Two-storey extensions in Holywell (Hertfordshire)
Everything for a two-storey extension in Holywell (Hertfordshire), in one place: types, guide prices for the East of England, the approval rules in England and how to get started.
Holywell (Hertfordshire) at a glance
- Postcode districts
- WD18
- Area
- Hertfordshire, England
- Price region
- East of England
- Nearest towns
- West Watford (0.8 miles), Watford (1.4 miles), Croxley Green (1.4 miles), Batchworth (1.9 miles)
- Distance to Watford
- about 1.4 miles
- Approvals
- Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission.
We cover postcode district WD18 in and around Holywell (Hertfordshire), along with neighbouring West Watford, Watford and Croxley Green.
Extensions available in Holywell (Hertfordshire)
Two-storey rear extensions
Guide from £57,500 in Holywell (Hertfordshire), including VAT.
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Two-storey side extensions
From £88,500 in Holywell (Hertfordshire). Free visit to firm it up.
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Two-storey wraparound extensions
Guide from £124,000 in Holywell (Hertfordshire), including VAT.
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Part single, part two-storey extensions
Our East of England guide starts at £74,000 for this type.
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Extensions over a garage
For homes in Holywell (Hertfordshire): typical guide from £32,500.
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First-floor extensions
For homes in Holywell (Hertfordshire): typical guide from £26,000.
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Two-storey extensions for semi-detached houses
Holywell (Hertfordshire) guide price from £57,500, Standard spec.
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Two-storey extensions for detached houses
Guide from £88,500 in Holywell (Hertfordshire), including VAT.
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Kitchen extensions with bedrooms above
Design, approvals and build for Holywell (Hertfordshire) homes. Guide from £57,500 (before kitchen units).
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Extra bedroom and en-suite extensions
Holywell (Hertfordshire) guide price from £57,500 (plus en-suite), Standard spec.
Learn moreWhich type suits your house?
If you're not sure which type fits, that's what the free visit is for. We'll sketch the realistic options for your house in Holywell (Hertfordshire), with a rough idea of the approval route and cost for each.
Also available in Hertfordshire
- Two-storey front extensions
- Two-storey extensions for end-of-terrace houses
- Two-storey annexe extensions
- Garage conversions with a room above
- Two-storey extension plans and drawings
- Planning permission for two-storey extensions
- Structural engineering for two-storey extensions
- Building regulations for two-storey extensions
- Party wall notices for extensions
- Design and build two-storey extensions
Rules for Holywell (Hertfordshire)
Holywell (Hertfordshire) is in England. Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission. Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
The full England rules explained
Questions about extensions in Holywell (Hertfordshire)
Do you cover Holywell (Hertfordshire)?
Yes. We cover Holywell (Hertfordshire) (WD18) and the surrounding area, including West Watford and Watford. The first site visit is free.
What does a two-storey extension cost in Holywell (Hertfordshire)?
Using our East of England guide, a two-storey rear extension with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) is about £57,500–£78,000 including VAT. An extension over a garage is about £32,500–£47,500.
Which other places near Holywell (Hertfordshire) do you cover?
Everywhere around it, including West Watford (0.8 miles), Watford (1.4 miles) and Croxley Green (1.4 miles), and the rest of Hertfordshire.