First-floor extensions in Hythe (Kent)

Quick reference for homeowners in Hythe (Kent).

Postcode districts: CT21
County / area: Kent, England
Price region: South East England
Guide price: £27,500–£40,000 (£1,980–£2,860 per m²)
Approval route: It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
Nearest towns: Folkestone (3.7 miles), New Romney (8.6 miles), Ashford (Kent) (10.5 miles)
Distance to Maidstone: about 28 miles
First visit: Free, no obligation

About a first-floor extension

A first-floor extension suits you if your house already has a single-storey extension and you need more space upstairs. You get a structural check of the existing walls and foundations, a design that ties the new floor into the house, the approvals your nation needs, building regulations approval and the build, managed by us and carried out by vetted teams working under S&K.

Hythe (Kent) sits about 28.0 miles from Maidstone. Closer to home, Folkestone is 3.7 miles away and New Romney 8.6 miles.

What it costs in Hythe (Kent)

Most of the cost of a first-floor extension is set by its size and specification. For Hythe (Kent) and the rest of South East England, our guide is £1,980–£2,860 per m² including VAT, so about £27,500–£40,000 for 4 m × 3.5 m of new first-floor space (14 m²). Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.

Spec	Per m²	4 m × 3.5 m of new first-floor space (14 m²)
Essential	£1,820–£2,630 per m²	£25,500–£37,000
Standard	£1,980–£2,860 per m²	£27,500–£40,000
Premium	£2,380–£3,430 per m²	£33,500–£48,000

Planning and building regulations in Hythe (Kent)

In England, adding a first floor turns a single-storey extension into one of more than one storey. To be permitted development, the extension as a whole must go no more than 3 m beyond the rear wall of the original house and stay at least 7 m from the rear boundary, with matching materials and roof pitch. Over a side extension it always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026).

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Hythe (Kent) homes

Matching the roofline

A first-floor extension often changes how the back or side of the house looks more than the original single storey did. Matching the main roof pitch and materials, and keeping the ridge below the main ridge, usually gives the best result and is expected for permitted development in England.

Can the existing structure take it?

Many single-storey extensions were built with foundations, walls and lintels sized for one storey. We find out what is there with trial holes and, where available, the original building control drawings. The engineer then decides whether to reuse, strengthen or rebuild parts of the structure.

How we'd run your project

Look at the house
We start in Hythe (Kent) with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about first-floor extensions in Hythe (Kent)

How long does a first-floor extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

How much does a first-floor extension cost in Hythe (Kent)?

Our guide for South East England, which covers Hythe (Kent), is £1,980–£2,860 per m² including VAT. A typical project with 4 m × 3.5 m of new first-floor space (14 m²) comes to about £27,500–£40,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Which postcodes do you cover around Hythe (Kent)?

We cover Hythe (Kent) (CT21) and nearby places including Folkestone, New Romney and Ashford (Kent), plus the rest of Kent. The first site visit is free.

What happens to the room below while the first floor is built?

The old roof is removed, so the room below is exposed for a short period. We fit temporary weather protection, plan the work so the roof comes off only when the new structure is ready, and agree with you which rooms will be out of use and for roughly how long.

Will the first-floor extension match my house?

It should, and in England matching materials and roof pitch is a condition of permitted development. We match brick, tile, mortar colour and window style where we can, and tell you at the design stage if an exact brick match is not available, so you can choose between the closest match and render or cladding.

Nearby

We also cover places near Hythe (Kent), including:

Other extensions in Hythe (Kent)

All two-storey extension services in Hythe (Kent) · First-floor extensions across Kent

The quickest next step is a visit. We'll look at your house in Hythe (Kent) and give you an honest view of the options.