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 Llandrindod Wells?
In Llandrindod Wells, 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. Building costs in Wales run about 8% below the UK average, and the figures for Llandrindod Wells are adjusted to reflect that. 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 |
The biggest cost drivers are:
- Drains, gas meters or soil pipes that need moving
- Roof design and tile matching
- 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 Llandrindod Wells?
The approval route for Llandrindod Wells 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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
The work we manage on a side extension:
- Building control completion
- Survey of the boundary, drains and access
- Structural calculations
- Walls, roof and windows to match the house
- Opening into the existing house
- Foundations and drainage alterations
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 Llandrindod Wells
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
From LD1 outwards, we take on projects throughout Llandrindod Wells and the surrounding parts of Powys.
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 pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 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 Llandrindod Wells
Who approves a side extension in Llandrindod Wells?
Planning matters in Llandrindod Wells go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.
How much does a side extension cost in Llandrindod Wells?
In Llandrindod Wells, 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.
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.
Do I need planning permission for a side extension in Llandrindod Wells?
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 long does it take?
Roughly 10 to 16 weeks on site once approvals are in place, depending on whether it is one or two storeys.
