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Imposed loads of buildings

What are the imposed loads of buildings ?

Imposed loads on buildings are those arising from occupancy. Values given in Eurocode 1 Part 1-1 Section 6, include:

The imposed loads can be modelled by uniformly distributed loads, line loads or concentrated loads or combinations of these loads.

For the determination of the imposed loads, floor and roof areas in buildings should be sub-divided into categories according to their use.

Heavy equipment (e.g. in communal kitchens, radiology rooms, boiler rooms etc) are not included in the loads given in this Section. Loads for heavy equipment should be agreed between the client and/or the relevant Authority.

How to arrange the charges ?

Floors, beams and roofs

For the design of a floor structure within one storey or a roof, the imposed load shall be taken into account as a free action applied at the most unfavourable part of the influence area of the action effects considered.

Where the loads on other storeys are relevant, they may be assumed to be distributed uniformly (fixed actions).

To ensure a minimum local resistance of the floor structure a separate verification shall be performed with a concentrated load that, unless stated otherwise, shall not be conlbined with the uniformly distributed loads or other variable actions.

Imposed loads from a single category may be reduced according to the areas supported by the appropriate member, by a reduction factor αA.
αA may be applied to the qk values for imposed loads for floors and for accessible roofs, Category I.
The general method is : (6.3.1.2(10))
where:

NOTE: The National Annex may give an alternative method, e.g. for France :
(Clause 6.3.1.2(10))
where:
  • The reduction coefficient αA is only used for the following use categories: A, B, C3, D1, and F.
    There is no reduction to apply for the other categories.
  • A0 = 3.5m2,
  • A is the loaded area.

Walls and columns

For the design of columns and walls, the imposed load should be placed at all unfavourable locations.
NOTE: The National Annex may introduce further simplifying rules. It is recommended that the maximum axial force may be calculated assuming the total imposed load on the floor of each story to be uniformly distributed.

Where imposed loads from several storeys act on columns and walls, the total imposed loads may be reduced by a factor αn.
The general method is : (6.3.1.2(11))
where:

NOTE: The National Annex may give an alternative method, e.g. for France :
The reduction coefficient αn is only used for the following use categories: A, B, and F.
There is no reduction to apply for the other categories.

(Clause 6.3.1.2(11) for category A)

(Clause 6.3.1.2(11) for categories B and F)

The coefficients αA and αn are not to be taken into account simultaneously.

When the imposed load is considered as an accompanying action, in accordance with Eurocode 0, only one of the two factors Ψ (Eurocode 0, Table A1.1) and αn (6.3.1.2 (11)) shall be applied.

Characteristics values

Residential, social, commercial and administration areas

Usage categories A to D

Category Specific Use Examples
A Areas for domestic and residential activities Rooms in residential buildings and houses; bedrooms and wards in hospitals; bedrooms in hotels and hostels kitchens and toilets.
B Office areas
C Areas where people may congregate (with the exception of areas defined under category A, B, and D1 C1: Areas with tables, etc. e.g. areas in schools, cafes, restaurants, dining halls, reading rooms, receptions.
C2: Areas with fixed seats, e.g. areas in churches, theatres or cinemas, conference rooms, lecture halls, assembly halls, waiting rooms, railway waiting rooms.
C3: Areas without obstacles for moving people, areas in museums, exhibition rooms, etc. and access areas in public and administration buildings, hotels, hospitals, railway station forecourts.
C4: Areas with possible physical activities, e.g. dance halls, gymnastic rooms, stages.
C5: Areas susceptible to large crowds, e.g. in buildings for public events like concert halls, sports halls including stands, terraces and access areas and railway platforms.
D Shopping areas D1: Areas in general retail shops
D2: Areas in department stores
Independent of this classification of areas, dynamic effects shall be considered where it is anticipated that the occupancy will cause significant dynamic effects, in particular for C4 and C5. See Eurocode 0 when dynamic effects need to be considered.
Depending on their anticipated uses, areas likely to be categorised as C2, C3, C4 may be categorised as C5 by decision of the client and/or National annex.
The National annex may provide sub categories to A, B, Cl to C5, D I and D2.
See « Areas for storage and industrial activities » for storage or industrial activity.

