ISO INTERNATIONAL STANDARD 4355 Third edition 2013-12-01 Bases for design of structures Determination of snow loads on roofs Bases du calcul des constructions - Détermination de la charge de neigesurlestoitures Reference number ISO 4355:2013(E) ISO @IS02013 I by IHS under No reproduction or networking permitted without license from IHS Not for Resale IS0 4355:2013(E) COPYRIGHTPROTECTEDDOCUMENT @IS02013 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 : CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax +41 22 749 09 47 E-mail copyright@iso.org Web www.iso.org Published in Switzerland @ IS0 2013 - All rights reserved No reproduction or networking permited without license from IHS Not for Resale IS0 4355:2013(E) Contents Page Foreword ..iv Introduction. .. 1 Scope. ..1 2 Normative references. ..1 3 Terms and definitions ..1 4 Snow loads on roofs .3 4.1 General function describing intensity and distribution of the snow load on roofs .3 4.2 Approximate formats for the determination of the snow load on roofs .3 4.3 Partial loading due to melting, sliding, snow redistribution, and snow removal. .4 4.4 Ponding instability.... .4 5 Characteristic snow load on the ground ..4 6 Snow load coefficients ..4 6.1 Exposure coefficient .4 6.2 Thermal coefficient 6.3 Surface material coefficient .6 6.4 Shape coefficients.. ..6 Annex A (informative) Background on the determination of some snow parameters ..8 Annex B (normative) Snow load distribution on selected types of roof. ..13 Annex C (informative) Determination ofthe exposure coefficient for small roofs ..28 Annex D (informative) Determination of thermal coefficient ..31 Annex E (informative) Roof snow retention devices. ..34 Annex F (informative) Snow loads on roof with snow control .36 Annex G (informative) Alternative methods to determine snow loads on roofs not covered by the prescriptive methods in this International Standard .38 Bibliography .39 ii lout license from IHS Not for Resale