First-floor extensions in Colwyn Bay
Thinking about a first-floor extension in Colwyn Bay? We design it, take it through the approvals it needs and build it, with one team responsible from the first visit to the final certificate.
What we'd confirm first for a project in Colwyn Bay.
- Postcode districts
- LL28 and LL29
- County / area
- Clwyd, Wales
- Price region
- Wales
- Guide price
- £23,000–£33,500 (£1,660–£2,390 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
- Deganwy (4.2 miles), Llandudno (4.8 miles), Abergele (6 miles)
- Distance to Wrexham
- about 35 miles
- First visit
- Free, no obligation
About a first-floor extension
A first-floor extension suits you if your house already has a single-storey extension and you need more space upstairs. You get a structural check of the existing walls and foundations, a design that ties the new floor into the house, the approvals your nation needs, building regulations approval and the build, managed by us and carried out by vetted teams working under S&K.
We cover postcode districts LL28 and LL29 in and around Colwyn Bay, along with neighbouring Deganwy, Llandudno and Abergele.
What it costs in Colwyn Bay
For budgeting in Colwyn Bay, allow around £23,000–£33,500 for a first-floor extension with 4 m × 3.5 m of new first-floor space (14 m²). That's based on £1,660–£2,390 per m² including VAT for Wales. Professional fees for drawings and the structural engineer are listed separately on our prices page.
| Spec | Per m² | 4 m × 3.5 m of new first-floor space (14 m²) |
|---|---|---|
| Essential | £1,520–£2,200 per m² | £21,500–£31,000 |
| Standard | £1,660–£2,390 per m² | £23,000–£33,500 |
| Premium | £1,990–£2,870 per m² | £28,000–£40,000 |
Planning and building regulations in Colwyn Bay
In Wales, a first floor over a rear extension can be permitted development if it goes no more than 3 m beyond the original rear wall and stays at least 10.5 m from the rear boundary, with the ground floor within 4 m. Over a side extension, the 10.5 m, 1 m set-back and 50% width tests apply. Otherwise 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 Colwyn Bay homes
Tying into the house
The new floor and walls must line up with the existing first floor, often through a new opening in the rear wall above the old one. Floor levels, the position of upstairs windows and the existing roof all affect where the opening can go, so we survey both floors carefully.
Escape 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 450 mm high, with the bottom no more than 1,100 mm above the floor, unless there is a protected route to the stairs.
How we'd run your project
Free site visit
We visit your home in Colwyn Bay, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.
Questions about first-floor extensions in Colwyn Bay
How much does a first-floor extension cost in Colwyn Bay?
Our guide for Wales, which covers Colwyn Bay, is £1,660–£2,390 per m² including VAT. A typical project with 4 m × 3.5 m of new first-floor space (14 m²) comes to about £23,000–£33,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Do I need planning permission for a first-floor extension in Colwyn Bay?
Colwyn Bay 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.
Which postcodes do you cover around Colwyn Bay?
We cover Colwyn Bay (LL28 and LL29) and nearby places including Deganwy, Llandudno and Abergele, plus the rest of Clwyd. The first site visit is free.
Can I build on top of my existing single-storey extension?
Often yes, but only after the structure has been checked. Foundations, walls and lintels built for one storey may not carry two. We dig trial holes, look for the original building control approval and ask the structural engineer to confirm what can stay, what needs strengthening and what must be rebuilt.
What happens to the room below while the first floor is built?
The old roof is removed, so the room below is exposed for a short period. We fit temporary weather protection, plan the work so the roof comes off only when the new structure is ready, and agree with you which rooms will be out of use and for roughly how long.
Nearby
The same service in neighbouring towns:
Other extensions in Colwyn Bay
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Colwyn Bay · First-floor extensions across Clwyd
Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Colwyn Bay.