What is a red line boundary in Planning?

A red line boundary is the line drawn on a planning location plan to show the main site covered by a planning application. This matters because if it’s wrong, then the application can run into problems.

Planning Portal describes it as the primary boundary on a location plan and the minimum requirement for supporting a planning application. In simple terms, it marks the land your application relates to.

That red line should include all the land needed to carry out the proposed development - and that may be more than just the building itself. It can also include things like access from the public highway, parking areas, gardens, landscaping, visibility splays, and outbuildings such as garages, depending on the proposal. 

The easiest way to think about it is this: a red line shows the planning site - the land included in the application - while a blue line shows any other nearby land you own.

A boundary that misses access land, excludes part of the site, or does not reflect the true extent of the proposal can delay validation or lead to the wrong land being assessed. Council validation checklists repeatedly say the application site should be edged clearly in red and include all land necessary to carry out the development.

In practice, if you are applying for planning permission, the red line boundary is one of the most important things on the map. And if you need the right OS-based plan to mark-up correctly, our MapShop can help you get the planning map you need quickly and in the right format for submission.

How Emapsite can help

If you can't find exactly what you need, we can also help you choose the right mapping data solution for your project via email, chat or over the phone.

For more information, reach out to our Customer Support team.

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