Planning maps often use two coloured boundaries, but they answer different questions.
The red line identifies the land included in the planning application. The blue line can identify other nearby or adjoining land owned or controlled by the applicant that is outside the application site.
The blue line is not a decorative second border and it is not automatically the same as the edge of a Land Registry title. It is part of the application information, so it should be used deliberately and consistently.
Red land and blue land have different jobs
Suppose you own a house, its garden and a field behind it, but your application is only for a rear extension to the house. The house and the land needed for the extension normally belong inside the red application boundary. The field may be shown separately in blue if the circumstances and local requirements make that relevant.
That does not mean the field is being developed. It tells the authority that other nearby land is connected to the applicant and may need to be understood when the application is assessed.
Start with the proposal and the land needed to carry it out. Do not start by colouring every parcel that appears in your ownership documents.
When a blue line may be relevant
A blue boundary may be appropriate where the applicant owns or controls nearby land such as:
- An adjoining field or paddock.
- A separate garage or parking parcel.
- A neighbouring property.
- A second part of a larger estate.
- Woodland or open land close to the application site.
The exact requirement depends on the application, the ownership position and the planning authority's current validation guidance. Check the relevant council checklist before finalising the map.
Do not confuse ownership with the application site
A title plan and a planning map do different jobs. A title plan helps show the general extent of registered land. A planning map identifies the land to which the proposal relates and provides the context needed for validation.
The red line may need to include access, visibility splays, parking, drainage or other land required to deliver the development. Conversely, nearby land that you own may remain outside the red line and be shown separately in blue.
If the ownership position is unclear, use Boundary Finder as an initial way to locate a registered general-boundary polygon, then check the register, filed documents and professional advice where the issue matters.
Keep the colours consistent
If a blue line is required, it should be clear, continuous and distinguishable from the red application boundary. Use the same red and blue geometry on every plan that shows the application site.
Before submitting, compare:
- The red boundary on the location plan.
- The red boundary on the block or site plan.
- The site area stated on the application form.
- The ownership certificate and any notices.
- The blue boundary, if one is shown.
A mismatch can create uncertainty even when each individual drawing looks tidy.
Common mistakes
Drawing blue around the application site
The application site normally belongs in red. Blue is not a lighter version of red and should not be used simply because the applicant owns the land.
Showing all owned land without checking relevance
A very large blue area can make the application scope difficult to understand. Show the relevant nearby or adjoining land required by the guidance, not an arbitrary collection of distant holdings.
Leaving out necessary access
If the development depends on a track or frontage, consider whether that land belongs in the red application site. A blue line does not fix an incomplete red boundary.
Using different boundaries across documents
The application form, ownership information, location plan and detailed plan should describe the same proposal and site.
The practical rule
Use red to define the application. Use blue to identify relevant nearby ownership outside that application. Then check the current authority guidance and make every document agree.
Create a site location plan when you need the wider context, and add a block plan when the proposal needs a closer view of buildings, access and boundaries.
A planning map should make the relationship between the application site and relevant surrounding ownership easy to understand.
A worked boundary scenario
Imagine a rear extension where the homeowner owns the house and garden but also owns a narrow strip of land beside the driveway. If only the house and garden are part of the application, the red line should define that application area. The separate strip may be relevant ownership information, but it should not be coloured as part of the proposal unless the works or certificate question include it.
Now change the proposal so that the driveway is widened and a new parking space is created on the strip. The application site has changed. The red boundary may need to include that land, and the detailed plan should show the access and parking work. The map is not deciding ownership; it is communicating the land to which the application relates.
Avoid colour without a key
Colour is only useful when the reader knows what it means. If blue land is shown, provide a simple key or make the accompanying statement explain its purpose. Avoid using several shades that become indistinguishable when printed in black and white. The red application boundary must remain prominent at normal viewing size.
The safest approach is restrained presentation: one clear red boundary, a blue ownership indication only where needed, and factual labels for existing and proposed features. Keep the map legible for reviewers who may print it or view it on a smaller screen.
Use a two-question boundary test
Work through the land parcel by parcel rather than colouring the map by instinct.
| Question | If yes | If no |
|---|---|---|
| Is this land part of the site needed for the development, including relevant access, parking or landscaping? | Consider it for the red application boundary. | Move to the ownership question. |
| Is it other land owned by the applicant, close to or adjoining the application site? | Show it in blue where the application requirements call for it. | Do not colour it merely because it appears on the map. |
This reflects the Planning Portal’s explanation of red and blue boundaries: the development site is outlined in red, while other nearby or adjoining land owned by the applicant is outlined in blue. Your local planning authority’s current checklist and the facts of the proposal still need to be checked.
The sequence matters. If you ask only “do I own this?”, a driveway needed for the proposal might be coloured blue when it belongs inside the application site. If you ask only “is work happening here?”, the red line may become too tight and omit land necessary to carry out or operate the development.
Ownership evidence and planning boundaries are not interchangeable
A planning boundary communicates the scope of an application; it does not determine a disputed legal boundary. HM Land Registry explains that registered title plans generally show the general position of boundaries, not their exact line. A red edge on a title plan is also doing a different job from the red application line on a planning location plan.
If ownership is uncertain, do not “solve” it by choosing a colour. Review the title register, title plan and relevant deeds, and obtain professional legal or surveying advice where the uncertainty is material. The application’s ownership certificate and any notices must align with the actual position.
Three situations that deserve a pause
A shared private drive: access rights and ownership may differ. Decide what land the proposal relies on, then make sure the plan, certificate and notices are consistent. Blue does not mean “shared”.
A farm surrounding a small building site: the whole holding does not automatically belong inside the red line. A carefully defined red application site plus relevant nearby blue ownership land can be clearer than outlining every field visible on the sheet.
An option or purchase agreement: control of land, legal ownership and the application site may not align neatly. This is a document-coordination issue, not a drawing shortcut. Ask the planning adviser or solicitor how the ownership certificate should be completed before finalising the boundaries.
Colour should survive real-world use
Use a closed line with adequate contrast and avoid translucent fills that hide map detail. Add a concise key, because some reviewers will use small screens or monochrome prints. Check that road names and building outlines remain readable beneath or beside the line.
The strongest plan is not the one with the most colour. It is the one where a reviewer can explain, without guessing, which land is the application site, which nearby land is shown for ownership context and how the site reaches the public highway.