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What changes a side extension price in Cheshire?
In Cheshire, a side extension price is driven by how wide the original house is, how close the boundary sits, and whether the plot still has permitted development rights. No pound total is printed on this page, which instead lists the limits and the lines a written quote should show.
Last reviewed:Width is the first number
A side extension in Cheshire is the strip of building along the flank of the house, not a rear box and not a loft. People searching for a side extension are often trying to capture a narrow piece of land beside the kitchen. The price moves with the width you are allowed, the height you are allowed, and how you get materials down that side. Nothing on this page is a contractor's pound rate.
Crewe, Nantwich and Sandbach are the towns QuoteZila is writing for first. A flank wall in one of those towns is still drawn house by house. Builders should see the passage, the neighbour's gutter and the manhole before they commit a figure.
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The side-specific planning limits
The Planning Portal's extension rules include a block that applies only where the work extends beyond the side elevation of the original house. That extension cannot exceed four metres in height. It can only be a single storey. It can only be up to half the width of the original house [S1].
On Article 2(3) designated land, all side extensions require householder planning permission. That land includes a conservation area, an area of outstanding natural beauty, the Broads, a National Park and a World Heritage Site [S1].
There is a wider rule for every extension, not just a side one: it cannot be built forward of the principal elevation or, where it fronts a highway, the side elevation [S1]. A side addition that steps forward of the flank that faces the road is the case to check, not to assume. Only half the area of land around the original house can be covered by extensions and other buildings [S1]. Within two metres of a boundary, eaves height cannot exceed three metres [S1]. The original house is the house as first built, or as it stood on 1 July 1948 if it was already there [S1].
All side extensions of more than one storey require householder planning permission [S1]. A room over the new side piece is that case. It is not a permitted-development single-storey flank.
Flats and maisonettes are outside these householder rights. So is a house created under certain change-of-use rights, or built as a new dwellinghouse under the permitted development rights for new dwellinghouses. An Article 4 direction or a planning condition can remove the rights that would otherwise exist [S1]. If the added floor space is over 100 square metres, a Community Infrastructure Levy charge may also apply [S1].
The page to read against the drawing is the Planning Portal extension guidance.
Structure, glazing and building control
GOV.UK treats building regulations approval as different from planning permission. You might need both. The Building Regulations 2010 cover the construction and extension of buildings [S2]. Selling later without a certificate is one of the problems that page names, and the person doing non-compliant work could be prosecuted [S2].
Citizens Advice says an extension is an example of work you cannot leave solely to a competent person scheme. Approval from a building control body comes before the work starts. A fee is usually paid when you apply, and another payment can fall due when they inspect [S3]. The council's building control team, or a private registered building control approver, are the two routes GOV.UK describes for projects that are not higher-risk buildings [S2]. Higher-risk buildings are at least 7 storeys or 18 metres high, and are a hospital, a care home, or hold at least two homes [S2]. A domestic side extension is not that category. Ask the building control body anyway, because the extension itself is controlled work.
GOV.UK: building regulations approval. QuoteZila is not affiliated with this organisation. GOV.UK: find your local council for building control. QuoteZila is not affiliated with this organisation.
Glazing on a side extension is part of the quote, not a later shopping trip. Glaziers may supply the side windows. Ask whether those windows are in the builder's figure or in a separate supply. Do not fit the glass yourself from these notes.
Boundary walls and pipes
New building on or at the boundary of two properties is one of the things the Party Wall etc. Act 1996 covers. Excavation near to and below a neighbour's foundation is another [S4]. A side extension is the project most likely to sit on that line, because the flank is often the boundary.
The Act stands apart from planning permission and from building regulations approval [S4]. A building owner who proposes covered work must give adjoining owners a party wall notice in the way the Act sets down [S4]. Read GOV.UK's party wall guidance if the new footing is close to next door.
Rainwater pipes, soil pipes and a side gate all live in the same narrow strip. The quote should say whether the downpipe moves, whether the gate is rehung, and whether a shared drain is affected. None of those lines is included merely because the wall is priced.
A quote you can actually compare
Citizens Advice wants written quotes from at least three traders, and it treats a quote as the fixed price [S3]. An estimate is described there as a rough guess that can rise [S3]. Be wary of a figure far below the other two: the cheaper paper may be pricing a different specification [S3].
