What is a double-storey extension?
A double-storey extension (also called a two-storey extension) adds rooms on both the ground and first floor in one build. It typically gives a larger kitchen or living space downstairs and an extra bedroom or bathroom above.
How much does a double-storey extension cost in Prestatyn?
In Prestatyn, a double-storey extension typically costs £1,500–£2,300 per m² of floor area (both floors), including VAT at 20% (standard rate). For a typical 36 m² project that is roughly £54,000–£83,000. The guide for Prestatyn reflects typical costs in Wales, roughly 8% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (25 m²) | £37,500–£57,500 |
| Typical project (36 m²) | £54,000–£83,000 |
| Larger project (50 m²) | £75,000–£115,000 |
| Rate per m² | £1,500–£2,300 |
The main things that change the cost:
- Bathrooms or en-suites on the first floor
- Roof design and how it joins the existing roof
- Scaffolding and access to the rear
- Total floor area across both floors
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a double-storey extension in Prestatyn?
Whether you need planning permission depends on your house and its location in Wales. In Wales a rear extension of more than one storey can be permitted development if the ground floor projects no more than 4 metres and the upper floor no more than 3 metres, with at least 10.5 metres to the rear boundary and obscure-glazed upper side windows. It is not permitted development in conservation areas, National Parks or National Landscapes, so many double-storey extensions need a householder application.
The Party Wall etc. Act 1996 applies in Wales, so notices must be served before work on a shared wall, on the boundary, or excavation close to a neighbour’s foundations.
We check this for your address before design work starts, so there are no surprises later.
What we handle
On a typical double-storey extension we handle:
- Opening up at both levels with steel beams
- Foundations, drainage and scaffolding
- Building control sign-off
- Electrics, heating, plumbing and plastering
- Design drawings and planning application
- Structural engineer’s calculations
How long does it take?
Allow 14 to 20 weeks on site, after planning and building control approval. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Prestatyn
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Projects in Prestatyn (LL19) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about double-storey extensions in Prestatyn
Do I need planning permission for a double-storey extension in Prestatyn?
In Wales a rear extension of more than one storey can be permitted development if the ground floor projects no more than 4 metres and the upper floor no more than 3 metres, with at least 10.5 metres to the rear boundary and obscure-glazed upper side windows. It is not permitted development in conservation areas, National Parks or National Landscapes, so many double-storey extensions need a householder application.
How much does a double-storey extension cost in Prestatyn?
In Prestatyn, a double-storey extension typically costs £1,500–£2,300 per m² of floor area (both floors), including VAT at 20% (standard rate). A typical 36 m² project comes to roughly £54,000–£83,000. Your fixed price depends on the survey and drawings.
Is a double-storey extension cheaper per square metre?
Usually yes. You pay for one set of foundations and one roof but get two floors of space, so the cost per square metre is often lower than a single-storey extension.
Can I live at home during the work?
Most families stay put. The shell is built first and the house is opened up late in the job, so disruption inside is limited to a few weeks.
Will the first floor need a new staircase?
Not normally. The new rooms are reached from the existing landing, though a doorway or short corridor may need to be formed.
How long does a double-storey extension take in Prestatyn?
Typically 14 to 20 weeks on site, after planning and building control approval. Design and approvals beforehand usually take 3 to 4 months.