Two-storey rear extensions in Tywyn
Adding a two-storey rear extension in Tywyn gives you two new rooms stacked on one footprint. Here's how we'd approach it, what it typically costs and the rules that apply in Wales.
Quick reference for homeowners in Tywyn.
- Postcode districts
- LL35, LL36, LL37, LL38, LL39 and LL42
- 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
- Aberystwyth (11.8 miles), Penparcau (12.6 miles), Pwllheli (25 miles)
- Distance to Bangor (Gwynedd and Anglesey)
- about 44.4 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.
Tywyn sits about 44.4 miles from Bangor (Gwynedd and Anglesey). Closer to home, Aberystwyth is 11.8 miles away and Penparcau 12.6 miles.
What it costs in Tywyn
Our guide for Wales is £1,840–£2,480 per m² including VAT. On a project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that puts a two-storey rear extension in Tywyn at roughly £51,500–£69,500. Professional fees for drawings and the structural engineer are listed separately 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 Tywyn
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 Tywyn homes
Depth and neighbours' light
Councils check that a two-storey rear extension does not take too much light or outlook from neighbouring windows, and many use a 45-degree line drawn from the nearest habitable window. We test this at sketch stage, so the depth you are shown is one that can realistically be approved.
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.
How we'd run your project
Visit and first ideas
One of our team visits your house in Tywyn, 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 Tywyn and deal with any questions from the planning officer.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.
Questions about two-storey rear extensions in Tywyn
Do I need planning permission for a two-storey rear extension in Tywyn?
Tywyn 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 Tywyn?
We cover Tywyn (LL35, LL36, LL37, LL38, LL39 and LL42) and nearby places including Aberystwyth, Penparcau and Pwllheli, plus the rest of Gwynedd and Anglesey. The first site visit is free.
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.
Who handles building regulations for a project in Tywyn?
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.
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
Other towns near Tywyn:
Other extensions in Tywyn
- Side
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Tywyn · 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.