Liam Blears, business and technical development manager for Facades at FSi, discusses the advantages modern methods of construction bring to ensure optimal passive fire protection
When it comes to passive fire protection, staying ahead of the technological curve is never a bad idea.
Identified as a key growth area in the UK building industry, offsite construction currently accounts for 7% of the UK market and this is expected to increase considerably. Industry estimates suggest the completion time of modular projects can be as much as 50% faster using offsite construction, making the appeal of this type of build very clear.
The importance of sequencing
To succeed in meeting tight timeframes that are key to the delivery of offsite projects, the sequencing of the elements within the building is vital to allow the schedule to progress as planned without any delays that could cause a knock-on effect.
This also means factoring in the correct time to allow the installation to be carried out with the technical capability needed. In a unitised system, entire prefabricated units are built offsite, with the facades and cavity barriers already in place ready to be locked to the core that has been constructed on site. In the sequence of building, this sees cavity barriers fixed into place after rain screens have been added to facades. In a modular building the facades will also be constructed offsite but attached to the exterior of the modules when they are on site.
In both methods the availability of each element of the build when it is needed is vital to the speed of construction. To ensure a fast and efficient process in installing cavity barriers a forward-thinking approach to the use of passive fire protection can save time and materials. By planning passive fire protection into the design stage, the specification can be considered in detail, including the level of passive fire protection needed, what areas it would need to be applied to and if third-party approved testing has been carried out to support that use. In a uniform design this is especially time-saving as the specification is repeated.
This carefully strategised approach to building brings a number of benefits to passive fire protection including a reduction in time to install cavity barriers, and the ability to carry out comprehensive checks in situ to ensure these have been fitted correctly and that no gaps have been left that could compromise the protection provided in the event of a fire breaking out.
Early planning also allows for a complete overview of the fire protection that is needed to accommodate the modular design. It is important that the shift to modular construction must consider the impact on materials, installation, and how the construction affects joins, gaps and cavities that need to be fitted with the correct built-in fire protection.
Precision installation
Once the correct level of passive fire protection has been specified, the approach should support first-time accuracy.
One of the major plus points of offsite construction is that the environment supports a more uniform and accurate way of working to create aligned modules. Fitting cavity barriers in a warehouse environment is ideal for ensuring absolute precision in both the specification and installation. As different sections of the building envelope are completed at the same time to support the sequenced timeframe this allows for excellent control in the standard of the installation.
In a traditional site environment, FSi provides specialist training to sub-contractors, with the technical team returning to ensure passive fire protection has been correctly installed – any errors will mean that the cavity wall needs to be removed and reinstalled.
If installation is planned in advance and carried out within a strict time frame as part of a compartmentalised process this supports fast and efficient monitoring of installation, allowing cavity walling to be checked as it is put in place. With fewer variables to impact the installation of cavity barriers, precise placement is able to take place on site, supporting increased accuracy in installation – and in a faster timeframe.
Standards need to be at the forefront of industry progress, especially so from a fire safety point of view. Planning, adequate checks and raising awareness of skills competence are all key factors in delivering the high standards needed for cavity barrier installation – and offsite construction by its nature does support this.
Looking to the future of passive fire protection
Leading examples of what can be achieved using modular building include the recently completed Croydon towers scheme.
Standing at 135 metres tall the buildings at 101 George Street are among the tallest modular constructions in the world. A 44-storey and 38-storey, build-to-rent project, the two towers of the Croydon Tower saw everything above the ground level completed through modular construction. The project sets a clear example of how offsite construction can help to decrease waste, reduce carbon emissions and cut construction times significantly.
Cavity barriers to provide passive fire protection within the envelope of the building were supplied by FSi with Silverliner Open State Cavity Barrier OSCB 1 and Paraflam fitted to the outer substrate during the modular construction phase. The cavity barriers are fitted behind the cladding and are designed to provide passive fire protection while maintaining airflow.
In the event of a fire breaking out the intumescent edge of the cavity barrier reacts to reinstate the compartmentation, stopping the spread of fire for a set period of time – for Silverliner OSCB 1 this is 90 minutes integrity and 30 minutes insulation (90/30- EI). With modules installed in a similar way across the project and added to the building core, this supported the fast and efficient installation of cavity barriers.
It is anticipated that more and more building projects will make use of the convenience, accuracy and sustainability savings offsite modular construction can deliver.
Happily, this is a great fit for the safe, accurate installation of passive fire protection products. Precision is vital and as a system that incorporates that from the early stages modular offsite construction is an ideal way to ensure cavity walling is installed expertly – and will do its job to protect lives if needed.
