How Long Should Paint Last?

Inside: Well for inside paint it is very simple – it will last until you get tired of looking at it. And if you bang the vacuum into the baseboards and kids grind muck into the walls and so on well then, a little less. But outside paint is a much, much different story…

Outside: Inside the home there is no weather, which is the biggest factor damaging paint. What do we mean by weather?

SUN

Well sunshine burns away at the paint. Imagine if you stood outside in one spot year-round with one coat of sunscreen. How much Ultra Violet (UV) radiation would you be exposed to in a year? 5 years? 10? The sun breaks down the paint over time and as we know, radiation doesn’t just hit the surface but goes t-h-r-o-u-g-h things and this affects the wood underneath to some degree, breaking up those cells. The heat from the sun also dries out the oils and glue that hold the wood cells together. (Ever seen an old grey barn? It’s sunburned.)

RAIN

Fortunately it is not sunny every day in Vancouver, which cuts down on UV exposure. But then that means rain! Have you ever seen the Grand Canyon in Arizona? That was created by running water over millions of years. And one of the biggest ways that rain affects paint is it gets underneath. How?

STRESSES ON PAINT

Well if there is any structural or design defect in the roof it can permit water to get in behind the siding. As well if you look at a rough board like a cedar siding board or any wood trim you will see it has sharp peaks and valleys or at least has a 90 degree (‘L’ shaped) edge. When you paint over a sharp edge you are counting on that thin layer of paint over the edge to protect. Now imagine the sun burning away at the paint and then trucks or busses rolling by outside or even tiny movements of the house from seismic activity or the kids bouncing off the walls inside. Any little movement could cause a hairline crack in the paint on that sharp edge and you can bet water will try to work its way in behind that microscopic gap.

Now the water is in there and later it warms up and wants to evaporate (expands) so it pushes against the paint. With oil paint this is a real problem because oil paint doesn’t breath. With latex it is less of a problem but to some degree will challenge the bond between wood and paint.

(By the way, I mention wood as it’s the most dramatically affected but stucco and other cementitious building materials are affected too.)

FREEZING

Another factor is freezing. Any moisture in or behind the paint will expand when frozen and contract when warmed. This is another motion that challenges the integrity of the paint. It is part of our Canadian climate and nothing we can do about it except move to Florida and why would anyone want to do that?

“I FEEL THE EARTH MOVE, UNDER MY FEET”

As I mentioned earlier there is a thing called seismic or earthquake activity. We experience minor tremors all the time. Vancouver is on a fault line and the government tells you to keep extra bottles of water and granola bars in your trunk. Maybe they should tell you to keep paint and a brush too! Although in a big earthquake paint would be the least of your problems, you can see how paint is affected by all these environmental factors.

MICRO-ORGANISMS

This is not part of weather but is weather related. Our temperate Vancouver climate is a breeding ground for mould and mildew. These persistent little organisms will find purchase to grow on any surface imaginable that can support life. A little city dirt settles on your outside walls, add a little fresh rainwater and presto! You have a science experiment growing on your house. This is most prominent on the north and east sides of homes as direct sunlight on the other sides kills the spores. These little plants do root into the walls and this is further penetration of that first layer of protection – your paint.

SUMMARY

In the end it means this; no matter how good the paint is or the painter or the prep or the application there is a bunch of stuff that is tearing away at your perfect exterior paint job all the time. The only thing you can do is to inspect your house often, touch up where needed and regularly repaint the exterior. The Master Painters Institute gives an expected life span of 6-8 years in the Vancouver area. (For the paint job – not for you!)

Gently cleaning the paint from time to time to remove contaminants also helps. Remember that the paint is the only thin layer of protection between your house and the nasty outside world so maintain it well.

Vancouver painter and contractor Peter Byrne“PETER BYRNE is the owner and hands-on manager of Kassel Painting Limited. In the last two decades he has run over 1500 painting projects totalling $5.5M. There is little that can go right (or wrong) on a job-site he has not seen, solved, and lived to talk about.”

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