases, painful when the claim is missed |
| Skip licence and bay suspension | Westminster skip licence, plus a paid bay suspension on the wider avenues | Recurring monthly across the programme |
| ULEZ charge | Maida Vale is outside the Congestion Charge zone, but ULEZ applies to non-compliant vehicles | £12.50 per non-compliant vehicle per day |
| Hand-carry and protection | No crane or compound; communal areas protected and reinstated | Adds labour weeks rather than material cost |
| Temporary works and propping | Propping schemes, underpinning sequences and mansard temporary roofs | £8,000 – £40,000 depending on scheme |
| Asbestos survey and removal | Common in mid-century repairs, and found on opening up | £500 survey; removal priced on discovery |
| Service diversions | Shared drainage and historic supplies that predate any record drawing | £2,000 – £15,000 |
| VAT | Standard-rated at 20%; 5% where a home has been empty two years or more | 20% of everything above |
How Do You Choose a Maida Vale Extension Contractor?
Judge a Maida Vale home extension contractor on consent fluency before you judge them on price. Anyone can produce a per-square-metre rate. The contractors who finish on programme here are the ones who can tell you, on the first visit, whether your home is freehold or leasehold and what your lease permits. They can also tell you which notices your neighbours will receive, and how the structure gets into the building at all.
Seven questions worth asking before you compare a single number:
- Is this home freehold or leasehold, and if leasehold, have you prepared a licence for alterations pack for a freeholder before?
- Is this building listed, and what will the heritage statement have to argue?
- Which party wall notices will my neighbours receive, when, and who pays for their surveyor?
- How does the structural steel physically get into the house, and what does that add to the programme?
- What are your working hours here, and how does that change the programme against a job outside Westminster?
- Does the quote include protection, licences, bay suspensions and any ULEZ charges, or are those excluded?
- Will you price against a consented scheme, or against a drawing that has not been approved yet?
The last one is the one that counts. A price given before consent is a guess wearing a spreadsheet.
You can see how we work locally on our page for home extension specialists in Maida Vale, which sets out how we run a Maida Vale home extension from feasibility to handover. Our home extensions service explains the design and build stages in more detail.
Planning an extension in W9 or the Little Venice canal streets? Buildaway handles the feasibility, the freeholder licence pack, the planning application and the build as one team, with one fixed quote - conservation areas and listed buildings included.
Request a free quote →Frequently Asked Questions
How much does a home extension cost in Maida Vale in 2026?
A small rear infill or closet-wing extension on a Maida Vale house costs £65,000 to £120,000. A full-width lower-ground rear extension with the garden reworked costs £120,000 to £240,000. A mansard or additional-storey roof extension costs £170,000 to £330,000. A single-storey basement excavation costs £330,000 to £700,000 and beyond. Per square metre, Buildaway's 2026 W9 rates run £4,000 to £6,200 above ground, £4,600 to £6,800 for roof work, and £6,200 to £9,500 for basement construction before fit-out. These are our own quoting ranges for W9 and the W2 canal fringe. They include structure, envelope, services, finishes and VAT.
Can you extend a flat in Maida Vale?
Rarely outwards. Maida Vale is dominated by purpose-built Victorian and Edwardian mansion flats, and permitted development rights under Schedule 2, Part 1 of the General Permitted Development Order apply only to a dwellinghouse. A flat is not a dwellinghouse, so there is no permitted development route to enlarge a mansion-block flat off Elgin Avenue or Maida Vale itself. Any enlargement needs full planning permission and the freeholder's consent under a licence for alterations, and usually the agreement of the other leaseholders whose light, structure or amenity is affected. What is realistically available is internal reconfiguration, lateral conversion into an adjoining flat, enclosing a lightwell or terrace where the lease allows, and reclaiming roof space in a top-floor flat.
Do I need planning permission for a home extension in Maida Vale?
Almost always. Most of Maida Vale lies within the Maida Vale and Little Venice conservation areas, both designated by Westminster. On conservation area land, side extensions and rear extensions of more than one storey fall outside permitted development, and the larger home extension and upward extension routes are unavailable. Westminster also confirmed a city-wide Article 4 direction on 31 July 2016 removing permitted development rights for basement development, so every basement, lightwell and excavation needs planning permission. The householder application fee in England is £548 from 1 April 2026. (Westminster City Council; Planning Portal)
Do I need freeholder consent for a Maida Vale extension?
If you own a leasehold flat, yes, and it is often the consent that sets your start date. Unlike neighbouring Marylebone, Maida Vale is not held by a single great estate; freeholds sit with a mix of private landlords, resident management companies and investors. But the mechanism is the same. A licence for alterations is required to make structural change, alter the appearance of the building or install plant, and even a new hard floor finish can trigger it because impact noise carries downwards. Budget for your own solicitor, the freeholder's legal and surveyor costs, and a refundable deposit that can run into five figures and sits out of your cash flow for the whole build. A freehold house avoids this layer but still needs planning and, where listed, listed building consent.
How long does a home extension take in Maida Vale?
Allow ten to eighteen months from first call to handover for an above-ground extension, and eighteen to thirty months where a basement is involved. On site, a rear infill takes twelve to eighteen weeks and a full-width lower-ground extension twenty to thirty weeks. A mansard takes twenty-four to thirty-six weeks, and a basement forty to seventy. The build is rarely the pacing item; planning determination in a conservation area, the freeholder's licence, any listed building consent and party wall awards on two neighbours consume most of the programme, along with Westminster's restricted hours of 08:00 to 18:00 on weekdays and 08:00 to 13:00 on Saturday. (Westminster City Council)
Do I have to pay the Community Infrastructure Levy on a Maida Vale extension?
Only where the scheme creates 100 square metres or more of new internal floorspace, or creates a new dwelling. Even then, a residential extension exemption can be claimed on an extension to your own home. The catch is procedural: the exemption must be claimed and granted before work starts, and a commencement notice served. Miss that sequence and the exemption is lost and the levy is payable in full. Westminster sits in Mayoral CIL band 1 alongside its own charging schedule, and the Mayoral levy has been index-linked to the BCIS tender price index since it took effect on 1 April 2019. (Westminster City Council; Mayor of London)
So What Should a Maida Vale Extension Cost You?
Maida Vale's costs are high, but they follow rules you can learn. And a cost you can predict is a cost you can plan for.
- A home extension cost in Maida Vale starts around £65,000 for a rear infill. A mansard reaches £170,000 to £330,000, and basement schemes pass £700,000. Per square metre that is £4,000 to £6,200 above ground, and £6,200 to £9,500 below. (Buildaway 2026 quoting data)
- National guidance of roughly £1,800 to £3,000 per square metre describes an unconstrained site, not the same work at a discount. (Federation of Master Builders)
- Ask whether you can extend before you ask what it costs. Mansion flats have no permitted development rights, and conservation area status removes most of what houses have. Westminster's Article 4 direction of 31 July 2016 means every basement needs planning permission. (GOV.UK; Westminster City Council)
- Where the home is leasehold, freeholder consent is the consent that sets your start date. Budget for the licence fee, legal costs on both sides and a refundable deposit that can run into five figures. (Westminster City Council)
- Plan for ten to eighteen months end to end above ground, and eighteen to thirty months with a basement. Consent and party wall awards are the pacing items, not the build.
- The strongest signal of a competent contractor here is not photographs. It is whether they can talk fluently about tenure, licences, listing, party wall notices, access and hours on the first visit.
At Buildaway we price Maida Vale extensions against a consented scheme rather than a hopeful one, and we build them under one fixed quote. To talk through your building's tenure and consent position, get in touch or see the areas we cover across London.