CROSS Safety Report
Junction of partitioning walls and ceilings
A potential issue has been raised with CROSS, regarding the order of works in partitioning assemblies and how these can affect the performance of compartmentation.
Key Learning Outcomes
Designers, internal partitions contractors, and dry lining operatives:
- Those who are programming the works need to be aware of the importance of fully completing the installation of one component before progressing works of connecting tasks
- Site operatives also need to be aware that they should not progress in connecting ceiling works before all works to the concealed wall element are completed
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A potential issue has been raised with CROSS, regarding the order of works in partitioning assemblies and how these can affect the performance of fire compartmentation.
The reporter has come across a number of situations where plasterboard wall partitioning has been installed to the soffit, with a suspended ceiling forming an additional junction below the soffit. They consider this a very common detail which can exist either as a standalone partition wall, or in a lining configuration internal to a concrete wall.
The usual sequence of works is to install the studs and partitioning boards and then tape and joint them to complete the finishing off. Depending on the sub-contracting of the works, it can be possible that the plasterboard wall finishing off (taping and jointing) is carried out by a separate team (a wet trade team) to that which installs the stud and boards (a dry trade team).
It follows that if the same team installs the boards and the ceiling, a situation can commonly occur where the part of the stud wall above the ceiling is not taped and jointed before the ceiling is installed. Once the ceiling is installed, then access for taping and jointing is harder, and the respective follow-up team may not proceed with the works, leaving that section of the partition unfinished. This could lead to a degradation in performance of the partitioning through the existence of gaps in the joints, which in some instances may relate to compartmentation performance and the respective fire resistance requirements of insulation, integrity, or protection to the structure.
the division of wet and dry trades on site
The problem appears to arise from the division of wet and dry trades on site, and the failure to complete wet works to the partition before dry trades complete the ceiling works. This indicates at a lack of appreciation of the importance of the taping and jointing by the contractor programming teams, along with a potential failure of coordination by the teams on site.
To address this issue, the reporter is suggesting that those who are programming the works need to be aware of the importance of fully completing the installation of one component before progressing to connecting works. Similarly, site operatives also need to be aware that they should not progress in connecting ceiling works before all works to the wall element are completed.
Expert Panel Comments
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The issue in this report is genuine and seems to be that hidden areas (e.g. above suspended ceilings) do not get completed properly. The lack of attention given to hidden areas is a common problem within the industry because any faults there are harder to see and inspect. These failures in the finishing of compartmentation work are quite regularly identified during thorough inspections and there needs to be a process implemented where those responsible for the programming of works are aware of the need to avoid this occurring. This is an awareness, skills, and knowledge issue, recognising the fact that many involved in this process may not have the appropriate understanding of the potential outcome of their actions, or inactions.
robust quality control process needed to ensure that the system is built as designed and tested
It is, of course, just as important to fully complete the parts of the wall construction that are in hidden areas, as it is to complete them in visible areas. Manufacturers’ details need to be followed and a robust quality control process needs to be in place to ensure that the system is built as designed and tested, checking that these issues are completed before the areas are covered up. Adequate site supervision, by suitably qualified and experienced persons, is needed to ensure such works are executed and inspected correctly.
Clearly, in the reported cases, the wall design and integrity will be compromised. Partition walls are a system, and they need to be assembled as such. The affected performance depends on the layers of boarding, the staggering of joints, and evaluating the additional benefit of taping and jointing in each case, in order to try to understand the consequences of omitting this process.
Tangentially, but of equal importance, is that penetrations through the walls in hidden areas are often not fire stopped correctly. The panel has come across plenty of examples of poor fire stopping of post-fixed services in hidden voids and, for example of unsealed gaps through walls, or the complete lack of compartmentation walls above suspended ceilings.
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