House Extension & Loft Conversion Costs in Maidstone (2026)

Maidstone extension and loft conversion prices for 2026

We model Maidstone prices by taking national build rates per m² and applying the South East multiplier of 1.12. Professional fees (design at 4–7% of the build, a structural engineer and building control), the relevant planning or certificate fee and VAT at 20% are then added. The results below are estimates from that model rather than quotes from Maidstone builders.

Project	Size	Basic	Standard	High-end
Single-storey rear extension	20m²	£52,000 – £68,000	£63,000 – £82,500	£77,000 – £105,500
Kitchen extension with mid-range kitchen	25m²	£82,500 – £120,000	£96,500 – £138,000	£114,000 – £166,500
Two-storey extension (planning)	40m²	£91,500 – £117,000	£111,000 – £143,000	£136,000 – £183,500
Wrap-around extension	30m²	£81,500 – £104,000	£98,000 – £130,000	£123,000 – £164,500
Hip to gable loft conversion	30m²	£58,000 – £81,500	£63,500 – £91,000	£78,500 – £109,500
Rear dormer loft conversion	30m²	£47,500 – £70,500	£53,000 – £80,000	£65,500 – £95,000
Rooflight (Velux) loft conversion	25m²	£23,000 – £34,500	£26,000 – £39,000	£32,000 – £47,000
Garage conversion	15m²	£11,000 – £16,500	£15,000 – £22,000	£20,000 – £29,000

Per-m² rates for the most common Maidstone projects at a standard finish, before VAT:

• Single-storey rear or kitchen extension: £2,464 – £3,024 per m²
• Two-storey extension: £2,184 – £2,688 per m² of total floor area
• Hip to gable loft: £1,658 – £2,240 per m²
• Rear dormer loft: £1,366 – £1,949 per m²
• Garage conversion: £739 – £1,030 per m²

The national picture behind these numbers is in our house extension cost guide and loft conversion cost guide.

Maidstone’s homes: town, suburbs and villages

Maidstone borough has around 171,800 residents, and the council’s spatial strategy topic paper says roughly three-quarters of them live in the Maidstone urban area in the north-west of the borough. The rest live in a large rural hinterland of villages such as Headcorn, Marden, Staplehurst, Lenham and Yalding. About 27% of the borough lies within the Kent Downs National Landscape (formerly the Kent Downs Area of Outstanding Natural Beauty), and a small slice, around 1.3%, is Metropolitan Green Belt.

Georgian and Victorian streets near the town centre

The council’s 2007 appraisal of the Holy Trinity conservation area, just east of the High Street, describes two- and three-storey terraces of the early to mid 19th century with a “late Georgian” character, mostly in pale yellow stock brick under low-pitched Welsh slate roofs, with Kent peg tiles on some earlier houses and Kentish ragstone on a few. Houses like these suit a modest rear dormer or rooflights, but conservation controls (see below) mean almost any roof change needs consent.

Twentieth-century suburbs

Much of the wider urban area is made up of semi-detached and detached houses from the 20th century, the kind of homes where a hipped roof is common. A hip to gable loft conversion with a rear dormer is usually the most effective way to gain a full-height bedroom, and a single-storey rear extension or wrap-around extension opens up the ground floor. Many of these houses also have an attached or integral garage that can be converted relatively cheaply; see our garage conversion cost guide.

Village properties

Older village houses, especially in Maidstone’s many village conservation areas, are often listed or sensitive to change, so extensions tend to be smaller and better detailed, with materials matched to the original building.

Planning permission for extensions in Maidstone

Maidstone Borough Council is the planning authority. Standard national permitted development rules apply across most of the borough: single-storey rear extensions of up to 3m on attached houses and 4m on detached houses (or up to 6m and 8m through prior approval), loft additions of up to 40m³ on terraces and 50m³ on semis and detached houses, and no rights for flats. A lawful development certificate costs £274 and is worth having when you sell; a householder application costs £548. See our extension planning permission and loft conversion planning permission guides for the detailed limits.

Maidstone’s Residential Extensions SPD

When you need planning, the council still refers to its Residential Extensions Supplementary Planning Document, adopted in May 2009. Some of the figures that shape Maidstone designs:

• Rear extensions: on semi-detached and terraced houses, normally no more than 3m from the rear wall; on detached houses close to a neighbour, generally no more than 4m.
• Single-storey height: eaves of about 3m and overall height of about 4m on attached houses.
• 45-degree test: if the centre of a neighbour’s habitable room window lies on or within 45-degree lines drawn from the extension on plan and elevation, the council may find a significant loss of light. Passing the test does not guarantee approval.
• Two-storey side extensions: where a street has a pattern of gaps between houses, keep a minimum 3m gap to the adjoining property, set back from the front with a lower roof.
• Dormers: set back at least 20cm from the eaves, never above the original ridge, and in proportion to the roof. New front dormers are not normally allowed on streets that have none.
• Roofs: extension roofs should match the main roof pitch, and flat roofs visible from the street are unlikely to be accepted.
• Countryside: outside settlements, the SPD treats an extension as modest if it adds no more than 50% to the volume of the original dwelling, counting garages and outbuildings within 5m.

Some of the national policy the SPD quotes has since been replaced, so check its status with the council. The adopted Maidstone Borough Local Plan Review 2021–2038 (adopted 20 March 2024) is the main test: its policy LPRHOU2 supports extensions in the built-up area where scale and appearance fit the house and street, neighbours do not suffer unacceptable loss of privacy, outlook or daylight, and enough parking is kept within the plot.

