Low Temperature Exterior Painting

What is the best temperature to paint outside?

Some may consider painting in cold weather less than ideal. However, low outdoor temperatures are less consequential with the appropriate low-temp exterior paint combined with professional service.

Although the proverbial “is it too cold to paint” is a focal question during cold weather paint applications. 

Product knowledge helps when painting in cooler weather. Otherwise, the paint could blister or peel. But that also stands true for humidity and heat.

The ideal temperature to paint is between 50 and 85 degrees Fahrenheit. So, temperatures below 55 are inevitably considered low-temperature applications.

Let’s see how your paint job could be affected.

Temperatures to Paint Outside

The possibility of painting outside in cold weather primarily depends on where you live. Northern US states have harsher winters, constituting a shorter winter painting season. Moderate temperatures with a clear forecast offer the best conditions to paint. Optimal oil paint temperatures range from 45 – 90 degrees.

Surface temperature must be 50 degrees Fahrenheit or above for most non-low-temp exterior latex paints. In contrast, a low-temperature exterior paint such as Sherwin-Williams Latitude allows surface temperatures to be as low as 35 degrees. 

In hotter months, an experienced painter will dodge the sun and chase the shade, while during winter months, it is the opposite.

But be mindful that atmospheric temperatures differ from surface temperatures, as outdoor temperatures may be higher than surfaces in shady areas. So, during winter, exterior painters want to paint on the sunny side.

What in paint allows low-temperature painting?

Exterior house paints are designed today to meet the primary application need while considering the health and safety of the product. Coatings designed for low-temperature applications contain additives that prevent the paint from freezing at low temps.

Ethylene glycol is a toxic additive once used in latex paint until the late ’80s and was replaced with propylene glycol. Although some paint manufacturers still use ethylene. On the other hand, propylene glycol deems less topical health concerns and is used in household cleaners.

Additional Benefits

Water is the solvent in modern latex paints. Propylene glycol improves latex paint emulsion properties, allowing the paint to dissolve in water and reducing water evaporation. Slowing water evaporation slows the paint drying time, allowing more time to correct application mistakes.

Propylene glycol is the main ingredient used for most low-temperature exterior paints. It acts like an anti-freezing agent allowing all water to evaporate before the acrylic and vinyl polymers are affected by cold temperatures.

Paint raw material solvents include water, glycols, blenders, and additional chemicals for making glycols and auxiliaries.

Cold Weather Exterior Painting Tips

Understanding exterior paint application temperatures are only one of many considerations. Caulk, painters’ putty, and primers are affected by lower temperatures too. 

Painting over caulking that has not dried will cause cracks in the paint coating. To decrease caulk dry times in cold weather, we recommend a high-performing quick dry caulking like Sherwin-Williams 1050A. If you or your painter have another caulking of choice, it may require more time to cure.

Another major factor is allowing more time between paint coats. Even cold weather paints will need additional time – particularly dark colors will be most affected. Dark colors contain more colorant, inherently making the paint dry slower. Allow 4 – 24 hrs. between coats at temperatures below 55 degrees.

Cold Weather Painting vs. Hot

Painting in colder temperatures will slow paint cure time, but that is not exactly a drawback. Slower house paint dry times can promote better adhesion, but the surface must be dry. So, why does colder weather take most of the shame?

Temperature, humidity, and surface moisture can all cause adverse effects to paint. Too much humidity can cause blistering and bubbles, while high temps can cause the same issue. There are also high-temperature exterior paints that will mitigate this issue. 

So, knowing which exterior paint to use during each season is crucial to paint performance.

How to Paint in Cold Temperatures

Here is a shortlist that simplifies the concept of painting in cooler weather.

1) Check the weather to ensure rain, high winds, or a cold front is not coming.

2) Check the surface for temperature and visible moisture. 

3) Heat the surface when needed using an outdoor heater.

4) Purchase low-temperature paints that allow cold weather applications.

5) Purchase fast-drying caulking and paint supplies.

6) Allow more drying time.

Cold Weather Painting Based on Region

There are additional considerations besides finding the sun when the temperatures are low, and you don’t need to be a painter to follow the basic rules. 

If you live in Southern areas of the US, the most considerable setbacks from painting in the winter months are fewer working hours, primarily due to minimal daylight. But planning times for when the painting will begin and end are ideal no matter what challenge you face. 

If you live in colder states and the weather is forecasted to have precipitation or change, use low temp paint and stop painting earlier to allow the paint to dry before being exposed. 

To play it safe, start painting two hours later than usual and stop two hours earlier. Usually, by 10 AM, the temperatures and ground-level moisture have reduced. If it gets dark at 5 PM, stop painting at 3 PM. Or, if you are painting and the temperature is projected to drop, stop even earlier. 

Allowing the paint to dry before reaching freezing temperatures will enable the paint to adhere to the surface. If paint freezes on the surface before it dries, it will not stick, resulting in cracking, blistering, and peeling.

Likewise, painting over wet surfaces will cause paint discoloration and loss of bond.

The paint will lose bonding power in both cases and should be avoided to prevent premature paint failure and repaints. 

Painting During Hot Summer Days

Water-based paints work best in hot conditions, although some will dry too quickly in temperatures above 90 degrees. So, while painting in the shade will help, there are paint extenders that increase how long the paint remains wet, also known as “open time.” 

Hot and humid seasons with evening storms are the hardest to paint in. When a non-heat-specific exterior paint is plagued by temperatures excessing 90 degrees and high moisture levels, it can cause the coating to hold excess moisture resulting in bubbling.

Cold Weather Paint Cure Time

Some refer to paint drying to touch as “cure time,” which is inaccurate, as cure time is the time it takes for paint to harden fully. You can expect exterior paint to take longer to cure in colder weather, sometimes upwards of 30 – 45 days. 

Slow paint cure times in cold temperatures are exacerbated with cheaper paints. We recommend using high-grade exterior coatings to keep doors and windows from sticking shut. 

If the temperature drops below freezing for over 48 hours, directly after painting, there will be no effect for low temp paints that have dried to the surface. Once the surface reaches 50 degrees, the curing process will continue.

Conclusion

We all know that water freezes at 32 degrees, and painting below this temperature can cause issues. So, if the season doesn’t offer a proper climate, you must wait until the temperature warm-ups.

Timing is essential whether you are working through a cold season or planning and budgeting for the future. But if you are paying for a house painting service and the painter is using a low temp paint in conditions above 35 degrees and will warranty the service, there’s not much to be concerned about. 

Contact us or see our exterior painting projects on our social channels.