Why planning drawings need a survey
Planning drawings must show the site as it is and how the proposal sits within it. Ordnance Survey mapping is a good start for location plans, but it does not give levels, accurate building footprints, trees, walls or neighbouring heights. For anything beyond a simple alteration, architects and engineers usually need a measured topographical survey to draw the existing site and design the new one.
When you are likely to need one
- New buildings and extensions – especially on sloping sites, where floor levels and ridge heights matter.
- Infill and backland sites – where the relationship with neighbouring buildings, windows and boundaries is scrutinised.
- Conservation areas and listed building settings – where accurate street elevations help show the scheme in context.
- Sites with flood risk – where levels to Ordnance Datum are needed for a flood risk assessment and finished floor levels.
- Sites with trees – where tree positions and canopies feed into the tree survey and layout.
- Roads, drainage and earthworks – where engineers need levels and a 3D surface to design.
What the survey should show
For most planning and building warrant work, the survey should include spot levels and contours, buildings, walls, fences and hedges, kerbs and surfaces, trees, manhole covers, overhead lines and street furniture, all tied to OS National Grid and Ordnance Datum. On tight sites, add neighbouring building heights and street elevations. For drainage and connections, add utilities and a drainage survey.
Flood risk and levels
National Planning Framework 4 (NPF4) sets the policy on flood risk in Scotland, and planning authorities often consult SEPA on sites at risk. A flood risk assessment relies on accurate ground levels, so the survey must be levelled to Ordnance Datum rather than an arbitrary site datum.
Boundaries in Scotland
A topographical survey records physical features – walls, fences and hedges – not legal boundaries. Legal boundaries are set by title and the Land Register of Scotland. If a boundary matters to the design, compare the survey with the title plan and take advice from your solicitor where they do not match.
Need a topographical survey? Call 0345 548 5451 or email us with your site plan for a fixed quote.
