Don't Ignore the Weather When Doing Exterior Painting

This past month, I have noticed a few homeowners tackling outdoor maintenance and painting their home exterior, but is now the right time to do this?






I write a lot of articles, do plenty of projects, and have undertaken extensive research on most home improvement, home maintenance, and home repair tasks. Over the past 40+ years, I have consulted with major players in the industry and have accumulated a fair share of knowledge. I like to think that the articles I write provide practical and sensible insight into the many tasks a homeowner needs to do to keep their property in tip-top shape and retain value. That is why I find it strange when some homeowners do things that confound me. For example, why would you paint your house during the rainy season? Why would you even bother applying paint to a wet wall? And why would you paint over wet mortar or plaster? I want to take a moment to address these questions:




Why it isn't a good idea to paint during the rainy season



There are plenty of posts on that stress the importance of doing any project the right way. Not only does it make sense as far as timesaving is concerned, but it also makes more sense not to throw your money on a project that might need to be done again, or one that will cost even more to put right. If you have any doubts as to this claim, it is easy enough to go online and visit professional painting sites to gather more information.







Moisture repels paint, so avoid painting when it is wet or there is excess humidity or precipitation



Moisture repels paint

Painting anything when it is wet is a waste of time. The formulation of paint is such that it needs to bond with the surface on which it is being applied, when that is sanded wood, sanded metal or steel, primed plastic or, in this case, exterior walls. Moisture repels paint, it prevents the paint from bonding to the surface. If you paint on a wet surface, it is simply going to leave a film on top of the moisture - one that will later peel off, blister or bubble, and will not last very long.



For more information on the best time to paint, prepping the surface properly, or ensuring a long-lasting job, visit our Decorating, Home Maintenance, or Home Improvement sections. They offer practical advice and step-by-step solutions to most problems encountered by homeowners.





Preparation matters

Preparation is everything, no matter what the project. Having the proper tools, materials and supplies on hand make for a quick, easy and successful job. Before any exterior painting takes place, any cracks need to be repaired, damp areas treated, and fixups attended to. These tasks require plenty of time to complete but just as much time to dry properly before being painted over.



Do not let a painting contractor coerce you into painting when you know rain is forecasted over the next week or two



What is not a good idea is to chase out cracks and apply mortar, plaster, or crack filler and not wait for this to set hard. Keep in mind that these fillers need to dry through layers right down to the bottom, and even though dry on the surface, they may still be wet underneath. Applying primer or paint over wet filler will result in failure.







Primer is important

Where chasing cracks is performed on exterior walls and a cement-based filler is used, a primer must be applied over the filler. Think of the filled cracks as raw plaster and that a primer will provide an essential key between the plaster and paint allowing the two to bond together properly. If you do not apply a primer over a cement-based filler, the grainy plaster will eventually shuck off the paint and cracking will occur.



Walls or plaster must be completely dry before you apply primer or paint



Wet walls need to dry thoroughly

We have experienced plenty of rain throughout the day over the past couple of weeks. It is hard to predict when it might rain. Only start any painting after a couple of days of sun, when the wall surface has time to dry completely and will not affect the paint layer. This also applies to any possibility of rain showers during or immediately after painting. Check the weather over a period of days to make sure it is going to stay clear - or put off the job until the chance of rain is zero.



Humidity and precipitation are just as bad as rain

Moisture is moisture, and whether it is high humidity, precipitation (water vapour), you want to avoid any painting under these weather conditions. Both have the same effect on the surface as water and will impede the painting and drying processes. Again, wait until the weather clears up before painting.






back to top