Extra bedroom and en-suite extensions in Bangor (Gwynedd and Anglesey)

Before you start in Bangor (Gwynedd and Anglesey), here's what applies.

Postcode districts: LL57 and LL58
County / area: Gwynedd and Anglesey, Wales
Price region: Wales
Guide price: £51,500–£69,500 (£1,840–£2,480 per m²), plus £5,500–£11,000 for the en-suite
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: Menai Bridge (1.7 miles), Bethesda (4.3 miles), Llangefni (7.7 miles)
First visit: Free, no obligation

About an extra bedroom and en-suite extension

An extra bedroom and en-suite extension is a two-storey extension planned around a new double bedroom with its own shower room on the first floor, with a ground-floor room below. It is one of the most effective ways to add space for a growing family. Nationwide's 2025 research linked adding a double bedroom and bathroom to a three-bed, one-bathroom house with value gains of up to 24%.

We cover Bangor (Gwynedd and Anglesey) (LL57 and LL58) and the places around it, including Menai Bridge (1.7 miles), Bethesda (4.3 miles) and Llangefni.

What it costs in Bangor (Gwynedd and Anglesey)

Guide prices for extra bedroom and en-suite extensions in Wales are around £1,840–£2,480 per m² of new floor space, including VAT. For a typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that's roughly £51,500–£69,500 (plus £5,500–£11,000 for the en-suite). Design fees, structural calculations and approval fees are separate and listed on our prices page.

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 Bangor (Gwynedd and Anglesey)

In Wales, an extra bedroom at the rear can be permitted development if the first floor goes no more than 3 m beyond the original rear wall and stays 10.5 m from the rear boundary. A two-storey side extension can also qualify if it is 10.5 m from the side boundary, set back 1 m and adds no more than 50% width. Otherwise the fee is £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 Bangor (Gwynedd and Anglesey) homes

Escape window and fire safety

A new first-floor bedroom needs an escape window with a clear opening of at least 0.33 m², at least 450 mm wide and high, and the bottom no more than 1,100 mm above the floor, unless there is a protected route to the stairs. We design the windows to meet this.

Sound and privacy

Bedrooms above a kitchen or family room benefit from an insulated floor to reduce noise. Side-facing upstairs windows usually have to be obscure-glazed, so we place the main bedroom window to the rear and the en-suite window to the side where possible.

How we'd run your project

Visit and first ideas
One of our team visits your house in Bangor (Gwynedd and Anglesey), checks the walls, roof and drains, and sketches out options with you.
Get it approved
Once you're happy with the design we submit it to the council for Bangor (Gwynedd and Anglesey) and deal with any questions from the planning officer.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Questions about extra bedroom and en-suite extensions in Bangor (Gwynedd and Anglesey)

How much does an extra bedroom and en-suite extension cost in Bangor (Gwynedd and Anglesey)?

Our guide for Wales, which covers Bangor (Gwynedd and Anglesey), 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 (plus £5,500–£11,000 for the en-suite). 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 Bangor (Gwynedd and Anglesey)?

We cover Bangor (Gwynedd and Anglesey) (LL57 and LL58) and nearby places including Menai Bridge, Bethesda and Llangefni, plus the rest of Gwynedd and Anglesey. The first site visit is free.

Do I need planning permission for an extra bedroom and en-suite extension in Bangor (Gwynedd and Anglesey)?

Bangor (Gwynedd and Anglesey) is in Wales, so Wales planning rules apply. 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. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

What goes on the ground floor below a new bedroom?

Whatever suits you: a bigger kitchen, a family room, a study, a utility or a downstairs shower room. The ground floor usually costs about the same whatever it is used for, apart from kitchen units and bathroom fittings, which are priced separately.

How big should a new double bedroom be?

There is no legal minimum size for a bedroom in a house you own, so the test is whether it works. A comfortable double needs room for the bed with space to walk round it, wardrobes and a door that opens freely. We draw furniture on the plans so you can judge the space before anything is built.

Nearby

Other towns near Bangor (Gwynedd and Anglesey):

Other extensions in Bangor (Gwynedd and Anglesey)

All two-storey extension services in Bangor (Gwynedd and Anglesey) · Extra bedroom and en-suite extensions across Gwynedd and Anglesey

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