Values of actions for categories A to D

The loaded areas shall be designed by using characteristic values qk (uniformly distributed load) and Qk (concentrated load).

NOTE: Values for qk and Qk are given in Table below.
Where a range is in this table, the value may be set by the National annex.
You can use our software to find the loads according to your country.
The recommended values, intended for separate application, are underlined.
qk is intended for determination of effects and Qk for local effects.
The National annex may define different conditions of use of this Table.

Categories of loaded areas qk [kN/m2] Qk [kN]
Category A - Floors 1.5 to 2.0 2.0 to 3.0
Category A - Stairs 2.0 to 4.0 2.0 to 4.0
Category A - Balconies 2.5 to 4.0 2.0 to 3.0
Category B 2.0 to 3.0 1.5 to 4.5
Category C1 2.0 to 3.0 3.0 to 4.0
Category C2 3.0 to 4.0 2.5 to 7.0 (4.0)
Category C3 3.0 to 5.0 4.0 to 7.0
Category C4 4.5 to 5.0 3.5 to 7.0
Category C5 5.0 to 7.5 3.5 to 4.5
Category D1 4.0 to 5.0 3.5 to 7.0 (4.0)
Category D2 4.0 to 5.0 3.5 to 7.0

Where necessary qk and Qk should be increased in the design (e.g. for stairs and balconies depending on the occupancy and on dimensions).

For local verifications a concentrated load Qk acting alone should be taken into account.

The concentrated load shall be considered to act at any point on the floor, balcony or stairs over an area with a shape which is appropriate to the use and form of the floor.
NOTE: The shape may normally be assumed as a square with a width of 50 mm.

Where floors are subjected to multiple use, they shall be designed for the most unfavourable category of loading which produces the highest effects of actions (e.g. forces or deflection) in the member under consideration.

Self-weight of partitions

Provided that a floor allows a lateral distribution of loads, the self-weight of movable partitions may be taken into account by a uniformly distributed load qk which should be added to the imposed loads of floors obtained from Table above. This defined uniformly distributed load is dependent on the self-weight of the partitions as follows:

Heavier partitions should be considered in the design taking account of:

Areas for storage and industrial activities

Usage categories E

Category Specific Use Examples
E1 Areas suceptible to accumulation of goods, including access areas. Areas for storage use including storage of books and other documents.
E2 Industrial use

Values of actions for categories E

Categories of loaded areas qk [kN/m2] Qk [kN]
Category E1 7.5 7.0
The values may be changed if necessary according to the usage for the particular project or by the National annex. You can use our software to find the loads according to your country, to the density and the upper design values for stacking heights of the stored material.

The dynamic effects should be considered if appropriate.

Loads in industrial areas should be assessed considering the intended use and the equipment which is to be installed.
Where equipment such as cranes, moving machinery etc, are to be installed the effects on the structure should be determined in accordance with Eurocode 1 Part 3.

Actions due to forklifts and transport vehicles should be considered as concentrated loads acting together with the appropriate imposed distributed loads.
See Eurocode 1 Part 1-1 :

Garages and vehicle traffic areas (excluding bridges)

Usage categories F and G

Categories of traffic areas Specific Use Examples
F Traffic and parking areas for light vehicles (≤30kN gross vehicle weight and ≤8 seats not including driver) garages; parking areas, parking halls.
G Traffic and parking areas for medium vehicles (>30kN, ≤160kN gross vehicle weight, on 2 axles) access route; delivery zones; zones accessible to fire engines (≤160kN gross vehicle weight)

Values of actions for categories F and G

The load model which should be used is a single axle with a load Qk with 1800mm of spacing between wheels axis and a uniformly distributed load qk.
The axle load should be applied on two square surfaces with a 100mm side for category F and a 200mm side for Category G in the possible positions which will produce the most adverse effects of the action.
The characteristic values for qk and Qk are given in Table below.
NOTE: qk is intended for determination of general effects and Qk for local effects.
The National annex may define different conditions of use of this Table.

