The recent annual state of the climate report shows that March, July, October and December 2023 were all top 10 wettest months in the UK monthly rainfall series since 1836, and the first year this has happened for four separate months. But you probably already knew that it’s getting wetter. Today more than ever, for any roofing programme, you are most likely watching the weather forecast as wet or cold days can cause significant delays.

Every day lost to weather increases costs and extends schedules, so how can we make the most of favourable weather windows? Flat roof waterproofing application can be particularly challenging. However, with the right waterproofing system you can maximise time and minimise disruption. This is where PMMA (or polymethacrylate) resins, can really make a difference. 

Curing properties maximise weather windows

PMMA cures exceptionally rapidly, and even very low temperatures cause minimal extensions to their cure times. This means that short weather windows can be maximised as rainproof times from Triflex PMMA systems, are as little as 30 minutes. The rapidly curing systems can be walked on after only 45 minutes at 20°C and approximately 60 minutes at 0°C. This is because the curing of PMMA is based on a chemical crosslinking process and neither temperature or atmospheric humidity have any significant impact. 

This contrasts with some alternative chemistries, most commonly polyurethane (PU) and polyurea (PUA). Most such systems require multiple application coats and maybe a primer too with cure times varying. With two or three application coats, each may take hours to dry or cure. And that can mean watching the forecast closely for a long enough dry spell to schedule the works.

Single process application reduces risks during installation

With a wet-on-wet application for reinforced PMMA systems, the complete waterproofing system build-up is quickly completed in a single process. That can be reassuring, as there is less risk of interrupted works that may leave areas vulnerable. Self-terminating, homogeneous and fully bonded to the substrate such cold liquid applied solutions are the result of decades of research and refinement, packing a lot of scientific know how into the resulting PMMA resin system.  

Such wet weather patterns also mean that leaks and water ingress become more prevalent. So, demands on temporary repairs and permanent solutions can be increased, just at the time of year when it could become harder to deliver that service. This is where rapid curing, more weather independent PMMA resins can really help to meet that increased demand.

Resistant to winter temperatures

But often winter doesn’t just bring wetter weather but cold temperatures too. With schedules of works under pressure, being able to undertake waterproofing installation on cold clear days can have a positive impact. PMMA resins quickly cure even in cold temperatures, with some detail systems curing at temperatures as low as -5°C. With more calendar days available for installation, the pressure can be reduced for squeezed schedules, or simply allowing those in the industry to do more year-round works.  

Ponding water risk and extreme weather events

Ponding water refers to the accumulation of water on a flat roof surface that does not drain or evaporate within 48 hours after precipitation. The BS 6229-2018 guidelines recommended to maintain a minimum 1:80 finished fall for both the entire roof surface and any internal gutters, to mitigate against ponding water. However ponding water can be evident on many flat roofs and negating it in the future considering heavier, more extreme weather events could be more challenging. PMMA resins are inherently hydrolysis resistant, meaning they won’t break down in water, providing reassurance for their durability too. 

Reduced programme times impact the sustainability profile of projects

There are other benefits to solutions that might expedite programme times as well. The wider impacts to help projects meet sustainability aims can merit consideration, as it stands to reason that less days on site can also mean less miles travelled, and less fuel spent. The cold applied systems also require minimal equipment and no hot works, negating any energy use consideration. Ultimately maximising weather windows and project times can mean less disruption for the client, ensuring their activities can continue with minimal impact.