Planning drawings for a house extension in Dorking cost £795 with us, fixed, from the measured survey to Mole Valley's decision. With building regulations drawings and structural calculations added, the package is from £1,395. The householder fee of £548 is paid to the council separately. Dorking sits where four planning layers meet: the town's conservation area, the Surrey Hills, the Green Belt and a council that tightened its validation rules in late 2025. Which of them reach your house decides what the drawings must show.
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What changed in Mole Valley's validation rules?
Since 10 November 2025 an application must meet Mole Valley's Local Validation Requirements and its Biodiversity Net Gain Requirements before the council will validate it (submitting a planning application). The council also says location and block plans must not be Land Registry documents, or use data from the Surrey County Council Interactive Map.
That last rule catches out a lot of self-prepared applications, because the title plan is the map most owners already have. We draw location and block plans from licensed mapping. Most householder extensions are exempt from mandatory Biodiversity Net Gain, but the application still has to deal with it in the form the council asks, so we cover it in the pack and confirm at the quote stage if any specialist input is needed.
Is my Dorking house in the Surrey Hills or the Green Belt?
The town itself is built up, but it is wrapped by protected land: Box Hill and Ranmore to the north and west, the Nower and the slopes towards Leith Hill to the south. Mole Valley says the Surrey Hills National Landscape and its Areas of Great Landscape Value together cover about a third of the district, and that it gives proposals there special attention (planning constraints). Within a national landscape, "great weight is given to conserving and enhancing its landscape and scenic beauty" (supplementary planning documents). In practice that means materials, roof forms and how visible the extension is from the hills matter more than in a typical suburb.
Most of the district's countryside is Metropolitan Green Belt, and the council says inappropriate development there "will be resisted" (planning constraints). National policy allows the extension of an existing house in the Green Belt only where it does not result in "a disproportionate increase in size compared to the original building". The original building is the one that stood on 1 July 1948, or as first built if later (NPPF chapter 13, GB7). So a cottage on the edge of Westcott or Mickleham that was extended in the 1980s has less room left than its size suggests. We ask for any old plans or permissions and set out original, existing and proposed floor areas in the application.
How does the Dorking conservation area change things?
Mole Valley has 26 conservation areas, and Dorking is one of three where the council says Article 4 directions add planning controls in parts of the area, to protect features that contribute to the streets' special interest (conservation areas). The council publishes the directions and maps in its document library. We have not read what each one removes, so for a house in or near the historic centre, around the High Street, West Street and South Street, we check the direction for your address before designing.
Two practical points follow. Side extensions lose their permitted development rights inside any conservation area, so more work needs an application. And Mole Valley says it does not give informal conservation or historic building pre-application advice, so the formal written service is the only route to an early view.
What design guidance applies in Dorking?
Mole Valley adopted a Design Guidance for House Extensions SPD in 2025. It covers daylight and sunlight, overlooking, single and two storey, front, porch, loft and roof extensions, the street scene, and garages and outbuildings. Separate 2025 Design Code SPDs apply to the main built-up areas, with Dorking's own code in two parts (supplementary planning documents). These replace older guidance, so advice from a neighbour's extension a decade ago may no longer hold. We design against the 2025 documents and say in the application how the scheme meets them.
How long does Mole Valley take to decide?
Longer than its neighbours. Between July 2025 and June 2026 Mole Valley decided 210 of its 307 householder applications (excluding prior approvals) within eight weeks (MHCLG live table PS2). Neighbouring Reigate and Banstead decided 438 of 458 in the same period. Plan your builder's start date with that in mind, and avoid the extra weeks an invalid submission adds.
Written householder pre-application advice costs £171.39 following the April 2026 fee rise, and advice from the council's Historic Buildings Officer is £257.09 extra (pre-application advice). The council also says pre-application advice cannot confirm whether a project is permitted development; for that it points you to a certificate of lawfulness.
What does the £795 include?
- A laser measured survey of the house, the plot and the neighbours' nearest windows.
- Existing and proposed plans, elevations and sections.
- Location and block plans from licensed mapping, and Green Belt floor area figures where they apply.
- Submission to Mole Valley and replies to the case officer until the decision.
Our Mole Valley page sets out the council's rules in full, and the Surrey page lists the other councils we cover. For a two storey scheme in the same district, see two storey extension plans in Leatherhead. Over the council boundary, extension plans in Reigate shows a council with fixed depth figures in its guidance.
Frequently asked questions
Can I use my Land Registry title plan as the location plan in Mole Valley? No. Mole Valley says location and block plans must not be Land Registry documents or use data from the Surrey County Council Interactive Map. We draw them from licensed mapping.
Is there a size limit for extending a house in Dorking's Green Belt? There is no fixed percentage in national policy. An extension must not be disproportionate to the original house, meaning the house as it stood on 1 July 1948 or as first built, and earlier additions count towards that.
Does the Surrey Hills mean I cannot extend? No. It means the council gives great weight to the landscape, so design, materials and visibility from the hills get closer attention.
How long will Mole Valley take? The statutory period is eight weeks, but in the year to June 2026 the council decided 210 of 307 householder applications within that time. Allow for longer.
Is the council's fee included? No. The householder fee of £548 is paid to Mole Valley at submission, separately from our fee.
If the application goes through the Planning Portal, the Portal adds its own service charge: nothing, £99 or £149 including VAT, depending on the application type and complexity, paid to the Portal at submission and not normally refunded with a council fee (Ashford Borough Council, Planning Portal service charges, 11 September 2026). It is not ours and not the council's. Other submission routes exist; where your council accepts one without a charge, we can use it.
