Extensions over a garage in Worthing

Useful details for planning an extension over a garage in Worthing.

Postcode districts: BN11, BN12, BN13 and BN14
County / area: West Sussex, England
Price region: South East England
Guide price: £34,500–£50,500 (£1,930–£2,800 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Lancing (2.4 miles), Shoreham-by-Sea (4.6 miles), Steyning (5.2 miles)
Distance to Crawley: about 22 miles
First visit: Free, no obligation

About an extension over a garage

An extension over a garage suits you if you have an attached single garage beside the house and need an extra bedroom or a larger main bedroom with an en-suite. You get an inspection of the garage structure, a design that matches the house, the approvals your nation needs, structural design, building regulations approval and the build, carried out by vetted teams working under S&K.

We cover postcode districts BN11, BN12, BN13 and BN14 in and around Worthing, along with neighbouring Lancing, Shoreham-by-Sea and Steyning.

What it costs in Worthing

A guide price for Worthing: around £34,500–£50,500 for 3 m × 6 m of new first-floor space (18 m²). That works out at £1,930–£2,800 per m² of new floor space, including VAT at 20%. Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	3 m × 6 m of new first-floor space (18 m²)
Essential	£1,770–£2,580 per m²	£32,000–£46,500
Standard	£1,930–£2,800 per m²	£34,500–£50,500
Premium	£2,310–£3,370 per m²	£41,500–£60,500

Planning and building regulations in Worthing

In England, most garages sit beside the house, so building over one makes a two-storey extension beyond a side wall, which always needs planning permission. If the garage is at the rear, the 3 m and 7 m rules for two-storey rear extensions apply, measured from the original house. A householder application costs £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 Worthing homes

Checking the garage foundations

Garages are often built on shallow strip footings sized for a single-storey wall and a light roof. A trial hole shows their depth and condition, and the engineer decides whether they can carry two storeys or need underpinning or new foundations inside the garage.

Fire separation

If the garage stays a garage, the floor between it and the room above, and any door into the house, must give fire separation under building regulations. That usually means fire-resisting plasterboard ceilings, sealed gaps and a fire door, which we design in from the start.

How we'd run your project

Visit and first ideas
One of our team visits your house in Worthing, checks the walls, roof and drains, and sketches out options with you.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.

Questions about extensions over a garage in Worthing

Who handles building regulations for a project in Worthing?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

How long does an extension over a garage 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.

Do I need planning permission for an extension over a garage in Worthing?

Worthing is in England, so England planning rules apply. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Can I add an en-suite above the garage?

Yes, and it is a common choice for a main bedroom. The en-suite needs an extract fan under Part F, a route for the soil pipe down to the drains and enough fall for the waste, which can be harder over a garage. We plan the pipe route through the garage or an outside wall early.

How do I get into a room over the garage?

Usually through a new opening off the existing landing or a bedroom, so the stairs stay where they are. If the floor levels do not match, a step or two may be needed inside the new room. Where a landing opening is not practical, a new stair from a converted garage is an option.

Nearby

Nearby towns we cover for extensions over a garage:

Other extensions in Worthing

All two-storey extension services in Worthing · Extensions over a garage across West Sussex

Book a free site visit in Worthing and we'll tell you what's possible, what approvals you need and what the design stage would cost.