# Snow zones map – France

## What are the French snow zones according to Eurocode 1 ?

On the map of the national annex, the French territory is divided by canton into five regions of snow identified from A to E. Three of these regions (A to C) are subdivided into two to account for accidental snow precipitation.

Zone | A1 | A2 | B1 | B2 | C1 | C2 | D | E |
---|---|---|---|---|---|---|---|---|

Characteristic value of snow on the ground without elevation
s_{k,0}
| 0.45 kN/m^{2} | 0.45 kN/m^{2} | 0.55 kN/m^{2} | 0.55 kN/m^{2} | 0.65 kN/m^{2} | 0.65 kN/m^{2} | 0.90 kN/m^{2} | 1.40 kN/m^{2} |

Design value of exceptional snow load on the ground>
s_{k,0}
| – | 1.00 kN/m^{2} | 1.00 kN/m^{2} | 1.35 kN/m^{2} | – | 1.35 kN/m^{2} | 1.80 kN/m^{2} | – |

The French overseas departments, overseas territories and overseas collectivities are not subject to snowfall except Saint Pierre and Miquelon.

Characteristic value of snow on the ground without elevation at Saint Pierre and Miquelon: s_{k,0} = 2.60kN/m^{2}

## How to determine the influence of elevation on the ground snow load in France ?

Two distinct variation laws must be applied depending on whether the construction is in snow zone E or not.

Snow loads are calculated as follows:

**Up to 200m:**

\[\displaystyle s_{k} = s_{k,0}\]
**From 200m to 500m:**

*All zones except zone E*:

*Zone E only:*

**From 500m to 1000m**:

*All zones except zone E:*

*Zone E only*:

**From 1000m to 2000m:**

*All zones except zone E:*

*Zone E only:*

where A is the elevation of the site.

## How to adjust the ground snow load according to return period in France ?

\[\displaystyle s_{n} = s_{k} \cdot \left[ \frac{ 1 – V \cdot \frac{\sqrt 6}{\pi} \cdot [\ln(-\ln(1-P_{n})) + 0.57722] } {(1 + 2.5923 \cdot V)} \right]\]- P
_{n}is the annual probability of exceedence :

- dwl is the design working life, in years.
- V is the coefficient of variation of annual maximum snow load with V=0.2 for a recurrence interval less than 50 years and V=0.6 for a recurrence interval greater than 50 years.
- It should not be applied for annual probabilities of exceedence greater than 0,2 (i.e. return period less than approximately 5 years).

## Example of results given by the software Eurocodes Zoning

### B1 – Localization

- Coordinates in World Geodetic System 1984 (WGS84) 3.5332°, 45.7153°
- Coordinates in French Geodetic System 1993 (Lambert 93) 741482m, 6512993m

Address D 304A, 63120 Sauviat, Auvergne-Rhône-Alpes

### B2 – Altitudes

Distances / Direction | At the place of construction | 500m | 1000m |
---|---|---|---|

North | 436 m | 360m | 407m |

Northeast | 405m | 465m | |

East | 456m | 473m | |

Southeast | 419m | 446m | |

South | 449m | 476m | |

Southwest | 432m | 411m | |

West | 360m | 468m | |

Northwest | 403m | 452m |

### B3 – Building

- Type of building: monumental building
- Design working life category: 100 years
- Max height: 15.0 m
- Orientation from North: 80°

### B4 – Terrain categories

Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|

Categories | IIIa | IV | IV | IV |

### C1 – Snow

NF EN 1991-1-3/NA (may 2007) + A1 (july 2011)

- Zone : A2(s
_{k,0}= 0.45 kN/m²) - Criteria for zoning : PUY-DE-DOME (63)
- Characteristic value of snow on the ground at the relevant site : s
_{k,436}= 0.686 kN/m² - Ground snow load with a return period of 100 years : s
_{100 ans}= 0.774 kN/m² - Design value of exceptional snow load on the ground : s
_{ad}= 1.0 kN/m²

### C2 – Vent

NF EN 1991-1-4/NA (march 2008) + A1 (july 2011) + A2 (september 2012) + A3 (april 2019)

- Zone : 2(v
_{b,0}= 24.0 m/s) - Criteria for zoning : PUY-DE-DOME (63)
- Zone c
_{dir}: 1

Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|

Sector definition | from 35 ° to 125 ° | from 125 ° to 215 ° | from 215 ° to 305 ° | from 305 ° to 35 ° |

Fundamental value of the basic wind velocity
v_{b,0}
| 24.0m/s | |||

Shape parameter K | 0.2 | |||

Exponent n | 0.5 | |||

Annual probability of exceedence p | 0.01 | |||

Probability factor
c_{prob}
| 1.038 | |||

Directional factor
c_{dir}
| 0.7 | 1.0 | 1.0 | 1.0 |

Basic wind velocity
v_{b}
| 17.4m/s | 24.9m/s | 24.9m/s | 24.9m/s |

Reference roughness length
z_{0,II}
| 0.05m | |||

Roughness length
z_{0}
| 0.2m | 1.0m | 1.0m | 1.0m |

Terrain factor
k_{r}
| 0.209 | 0.234 | 0.234 | 0.234 |

Height above ground z | 15.0m | |||

Minimum height
z_{min}
| 5.0m | 15.0m | 15.0m | 15.0m |

Roughness factor
c_{r(z)}
| 0.904 | 0.635 | 0.635 | 0.635 |

Orography factor
^{*} c_{o(z)}
| 1.0 | 1.0 | 1.0 | 1.0 |

Mean wind velocity
v_{m(z)}
| 15.8m/s | 15.8m/s | 15.8m/s | 15.8m/s |

Turbulence factor
k_{l}
| 0.97 | 0.854 | 0.854 | 0.854 |

Standard deviation of the turbulence
σ_{v}
| 3.544m/s | 4.989m/s | 4.989m/s | 4.989m/s |

Turbulence intensity
I_{v(z)}
| 0.225 | 0.315 | 0.315 | 0.315 |

Air density ρ | 1.225kg/m^{3} | |||

Exposure factor
c_{e(z)}
| 2.102 | 1.292 | 1.292 | 1.292 |

Peak velocity pressure
q_{p(z)}
| 392.0N/m^{2} | 491.5N/m^{2} | 491.5N/m^{2} | 491.5N/m^{2} |

Peak wind velocity for Serviceability Limit States
v_{p(z),SLS}
| 91.1km/h | 102.0km/h | 102.0km/h | 102.0km/h |

Peak wind velocity for Ultimate Limit States
v_{p(z),ULS}
| 111.5km/h | 124.9km/h | 124.9km/h | 124.9km/h |

Here, the orography factor is calculated according to Procedure 1, for an orography consisting of obstacles of various heights and shapes. This type of orography is the most frequently encountered.However, if the building is in a case of orography consisting of well individualized obstacle (isolated hills and ridges or cliffs and escarpments) the orography factor must be calculated according to the procedure 2. According to EN 1991-1-4 §4.3.3(1), the calculated orography factor (1.018) is not taken into account because it does not increase wind velocities by more than 5%.

### C3 – Seism

Code of the Environment – Article D563-8-1 (09/01/2015)

JORF n°0248 du 24/10/2010 texte N°5

- Zone : 3(1.1 m/s²)
- Criteria for zoning : Sauviat, Puy-de-Dome (63)
- A seismic analysis may be required for this building.