Deck stain is peeling

  • Green paint roller on white background

Washington Post
Friday, June 30, 2017

Q: 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?

A: 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. It even fills cracks and gaps less than a quarter of an inch wide, something that makes it seem more like half paint and half putty. Asked what qualifies it to be considered a stain, a person in the company’s customer service department said that it’s self-priming 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 fibers. 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 for DeckOver specify that you need one gallon for the required two coats on each 75 square feet of deck. “You have to measure your deck,” said the customer service rep, who by company policy was allowed to give only his first name, 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. (Mils means thousandths of an inch.)

What to do now?

First, remove all of the loose coating. The easiest way to do this is with a power washer. You can rent one or hire someone, but make sure the pressure is set no higher than 1200 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 ($10 for one gallon, homedepot.com). One gallon of the cleaner, diluted with an equal amount of water, treats 400 square feet 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.

One other tip: Josh said to call the company’s customer service number, 800-854-0133. A customer service representative will go over what you did and explain what you can try now and, as Josh put it, “come up with a solution.” Asked whether that meant offering a free coating, he said: “We have provided product to customers to get it fixed. We’re here to help.”

Q: The front door of my home needs to be refinished. Estimates from two handymen are expensive (in the $850 range) because of the intense labor and the need to take down and put up the door several times during the sanding and varnishing process. One handyman suggested painting the door instead. What is your opinion?

A: It’s true that paint is likely to last longer than a clear finish on an exterior door, especially if the door gets a direct hit from the sun. Ultraviolet rays from the sun break down lignin, the glue that holds wood fibers together. A clear coating with UV inhibitors or blockers can slow down the damage but not prevent it. So at some point, unless you restore the finish regularly, fibers at the surface will lose their grip on fibers underneath, and they and the surface coating will peel away.

Paint, however, is opaque, so it effectively blocks UV rays from reaching the wood, and this protection lasts as long as paint is on the door. The paint may fade or become dull over time. But there’s an easy solution to that: Apply a fresh coat of paint.