Double-storey extensions in Caernarfon

Covering Caernarfon

We work in Caernarfon (LL55) and the places around it, including Llangefni, Bangor and Pwllheli.

Homes in Gwynedd and Anglesey

Welsh homes include long terraces built into hillsides, stone cottages and modern estates, and sloping sites often shape how and where an extension can go.

What is included in a double-storey extension in Caernarfon?

A double-storey extension adds new rooms on both the ground and first floor in one build, typically a larger kitchen or living space downstairs and an extra bedroom or bathroom above. Because the roof and foundations are shared, the cost per square metre is usually lower than a single-storey extension.

Planning and building regulations checks under Welsh rules
Measured survey, design and planning drawings
Householder planning application

How much does a double-storey extension cost in Caernarfon?

Typical ranges for double-storey extensions. Ground conditions, access and specification move the final figure, which we fix in writing before work starts.

Double-storey extensions	Guide price incl. VAT
Standard specification	£2,400 to £2,900 per m²
Good specification	£2,900 to £3,400 per m²
High specification	£3,400 to £3,850 per m²

Planning and building rules in Caernarfon

In Wales the planning rules, including what counts as permitted development, are set by the Welsh Government, and Welsh building regulations differ in places from England’s. We check both against your house before drawings are finalised, and handle party wall notices where needed.

Most two-storey extensions in Wales need householder planning permission from the council. We prepare and submit the application and deal with any questions from the planning officer.

What can change the price or programme?

Neighbours’ light is assessed using the 45-degree guide many councils use.
The new roof is tied into the old one, so roof tiles and ridge details need to match.

How does the project run?

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

Questions about a double-storey extension in Caernarfon

How much does a two-storey extension cost?

Typically about £2,400 to £3,850 per square metre of new floor area including VAT. A 40 m² extension across two floors is often around £100,000 to £150,000 depending on specification.

Will we need to move out?

Most people stay. The noisiest stage is when we break through into the existing first floor, which we plan for a short window.

How do I get a price for double-storey extensions in Caernarfon?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Other towns nearby

Learn more about double-storey extensions, or see every project we cover in Caernarfon.