The temperature on site is around 0 deg C and we need to apply PROMASEAL® Intumescent Acrylic Sealant. The brochure says application temperature is +5 to +30 deg C. If we keep the sealant warm (i.e. around 15 deg C) before applying; can this be used or do we just wait until the temperature rises on site?

If the temperature is below 5 deg C, the sealant will not cure, and there is the risk that the sealant will crack once the temperature starts to rise. Therefore, our recommendation would be not to apply the sealant until the temperature is above 5 deg C.