The three things you need to re-finish your deck

Don't tackle a deck stripping job without a pressure washer if you can help it. Besides speeding the work, a high-pressure spray removes old finish from nooks and crannies that are too small to clean by sanding or scraping.

This past week as I was refinishing the floor of a large, open verandah, it reminded me of a friend, Mark, who dropped by for a visit a few summers ago. He came asking to borrow sandpaper, but the look on his face showed he needed something powerfully soothing, of the sort you can only get legally with a doctor's prescription.

Mark was refinishing the deck at his cottage not far away, had just this one weekend to complete the job, and had spent the last three hours on his hands and knees with a finishing sander. The effort to strip the old finish had exhausted his sandpaper supply as well as his patience, while only clearing a 2-foot x 2-foot patch of the 400 sq. ft. peeling mess that was his deck. As it turns out, the problem didn't have so much to do with the task, but the tool applied to the job. Mark's palm sander was simply too tiny and under-powered for the situation. When it comes to resurrecting your peeling deck, the difference between misery and mastery is appropriate tools, technique and approach.

Stripping a peeling, grey deck is heavy-duty work, and to succeed in a reasonable amount of time you need to engage three different kinds of powerful tools: a chemical stripper; a pressure washer; and a random orbit sander. While each is effective on its own, taken together the group creates a synergy that works better and faster than any single approach.

The latest generation of water-soluble deck strippers are surprisingly effective and safe. I tried two products on my latest deck job: Stripex and Stripex-L, both from a Canadian company called Biowash. Of the two products, Stripex-L worked more powerfully on the film-type finish I was removing. It softened the dark brown surface coating in about 20 minutes, though I did have to apply and wash it off twice to get completely down to bare wood.

According to the instructions, Stripex-L is supposed to soften deck finishes enough that you can remove the old coating with just the spray from a garden hose. That said, I found my pressure-washer indispensable. In fact, don't tackle a deck stripping job without one if you can help it. Besides speeding the work, a high-pressure spray removes old finish from nooks and crannies that are too small to clean by sanding or scraping. Pressure washers create superior results in much less time, though not necessarily without hassle.

One of the side effects of pressure washing to remove a softened deck finish is the frothy residue that gets blasted off the surface. And in my case that left neighbouring zinnias swimming in a foamy soup that looked like effluent from a paper plant. Both strippers I used on this latest job are specifically rated not to harm vegetation, but that seemed hard to believe based on what I saw. But the claims must be right. A week after the foamy deluge had soaked away, all the flowers look fine.

While a pressure washer is a powerful deck renovation tool, it does have a drawback - the fuzzy wood surface it leaves behind. That's especially true when used on the eastern white cedar deck I worked on last week. The force of the spray partially tears the surface fibres, creating a sort of surface fur, sometimes with a nap as deep as 1/8-inch. Besides looking bad, such a beard is a poor candidate for a long-lasting finish. The loosened fibres are weak and likely to separate from the underlying solid wood in short order, taking your new deck finish with them.

Sanding is the cure for fuzzy deck syndrome, but there are two things to remember. First, the wood has to be bone-dry for the operation to work. Allow two or three good drying days after pressure washing before sanding. And second, use a random orbit sander spinning an 80-grit disc to do the job. No other hand-held sander combines the power and maneuverability of this tool when it comes to decks. As a final step in the deck prep process, sanding leaves a smooth, thirsty surface -- an ideal base for a long-lasting deck finish. Resist the temptation to sand with a finer grade of paper. 80-grit may seem too coarse, but it maximizes surface absorbency. It's the one to use.

In the time it takes to sand a few square feet of deck with an inappropriate sander you can strip hundreds of square feet of peeling mess with ease. And that gets you back on your deck chair faster, which is what decks are all about in the first place.