Do You Need a Survey
for a Planning Application?

The Short Answer

For the vast majority of planning applications involving changes to an existing building, the answer is yes. Planning authorities require accurate drawings of the existing building before they can assess what's being proposed — and those drawings need to come from a professional measured survey.

Working from old drawings, builder's plans or dimensions measured with a tape measure introduces inaccuracies that planning officers are increasingly trained to spot.

What Drawings Does a Planning Application Require?

Most householder and commercial planning applications require a standard set of existing condition drawings. The exact requirements vary slightly by local authority, but the following are required in almost every case:

Existing Floor Plans

A plan of each floor level showing all rooms, wall positions, door and window openings, and any structural elements. Produced at 1:50 or 1:100 scale, depending on the size of the property and local authority requirements.

Existing Elevations

External elevation drawings showing all faces of the building that are affected by the proposed works — and in most cases, all four elevations. These need to show all architectural features accurately: window and door positions, heights, eaves and ridge levels, and any external detailing.

Existing Sections

A section cut through the building showing floor-to-floor heights, ceiling levels, roof structure and any split levels. Required on most applications involving changes to roof height or internal levels.

Site or Block Plan

A plan showing the property in the context of its site and immediate surroundings, typically at 1:500 or 1:200 scale. This usually needs to be based on an Ordnance Survey base map.

Planning Drawings — existing condition package required for most applications

Why You Need a Professional Survey

Your architect cannot produce accurate existing condition drawings without accurate measurements. There are broadly three approaches — and only one produces drawings reliable enough for planning:

On Site — professional measured survey of a residential property

The Real Cost of Skipping a Survey

We see the consequences of skipping a professional survey regularly. Here's what typically happens:

• The architect produces drawings based on inaccurate dimensions. A wall is 200mm further out than expected. The proposed extension no longer fits within the permitted development envelope. The drawings need to be redrawn.
• The planning officer queries a discrepancy. Submitted drawings don't match the property's appearance on Street View. A request for additional information delays the application by weeks.
• The contractor finds something unexpected on site. Floor levels don't match the drawings. A structural element is in the wrong position. Remedial work is required.

Each of these scenarios costs more — in time and money — than a professional survey would have cost at the outset.

Drawing Package — complete existing condition drawings ready for planning submission

How Much Does a Survey Cost?

For a typical residential extension project, a professional measured survey represents less than 1–2% of the total project budget. On a £50,000 extension, the survey cost is typically £400–£800 depending on the size and complexity of the property.

The cost of amending an architect's drawing package mid-planning, or redesigning around a dimension that turned out to be wrong, almost always exceeds the cost of the survey.