Conservation areas, Article 4 and the Kent Downs

The borough has 41 conservation areas, six of them in Maidstone town (All Saints, Ashford Road, Chillington House, Holy Trinity Church, Rocky Hill and the Town Centre), with the rest in villages from Bearsted to Yalding and the Loose Valley. Most of the borough’s current Article 4 directions deal with converting town-centre offices to flats or with parcels of rural land, rather than ordinary houses. The exception to watch is Holy Trinity: the 2007 appraisal records a 1996 Article 4(2) direction bringing roof alterations, enlargements, porches, outbuildings and exterior painting of single houses under planning control.

In the Kent Downs National Landscape and in conservation areas, side extensions, roof additions such as dormers, and cladding are not permitted development, and rear extensions are limited to a single storey. A hip to gable conversion that is routine in a town suburb will need a full planning application in villages such as Detling, Hollingbourne or Boxley if they fall within these areas.

Practical Maidstone factors: Kent highway permits and access

Kent County Council, not Maidstone Borough Council, issues permits for anything placed on the public highway. Its published fees for 2026–27 are:

• Skip on the highway: £45 per week.
• Scaffolding on the highway: £52 per week, plus a £78 site inspection before and after placement.
• Hoarding: £76 per week.
• Materials stored on the highway: £52 per week.
• Mobile crane or work platform: £235 per week.

Because the charges are weekly, a front scaffold left up for eight weeks costs around £416 plus the inspection fee, so a tight programme saves money. KCC also lists a £120 defect fee for an unlicensed or non-compliant skip. Party wall notices will apply to most semi and terrace conversions; read our party wall agreement guide and budget £1,000–£3,000 per neighbour if a party wall surveyor is appointed.

Loft conversion Maidstone: matching the type to the house

• Hipped-roof semi or detached house: hip to gable plus rear dormer, usually permitted development in the town.
• Gable-ended house or terrace: a rear dormer loft conversion on its own, set back from the eaves in line with the council’s SPD.
• Listed or conservation-area house: rooflights on the rear slope or a small pitched dormer, with planning permission or listed building consent.
• Bungalow: a dormer or rooflight conversion can turn a two-bedroom bungalow into a three- or four-bedroom home; see our bungalow loft conversion cost guide.

Our loft conversion cost calculator compares all four main loft types for your floor area.

House extension Maidstone: what fits the rules

Because the SPD points to about 3m for rear extensions on attached houses, many Maidstone owners combine a 3m single-storey rear extension with a side infill or side extension to gain width rather than depth. Detached houses have more room, and a two-storey extension to the side is common where the 3m gap and set-back can be achieved. Keep enough parking on the drive: the local plan expects it to be retained within the plot.

How long a Maidstone project takes

1. Survey and design: 3–6 weeks.
2. Approval: 8 weeks for a lawful development certificate or householder application; party wall notices run alongside.
3. Build: about 7–10 weeks for a hip to gable with dormer and 10–16 weeks for a single-storey extension.
4. Sign-off: a building control completion certificate after the final inspection.

Does an extension add value in Maidstone?

ONS data drawn from the HM Land Registry UK House Price Index puts the average Maidstone price at £353,000 in August 2026 (provisional), down 1.1% on a year earlier. Semi-detached homes averaged £378,000 and detached homes £608,000, a gap of £230,000. That gap is why many semi owners extend: a four-bedroom semi with a hip to gable loft can sell closer to small detached houses on similar streets, although it will rarely close the gap completely. With prices flat over the past year, base your budget on current sold prices nearby rather than expecting the market to cover a high-end finish. For borrowing options, see how to finance an extension.

Saving money on a Maidstone extension or loft

• Design to the 2009 SPD figures from the start if you need planning, so you are not redrawing after a refusal.
• Check designations for the Kent Downs, conservation areas and Holy Trinity’s Article 4 direction before paying for drawings.
• Keep highway permits short: KCC charges by the week, so plan scaffold and skip dates tightly.

Maidstone extension and loft conversion FAQs

How much is a loft conversion in Maidstone?

On our 2026 model, a 30m² rear dormer costs about £53,000–£80,000 and a hip to gable about £63,500–£91,000 with a standard finish, including fees and VAT.

How much does a single-storey extension cost in Maidstone?

About £63,000–£82,500 for 20m² at a standard finish, including design, building control and VAT. A 25m² kitchen extension with a mid-range kitchen is around £96,500–£138,000.

Do I need planning permission for an extension in Maidstone?

Not always. Many rear extensions and lofts are permitted development, but you need permission for flats, most two-storey extensions, and side extensions or dormers in conservation areas or the Kent Downs National Landscape.

How deep can a rear extension be in Maidstone?

Under permitted development, 3m on an attached house and 4m detached, or 6m and 8m with prior approval. If you need planning, the council’s SPD normally looks for no more than 3m on semis and terraces.

Who issues skip and scaffold permits in Maidstone?

Kent County Council. Its 2026–27 fees are £45 a week for a skip and £52 a week for scaffolding, plus a £78 inspection fee for scaffolding.

How many conservation areas are there in Maidstone?

The council lists 41 across the borough, including six in Maidstone town. Check its online map before planning any roof or side extension.

Costs in other areas: London extensions · London lofts · Beckton · Leatherhead · Portsmouth · Essex · Peterborough · Bristol · Birmingham · Nottingham · Manchester · Leeds · Liverpool · Llanelli · Glasgow · All areas compared

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