Algae on Roof

[Steven Hockstein]

14 year old house with algae on dimensional asphalt shingle roof (northern exposure side only). Can algae be removed or should the roof be replaced. Any suggestions?

[hausdok]

Hi,

Sure, it can be removed if it hasn't damaged the cover to this point. Use a pump sprayer to treat it with a 4 gal to 1 gal mix of water to liquid sodium hypochlorite with about a pint of liquid dishwashing detergent thrown in for suspension. Apply on an overcast or cool day so it won't evaporate too quickly. Let it work and then rinse it off with a garden hose. How long it needs to work depends on how long it's been on the roof.

Don't get this stuff on the plants or grass around the house or you'll be planting.

ONE TEAM - ONE FIGHT!!!

Mike

[kurt]

It's certainly not "good", but I've never seen algae/lichen cause any particular problems. I've had lichen on the north side of my cottage roof for about 18 years.

I'd broom off what could be broomed off & not worry about it too much after that.