National foreword

This British Standard is the UK implementation of EN 1991‑1‑3:2025. It supersedes BS EN 1991‑1‑3:2003+A1:2015, which will be withdrawn on 30 March 2028.

The UK participation in its preparation was entrusted to Technical Committee B/525/1, Actions (loadings) and basis of design.

A list of organizations represented on this committee can be obtained on request to its committee manager.

National choice is allowed in this standard where explicitly stated within notes. The National Annex to this standard contains the national choices to be used for buildings and civil engineering works constructed in the UK.

The first generation of EN Eurocodes was published between 2002 and 2007, with conflicting British Standards withdrawn in 2010. This document forms part of the second generation of EN Eurocodes.

The second generation of EN Eurocodes is expected to be published between 2023 and 2026. These documents are being published as soon as they are available. This is being done to enable users to prepare for the transition from the first generation to second generation of EN Eurocodes.

UK adoptions of the first generation of EN Eurocodes will be withdrawn by BSI on 30 March 2028. Until that date, the first generation documents should be considered as the applicable standards for buildings and civil engineering works constructed in the UK unless otherwise specified by the relevant authority or in the specification for a particular project.

This standard is intended to be used with its National Annex and other referenced documents, including other second generation Eurocodes, as an interdependent suite of documents.

While the use of provisions in this standard in conjunction with first generation Eurocodes is not precluded, it should be undertaken with care and should only be done when users are satisfied that it will not result in a lower level of reliability than the minimum level set in the first generation Eurocodes and associated UK National Annexes.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2025.

This European Standard was approved by CEN on 29 December 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and United Kingdom.

European foreword

This document (EN 1991‑1‑3:2025) has been prepared by Technical Committee CEN/TC 250 “Structural Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible for all Structural Eurocodes and has been assigned responsibility for structural and geotechnical design matters by CEN.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2027, and conflicting national standards shall be withdrawn at the latest by March 2028.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document will supersede EN 1991‑1‑3:2003.

The main changes compared to the previous edition are listed below:

refinement of load models closer to the physics and based on state-of-the-art experimental data available for European climates, considering the effects of wind exposure on the unbalanced load cases;
introduction of guidance for the treatment of climate change effects on the determination of snow loads on the ground;
update of roof snow load models for pitched (gabled), multi-span, cylindrical, domes and flat roofs. For the latter the influence of the roof dimensions, as well as the presence of rows of tilted (solar) panels are addressed;
update of the “unbalanced” roof snow load model for roof abutting and close to taller construction works, taking also into account the variability of the drift in relation to the difference in height of the adjacent buildings;
update of the snow load models (and related shape coefficients) for local verifications (local effects); a new load case is introduced to cover drifting at intersecting pitched roofs. A clear distinction between parapets and local obstructions on roofs is defined and specific models updated.

The first generation of EN Eurocodes was published between 2002 and 2007. This document forms part of the second generation of the Eurocodes, which have been prepared under Mandate M/515 issued to CEN by the European Commission and the European Free Trade Association.

The Eurocodes have been drafted to be used in conjunction with relevant execution, material, product and test standards, and to identify requirements for execution, materials, products and testing that are relied upon by the Eurocodes.

The Eurocodes recognize the responsibility of each Member State and have safeguarded their right to determine values related to regulatory safety matters at national level through the use of National Annexes.

Any feedback and questions on this document should be directed to the users’ national standards body. A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United Kingdom.

Introduction

0.1 Introduction to the Eurocodes

0.2

0.3

0.4 Verbal forms used in the Eurocodes

0.5

1 Scope

1.1 Scope of EN 1991‑1‑3

(1) EN 1991‑1‑3 gives principles and rules to determine the values of loads due to snow to be used for the structural design of buildings and civil engineering works.

(2) This document does not apply to sites at altitudes above 1 500 m, unless otherwise specified.

NOTE For rules for the treatment of snow loads for altitudes above 1 500 m, see 6.1.

(3) This document does not give guidance on specialist aspects of snow loading, for example:

impact snow loads resulting from snow sliding off or falling from a higher roof;
changes in shape or size of the construction works due to the presence of snow or the accretion of ice which could affect the wind action;
loads in areas where snow is present all year round;
lateral loading due to snow creep (e.g. lateral loads exerted by drifts);
loads due to artificial snow.

1.2 Assumptions

The assumptions given in EN 1990:2023, 1.2 apply.

2 Normative references

3 Terms, definitions and symbols

3.1 Terms and definitions

3.2 Symbols and abbreviations

4 Design situations

4.1 General

4.2 Normal conditions

4.3 Exceptional conditions

5 Modelling of snow load

5.1 Classification of actions

5.2 Design assisted by testing

6 Snow load on the ground

6.1 Characteristic values

6.2 Treatment of exceptional snow loads on the ground

7 Snow load on roofs

7.1 Load arrangements

7.2 Determination of snow load

7.3 Exposure coefficient

7.4 Thermal coefficient

7.5 Snow load shape coefficients

8 Local Effects

8.1 Local verifications

8.2 Drifting at obstructions on flat roofs

8.3 Drifting at parapets

8.4 Snow overhanging the edge of a roof

8.5 Snow loads on snow guards and other obstacles

8.6 Snow loads at intersecting pitched roofs

Bibliography

BS EN 1991-1-3:2025

Eurocode 1. Actions on structures - Snow loads

Current, Under Review

Published:

28 Feb 2025