Two-storey rear extensions in Bethesda

Before you start in Bethesda, here's what applies.

Postcode districts: LL57
County / area: Gwynedd and Anglesey, Wales
Price region: Wales
Guide price: £51,500–£69,500 (£1,840–£2,480 per m²)
Approval route: It may be permitted development if the ground floor goes no more than 4 m and the first floor no more than 3 m beyond the original rear wall, with the first floor 10.5 m from the rear boundary.
Nearest towns: Bangor (Gwynedd and Anglesey) (4.3 miles), Menai Bridge (5.6 miles), Caernarfon (9.2 miles)
Distance to Bangor (Gwynedd and Anglesey): about 4.3 miles
First visit: Free, no obligation

About a two-storey rear extension

A two-storey rear extension is a new two-floor addition built onto the back of your house, usually giving a larger kitchen or living space on the ground floor and one or two bedrooms or a bathroom above. Because both floors share one set of foundations and one roof, it adds a lot of floor space for the garden it uses. In some cases it can be built under permitted development, depending on where you live.

We cover postcode district LL57 in and around Bethesda, along with neighbouring Bangor (Gwynedd and Anglesey), Menai Bridge and Caernarfon.

What it costs in Bethesda

For budgeting in Bethesda, allow around £51,500–£69,500 for a two-storey rear extension with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). That's based on £1,840–£2,480 per m² including VAT for Wales. 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	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£1,690–£2,290 per m²	£47,500–£64,000
Standard	£1,840–£2,480 per m²	£51,500–£69,500
Premium	£2,210–£2,980 per m²	£62,000–£83,500

Planning and building regulations in Bethesda

In Wales, a two-storey rear extension can be permitted development if the ground floor goes no more than 4 m and the first floor no more than 3 m beyond the original rear wall, with the first floor at least 10.5 m from the rear boundary. Nothing within 2 m of a boundary can be higher than 4 m. Conservation areas and other protected areas are excluded, and a householder application costs £585.

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).

Design points for Bethesda homes

Opening up the ground floor

Knocking through the old rear wall means steel beams to carry the first floor and roof above. The structural engineer sets the beam sizes, padstones and any posts, and we plan them early so the open-plan layout you want is the one that gets built.

Foundations and drains

Foundations for two storeys carry more load than a single storey and may need to go deeper near trees or on clay. Rear extensions often sit near drains, so we check sewer records early, as building over or near a public sewer may need the water company's agreement.

How we'd run your project

Visit and first ideas
One of our team visits your house in Bethesda, checks the walls, roof and drains, and sketches out options with you.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in Wales before drawing in detail.
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 two-storey rear extensions in Bethesda

How much does a two-storey rear extension cost in Bethesda?

Our guide for Wales, which covers Bethesda, is £1,840–£2,480 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £51,500–£69,500. 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 Bethesda?

We cover Bethesda (LL57) and nearby places including Bangor (Gwynedd and Anglesey), Menai Bridge and Caernarfon, plus the rest of Gwynedd and Anglesey. The first site visit is free.

Who handles building regulations for a project in Bethesda?

We handle it as part of the project. What's needed in Wales: building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency). We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

How long does a two-storey rear extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils normally decide householder applications within 8 weeks), 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.

Will a two-storey rear extension block my neighbour's light?

It can if it is too deep or too close to the boundary, which is why councils look closely at its effect on neighbouring windows and gardens. We test the design against light and outlook early, keep the first floor shorter or set in where needed, and use a hipped roof to reduce bulk on the boundary side.

Nearby

We also cover places near Bethesda, including:

Other extensions in Bethesda

All two-storey extension services in Bethesda · Two-storey rear extensions across Gwynedd and Anglesey

Want a figure first? Try our guide price tool, then book a free visit to firm it up.