Peeling deck stain indicates issues with application
I had my back deck painted with DeckOver in spring 2016. A year later, the coating is peeling off in a few places, exposing bare wood. What to do?
Behr, the manufacturer of DeckOver, describes this coating as a stain, but it certainly fits the definition of what most people consider paint. It’s opaque, completely hiding the wood grain, and it goes on thick and sits on the surface of the wood.
Asked what qualifies it to be considered a stain, a person in the company’s customer service department said that it’s selfpriming and self-sealing. “It’s more of an adhesive stain,” he said. “It creates a film-forming stain over the top.”
Regardless of the semantics, the peeling you’re seeing could have a couple of causes. The surface might not have been cleaned thoroughly, leaving loose fibres. The coating could have stuck to them just fine, but if they weren’t stuck to the underlying wood, they and the coating could have peeled off. Or the initial coating might not have been thick enough.
Behr’s instructions specify that you need one gallon (in this case, 3.43 L) for the required two coats on each 75 square feet (nearly seven square metres) of deck.
“You have to measure your deck,” said the customer service rep Josh. “You can’t just eyeball it. It will look very nice after one coat. But it needs a certain mil thickness in order to last.” When dry, that’s 10.9 mils, about the thickness of three sheets of copy paper.
What to do now?
First, remove all of the loose coating. The easiest way to do this is with a power washer but make sure the pressure is set no higher than 1,200 psi (pounds per square inch), which shouldn’t damage DeckOver where it is well-adhered but should take off all the loose material, Josh said.
Then let the deck dry for several days.
During the interim, sand any rough edges on the wood or where an intact section abruptly changes to a peeled section.
The idea is to eliminate any sharp edges, where coatings have a hard time gripping.
Once the deck is relatively dry, clean the entire surface with Behr Premium All-in-One Wood Cleaner No. 63 ($13.47 for 3.79 L, homedepot.ca). One gallon (3.79 L) of this cleaner, diluted with an equal amount of water, treats 400 square feet (37.16 square metres) of deck. Working in sections, dampen the surface with water from a hose, spread a liberal amount of cleaner with a pump sprayer, brush, mop or roller, and wait 10 to 15 minutes.
The cleaner should not dry on the surface during that time, which is the reason to tackle only a small section at once, especially if your deck is in the sun or if it’s windy. After the wait time, scrub the area with a stiff-bristle broom or brush, then rinse with water from a hose. Do not use a power washer this time, unless it is set for a very low pressure, 500 psi.
Why must the deck dry for several days after you power wash if you are then going to get the deck wet again while using the cleaner?
Josh said that after five to seven days, the cleaner loses its effectiveness in preparing the surface to grip well to the coating.
So if the deck is too damp when the cleaner is applied, the wood won’t dry enough during the window when you need to apply the coating.
When the deck is again dry, if there are relatively few bare spots, touch those up, wait three or four hours, then give the whole deck a fresh coat. If there are lots of bare spots, skip the touch-up and just give the whole deck two coats.