What existing drawings do you need for a planning application?

By the Section Scale team · Published 7 November 2026

The short answer

Most householder applications need a location plan, a site plan, and existing and proposed floor plans and elevations. Sections and a roof plan are often asked for on loft conversions, basements and sloping sites. Every council publishes a validation checklist, and that list is the final word for your application.

Drawings and the scales councils usually expect

• Location plan at 1:1250 or 1:2500, on up-to-date Ordnance Survey mapping, with the site outlined in red
• Site or block plan at 1:500 or 1:200, showing the building, boundaries and what is being added
• Existing and proposed floor plans at 1:50 or 1:100
• Existing and proposed elevations of every side affected, at 1:50 or 1:100
• Sections at 1:50 or 1:100 where levels or heights change
• A roof plan where the roof shape changes

Why the existing drawings matter

Your architect draws the proposal on top of the existing drawings. If a wall is 200 mm out or a ridge height is guessed, the error carries into the proposed drawings, and it often surfaces later as a redesign or a problem on site.

Planning officers and neighbours also compare the drawings against the building. Heights to the eaves and ridge, window positions and the distance to the boundary are the details most likely to be checked.

What a measured survey gives your architect

• Floor plans of every level, with wall thicknesses, openings and room sizes
• Elevations with window and door positions, eaves and ridge heights
• Sections through the building showing floor-to-ceiling heights and levels
• A roof plan, where the roof can be seen or scanned safely
• Files in AutoCAD and PDF, or a Revit model, ready to draw over

Location and site plans

Location plans are based on Ordnance Survey mapping and are usually bought from an approved map supplier rather than surveyed. Where levels or the exact line of a boundary matter, for example on a sloping garden or a tight plot, a topographical survey gives the site plan something reliable to work from.

Related services

• Measured building surveys
• Elevation and roof surveys
• Topographical surveys