Merseyside
Rear extensions in Knotty Ash
Rear extensions in Knotty Ash: single-storey and two-storey extensions, side returns, wraparounds and glass-led designs, planned around terraced streets and 1930s semis and the English rules.
Knotty Ash is in Merseyside, with postcode districts including L13, L14 and L16. The nearest places we also cover are Old Swan (0.5 miles) and West Derby (1.3 miles).
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Rear extensions we build in Knotty Ash
- Single-storey rear extensions
- Two-storey rear extensions
- Kitchen-diner rear extensions
- Side return extensions
- Wraparound extensions
- Glazed and glass-box rear extensions
- Rear extensions for terraced houses
- Rear extensions for semi-detached houses
- Rear extensions for bungalows
- Rear extension plans and planning applications
Also available across Merseyside:
- Rear extensions for detached houses
- Flat-roof rear extensions
- Pitched and lean-to roof rear extensions
- Knocking through to a rear extension
- Roof lanterns and rooflights for rear extensions
- Permitted development rear extensions
- Larger home extension prior approval (England)
- Building Regulations for rear extensions
Rear extension prices in Knotty Ash
North West prices sit below our West Midlands baseline; access on terraced streets is the main variable.
| Example | Guide inc VAT |
|---|---|
| Single-storey, 3 m × 4 m (12 m²) | £21,500–£35,000 |
| Single-storey, 4 m × 6 m (24 m²) | £43,000–£70,000 |
| Two-storey, 3 m × 5 m footprint (30 m²) | £51,000–£76,000 |
| Side return, about 14 m² | £30,500–£50,000 |
| Wraparound, about 25 m² | £51,500–£84,500 |
What are homes in Knotty Ash like to extend?
Knotty Ash has long runs of terraced houses with back yards and alleys, plus 1930s semis further out. Yard extensions on terraces are often single-storey and close to both boundaries.
Planning rules for Knotty Ash
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Every rear extension in England needs Building Regulations approval, whether or not planning is needed. You can use the council's building control service or a registered building control approver, by full plans (checked before work, usually within five weeks) or a building notice, and you get a completion certificate at the end.
Nearby towns
FAQ
Questions people ask
How much is a rear extension in Knotty Ash?
A 3 m × 4 m single-storey rear extension is about £21,500–£35,000 including VAT at our North West England guide rates; the written price follows a survey.
Do I need planning permission in Knotty Ash?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Is the site visit in Knotty Ash free?
Yes, with no obligation.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.