Get a human review of your red line!
Get a member of our team to review your red line diagram to make sure all are drawn accurately (please note that this may take up to two working days)
On this page, you need to draw the redline boundary of your site. This is the total perimeter of your site and should be the same as the red line that you provided on other parts of your application.
A finished red line diagram should look something like this:
Please note that the red line is a simple perimeter of the site, there are no red lines within the red line perimeter.
How to use this page
1) When you arrive on this page, you will see a map of the location you previously identified your site being on.
2) You should draw the red line boundary of your site using either the Select OS Features option (automatically selected) or the Draw option.
At the bottom of the page is a information box (next to to the undo and redo button) letting you know what the tools you have selected do.
Important point: Make sure you have a simple boundary and no 'red line within the red line'
You should make sure that there are no red lines within your red line diagram. For example, this site has a red line within it:
You should, instead, click on the house inside so that it is also selected within the red line and look like this:
Once you are done, press Continue at the bottom of the page to proceed.
Error Information: Unfortunately, your site area makes you a 'Large Site'
When you hit "continue" you might see a box appear saying "Unfortunately, your site area makes you a 'Large Site' Your site area exceeds the maximum permitted for the Small Site Metric"
The Biodiversity Net Gain Tool is currently designed for people who are eligible to use the "Small Site Metric". This means that only the following can use the tool:
If you are building a residential development and don't know how many residential units you are building. Under the laws set out by the Government, we can only accept a red line diagram that is under 5,000m² if there are an unknown number of residential dwellings being built.
For all other types of development. Under the laws set out by the Government, we can only accept a red line diagram that is under 10,000m².
You will need to commission a suitably qualified ecologist to complete the full statutory metric calculator. You may also wish to contact CIEEM to find a suitably qualified ecologist.
We will be releasing a new tool for larger sites soon. You can register your interest here.
You will be able to either return to the project page or, if you think there has been a mistake, you can revise the red line and readjust the size. If you get the size below the thresholds, you will be able to proceed.
Error Information: Self Intersecting Polygons are not allowed
This happens when you draw a red line diagram that intersects itself. These sorts of diagrams are not permitted under the rules.
Suggested steps
Try and use the Select OS Features to see if you can draw the site easily
If that doesn't work, then try and draw a basic shape with the draw tool which roughly aligns with the area. Then use the Edit tool to amend it to reflect your site's perimeter. There will not an error if you are in edit mode.
Tools on the page
At the top of the page you should see four options:
Draw
Select OS Features.
Edit
Delete
In the top left of the screen you will see a zoom tool.
In the top right of the screen, you will see a scale
At the bottom of the screen, you will see Undo and Redo tools.
In the right of the screen you will see Advanced Tools, with six options:
Angular Snapping
Map Features
Building Guides
Opacity
Edit / Adjust Plans
Upload Plans
How to use the tools on the page
You can tell a tool is active because it will be highlighted in yellow. You should click on the button a second time to turn off the tool.
Basic tools
Draw: This will allow you to draw a polygon onto the map. When this mode is on you will see a blue circle under your cursor.
Click on the map to start drawing. You will see a blue dot be placed on the map.
Now drag the map in any direction to create a length. As you do so, you will see the size of the length next to the line you are drawing. Simply click to create a corner.
One you have created two or more corners, the area will also be displayed.
Simply click on the blue dot to complete the polygon.
Select OS Features: Will automatically be selected. When this mode is on, if you move the mouse cursor over a part of the map, part of the map will automatically be highlighted in red. This is based on preexisting information, and may either select your whole site or part of the site. Simply clicking anywhere on the highlighted parcel will result in it being selected (you will see the red line become thick). You can adjust this red line by either going to edit mode, or - if you move the cursor over an adjacent parcel - you will be able to expand by clicking on this parcel. Please note, if you click on a area that is not adjacent, you will start a new red line diagram.
Edit: When this mode is selected, you will see the following information appear:
White Boxes. These are all the corners on your red line diagram.
You can click and drag these boxes to adjust the shape of the red line diagram.
If you click once you will delete the white box (if you do this by accident you can simply hit Undo at the bottom of the page.
Grey Boxes. If you click on one of these it will turn into a white box.
Angles. Each white corner will have the angle of the corner. As you adjust it you will see this angle change.
Lengths. Each length will have a length in metres.
Delete: When this mode is on, simply click on the red line to delete it.
Undo: Click on this button to undo your last action.
Redo: Click on this button to redo your last action.
Advanced tools
Angular Snapping: When you tick this option, you will be able to select an angle
5°
10°
45°
90°
When you select one of these options, when you are using the draw tool, you will always 'snap' to this angle or a multiple of it (e.g. if you select 5°, you will only be able to draw at a 5°, 10°, 15°, 20°... etc angle).
