Two-storey annexe extensions in Hampshire

Hampshire at a glance

Nation: England
Price region: South East England
Postcode areas: BH, GU, PO, RG, SO, SP
Towns covered: 34 listed below, plus surrounding villages
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Site visits: Free, no obligation

What a two-storey annexe extension involves

This service suits you if a parent, grown-up child or carer is moving in and you want them to have their own space while staying connected to the house. You get a layout that can be self-contained or shared, the approvals your nation needs with the annexe use made clear, accessible design where needed and the build, carried out by vetted teams working under S&K.

Across Hampshire we cover Southampton (SO14), Portsmouth (PO1), Basingstoke (RG21), Gosport (PO12), Waterlooville (PO7) and Farnborough (Hampshire) (GU14), plus the smaller places around them.

Guide price in South East England

A guide price for Hampshire: around £94,500–£127,000 (plus kitchenette and shower room fittings, priced to your choice) for a 3 m × 7 m footprint on two floors (42 m² of new floor space). That works out at £2,260–£3,030 per m² of new floor space, including VAT at 20%. The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.

Spec	Per m²	Typical project
Essential	£2,070–£2,780 per m²	£87,000–£117,000
Standard	£2,260–£3,030 per m²	£94,500–£127,000
Premium	£2,710–£3,630 per m²	£113,500–£152,500

Rules in England

In England, an annexe on two floors is assessed like any two-storey extension: at the rear it can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, but at the side it needs planning permission, costing £548 (or £575 for applications made from 8 December 2026). Councils often add a condition that the annexe stays ancillary to the main house and is not let separately.

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.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Ground-floor living for the future

Many annexes are planned so the occupant could live on the ground floor if stairs become difficult. A ground-floor bedroom space, a level-access shower and wider doorways cost little at the design stage and are expensive to add later.

Services and metering

An annexe usually shares the main house's water, gas and electricity, with a separate circuit or sub-meter if you want to split costs. We plan heating, hot water and drainage so the annexe works well without needing new supplies.

How we work in Hampshire

Visit and first ideas
One of our team visits your house in Hampshire, 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.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Towns we cover in Hampshire

Two-storey annexe extensions in Hampshire: questions

How much does a two-storey annexe extension cost in Hampshire?

In South East England our guide is £2,260–£3,030 per m² including VAT, so about £94,500–£127,000 (plus kitchenette and shower room fittings, priced to your choice) for a 3 m × 7 m footprint on two floors (42 m² of new floor space). Essential and Premium specs move that by roughly 8% down or 20% up.

Can an annexe have its own front door?

It can, but a separate front door, kitchen and address together make it look more like a separate home, which can change how the council treats it for planning. Many annexes have their own door to the garden or side and an internal door to the main house. We explain how each choice is likely to be viewed before the design is fixed.

Can an annexe be designed for someone with limited mobility?

Yes. We can plan a ground-floor bedroom space, a level-access shower, wider doorways, lever handles and space for a stairlift later. These features are much cheaper to build in at the start than to add afterwards, and they keep the annexe useful as needs change.

Can I rent out an annexe later?

Not always. Many annexe permissions include a condition that it is only used by members of the household, so renting it out may need a fresh planning application. If you think you might want to let it, tell us at the start so we can explain the options.

Will I need planning permission in Hampshire?

Hampshire is in England. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.

Neighbouring areas

All extension services in Hampshire · About two-storey annexe extensions