| Item | Side-extension version of the question | Why two quotes diverge |
|---|---|---|
| Width | Half the original house width is the permitted-development cap, and Article 2(3) land needs an application for any side extension [S1] | One firm may be pricing a lawful width and another a wider design that needs permission |
| Height | Four metres maximum, and single storey only, under the side rule [S1] | A parapet or a raised roof can take the job out of that rule |
| Eaves near the fence | Within two metres of the boundary, eaves cannot exceed three metres [S1] | A flat roof and a pitched roof hit that limit differently |
| Footings | Depth and whether they pass the neighbour's foundation [S4] | Underpinning the neighbour is a different job from a trench on your side |
| Passage | Clear width for materials, named in metres by you | A price that assumes a clear side can fail on the day |
| Kitchen services | Sink, boiler flue and electrics if the side return becomes the kitchen | Plumbers and electricians may be extras |
| Making good the drive | The flank often is the drive | See also the driveway cost guide if the hardstanding is a separate job |
| VAT | 20% standard rate on most work to an existing house [S5] | A net total and a gross total are not the same offer |
If you cannot avoid a deposit, Citizens Advice says to keep it to no more than 25% and to get a receipt, or to buy the materials yourself so they remain yours [S3]. Register for VAT is required when the last 12 months of taxable turnover exceed £90,000 [S6]. Ask the builder which side of that line they are on, and whether their total includes VAT [S3].
Phone the buildings insurer before the flank is opened up. Citizens Advice says the policy may cost more while the work is underway and after it finishes, and that the insurer will probably want the trader's name and insurance details [S3].
Getting down the side in Crewe or Nantwich
Crewe station is the railway junction on the West Coast Main Line. Nantwich's centre is on the River Weaver. A side extension does not take its price from either landmark. It takes it from the gap between the flank wall and the boundary.
Measure that gap at the front and at the back, because passages taper. Photograph the neighbour's fence, any shared gutter, and the manhole. A house in Sandbach with a gate under a metre wide is a carrying job. Say so in the first message, or the quote will assume a route you do not have.
Jobs you might post
These are examples, not taken from real job posts.
- Single-storey side return on a terraced house in Crewe, within half the house width, kitchen in the new space, and a side gate too narrow for a wheelbarrow.
- Side extension on a detached house in Nantwich, with a utility and a downstairs toilet, drain to be confirmed.
- Planning drawings only, for a side extension on Article 2(3) land, before any build price is sought.
- Rebuild of a failed side lean-to in Sandbach, including a party wall conversation with the neighbour.
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Questions about side extensions
Does QuoteZila check the businesses?
No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.
Can a side extension be two storeys under permitted development?
No. The Planning Portal says that where an extension goes beyond the side elevation of the original house, it can only be a single storey, it cannot exceed four metres in height, and it can only be up to half the width of the original house. It also says all side extensions of more than one storey require householder planning permission. On Article 2(3) designated land, every side extension needs that permission.
Does the side passage count as the width?
The Planning Portal measures the limit as half the width of the original house, not as whatever gap is left to the fence. A wide house can still have a narrow passage, and the passage is an access problem rather than the planning measurement. Put both numbers in the enquiry: the house width on the drawing, and the clear gap the builder would actually walk through.
Who approves the structure of a side extension?
GOV.UK says building regulations approval is different from planning permission and that you might need both. Citizens Advice uses an extension as the example of work that is not carried only under a competent person scheme, so a building control body has to approve it before work starts. You usually pay that body a fee on application and you might pay again at inspection.
What happens if the new wall is on the boundary?
GOV.UK says the Party Wall etc. Act 1996 covers new building on or at the boundary of two properties, and excavation near to and below a neighbour's foundation. The Act is separate from planning and from building regulations. If the side wall is on that line, ask whether a party wall notice is required, and do not treat a chat over the fence as the paperwork.
How do I compare side-extension quotes that use different VAT treatments?
Most builder's work on an existing house is charged at the standard rate. GOV.UK states that rate as 20%. A firm must register for VAT when taxable turnover over the last 12 months passes £90,000. Citizens Advice says the written quote should say whether VAT is included. Put the two totals in the same VAT position before you call one of them lower.
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Related pages
- Single-storey extension: what changes the price. A single-storey extension is £1,800 to £3,000 per square metre in Master Builders guides. Compare the same drawing in Cheshire. QuoteZila does not set prices.
- Soakaway Drains in Cheshire: What to Ask. What to ask about a soakaway drain in Cheshire before anyone digs. This guide prints no pound figure. It points at planning and building rules, not a tariff.
Sources
- QZ1: QuoteZila product fact. QuoteZila pricing line.
- QZ2: QuoteZila product fact. QuoteZila matching cap.
- S1: Planning permission: extensions, Planning Portal. Accessed 2026-10-26. https://www.planningportal.co.uk/permission/common-projects/extensions/planning-permission
- S2: Building regulations approval, GOV.UK. Accessed 2026-10-26. https://www.gov.uk/building-regulations-approval
- S3: Before you get work done on your home, Citizens Advice. Accessed 2026-10-26. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/
- S4: Party Wall etc. Act 1996 guidance, GOV.UK. Accessed 2026-10-26. https://www.gov.uk/guidance/party-wall-etc-act-1996-guidance
- S5: VAT for builders, GOV.UK. Accessed 2026-10-26. https://www.gov.uk/vat-builders
- S6: Register for VAT, GOV.UK. Accessed 2026-10-26. https://www.gov.uk/register-for-vat