Best Type of Caulk

• You can choose between a variety of caulks on the market today. Water-based and latex caulks are susceptible to freezing but most silicones will remain pliable even in cold weather. Modified polyurethane sealants will also resist freezing and the moisture in the air may help it cure faster. Look for brands that specify outdoor use and use in extreme low temperatures on the label. You want a sealant that can expand and contract as the temperature changes. Look for high quality sealants that can handle up to 50 percent joint movement.
  
  

Sealant Tape

• Depending on your project, a better option might be one of the many sealant tapes available on the market. There are pre-cured silicone strips that do not require any cure time, except for the thin layer of sealant you use to adhere the strip to the surface. This solidifies much faster than the thick bead you would need without the strip. There are also butyl tapes that remain flexible in both intense heat and extreme cold.
  
  

Get a Caulk Warmer

• To soften the caulk enough for application, warm the caulk for at least 24 hours before you intend to use it. In addition to warming the caulk, also warm the surface to be sealed with a hair dryer or electric space heater. Cold temperatures cause surfaces to contract. As the weather warms up the surface will begin to expand, possibly breaking your seal. This is why warming the surface before caulking is so important.
  
  

Other Hints

• Make sure to clean the surface thoroughly right before you apply the caulk so there is no ice that can interfere with the seal. Using a primer before applying the sealant will also help adhesion. Keep in mind that most primers and sealants will take longer to dry in colder temperatures.