Home improvement Q&A: Getting that deck cleaned, better late than never

Q: I know you've written many times about cleaning decks, but mine is looking kind of dingy and, because it sits on the north side of our house, is coated in mildew. The deck is gray, but the color is more greenish-black. Can you dig into your files and see if you can find your advice? I would have liked to have gotten it done for July 4. Maybe I'll get it done in time for Labor Day. Thanks.

A: First, if you don't want to do the job yourself — especially if it has been a while since the last cleaning — there are companies that will do it for you. Check out the Yellow Pages or ask your friends or neighbors for recommendations. (I can't provide names because of newspaper policy and personal ethics.)

We had a mixed bag of weather in the last six months: Dampish fall, cold and dry winter, wet and cool spring. If the weather had been dry and sunny, as in the Southwest, and you had cleaned your deck last fall, you might need to just spot-clean and add a coat or two of waterproofing that needs 24 to 48 hours to dry between coats.

At least three days of good drying weather should elapse between cleaning and coating the deck. A cloudy day is best for cleaning, because the deck needs to stay wet to thoroughly clean the surface.

If you haven't cleaned the deck in a couple of years, you might want to rent a power washer, but check them out first and read the instructions when you get one.

The appropriate washer for this kind of job is one that delivers 1,500 to 2,100 pounds of pressure per square inch. Be very, very careful if you've never used a power washer before. You can do serious damage to the wood if the spray is too hard or you lose control of the machine.

What cleaner do you use?

I've had great success with vinegar, as well as with diluted household bleach and with chemical-based cleaners you can buy in the store. I've also had some luck with oxygenated bleach.

Don't ask how I know, but OxiClean and water easily removes mildew from centuries-old headstones.

The odor of bleach and chemical cleaners, however, can be overwhelming with prolonged use. Vinegar just makes me hungry for salad.

I mix whatever I'm using — a quart of white vinegar to four quarts of water, a 3-1 solution of water to bleach, or whatever is called for in the powdered or liquid chemical cleaner — and then let it sit for 10 minutes or so to settle.

I give the cleaner time to work. I choose an area about 4 feet square and apply the cleaner with a sprayer.

Then I wait five minutes. To clean the area, I use a short-bristle brush that doesn't dig into the wood. Next, I rinse the spot thoroughly with water, to stop the cleaning action, and move on to the next 4-by-4 area.