Best Way to Clean Mildew Off Wood and Bricks

Brick Cleaning and Maintenance
Last June we installed a new redwood deck. After waiting two weeks, my husband treated it with Cabot Australian tree oil. We now have areas that are almost black and others as pristine as the day the deck was installed. I have wiped off the black areas and have found the rag to be covered in a black residue. An apricot tree hangs over part of the deck but the color between the tree's droppings and the color on the deck is inconsistent. What is our problem and how can it be solved?

A: You've posed the first of what are usually many of our annual deck maintenance questions. Without question there's a fungus among us. You have a mildew problem. The clues are that the apricot tree shades the deck and the black residue covers the rag when you wipe the discolored area. The deck is protected from sunlight by the shade of the tree. Especially in winter, areas getting little sun are prone to be damp, making them perfect breeding grounds for mildew. Kevin had a similar problem in Alameda, Calif., with a deck that was on the north side of his house. It got some sun in the summer, but in the wet winter months the black slime came out. At one point he even started to grow a nice crop of moss. Fortunately, the solution is simple. Kill the mildew with a mildewcide, pressure-wash the deck and reseal it.