Ah, the British weather. Notoriously unpredictable and often extreme, in recent years it’s not been unusual to experience unprecedented rainfall in November, blazing sunshine in December, followed by snow in spring just as the daffodils are emerging.
With global weather patterns changing, and even areas within the UK itself subject to different weather conditions, installation teams need to be prepared for all eventualities to keep projects on track and avoid delays. Paul Michaelson, Construction Director at Eden Facades, talks about some of the challenges associated with rendering during the winter months and periods of poor weather in the UK, and how these can be overcome.
Q: What are the ideal weather conditions for rendering? Is there a ‘rendering season’?
A: There isn’t a rendering season as such, obviously there are preferable conditions, but we aren’t always so lucky as to be able to choose those. So, we have to be able to maximise our worktimes and one of the influencing factors is render product choice. It varies between manufacturers but, depending on the product, the ideal conditions would be not below 5°C or above 25°C, and dry.
Q: What types of weather conditions would delay works?
A: Heat (above 30°C), humidity, snow, ice (below 5°C) or rain and sleet considerably extend drying times.
Q: How is rendering affected by extreme weather?
A: In very warm weather, the rendering can dry out too quickly, causing shrinking or resulting in an uneven finish. However, in cold or wet weather, the render may not dry fast enough and could be washed off, damaged by trapped moisture or even end up with tiny holes caused by the wind.
Q: What’s the best way to assess projects to avoid unnecessary delays during bad weather?
A: The type of rendering system is a consideration, but also taking into account the time of year and checking the weather forecast for the planned application dates, to try and avoid any period of extreme weather conditions that could affect the drying times of the render.
Another factor to bear in mind is the orientation of the elevation – a wall in shade will take longer to cure than one that is facing the sun – or there could be other different conditions affecting the same building.
Q: What sort of workarounds are there for unexpected delays due to weather?
A: The increasingly erratic weather in the UK, particularly as it gets wetter, means we need to be prepared to be flexible, such as making changes to contracted hours if necessary, in order to keep the project on time and budget. Every project has its challenges and our ability to overcome these is down to our experience and knowledge.
The way the workforce is managed in case of severe weather conditions on site is crucial – our main contractors and clients are always informed of our intentions regarding weather.
Q: How have manufacturers adapted their formulas to cope with colder weather?
A: One of our preferred suppliers, Wetherby, has developed a range specifically for use in adverse weather conditions. Their Wetherby Mineral Render works in a different way to silicone and acrylic renders – a chemical reaction during the curing process enables it to dry independently of weather condition – unlike silicone and acrylic which need to air dry. The Mineral Render doesn’t allow a water film to form on the surface, meaning that it typically dries within two hours and can be a cost-effective solution.
Wetherby’s ‘Four Seasons Premium Silicone’ significantly improves resistance to rain, can be applied in low temperatures and can dramatically increase the number of working days and productivity over the course of the winter months – as many as 55 additional working days over the course of a year, when the weather is both cold and wet.
Q: Do you recommend certain types of products for certain weather conditions?
A: In terms of the topcoat, adding a render accelerator to a pre-mixed silicon-based topcoat will reduce drying time from 48 hours to 12 hours. Alternatively, mineral render dries very quickly and can either be left in its natural colour or painted.
Q: Are there any other considerations or factors that should be taken into account?
A: The type of substrate and/or material the rendering is being applied to should be considered, as well as the age and condition of that substrate and/or material. We would also take into account the surrounding environment and location.
In addition to our original rendering service and providing the individual aspects of cladding, rainscreen protection, external wall insulation and lightweight steel framing systems, Eden Facades also offers a window and curtain walling service.
Get in touch today to discuss your next new build or redevelopment project requirements with us.