Whitby, North Yorkshire
Semi-detached rear extension in Whitby
Thinking about a semi-detached rear extension in Whitby? Single or two-storey extensions for semi-detached houses, with side access and one party wall. Our team handles the drawings, the planning route and the build, and your contract is with one company throughout.
We cover Whitby (YO21 and YO22) as part of our North Yorkshire work. Where a Whitby semi already has a small lean-to at the back, we usually replace it rather than extend it.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Whitby?
For Whitby we work from the Yorkshire and the Humber rate: £1,770–£2,880 per square metre of new floor, including VAT, standard specification. Yorkshire prices sit below our West Midlands baseline; matching natural stone is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,000–£34,500 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£57,500 |
| 4 m wide × 6 m deep (24 m²) | £42,500–£69,000 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a semi-detached rear extension in Whitby?
Whether your semi-detached rear extension in Whitby needs a planning application depends on its size, your house and any local restrictions.
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.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Whitby like to extend?
Stone terraces and brick semis are typical of Whitby. Matching sandstone or gritstone on a terrace is one of the biggest cost variables, and reclaimed stone is often the best match.
How a semi-detached rear extension in Whitby comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Semi-detached rear extensions near Whitby
Neighbouring places we cover include Scarborough (16.7 miles) and Guisborough (18.0 miles).
- Semi-detached rear extension in Scarborough
- Semi-detached rear extension in Guisborough
- Semi-detached rear extension in Redcar
- Semi-detached rear extension in Middlesbrough
- Semi-detached rear extension in Hartlepool
Other work in Whitby:
FAQ
Semi-detached rear extension questions in Whitby
How long does a rear extension take to build in Whitby?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.
Do you handle building control in Whitby?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
How much does a semi-detached rear extension cost in Whitby?
As a guide, £1,770–£2,880 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £21,000–£34,500 at that rate. Your written price follows the survey.