Site check The timber frame pocket guide

Transcription

1 PREVIEW PAGES Site check The timber frame pocket guide Sample pages

2 2 Frame erection ISBN First published in 2018 This is a technical publication for professionals in the built environment sector. While this document has been prepared in good faith and all reasonable efforts have been made to ensure its adequacy and accuracy, 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 Exova BM TRADA and the Structural Timber Association. Exova (UK) Ltd and the Structural Timber Association 2018 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form, by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owners. Text prepared with the technical assistance of: Robin Lancashire, Exova BM TRADA Lewis Taylor, Exova BM TRADA Martin Milner, Structural Timber Association All illustrations Exova (UK) Ltd or the Structural Timber Association, unless otherwise credited. Exova BM TRADA is TRADA s appointed provider for its research and information programmes, and for the administration of its membership services. Exova BM TRADA Chiltern House Stocking Lane Hughenden Valley High Wycombe Buckinghamshire HP14 4ND tel: +44 (0) fax: +44 (0) publications@exova.com website:

3 Contents 3 Contents Foreword 4 Introduction 5 Substructure 6 Sole plates 9 Delivery and storage 15 Walls 18 Floors 24 Breather membrane 30 Roof framing 33 Cavity barriers and fire-stopping 36 Handover of frame 41 Services installation 43 Insulation 48 Vapour control layer 51 Dry lining 53 Party floors and ceilings/walls 55 Party wall cavity insulation 58 Damp-proof courses, cavity trays 60 and window/door seals Masonry cladding 62 Other cladding 66 Roofing 70 Differential movement 73 Further reading 78

4 4 Foreword Foreword At a time when timber frame is growing at almost twice the market rate* it s particularly appropriate to launch this new guide for use on construction sites. While modern timber frames may be made in the factory, a successful project still requires every aspect of the construction process to be completed to a high standard of workmanship. We hope therefore that this handy pocket-sized book will equip site managers and other construction professionals with a reliable aid to supervising and checking subcontractors work. Site check: the timber frame pocket guide is a concise summary of the key timber construction requirements. It has been jointly produced by TRADA and the STA, and prepared with the assistance of the framecheck team at Exova BM TRADA and the technical adviser to the STA. Previously both TRADA and the STA published separate guides to site practice. Now the best of both books has been combined and updated with new illustrations to reflect current best practice. We are delighted to collaborate in order to provide the timber industry with a single source of information. Nick Milestone, Chairman, TRADA Andrew Carpenter, Chief Executive, STA * 8.7% timber frame to 4.4% market growth, Annual survey of UK structural timber markets, Market report 2016, Egan/STA 2017

5 Introduction 5 Introduction Site check: the timber frame pocket guide presents best practice site checks that deliver good build quality for low rise domestic timber buildings. It is not a substitute for the drawings, specifications or standard details issued with your project, but has been written to complement the specific project design and specification. Those using this guide should be familiar with construction terms and have access to additional, more detailed literature. How to use this guide This pocket book contains colour-coded sections for each stage of construction, and summarises core activities in a checklist format. It concentrates on the most important aspects of the assembly and the operations required in order to complete the superstructure. Important Do and Do not boxes are highlighted in each section. The quoted building tolerances are within acceptable limits and are achievable using a reasonable degree of care. This guide also references the typical tasks and responsibilities of various members of the construction team. However, some projects will be set up differently. It is the responsibility of the site manager to clarify roles and responsibilities before work starts on site.

6 18 Walls Walls Ensure that all wall panels are square and dimensionally accurate before following the fixing schedule prepared for the site. The structural engineer s specification should be followed in all cases if there is no specification, ask for one. DO Install temporary bracing to maintain alignment accuracy of the assembled components. DO NOT Do not use out of square panels. An out of square panel has unequal diagonals. This can cause the overall length of the wall to grow and could lead to the wall panels overhanging the sole plates.

7 Walls 19 Checklist 1 Check sheathed wall panels for length, height and squareness (if not checked on delivery), in particular the corner panels. Lift panels on to sole plates where present, install temporary bracing and fix to structural engineer s specifications in correct position; check end for end and right way up. More information can be found in the STA Design guide to propping and bracing and TRADA s Timber frame construction. Check length, height and squareness 2 Corner panels should be plumb within the accepted tolerance of ±10mm vertical over any storey height. With corners plumb and the use of string lines all walls should be plumb within tolerance. Walls can then be checked with a spirit level.

8 62 Masonry cladding Masonry cladding Providing a drained and vented cavity between the masonry cladding and the timber frame structure is vital to ensure longevity of the timber frame. Masonry cladding should be constructed using a coursing rod to ensure the right levels are achieved at the openings and eaves levels. Pre-plan the coursing to allow for a clearance between window sills, soffits, balcony structures, etc for differential movement. DO Ensure that open perpends are installed in the masonry at the correct levels. DO NOT Do not overlook differential movement where the timber frame, services or windows penetrate the masonry cladding.

9 Masonry cladding 63 Checklist 1 Ensure that the cavity between masonry and sheathing is a nominal 50mm ±10mm. 2 Keep cavities clean and vented and clear of mortar droppings. On no account should breather membrane, cavity trays or cavity barriers be damaged when cleaning cavities. 3 Ensure that wall ties are stainless steel and suitable for use with timber frame and appropriate for differential movement. 4 Nail wall ties securely to timber studs and/or header joists at specified centres and fully bed ends of ties in mortar joints. Stud Sheathing Breather membrane Ensure wall ties are securely fixed

10 Site check The timber frame pocket guide A concise summary of on-site best practice in timber frame construction Checklists and illustrations of core activities enable you to verify that work is of the highest standard Researched and written by experts representing TRADA and the STA Site check: the timber frame pocket book focuses on best practice in the construction of timber frame buildings, providing an essential guide for site managers, timber frame erectors and site inspectors. Prepared by framecheck experts for the Timber Research and Development Association in collaboration with the Technical Committee of the Structural Timber Association, this book covers the most important construction processes involved in completing the superstructure, with illustrated Do and Do not sections for added clarity. Exova BM TRADA provides independent certification, testing, training, technical services and information around the world, and is TRADA s appointed provider for its research and information programmes, and for the administration of its membership services. ISBN Sample pages