SOUTH AFRICAN NATIONAL STANDARD

Transcription

1 ISBN Any reference to SABS 0155 is deemed to be a reference to this standard (Government Notice No of 8 November 2002) SOUTH AFRICAN NATIONAL STANDARD Accuracy in buildings Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: Fax: SABS

2 Table of changes Change No. Date Scope Amdt Amended to comply with present accepted practices in the building industry. Amdt Amended to change the designation of SABS standards to SANS standards, and to update referenced standards. Acknowledgement The SABS Standards Division wishes to acknowledge the valuable assistance derived from publications of the British Standards Institution. Foreword This South African standard was approved by National Committee SABS TC 59, Construction standards, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in September This document supersedes SABS 0155:1980 (edition 1). A vertical line in the margin shows where the text has been technically modified by amendment Nos 1 and 2.

3 Contents Page Acknowledgement Foreword 1 Scope Definitions Accuracy in building General Factors relating to permissible deviations Grades of accuracy Sources of dimensional inaccuracy General Inherent inaccuracies Induced inaccuracies Allowance for inaccuracies Design stage Components manufactured off site Tolerances and fit in the design of a building Design stage Prefabricated components The use of grids Setting out The control of accuracy Sources of inaccuracy Control of accuracy in setting out General Measuring instruments Use of measuring instruments Setting-out methods Control of accuracy in the manufacturing process Manufacture off site Manufacture on site Manufacture of formwork Control of accuracy in the erection process (including in situ work) Erection of components Erection of formwork Limitation of displacement during concreting Permissible deviations (PD) General Selection of grades of accuracy Setting out Concrete In situ concrete and erection of precast concrete Permissible deviations Lift-shafts

4 Contents (concluded) 5.5 Masonry work General Workmanship Structural steel General Timber General Structural frames (other than roof trusses) Timber components Timber roof trusses Floor and ceiling finishes General Prefabricated floor units Stairs Appendix A Applicable standards Page 2

5 Accuracy in buildings 1 Scope 1.1 This code of practice covers the method of measurement and accuracy of dimensions required for the setting out of structures and for completed building work. Permissible deviations are prescribed for the positioning and dimensions of the various elements. NOTE The standards referred to in the code are listed in appendix A. 2 Definitions 2.1 For the purposes of this code the following definitions shall apply: bow curvature of the length or width of the component expressed as the maximum deviation from a straight line connecting the extremities component a building product formed as a distinct unit, having specified sizes in three dimensions creep slow inelastic deformation (or movement) due to stress or other factors deviation the difference between a size or position (actual, limiting, etc.) and a specified size or position element a functional part of a building, constructed from building materials, or building components, or both kicker a starter member used for locating construction which follows (see figures 1, 2, and 3) master datum MD the datum level from which all levels on site are derived NOTE The level of the master datum is determined usually by reference to the nearest convenient Trigonometrical Survey Datum, or Local Authority Datum derived from it. Permissible deviation PD specified limit(s) of deviation 3