Area guide · KT11
House Extensions in Cobham (KT11)
Extending a Cobham house? Few Surrey villages combine this much value with this much variety. The average sale in Cobham is about £1.23 million and the detached average about £1.88 million (Rightmove sold-price data), yet the stock runs from the Fairmile estate's pine-lined plots through gated new mansions to characterful inter-war houses, with a proper village high street in the middle and river meadows and parkland out at Painshill. Elmbridge Borough Council decides applications, green belt rings the village, and the briefs we take here lean large: basement floors, double-storey reworks and whole-house programmes. Our best work here is the substantial kind, and the Fairmile takes it as far as owners want to go.
Live planning data
Winning approval in KT11
Elmbridge's householder policies are consistent across the borough, and Cobham schemes succeed when the design answers the plot honestly. On the Fairmile that means showing the enlarged house keeping its distance from the pines and its composure on the road. Nearer the High Street side it means respecting a tighter village grain. We front-load that thinking into every application, which is the same discipline our luxury extensions clients hire us for.
The green belt ring matters to anyone on the village edge. Additions out there are judged as a proportion of the original dwelling, and the sums are unforgiving if earlier owners already used the allowance. Our green belt guide sets out how we establish the remaining headroom, and we do it before design money is spent, not after.
Officers weigh each scheme on its merits; our job is making those merits obvious.
Local knowledge
From the Fairmile to the High Street: the stock
The Fairmile. Pine-lined plots carrying the village's largest houses. This is basement and whole-house territory, where a lower-ground floor and a reorganised main house transform how the property lives without straining the plot. Projects here tend to grow in ambition once owners see what the footprint can really hold.
The Painshill edge. Toward the river meadows and parkland, houses trade on their outlook, so we design glazed rear elevations that make the borrowed landscape the main event.
The High Street side. Behind the shops the streets tighten, and well-judged side-returns, rear extensions and lofts do the heavy lifting for family space. Living within walking distance of a proper village high street is worth designing to keep.
The inter-war stock and the gated mansions. Cobham mixes both freely. Older houses take extension and reinvention beautifully, while owners of newer mansions usually brief us on reconfiguration: making existing volume finally earn its keep.
Every street is different. That's the point.
We design to Cobham's stock and to what the council demonstrably approves — not to a template. A free site visit tells you what your house can take.
Get my free estimateHonest numbers
What an extension costs in Cobham in 2026
Cobham pricing sits at the upper end of our Surrey range and climbs on the Fairmile. Construction ranges below exclude VAT, professional fees and kitchen supply:
| Extension type | Typical Cobham cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £50,000 to £100,000 | 2 to 3 months | Often permitted development |
| Single-storey rear | £60,000 to £130,000 | 3 to 4 months | Often permitted development |
| Kitchen extension (incl. mid-range kitchen) | £75,000 to £155,000 | 3 to 4 months | Often permitted development |
| Loft conversion with dormer | £75,000 to £120,000 | 6 to 9 weeks | Usually permitted development |
| Double-storey rework | £105,000 to £235,000 | 5 to 7 months | Full application |
| Whole-house transformation | Priced on design | Phased programme | Design-led application |
Plan around £3,600 to £5,800 per square metre depending on street and specification. The way the larger budgets break into structure, envelope and finish is covered in our luxury extension cost guide. One free design visit produces one fixed, itemised quote, and we hold to it.
Permissions, handled
Planning notes, green belt included
Find the boundary line early. Whether your plot sits inside the settlement or in the green belt ring is the single biggest variable in Cobham planning, so it is the first thing we confirm.
Permitted development carries the village's staples. Rear extensions and lofts on unrestricted plots frequently need no application at all, and every PD scheme we build is evidenced with a Lawful Development Certificate.
Expect eight weeks for a decision. Elmbridge householder applications usually resolve in about that time, and the programme we quote allows for it honestly.
Budget for the boundary. Party Wall procedures accompany basement digs and close-boundary work; where surveyors are appointed, provision of £1,000 to £2,500 per neighbour is realistic and we administer the notices throughout.
How it works
How it works
- First visit. Free of charge; we assess the house, check the green belt position and talk numbers plainly.
- Drawings. A design resolved for your street's character and Elmbridge's policy tests.
- Through Elmbridge. We prepare, submit and manage the application until the decision notice arrives.
- On site. A fixed itemised price, a team we stand behind, and building control completion at the finish.
Questions, answered
Cobham extension FAQs
Can I extend if my house sits in the green belt ring?
Usually yes, within limits. The council measures additions against the original dwelling, so the available headroom depends on the house's history. We calculate it at the first visit and design inside it.
What does a Fairmile-scale project cost?
Double-storey reworks run £105,000 to £235,000, and basement or whole-house programmes are priced on design, typically beyond £250,000. With detached averages near £1.88 million (Rightmove sold-price data), the values support the ambition.
Will my kitchen extension need planning permission?
On many Cobham plots a single-storey rear scheme proceeds under permitted development, which we document with a Lawful Development Certificate. Conservation constraints or removed rights push it to a full application instead.
Do you build basements in Cobham?
Yes, and the Fairmile's plots suit them particularly well. They are engineered, full-application projects with party wall workstreams, and each one is priced individually on design.
How disruptive is a whole-house programme?
We phase the work so the sequence is predictable, agree logistics with neighbours in advance and keep one senior team on the job. Most families plan around the programme dates in the quote.
Why do clients pick you over a local builder?
Because design, planning and construction sit under one roof with one fixed number attached. You get planning managed end to end, honest cost advice at the top of the market, and a build run by people whose name is on it.
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What clients say
Rated 5.0 on Google
“Used The Extension Company for a loft conversion on our semi detached in Barnet and couldn't be happier. They explained what was possible at the first visit, sorted the planning side, and gave a fixed price with no surprises at the end.…” read the full review
“Really impressed with the entire project. The side extension and conservatory have been finished to a very high standard and the team made the process straight forward and stress-free. It’s transformed the space and added so much value, would definitely recommend.”
“Brilliant experience with the extension company, transparent from the word go. Completed a double story extension for me and I couldn’t be more pleased. Thank you”
“I got the extension company to do a bathroom refurb for us a January they done a great job they managed to fit in a large shower as well as a bath”
Reviews shown word for word from our Google profile. Read all 8 reviews on Google
Free site visit
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Free site visit anywhere in Cobham, honest feasibility advice and a fixed, itemised price — design, planning and build handled end to end by the Pine Grove team.
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