What causes paint to peel prematurely on the exterior of a house?
Thursday, July 12, 2018
All exterior paint peels eventually, and it is a clear signal that you are overdue for repainting. The only exception is paint on stucco, which tends to deteriorate by oxidation powdering as it ages, unless there is a buildup of multiple layers of paint. But what about areas of peeling paint that appear just a few years after a new paint job? We know of five reasons why paint will begin to peel too early in its lifespan:
1) Inadequate surface prep - For paint to adhere properly, the surface has to be cleaned and any loose areas of paint scraped off and sanded down before actually applying the paint. Also, caulking needs to be applied or repaired where necessary to keep water from getting behind the surface. The classic “flip” houses we regularly inspect often have a quick coat of spray paint applied over the walls without any surface prep at all, and it is not unusual to see the underlying paint surface bubbling up under the fresh coat.
2) No primer - One type of inadequate prep that will cause paint to peel after as few as four years on a new home is wood trim that was not primed, and only got two coats of paint. Because the HardiPlank® and SmartSide® siding on many new homes comes pre-primed, but dimensional lumber trim around windows and doors does not, sometimes a painting contractor will just put two coats of paint over everything, neglecting the coat of primer for the trim, An example of the result is shown below.
3) Cheap paint - The label of every can of paint raves about it’s superior quality; but, if you buy the lowest priced paint in the store, you get the lowest quality paint and it will have the shortest lifespan. Discount paint does not have the adhesion and opacity of better quality paint, and that begins to show after a few years. Old paint and mixing different paints together can also cause problems.
4) Moisture in the wall - High moisture content within siding or a wet surface will keep the paint from penetrating to stick to the surface.
5) Location on the house - Some surfaces take more of a beating from the elements and will deteriorate sooner. South and west facing walls get more sun, and window sills, like in the photo at the top of this page, also take more direct sun and tend to have water standing on them for longer. The lower part of the wall within a foot of the ground will get splash-back from rain falling off the the roof overhang if the house does not have gutters. The base of a wall directly below an inside corner where a roof valley drains onto the the ground will be especially problematic.
You can avoid premature peeling and make the paint job on your home last longer if you carefully prep the surface and caulk before applying paint, use quality paint, and install gutters around the home—especially where there are hard surfaces, like a driveway or patio, directly below the roof overhang.
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To learn more about exterior walls and structures, see these other blog posts:
How To Look At A House
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