Loft conversion drawings for a Cobham house cost from £1,395 with us as a complete set: the planning drawings and their submission to Elmbridge, the building regulations drawings and the structural calculations. If the loft turns out to be permitted development, the building regulations drawings and calculations on their own are from £1,095, and a lawful development certificate to prove it is from £695. Which of those you need in Cobham depends on two questions: is the house in a conservation area, and is it in the Green Belt?
On this page
- Can I build a Cobham dormer without planning permission?
- Which parts of Cobham are conservation areas?
- Do Cobham's Article 4 directions affect my loft?
- How does the Green Belt change a Cobham loft?
- What else does Elmbridge ask for with a loft?
- What do the building regulations drawings cover?
- How long does it take in Elmbridge?
- Frequently asked questions
Can I build a Cobham dormer without planning permission?
Outside a conservation area, often yes. The national rules in Class B of the permitted development order allow a roof enlargement of up to 50 cubic metres of extra roof space on a detached or semi-detached house, and 40 on a terrace. It must not rise above the existing ridge or project beyond the roof slope that faces the road (GPDO 2015, Class B).
The same rules say Class B does not apply at all on article 2(3) land, which includes conservation areas. In a conservation area, every dormer needs planning permission, whatever its size.
Many Cobham houses are large detached homes with hipped roofs. On those, a rear dormer alone often gives less headroom over the stair than owners expect, and a hip-to-gable change uses a lot of the 50 cubic metres before the dormer starts. We calculate the volume from the survey, because a scheme that is a cubic metre over is not permitted development.
Which parts of Cobham are conservation areas?
Four of Elmbridge's 24 conservation areas are Cobham's (Planning Data, Elmbridge conservation areas):
- Cobham, designated by Surrey County Council on 31 July 1973: Church Street, Mill Road, River Hill and the river frontage along the Mole (Cobham designation statement).
- Cobham The Tilt, designated on 31 July 1979 and extended on 10 March 2015. The council describes it as a linear settlement around a series of open spaces that were once part of a much larger common (Elmbridge, The Tilt).
- Cobham Plough Corner.
- Downside Village, south of the town.
Stoke D'Abernon, next door, has its own. Because the 2015 extension of The Tilt took in more houses, check the current map rather than an older one. A house in any of these needs a planning application for a dormer or a hip-to-gable change, and Elmbridge will judge how the roof reads from the street, not only from the garden.
Do Cobham's Article 4 directions affect my loft?
Almost certainly not. Elmbridge has two Article 4 directions in force, and both are in Cobham: one on land off Woodlands Lane, confirmed as modified on 3 September 2024, and one on land off Pointers Road, confirmed on 16 March 2020 (Elmbridge Article 4 directions). Both remove rights for gates, fences and walls and for the temporary use of land. They cover parcels of open land, not the roofs of houses, so they do not touch a loft conversion.
How does the Green Belt change a Cobham loft?
Cobham is ringed by Green Belt, and houses towards Downside, Stoke D'Abernon and the town's edges may be inside it. The Green Belt is not article 2(3) land, so permitted development for a loft can still apply there, unless an earlier permission removed it by condition.
Where you need an application, Elmbridge's policy DM18 applies. It supports extensions that do not cause disproportionate additions over the original building, "either individually or cumulatively", do not exceed 25% in volume and 25% in footprint, and do not materially increase the overall height of the building (Elmbridge Development Management Plan, DM18). Three points follow for a loft:
- A dormer adds volume. Converting the roof space inside the existing roof adds none, but every dormer and every hip-to-gable change does, and it counts towards the 25%.
- Raising the ridge is a problem. A loft that needs a taller roof to get headroom runs into the height test as well.
- It is cumulative. The original house is the one that stood on 1 July 1948, or as first built, so a garage or conservatory added since then has already used part of the allowance.
Elmbridge's validation list asks for the percentage increase in volume on a Green Belt application (Elmbridge validation checklist). We work it out from the survey and the planning history before the dormer is drawn, so you know how big it can be. Our Esher post covers the same test for extensions.
What else does Elmbridge ask for with a loft?
Two things catch Cobham lofts out. First, works that disturb the roof need biodiversity information, and a protected species survey more than 18 months old is out of date (Elmbridge validation checklist). A bat survey is a specialist ecologist's job outside our fee; we tell you at the quote stage whether the list is likely to call for one.
Second, since 6 January 2025 every Elmbridge householder application needs a completed Design Code Checklist (Elmbridge Design Code). We complete it with the drawings.
What do the building regulations drawings cover?
A loft is a new storey, so the building regulations matter as much as the planning drawings. Ours show the new floor and the beams that carry it, the stair, the fire-protected escape route down through the house, insulation to the roof and dormer, and ventilation. The structural calculations size the steels and the floor joists. Our guide to fire safety in loft conversions explains why the escape route usually decides the layout of the floor below.
How long does it take in Elmbridge?
Elmbridge decided 492 of its 581 householder applications within eight weeks in the year to June 2026, according to the government's PS2 statistics (MHCLG live tables). A lawful development certificate also has an eight-week target. The council's pre-application service does not advise on permitted development, so for that question our permitted development checker gives a first answer and we confirm it from the survey.
Our Elmbridge page has the council's rules in full, and the Surrey page covers the other councils we work in. Next door, see house extension plans in Weybridge, and over the Mole Valley boundary two storey extension plans in Leatherhead. Our loft conversions service explains each drawing.
Frequently asked questions
Is a rear dormer on Church Street in Cobham permitted development? No. Church Street is in the Cobham conservation area, and roof enlargements are not permitted development in a conservation area. You need planning permission.
Can I convert a loft without planning permission on a Green Belt house in Cobham? Often yes, if the house is outside a conservation area, its rights have not been removed by condition, and the loft stays within 50 cubic metres. A lawful development certificate proves it.
Does a loft count towards the Green Belt 25% in Elmbridge? The volume a dormer or hip-to-gable change adds does. Converting space already inside the roof does not add volume.
Do Cobham's Article 4 directions cover roofs? No. Both cover parcels of land off Woodlands Lane and Pointers Road, and remove rights for gates, fences, walls and temporary uses.
Is the council fee included? No. The £548 householder fee is paid to Elmbridge at submission, and the receipt is yours.
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.
