How do I create a dimensioned 3-D floor plan?
How do I draw up a site plan?
Because architectural ground plans are a mandatory part of building permit applications and other preliminary building declarations (in the same way as site plans and façade plans), they need to be particularly precise.
The aim? To provide the most accurate possible projection of a future construction.
So what are the rules for drawing a dimensioned site plan ? 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.
To 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, built to scale, is also dimensioned in three dimensions. For certain elements, it specifies :
- width,
- length,
- height.
☝️ A floor plan doesn't actually involve drawing in three dimensions. In fact, this formatting involves the use of annotations, as we'll see below.
When is a site plan mandatory?
- Building permit applications. This is required if the planned construction exceeds 20 m2 floor area. In this case, you need to enclose a site plan (called 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 Service Public website. In this context, the ground plan is known as DP2.
The aim of these obligations? To ensure that future constructions comply with current town planning regulations. This is why a site plan must include as much detail as possible, to avoid any risk of rejection of the building permit or preliminary works declaration dossier by the authorities.
Who can supply a site plan?
A dimensioned site plan requires precise measurements and a rigorous approach.
This is why the services of an expert surveyor (whose fees range from around €500 to €1,500) are often the preferred solution.
However, with a little practice, anyone can draw up this document themselves.
☝️ Please note, however, that the services of a surveyor are obligatory in certain cases: if there are disputes, or if the land has never been marked out.
How do I draw up a site plan?
Produce two ground plans
First and foremost, you'll need to include two ground plans in your file:
- the ground plan of the plot before construction,
- the ground plan with the construction project.
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 construction.
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.
In this way, you help the authorities to see whether the setbacks (which vary from one location or type of construction to another) from the dividing lines between private properties or the public domain have been respected.
In the example below, property boundaries are symbolized by a thick, dark green line:
© Permis de Construire
💡 Use the cadastral map of your plot of land, available on cadastre.gouv.fr!
Existing and future constructions
As you're providing two ground plans, the first shows existing constructions, and the second future constructions.
For each, specify :
- their location,
- and their dimensions.
☝️ By constructions, we certainly mean the main building (such as a detached house), but also all ancillary developments: garden shed, swimming pool, garage, etc.
💡 To make it easier for the authorities to read your project, we recommend that you highlight future constructions on the second site plan, using colored hatching for example.
Landscaping and planting
Draw all existing and future plantings on your site plan, subject to certain regulations: for example, trees over two meters tall must be set back two meters.
Example of a site plan with plantings :
Systeme Ceramique
It's also important to show any exterior fittings (flagstones, driveways, terraces, pylons, barbecues, etc.).
Last but not least, 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 by the Tn marker (+ 2 metres).
Urbinfos
Access to land, buildings and parking areas
Roads and access roads to plots and buildings, as well as parking areas, must also be shown on both site plans. This ensures that everything is in order, particularly in terms of safety.
To this end, please indicate the exact locations and dimensions of accesses to buildings (e.g. gate dimensions).
In the floor plan below, we have a clear view of the parking area, the two lanes and the two gates leading from Rue du Parc to the various buildings.
Building Permits
The various networks
Indicate on your ground plans the location of the various networks (sewage, drinking water, electricity, telephone, etc.).
Additional information
The following information should be added to your site plans, to make them easier to read for the authorities:
- the orientation of the plan, indicating north with a compass rose for example,
- the location of the two photographs to be attached to the application for a building permit or prior declaration of works (documents PC7 and PC8),
- a legend to facilitate general understanding,
- the scale of the plan, both graphic 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 meter = 1 cm on your plan, to facilitate calculation and reading.
Dimensions
Finally, several types of dimensioning must appear on the ground plan. They are used to indicate :
- building dimensions. Specify the length, width and, in some cases, the height of the structure directly on the drawing:
- height to roof peak (ridge),
- fence height,
- eave height.
- distances :
- from buildings to property boundaries,
- between buildings themselves.
What tools are needed to draw up a site plan?
There are two ways to draw up a site plan.
Drawing by hand...
Firstly, you can draw your ground plan by hand. In this case, a sheet of paper (generally A3 in size), a ruler, a mechanical pencil or colored pencils will be your best allies in producing drawings worthy of the name.
You'll find all the drawing materials you'll need in our article on architectural tools.
... or architectural software?
You can also use specialized software. The famous Sketchup, for example, allows you to make 2D drawings (even with its free version). What's more, thanks to the tool's popularity, you can take advantage of numerous online tutorials and training courses to master all its subtleties.
We should also mention 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, a free version is also available.
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