Map Features: When you tick this option, your cursor will automatically "snap" to preexisting map features (e.g. a road, or a site boundary, or feature). This can help to create a very accurate red line diagram.
Building Guides: If you have uploaded a site plan (see below) you can click on the eye icon to show or hide this plan.
Opacity: If you have uploaded a site plan (see below) you can use the scale here to make the site plan more or less transparent.
Edit / Adjust Plans: When this mode is selected, you will be able to:
Move the site plan by clicking and holding on the image and then dragging it to a new location.
Change the size of the site plan by clicking and dragging the corners
Spin the site plan by clicking and holding the black dot that hovers over the top part of the diagram
Delete the site plan by clicking on the delete icon in the white circule.
Upload Plans: When you click this you will open a window that will allow you to upload your site plan.
You should use the top left hand box (in grey) to upload your site plan (you can either click on the "Browse Files" to select the file from your computer or you can drag the image into your grey box). When selected, you can preview the image and then click Save Files to upload it to your site.
Please note that, if you upload a pdf, you will need to select the right page. To do this:
Upload the pdf by dragging it onto the box on the top left hand side of the grey box
The pdf will appear below the upload box (i.e. in the bottom left hand side). Please click on this pdf file name.
You will see page numbers appear at the bottom. It should look like this:
Using the arrow buttons, move across to the page that has your site plan on it. Then press Add Page
Questions and Answers
What is a "redline boundary"?
What is a "redline boundary"?
This is the "red line", the edge of your development site.
What is a "red line diagram"?
What is a "red line diagram"?
The red line boundary is the primary boundary that you need to identify on a location plan. It is the minimum requirement for a location plan and highlights the area of the property that is included in an application for planning permission.
Our partners at Planning Portal have done a great guide that you can read here!
I already have a red line diagram; can't I just import it?
I already have a red line diagram; can't I just import it?
You can import an image of your red line diagram using the Upload Plans diagram on the left hand of the screen. Please note that, at the moment, we can only accept images and you will need to use this to trace the red line diagram, but we will be adding new functionality later in 2024.
I added my Building Plans but I can't see them!
I added my Building Plans but I can't see them!
Pease try clicking on the eye symbol on the Building Guides option on the right hand hand of the screen. If you still can't see it, try to zoom out and see if it is located elsewhere.
I am trying to draw a freehand red line diagram, but the cursor keeps jumping around!
I am trying to draw a freehand red line diagram, but the cursor keeps jumping around!
This likely means that you have the Map Features snapping features turned on. With the Biodiversity Net Gain Tool, we have snapping features to help you draw the most accurate diagram possible, but sometimes you might want to turn them off.
Simply click on tick box next to Map Features on the right of the screen untick the various options to ensure that there is no bouncing around.
My screen keeps zooming in and out!
My screen keeps zooming in and out!
First, please make sure that you are using Joe's Blooms on a desktop computer or laptop with a mouse that has a scroll wheel. We will be updating the tools soon to make sure that they work well on smartphones and tablets, but at the moment, it's much easier to use the Biodiversity Net Gain Tool on a desktop.
If you are using a Mac, it is possible that you are using a magic mouse. The sensitivity of these mice is well known as an issue. To fix this, simply do the following:
Go to system preferences on your Mac.
Click on Accessibility.
Click on Pointer Control
Make sure you are on the "Mouse and & Tracker' tab and click "Mouse Options"
Untick "scrolling"
Click OK.
This will stop scrolling on your magic mouse. Follow the same process to reactive the mouse
I was drawing the red line but then it said "Self Intersecting Polygons are now allowed and my work vanished
I was drawing the red line but then it said "Self Intersecting Polygons are now allowed and my work vanished
Please see this information box
I am in "Select OS Features" mode but no red line is appearing
I am in "Select OS Features" mode but no red line is appearing
It is possible that you are trying to select a site where there isn't any preexisting data. If this is the case, you should use the draw tool (at the centre on the left of the screen) and draw the site freehand.
How do I edit the red line?
How do I edit the red line?
Select the edit option at the top of the screen (near the centre) to activate edit mode.
How do I delete a red line?
How do I delete a red line?
Select the Delete option at the top of the screen (near the right side) to activate delete mode
I am clicking on the map, but it : seem to be doing anything
I am clicking on the map, but it : seem to be doing anything
Please take the following steps:
1) Check to make sure you have either Draw or Select OS Features mode active. If you are in Select OS Features mode then please also check this guide.
2) Make sure that you don't have any option turned on (i.e. make sure that there isn't yellow highlighting) over any of the following:
Edit
Delete
3) Refresh your browser