What is a side extension?

A side extension builds into the space beside a semi-detached or detached house, often over a driveway or side passage. It can be single-storey, for a utility room, downstairs toilet or study, or two-storey to add a bedroom above.
How much does a side extension cost in Llandudno?
In Llandudno, a side extension typically costs £1,550–£2,450 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £43,500–£68,500. The guide for Llandudno 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 (20 m²) | £31,000–£49,000 |
| Typical project (28 m²) | £43,500–£68,500 |
| Larger project (39 m²) | £60,500–£95,500 |
| Rate per m² | £1,550–£2,450 |
What moves the price most:
- Roof design and tile matching
- Boundary walls and access for materials
- Steel work where the side wall is opened
- Single or two storeys
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a side extension in Llandudno?
The approval route for Llandudno is set by planning law in Wales. In Wales a single-storey side extension can be permitted development if it is no more than 4 metres high and the widest part of the house ends up no more than 50% wider than the original. Two-storey side extensions must be at least 10.5 metres from the side boundary and set back 1 metre from the front, so most need planning permission. In conservation areas single-storey side extensions are limited to 3 metres.
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
From survey to sign-off, the job normally involves:
- Electrics, heating and plastering
- Survey of the boundary, drains and access
- Foundations and drainage alterations
- Opening into the existing house
- Structural calculations
- Planning drawings and application
How long does it take?
The build itself usually takes 10 to 16 weeks on site depending on size and storeys. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Llandudno
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 Llandudno (LL30) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about side extensions in Llandudno
Can a side extension go over a drain?
Often yes, with a build-over agreement from the water company or by rerouting the drain. We check this during the survey.
Do I need planning permission for a side extension in Llandudno?
In Wales a single-storey side extension can be permitted development if it is no more than 4 metres high and the widest part of the house ends up no more than 50% wider than the original. Two-storey side extensions must be at least 10.5 metres from the side boundary and set back 1 metre from the front, so most need planning permission. In conservation areas single-storey side extensions are limited to 3 metres.
How much does a side extension cost in Llandudno?
In Llandudno, a side extension typically costs £1,550–£2,450 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £43,500–£68,500. Your fixed price depends on the survey and drawings.
Who approves a side extension in Llandudno?
Planning matters in Llandudno go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Will a two-storey side extension look odd?
Not if it is designed well. Setting it back from the front and keeping the roof lower than the main ridge usually gives a natural look and is what most councils ask for.
Will I lose my driveway?
A side extension often takes the side drive. We look at whether parking can be kept at the front and whether a dropped kerb is needed.
