Waiting for the proverbial ‘perfect painting day’ can get frustrating – sooner or later, you need to work around mother nature. The eaves and soffits on your house can block some of the rain after all, and windows can keep the worst out during an indoor paint job.
Can you paint a house when it’s raining?
You can paint a home’s exterior and interior in rainy conditions if the rain doesn’t touch the finished or pre-painted surface. Humidity must remain 40-50% to ensure the paint adheres to surfaces and cures well to prevent delaying re-coats. Ventilation is also key to preventing mold and condensation.
It may take a little planning and extra vigilance on your part, but you can get that home paint project done in rainy weather!
Let’s look into the common concerns that crop up, plus our top tips for ensuring your efforts won’t be a washout…
Exterior Painting When It’s Raining
Painting your home’s exterior in rainy weather presents its challenges as you can’t control the conditions, but you can pick your moment, make timely repairs, and keep an eye on humidity levels.
Concern #1 – Humidity
Humidity causes water to evaporate sluggishly, and since the water in paint needs to evaporate before the solvent does, too much moisture in the air results in a sticky surface instead of a cured, dry one.
Concern #2 – Wet Surface
Obviously, wet-to-the-touch surfaces cannot be painted on, but the danger with rainy conditions is that latent moisture may have seeped deep into material that feels dry on the surface. Any areas hidden from the sun, such as nail holes, hairline cracks, and trim, will affect your paint when wet.
Concern #3 – Paint May Be Washed Off
Even if your surfaces are bone-dry for painting on, an ill-timed rainstorm can mean your fresh lick of paint will be washed off before it’s had a chance to cure!
How Long Does It Take Exterior Paint To Dry?
According to Forbes Advisor, exterior paints generally dry within one hour and require a re-coat within 2 hours, but this will depend on the paint type used. Latex paints take 4-8 hours to fully dry, and thicker 2-in-1 paint and primers will take longer to dry than thinner water-based paints.
How Long Does Exterior Paint Need To Dry Before Rain?
It needs at least 8-12 hours of drying time before it rains, but 24 hours is ideal. Paint begins to bond much more effectively after the 8-hour mark, especially in low humidity and rain may not completely ruin paint that has been drying for less time – it will just require repainting.
What Happens if It Rains on Fresh Paint?
The rainwater will form rivulets (small streams dripping down the paint surface). This can’t be saved in the moment, but contractor and home improvement writer Lee Wallender advises taking action as soon as the paint has dried: “cut away the raised lines of paint with a straight-edge razor. You may need to smooth down the area with light sanding before repainting the surface.”
Tips for Exterior House Painting
- Eric Morud from TruNorth Painting advises using the ‘sidewalk test’ – “if you note that the sidewalk is dry after a rain, then your house siding is likely to be too.”
- Check the forecast and earmark at least two good weather days for your paint project (mid humidity, low winds, and no rain!)
- if you must paint in the rain, completely cover the area with a giant plastic enclosure to prevent any moisture from getting in
- To ensure proper curing, paint only when relative humidity is between 40-50% and painting between late morning up until midday when the day’s humidity is at its lowest
Interior Painting in Rainy Weather
Interior painting can generally be done in rainy weather, but the added humidity will affect drying times, delaying re-coating. The need to ventilate during a paint job can also risk rainwater landing on newly-painted surfaces.
Humidity and Painting Indoors
When interior humidity is too great, painted wooden window ledges and frames suffer the most as the paint can’t adhere to the porous wood, resulting in bubbling and peeling. Also, cold damp days can result in condensation forming on painted surfaces, essentially ‘lifting’ the paint off.
Painting in Garage When Raining
Many homeowners assert that rainy weather is the best time to paint garage interiors as it keeps down dust that would otherwise fly in and stick to the paint.
As long as your garage is fitted with proper ventilation, you can paint inside a closed garage with little fuss. Just be sure to keep temps between 65-70°F using an electric heater to promote better drying/curing.
6 Tips To Be Sure Your Project Turns Out Well
- Attached or stand-alone garages without ventilation will need the doors open, so attach a plastic shield 2-3ft from the door to keep rainwater out (make a similar window shield/blind in rooms too)
- Paint during relative humidity levels of 40-50% for optimal results and never higher than 85%
- Check paint cans for advised moisture/temperature conditions
- Check garage for signs of damp before painting (leaks, penetrating damp etc) and perform sealing and waterproofing repairs as needed
- Make allowances for extended drying periods
- Keep an eye out for mold and treat it on sight
Can You Paint When It’s Cold Outside?
Modern acrylic latex paint allows you to paint home exteriors when temperatures dip to 35°F and you can paint interior walls when it’s cold, provided the room/surfaces are 50°F and above. If you need to paint a small exterior area, you can use a tarp and a patio heater to create a warm, enclosed space.
What Happens if You Paint in High Humidity?
High humidity leads to surfactant leaching, mold, and much slower drying times. Surfactant leaching leads to brown/white spots on the surface and streaking. Water in the paint also struggles to evaporate, resulting in a sloppy, gel-like finish. Aim to paint only when humidity levels are 40-50%.
In summary, rainy weather shouldn’t stop exterior/interior paint jobs altogether. Still, you must take things like humidity levels, paint types, and indoor temperatures into consideration, as this will affect how well the paint bonds and cures on surfaces.
As always, the prevention is better than the cure, so prevent the headache of potential re-paints and check the forecast ahead of time so you’ll have dry surfaces to paint on and quicker drying times.