Allen Coldrake, director at waterproofing system specialist Carlisle Construction Materials, discusses the need to consider installation benefits to deliver faster construction programmes and clarity in costs
ONE of the most enduring challenges of delivering construction projects is cost management. While price rises for materials have exacerbated this issue over the past couple of years, the real uncertainty is not in the cost of materials, which can be fixed at procurement and managed effectively by expert quantity surveying to prevent waste. The more intangible cost uncertainty comes with labour costs, which can not only rise during the project, but can become an open-ended additional cost if the programme over-runs.
Skills and experience are in high demand across the construction sector, making hiring the right people for the job more difficult and expensive. In the roofing sector, the pressure on skills is especially high, so keeping programme lengths down and enabling faster, easier installation is mission critical for many projects.
The installation and programme length of the roofing project is not the only consideration either. Getting the building watertight is critical to both the progress of the wider construction project and the quality of the finished building, so a failure to consider ease and speed of installation for the roofing specification could have a significant effect on cost management of the project and performance of built asset.
The answer to these challenges is to identify roofing systems that, while requiring skilled labour for installation, are simpler and faster to install, while also providing robust and proven waterproofing performance with a BBA-certified service life. Choosing the most appropriate system depends on the performance criteria and required lifespan for the project, but working with the roofing supply chain to identify an optimised solution for the project is essential.
Selecting the right system for the project
With varied roofing technologies available, the choice of which type of system to use is often aligned to the specific needs of the project: from the level of detailing, pitch and surface area involved, through to the roof build-up, performance criteria and intended service life. However, even within the parameters of a specific roofing technology, the choice of system can result in significant variation in programme length and ease of installation.
Liquid waterproofing systems are often selected because of the ease and accuracy of detailing they offer, their suitability as an overlay for refurbishment projects, and the speed and flexibility of installation they provide. Often a liquid can enable greater fluidity in the wider construction programme because the sequence in which roof areas are waterproofed can be adapted to fit around other site activities.
But installation times for liquid waterproofing systems vary considerably, and it is essential that any roofing system is installed to the manufacturer’s guidelines and clear quality assurance protocols. A wet-on-wet system, such as Carlisle’s Arboflex PU liquid waterproofing system, saves time on site because there is no wait time for the liquid to cure prior to the application of a second coat. This provides a faster journey to a watertight building, along with increased flexibility for scheduling the installation. On most substrates, Arboflex PU requires no primer or vapour control layer either, and the single component liquid requires no mixing. The combination of these features equates to a substantial time-saving on site, which delivers both cost savings and health and safety benefits for the project.
The glass fibre membrane used with the Arboflex PU system can be torn to size and shape and is laid onto the wet membrane, with a clean roller used to draw the liquid through the mesh. This is both part of the system and a quality assurance check to verify that the correct amount of liquid has been applied, delivering both speed of installation and performance benefits for the project. The mesh absorbs into the liquid waterproofing during the curing process to provide a completely seamless roof surface. These simple steps complete the installation for a 10-year Arboflex PU system, and make the building watertight. Where a longer service life is required or a green roof will be installed, the Arboflex PU U/V resistant top coat can be applied.
Improved cost certainty
Often, cost considerations for roofing system selection is based heavily on material costs, but the cost of the product is only part of the picture. For improved cost certainty – for the roofing elements of a project and the wider programme – installation time and flexibility must also be understood.
