Mablethorpe, Lincolnshire
Semi-detached rear extension in Mablethorpe
We plan and build rear extensions for semi-detached houses for homeowners in Mablethorpe. Single or two-storey extensions for semi-detached houses, with side access and one party wall. Start with a free site visit, then a written price once the design is agreed.
Mablethorpe sits in Lincolnshire, with postcode districts including LN12. Where a Mablethorpe 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 Mablethorpe?
For Mablethorpe we work from the East Midlands rate: £1,840–£3,010 per square metre of new floor, including VAT, standard specification. East Midlands prices sit a little below our West Midlands baseline.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £22,000–£36,000 |
| 4 m wide × 5 m deep (20 m²) | £37,000–£60,000 |
| 4 m wide × 6 m deep (24 m²) | £44,000–£72,000 |
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 Mablethorpe?
Here is how the rules in England apply to a semi-detached rear extension in Mablethorpe.
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
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.
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 Mablethorpe like to extend?
Red-brick terraces and semis are typical of Mablethorpe. Coal-mining legacy areas in parts of the East Midlands can need a Coal Authority check before foundations are designed.
How a semi-detached rear extension in Mablethorpe 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.
Paperwork handled
Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Semi-detached rear extensions near Mablethorpe
Neighbouring places we cover include Louth (11.1 miles) and Skegness (14.0 miles).
- Semi-detached rear extension in Louth
- Semi-detached rear extension in Skegness
- Semi-detached rear extension in Cleethorpes
- Semi-detached rear extension in Grimsby
- Semi-detached rear extension in Immingham
Other work in Mablethorpe:
FAQ
Semi-detached rear extension questions in Mablethorpe
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.
How much does a semi-detached rear extension cost in Mablethorpe?
As a guide, £1,840–£3,010 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £22,000–£36,000 at that rate. Your written price follows the survey.
Single or two-storey on a semi?
Two-storey if you need bedrooms, single-storey if you need a bigger kitchen. Planning risk is lower for single-storey.
What postcode areas do you cover around Mablethorpe?
Including LN12, and the surrounding Lincolnshire area.
How long does a rear extension take to build in Mablethorpe?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.