The phone has rang a couple of times this week with customers a little flabbergasted that the thin coat render they applied a few days ago has washed off in the last rain shower with a slightly accusatory tone in their voice.
All I will say on this matter is that there is nothing wrong with the material when this happens, and its not unusual for customers to start flagging this issue up at this time of the year, as its the same every year. The simple fact is that some thin coat renders perform better in cold and damp conditions than others and each job needs planning accordingly.
Traditional thin coat resin based bucket renders generally depend on good air drying conditions as there's no curing process with these. If the air is constantly cold and damp they struggle to dry if not protected and can hang around for days only for a rain shower then take them off the wall in a hair curlingly frustrating fashion. They will dry in cold (5c+) air if the air is dry and crisp and the background is dry, but it may still need a good 24 hours before it is considered safe from the weather. Be careful with these at this time of year, a weather shielded scaffold and a space heater goes a long way to alleviating some of the problems cold damp weather may bring with these types of renders.
The new mineral thin coat renders such as K Rend Mineral TC perform better in colder conditions with less risk of washing off because they cure and are much less dependent on good air drying conditions to harden. They still need to be applied on a dry background, but a bit of fog or moisture in the air won't prevent them from going off completely and drying times will be measured in hours rather than days. Temperatures still need to be a minimum of 5c on a rising thermometer. This is an excellent winter alternative to a traditional thin coat render if you have a job that needs to be done!
If you have any questions or need advice, please contact us!