Categories qk [kN/m2] Qk [kN]
Category F - Gross vehicle weight: ≤ 30kN 1.5 to 2.5 10.0 to 20.0
Category G - 30kN < gross vehicle weight ≤ 160kN 5.0 40.0 to 90.0
The values may be set by the National annex. The recommended values are underlined.

Roofs

Usage categories H to K

Categories of loaded areas Specific Use
H Roofs not accessible except for normal maintenance and repair.
I Roofs accessible with occupancy according to categories A to D.
K Roofs accessible for special services, such as helicopter landing areas.

Values of actions for categories H to K

Categories qk [kN/m2] Qk [kN]
Category H 0.0 to 1.0 0.9 to 1.5
The values may be set by the National annex. The recommended values are:
qk = 0.4kN/m2; Qk = 1.0kN
qk may be varied by the National Annex dependent upon the roof slope.
qk may be assumed to act on an area A which may be set by the National Annex. The recommended value for A is 10 m2, within the range of zero to the whole area of the roof. (France: 10 m2; Belgium: the area carried by the element; UK: the whole area of the roof).

For roofs separate verifications shall be performed for the concentrated load Qk and the uniformly distributed load qk, acting independently.

On roofs (particularly for category H roofs), imposed loads need not be applied in combination with either snow loads and/or wind actions.

Parapets and partition walls acting as barriers

The characteristic values of the line load qk acting at the height of the partition wall or parapets but not higher than 1,20m should be taken from Table below.

Loaded areas qk [kN/m]
Category A 0.2 to 1.0 (0.5)
Category B and C1 0.2 to 1.0 (0.5)
Categories C2 to C4 and D 0.8 to 1.0
Category C5 3.0 to 5.0
Category E 0.8 to 2.0
Category F A calculation according to Eurocode 1 Part 1-1 Annex B is requiered
Category G A calculation according to Eurocode 1 Part 1-1 Annex B is requiered
The values for qk may be chosen by the National Annex.
The recommended values are underlined.
For areas of category E the horizontal loads depend on the occupancy. Therefore the value of qk is defined as a minimum value and should be checked for the specific occupancy.
The National Annex may prescribe additional point loads Qk and/or hard or soft body impact specifications for analytical or experimental verification.

For areas susceptible to significant overcrowding associated with public events e.g. for sports stadia, stands, stages, assembly halls or conference rooms, the line load should be taken according to category C5.

Example of results given by the software

See the features of Usage Loads
Available in English/French, otherwise «Google Translate»!

B - Occupancy data

General use : Garages, vehicle traffic areas (excluding bridges)
Category of material : Garages for light vehicles
Gross vehicle weight : 1800.0kg
French flag

C - Description of imposed loads

(Eurocode 1)
Location Category qk Qk Recommandations
On the floor: F 2.3kN/m2 15.0kN These values ​​cover dynamic effects when the speed of circulation is less than 20km/h.
Along the parapets: F 100.0kN/m - over a length of 1.5m
NOTE: qk is intended for determination of general effects and Qk for local effects (on a square surface of 50 mm on the side).
Qk/2 Qk/2 a a a a 1.80m
with :
  • width of the square surface : a = 100mm
  • Qk/2 = 7.5kN

D - Combinations of actions

Factors for accompanying actions : (Eurocode 0)
  • Factor for combination value of a variable action : Ψ0 = 0.7
  • Factor for frequent value of a variable action : Ψ1 = 0.7
  • Factor for quasi-permanent value of a variable action : Ψ2 = 0.6