Overcoming Cold Weather Challenges For Roof Coatings

Working with roof coatings in winter months can be slightly challenging. Since the chemistry of each roof coating will react a little differently in cold weather, we will address the cold weather concerns for the materials that compose our core systems.


Acrylic coatings make up our Met-A-Gard and Met-A-Gard+ roof coating systems. Acrylic 211, High-Tensile Acrylic 211, Butter-Grade 221 and Red Oxide Primer 912 are the key components of these high-performance roof restoration systems.

As water-based products, they will freeze when left in below freezing temperatures for an extended period of time. Once frozen, even after they have thawed, these products can no longer be used for effective roof coating restorations.

A warehouse that reaches 30-32 °F will not cause a problem but if it will be much cooler you will need to move to a heated area. During application make sure that it is 50°F and rising. The dry time of acrylic coatings will slow down dramatically if the air temperature is below 50°F.  

If freezing may not be a concern, dew that comes in this time of year can cause major problems with the coating while still wet. Humidity is just as important to acrylic coatings as temperature. The higher the humidity the more reason for concern…

Silicone, & Urethane

Urethane 520, Brush-Grade Urethane 522, Silicone 410, and Silicone 412 are the key components of our Ure-A-Sil System. These chemistries all react similar to each other in cold weather. All are solvent based and can handle cold temperatures during the drying process. The issue with these coatings is they will thicken up dramatically in the pail or drum during storage. Best practice here is to keep the coating close to 75°F if possible. If storing on a job site, an enclosed trailer with portable heat can take care of this. If storage is on the roof top, make sure to keep covered with a black tarp. This will keep moisture off the pails and the dark color will help absorb the sun’s heat. Pail warmers can also help.

If you begin working with these coatings and determine the chemical to be too thick to work with on an extremely cold day, it is permissible to thin the material.  Use 100% pure mineral spirits or xylene to thin silicones without exceeding 5% of the solvent and ensure a thorough mixture.  

The only exception here is with Brush-Grade Urethane 522. As a mastic, this product is designed to be thick. It may not be possible to thin it down. The best practice when storing 522 is keeping it in an enclosed warm area .or it may be too difficult to work with.

Please call our technical department for more details and or questions. Eric Long in Technical Services will be glad to help. elong@weatherstar.net

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