Q I have a six-year-old asphalt shingle roof with a patch of moss on the north side. Is there a safe and effective way to remove it?
A It's unlikely to be moss. That usually takes longer than six years to establish itself. More likely it is lichens or algae, said Greg Reichelt of BAC Construction in Minneapolis. Moss is bright green and is about ¼-inch thick on the shingle surface. Lichens are flat, green roundish patches. Algae grows in flat, black streaks.
You can hire a roofing company to get rid of the problem for about 50 to 75 cents per square foot. Do-it-yourselfers can apply a solution that's half chlorine bleach and half water at the rate of 1 gallon per 30 to 50 square feet. You can also buy a product called Shingle Shield ($25, 1-800-942-3004, www.shingleshield.com) and apply it with a garden sprayer.
Wear protective goggles, gloves and clothes. Protect grass and plants by attaching plastic garbage bags to the ends of downspouts. Gutters should be rinsed with plain water to prevent corrosion. The solution will kill algae or lichens immediately, but the black or green discoloration might take several days to disappear.
To minimize recurrence, trim overhanging trees to allow more light and air. Also add copper or zinc strips (also available from Shingle Shield) to the roof ridge and under the shingles every 10 feet vertically up the roof. Algae-resistant shingles also can be installed, Reichelt said.
JOHN EWOLDT
Don't feed the pigeons Q Is it legal to feed pigeons in Minneapolis? I see people on a regular basis dump bird food along the streets and in the parks for the pigeons to eat.
A It is illegal to spread any bird food on the ground in a public or private space. According to Minneapolis ordinances, wild birds can be fed only from feeders or platforms raised at least 48 inches off the ground and not accessible to rats.
