Painting the exterior of your house is a project that requires you to keep your eye on the sky.
High humidity levels can slow the curing process even before it starts to rain; high winds can blow dirt onto your freshly painted building.
Before you start painting, you need to know how long it will take for the exterior paint to dry.
You will learn that not all paint is the same and the amount of time it takes to dry depends on several factors.
Consider the tips below to get the best results from your painting project.
How Long Does It Take For Exterior Paint To Dry?
There are many factors that can affect the drying time for exterior paint. On average, it can take about 3 hours if using a primer to up to 30 days if you choose not to prime.
Check out: How long does it take to paint a 12×12 room?
Drying Vs. Curing
There is a difference between paint that has dried and paint that has cured.
If you prime the exterior of your building, the drying time can be as quick as 30 minutes.
However, curing for primers generally takes about 3 hours.
If you apply your topcoat before the primer is completely cured, the primer may pull away from the wood prematurely and leave you with bare wood.
Depending on your region and color choice, you may choose not to prime. Be aware that some exterior paints can take as many as 30 days to cure.
Each brand and formulation is different. You may get more accurate advice if you buy your paint from a paint store than from a big box or hardware store.
Where Humidity Is a Factor
High humidity will slow the painting process. There is also a risk of mold growth.
Because mold can grow under paint, particularly flaking paint, your preparation process will have an impact on this risk.
Paint formulation can also reduce the risk of mold growth in the future.
If your home is in a very humid area, you may also need to paint with an eye toward expansion.
Wet wood swells, and this can crack the seal on a fresh coat of primer or paint.
Be aware that paint may not cling to metal features in very humid conditions.
For those with clapboard homes, carefully study the condition of the boards where pierced by nail holes. Old wood will split around the nail holes in areas of rapidly changing humidity.
You may need to sand these points and seal around these nail holes with a weather-resistant caulking.
Primed Vs. Unprimed
Primer is high in resins and low on pigment; it is formulated to produce a surface with a lot of “grab” for the top coat.
If the wood on your building is flaking, you will want to both scrape it and sand the edges for a ridge-free surface for primer to cling.
Over time, the weather will act on any ridges under the primer coat. Moisture will get under those ridges and they will ultimately pull away, leaving you with more flaking paint.
If you live in a region that is prone to rain in the spring and heat in the summer, you can still start your painting project in the spring.
You will need a 24-hour window of no rain to apply your primer so it can fully cure.
You can make the project easier by using a tinted primer that is close to your chosen top color.
For those working on a clapboard house, be ready to brush on your primer. This is not an easy or quick process; it may be tempting to use a spraying tool.
However, primer is your best defense against age, rot, and wear. Use a primer with plenty of tack and apply it with a sturdy nylon brush.
Cheap brushes will leave hair in your primer coat. Work the primer up under the clapboards to create an envelope of protection around each board.
Of course, you will also want to apply a smooth coat of primer to the face of each board.
If your siding is vertical, a roller can speed up the process. However, a brush to work primer into the seams is still a worthwhile tool.
If the weather allows, wear a face shield and always cover your hair. Primer is formulated to stick. Scrubbing it off your skin is challenging; getting it out of your hair can be a nightmare.
Do take care to keep your tools either in the primer or in water.
Once a brush that has been used for primer is allowed to dry out too much along the ferrule, it quickly becomes useless.
The Top Coat
Once your building is fully primed, allow it to cure for as long as recommended by the manufacturer.
When choosing your top coat paint, carefully review your weather conditions and the amount of sunlight the building gets.
UV protective paints are a great investment in almost any region. You may also need to consider using a mildew or mold-resistant paint.
Paints that offer UV protection can be tinted; paints that prevent mold growth cannot. However, mold and mildew-inhibiting paints can be purchased in clear shades and mixed into your top coat.
In such cases, a tinted primer can be a great help.
As ever, make sure you are mixing base to base. Oil-based primers, once cured, can support a latex top coat.
However, an oil-based mold-inhibiting top coat will not blend with your favorite latex color.
The higher the sheen, the better your top coat will resist flying dirt and clinging moisture.
However, high-sheen paints have a lower level of pigment than flat or eggshell paints. If your clapboards are getting rough and starting to crack, you may be happier with a low-sheen paint.
In such a case, focus on getting as much UV protection on your home as possible.