A Performance Barrier? Cavity Barrier Installation in Wall Envelope Makeups

Fire protection in wall envelope makeups post Grenfell has understandably focused on materials deemed acceptable for use depending on overall building height. Cladding and insulation products have received most attention in the aftermath of the amendment made to Regulation 7 of The Building (Amendment) Regulations 2018 (TSO, 2018). Whilst acknowledging the importance of the amendment to Regulation 7, this paper is suggesting that the area of workmanship related to detail assembly and product or component installation, more specifically cavity barrier installation, deserves equal focus in the drive for improved quality within the sector. The potential for defects in the installation of cavity barriers in ventilated rainscreen envelope makeups has been investigated by employing a mixed method research approach. Qualitative analysis in the form of an exploratory focus group was undertaken with industry professionals to gain a better understanding of potential defects occurring during wall envelope construction. The qualitative data was supplemented by a Failure Mode and Effect Analysis with building control professionals, evaluating the probability of a range of possible defects occurring during installation and the severity of the negative influence of each if they did occur. The results from this study highlight the importance of workmanship in the construction of wall envelope makeups to achieve the requisite standard of fire protection. The paper concludes by highlighting that breaks in the continuity of cavity barriers during on-site installation is an important parameter which requires consideration and proposes a method for assessing the impact of this occurrence in the stated wall envelope makeup.