Two-storey annexe extensions in Clwyd

Clwyd at a glance

Nation: Wales
Price region: Wales
Postcode areas: CH, LL
Towns covered: 20 listed below, plus surrounding villages
Approval route: Can be permitted development in Wales if it is 10.5 m from the side boundary, set back 1 m from the front and doesn't widen the house by more than half; otherwise planning permission.
Site visits: Free, no obligation

What a two-storey annexe extension involves

A two-storey annexe extension is an attached extension laid out as self-contained living space on two floors, usually with a living area and kitchenette below and a bedroom and shower room above, for a relative living with the family. It stays part of the main house rather than a separate home. Planning and council tax rules treat it differently from a separate dwelling.

Clwyd towns we list: Wrexham (LL13), Buckley (CH7), Deeside (CH5), Colwyn Bay (LL28), Flint (CH6) and Rhyl (LL18). Every other address in Clwyd is covered as well.

Guide price in Wales

Most of the cost of a two-storey annexe extension is set by its size and specification. For Clwyd and the rest of Wales, our guide is £1,890–£2,530 per m² including VAT, so about £79,000–£106,500 (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). Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	Typical project
Essential	£1,740–£2,330 per m²	£73,000–£98,000
Standard	£1,890–£2,530 per m²	£79,000–£106,500
Premium	£2,260–£3,040 per m²	£95,000–£127,500

Rules in Wales

In Wales, a two-storey annexe extension can use the same permitted development rules as other extensions: 4 m ground floor and 3 m first floor at the rear, or the 10.5 m, 1 m set-back and 50% width tests at the side. If you apply, the householder fee is £585, and councils may limit the annexe to use by the household.

Approval in Wales: Householder planning application: £585. Councils normally decide householder applications within 8 weeks.

Building regulations: Building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency).

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

Getting the design right

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.

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.

How we work in Clwyd

Free site visit
We visit your home in Clwyd, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Get it approved
Once you're happy with the design we submit it to the council for Clwyd and deal with any questions from the planning officer.
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.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Towns we cover in Clwyd

Two-storey annexe extensions in Clwyd: questions

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

In Wales our guide is £1,890–£2,530 per m² including VAT, so about £79,000–£106,500 (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 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.

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.

Will I need planning permission in Clwyd?

Clwyd is in Wales. Can be permitted development in Wales if it is 10.5 m from the side boundary, set back 1 m from the front and doesn't widen the house by more than half; otherwise planning permission.

Neighbouring areas

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