– Construction on a sloping lot: slope calculation
– The different types of layouts for building on sloping land
Risks of building on a slope
– Construction on a sloping ground: legislation
– Price of construction on a sloping lot

Construction on a sloping terrain must take into account the constraints related to the relief: the construction must adapt to the relief in a harmonious way and the structure must be stable. The stakes of such a construction are important and must be taken into account before starting large scale works.

Construction on a sloping terrain: calculation of the slope

The calculation of the percentage of the slope of the land allows knowing the type of slope: gentle, moderate or steep.
Knowing the inclination of the slope is essential to establish a construction plan adapted to the constraints of the terrain.
The calculation of the slope is expressed as a percentage and is obtained by applying the following formula:
– Slope (%) = Elevation (m) / Length travelled (m)
– Vertical drop = Total height between the arrival point and the departure point.

For example, a slope of 8% is equivalent to an elevation gain of 8 meters by 100 meters.

Note: The access slope to the construction must meet the requirements of the PLU (Local Urban Plan).

The different types of layout for building on a sloping lot

Depending on the configuration of the land and its inclination, 3 types of implantation are possible:

Cascade or stepped construction

Cascade or stepped construction is characterized by the creation of different levels depending on the degree of slope inclination.
It fits the slope perfectly. This choice of implantation is respectful of the relief but complicates the circulation in the places because of the number of stairs.

Built-in construction

Harmoniously anchored in the relief, this type of construction benefits from good thermal insulation. On the other hand, it limits the number of views and their location. This type of construction requires significant excavation work.

The belvedere construction

Raised thanks to a system of pilings, the belvedere construction is the one that distorts the terrain the least but requires the development of a complex load-bearing system. Access is also more complicated, requiring sometimes costly development work.

Risks of building on a slope

Terrain movements are characterized by the Earth’s gravity exerted on unstable elements. They can be natural (avalanches, mudflows) or related to the nature of the terrain (unstable soils) and construction (unsuitable foundations).
Land movements can endanger the buildings but above all their inhabitants: cracks, landslides or settling of land can occur.

Construction on sloping land: legislation

The construction of a building on sloping ground is subject, like all other new constructions, to obtaining a building permit to which must be attached technical documents: a geological and geotechnical study of the soil, the works envisaged (access, etc.).
The building permit related to the construction of a sloping land is accepted as soon as the construction project complies with the requirements of the Local Urban Planning Plan or the subdivision regulations if the envisaged construction is located in a subdivision.

Price of the construction on a sloping land

Construction on sloping land is more expensive than construction on flat land because of the work to be done.
The cost of this type of construction depends on:
– the access to the building site more or less complex;
– the inclination of the slope;
– the nature of the ground;
– the type of construction envisaged (construction on piles, embedded, etc.);
– its surface area.
The price also takes into account the volume of land to be disbursed.
In short, construction on a sloping ground generates an additional cost which can be important.