Wetherby Winter Working Practices
Wet and cold weather conditions during the winter months create many potential problems for rendering. Products
and systems must be applied to specification, in the correct conditions and protected adequately. It is important
contractors understand the best working practices during these months to reduce the risk of wash offs and product
failures:
- WBS products must be carefully stored and protected from frost. All bags and tubs must be stored off the ground and kept completely dry; using an insulation board to store products on will help to reduce the chances of the product freezing in storage containers.
- Should the product become partially frozen it will no longer be fit for purpose and will have to be discarded appropriately. In pre-mixed silicone products, even when the ice melts and the product returns to a liquid it must not be used as the binders that hold the render together will no longer work effectively.
- Weather forecasts must be sought before application to ensure the render has a reasonable period of adequate temperatures to allow the product to cure. Best practice is to apply in the morning, this gives the product the best chance to cure during the highest temperatures of the day.
- Application of all polymer modified renders, adhesives, pointing mortars, primers and silicone products can only take place when the temperature is above 5°C or above 3°C on a rising thermometer with no frost forecast.
- These products will only cure in temperatures above 4°C and applying in lower temperatures may result in the render remaining wet on the wall, increasing the chances of damage due to frost or wash offs in heavy rain. Cold temperatures significantly slow the drying process and extend drying times.
- Humidity levels must be considered when applying Wetherby products. Wetherby renders will only cure in relative humidity levels of less than 90%. Higher humidity levels will prevent the product from curing and will lead to the render remaining wet on the wall for extended periods, making it susceptible to frost damage and wash offs.
- Basecoats and primers must be allowed to fully cure before the application of a further coat. Basecoats may skin over but not be fully dry; applying wet on wet in this event will extend overall drying times. Ensuring products are applied to dry basecoats and primers will reduce the curing time of the system.
- WBS products can be applied in a protected and sheltered area with the addition of blow heaters. Heaters must not be directed at the substrate face at any point. The purpose of the blowers must be purely to raise the temperature and reduce the relative humidity in that particular work space. The area must be kept at temperatures above 4°C at all times during the curing process for this method to be effective, in particular when temperatures drop overnight.
The new Wetherby EpsiCoat Mineral Render Plus system is designed to combat winter conditions and dries independently of humidity, providing an improved product for the wetter and colder times of year. For further information please visit www.wbs-ltd.co.uk.
For further information on Winter Working Practices please contact the Wetherby Technical team on:
08458 382 380.