Blog

How to draw a red line boundary for a planning application

A practical guide to drawing red and blue line boundaries correctly, avoiding common mistakes that cause planning applications to be rejected.

Red line boundaries are one of the most important parts of a UK planning application. They show exactly which land is included in the proposal. A missing, unclear, or incorrect boundary is a frequent reason for validation delays. This guide explains how to draw the red line (and when to add a blue line) so your application passes validation first time.

If you are unsure about which plan needs the boundary, start with location plan vs site plan and your local validation checklist.

What is a red line boundary?

The red line boundary is the outline of the application site. It must enclose all land included in the planning proposal, including any land needed for access, parking, gardens, or shared areas.

What is a blue line boundary?

A blue line boundary shows land you own or control that is adjacent to the application site but not part of the proposal. You only need to add a blue line if you control other nearby land.

Where boundaries must appear

• Location plan: always required, at 1:1250 or 1:2500.
• Site plan (block plan): usually required, at 1:200 or 1:500.
• Both plans should show the red line clearly.
• Add the blue line on both plans if you own adjacent land.

Step-by-step: drawing the red line boundary

• Start with an up-to-date map base at the correct scale.
• Outline the entire application site in red, including access routes and shared areas.
• Ensure the line is continuous and fully encloses the site.
• Keep the line thin enough to avoid obscuring map detail.
• Add a clear north point and scale bar.
• Export as a PDF and verify the red line remains sharp and readable.

How to decide what land to include

Include all land directly affected by the proposal. This usually means the building footprint, private garden areas, access drives, parking spaces, and any shared access or bin areas. If the proposal relies on a shared access route, that route should be within the red line.

Common mistakes that cause validation delays

• Red line does not fully enclose the site.
• Red line excludes access routes or parking areas.
• Boundary drawn too thick, hiding map features.
• No blue line shown despite owning adjacent land.
• Using screenshots instead of a scaled PDF.
• Mismatch between the boundary shown on location plan and site plan.

What councils look for

Validation officers check that the boundary matches the application site and that the plan is clearly legible at the required scale. They also check for a scale bar, north point, and surrounding context. If anything is unclear, they may request corrections before validation starts.

Red line boundary checklist

• Correct scale and readable scale bar.
• Continuous red line fully enclosing the application site.
• Blue line shown where applicable.
• North point and enough surrounding context.
• Consistent boundaries across all submitted plans.

How Butler Floorplan helps

Butler Floorplan lets you draw red and blue boundaries directly on a compliant map base, choose the correct scale, and export planning-ready PDFs with scale bars and north points. This reduces validation delays and helps you submit the right documents the first time.