How do I create a dimensioned 3-D ground plan?
How do you draw up a site plan?
Because the architectural layout plan is a compulsory part of any application for planning permission or prior declaration of works (in the same way as the site plan or façade plan), it has to be particularly precise.
The aim? To provide the most accurate possible projection of a future building.
So what are the rules you need to follow to draw a site plan that has a town planning dimension ? What elements must be included? What is the scale of a site plan?
This article explains in detail how to draw a 3-dimensional site plan.
So get your pencils... and your software!
What is a dimensional floor plan?
A site plan is a schematic aerial view of existing and future buildings (house, garage, garden shed, etc.), their layout and dimensions.
The plan, which is built to scale, is also dimensioned in three dimensions. For example, it specifies for certain elements :
- their width
- length
- their height.
☝️ A site plan does not involve drawing in three dimensions. In fact, this formatting involves the use of annotations, as we will see below.
When is a site plan compulsory?
- Building permit applications. It is required if the proposed construction exceeds 20 m2 of floor area. You must enclose a site plan (known in this context as PCMI2 for single-family home projects, and PC2 for other types of construction).
- Prior declaration of works. This concerns a certain number of works, a list of which can be found on the Public Service website. In this context, the site plan is known as the DP2.
What is the purpose of these obligations? To ensure that future constructions comply with current planning regulations. That's why a site plan must include as much detail as possible, to avoid any risk of the authorities rejecting the planning permission or preliminary works declaration application.
Who can provide a site plan?
A dimensioned site plan requires precise measurements and meticulousness.
Consequently, using the services of an expert surveyor (whose fees range from around €500 to €1,500) is often the preferred solution.
However, with a little practice, anyone can draw up this document themselves.
☝️ Please note that the services of a surveyor are compulsory in certain cases: if there are disputes, or if the land has never been marked out.
How do you draw up a site plan?
Produce two ground plans
First and foremost, you will need to include two ground plans in your application:
- the ground plan of the plot before construction,
- the ground plan with the proposed building.
This gives the authorities a clearer picture of the project in relation to what already exists.
☝️ This obligation applies to all types of project, whether an extension to the main building or a new build.
Example of two ground plans showing the current state of the land and the project:
Allow me to build
Property boundaries
Show the property boundaries on your site plan.
This will help the authorities to see whether the setbacks (which vary from one location or type of building to another) from the dividing lines between private properties or the public domain have been respected.
In the example below, property boundaries are symbolised by a thick, dark green line:
Planning permission
💡 Use the cadastral map of your plot of land, available on the cadastre.gouv.fr website!
Existing and future buildings
As you are providing two ground plans, the first shows the existing buildings, and the second the buildings to come.
For each of them, specify :
- their location
- and their dimensions.
☝️ By constructions, we certainly mean the main building (such as the detached house), but also all the ancillary developments: garden shed, swimming pool, garage, etc.
💡 To make it easier for the authorities to read your project, we recommend that you highlight any future constructions on the second site plan, using coloured hatching for example.
Exterior landscaping and planting
Draw all existing and future planting on your site plan, subject to certain regulations: for example, trees over two metres tall must be set back two metres.
Example of a site plan with planting:
Systeme Ceramique
It's also important to show any outdoor features (paving stones, paths, terraces, pylons, barbecues, etc.).
Finally, reproduce any variations in ground level:
- the natural slope of the terrain, using the Tn (natural terrain) marker,
- unevenness, hollows, etc. In this case, you can use the Tf marker (finished ground).
In the example below, the mound is marked with dotted lines. Its height is also indicated using the Tn tag (+ 2 metres).
Urbinfos
Access to land, buildings and parking areas
The access roads and services to the land and buildings, as well as the parking areas, must also be shown on the two site plans. This ensures that everything is in order, particularly in terms of safety.
To do this, indicate the exact locations and dimensions of access to the buildings (dimensions of gates, for example).
The ground plan below shows the parking area, the two lanes and the two gates leading from Rue du Parc to the various buildings.
Planning permission
The various networks
Show the location of the various networks on your ground plans (connection to the sewage system, drinking water supply, electricity, telephone, etc.).
Additional information
The following information should be added to the site plans to make them easier for the authorities to read:
- the orientation of the plan, indicating north using a compass rose for example,
- the location from which the two photographs were taken, to be attached to the application for planning permission or prior declaration of works (documents PC7 and PC8),
- a legend to facilitate general understanding,
- the scale of the plan, both graphical and digital.
☝️ The scale of a site plan must be between 1:50 and 1:500. However, we suggest that you opt for a scale of 1/100, i.e. 1 metre = 1 cm on your plan, to make it easier to calculate and read.
Dimensions
Finally, there are several types of dimension that should appear on the site plan. These are used to indicate :
- the dimensions of the buildings. Specify the length, width and, in some cases, the height of the building directly on the plan:
- height at the top of the roof (ridge),
- fence height
- height at the eaves (gutter).
- distances :
- from buildings to the boundaries of the plot,
- between the buildings themselves.
What tools are needed to draw up a site plan?
There are two ways of drawing up a site plan.
Drawing by hand...
Firstly, you can draw your site plan by hand. In this case, a sheet of paper (usually A3 size), a ruler to scale, a mechanical pencil or coloured pencils are the perfect tools for producing drawings worthy of the name.
You can find all the drawing materials you need in our article on the architect's tools.
... or architecture software?
You can also use specialist software. The famous Sketchup, for example, allows you to make 2D drawings (even with the free version). What's more, thanks to the popularity of this tool, you can take advantage of numerous online tutorials and training courses to master all its subtleties.
There's also Archifacile, the 2D drawing specialist: its ease of use and user-friendly interface will appeal to those less familiar with architectural software. What's more, there's a free version of this too.
You now have all the tools you need to bring your construction projects to life, thanks to floor plans that comply with government requirements!
Article translated from French