Optimising Offsite Manufacturing of Timber-Frame Roof Trusses for UK Housing

Abstract

This study has been undertaken in response to drivers from the Welsh Government to increase the number of houses and quality and as such increase the offsite manufacturing of modern methods of construction and also to meet Wales’ low- to zero-carbon agenda, launched in March 2019. The need to increase the quality and operational energy use of buildings has been acknowledged since 2019 when it was recognised that the UK’s climate change targets were impossible to meet without almost 100% elimination of greenhouse gas emissions from UK buildings. This paper discusses and presents the first of three case studies undertaking time and motion and value stream mapping studies by one of Wales’ (UK) largest offsite manufacturers (referred to as the company hereafter) of timber-frame construction systems, in order to evaluate optimisation opportunities in the offsite manufacture of the company’s modern methods of construction within roof component production, such as trusses. A time and motion matrix to capture the live manufacturing data is presented and discussed. The preliminary results from the time and motion and value stream mapping assessments of the company’s manufacture of a number of roof truss case studies conducted between May and September 2019 are presented and highlight opportunities for quick win refinement to their operational processes with the aim to increase production efficiency, reduce waste and close the performance gap, therefore increasing the quality and thermal performance of offsite manufactured timber-frame buildings resulting in reduced operational energy usage and therefore minimising greenhouse gas emissions. This paper will be useful for academics, timber-frame manufacturers, offsite manufacturers, building contractors, estimators, housing developers and clients.