How do you stop moss from growing on a house?

[trish]

I'm in Southern Calif, have a standard stucco track house with no trees shading it.  I live in a very sunny area.  Yet, I stll get moss growing on the North side of the house.  Does that mean there is mold growing in the wall?

I've tried bleach to kill the moss--didn't work.  Anyone have any idea how I can permanently stop the moss?

Thanks

[Greenbank]

I think Zinc will do it...you can buy strips that are placed on the peak of the roof. When it rains, a bit of zinc is washed off, which prevent the moss from growing.

Hmmm, have to go look it up. Something like this:

http://www.awardmetals.com/GoodbyMossPage.htm

[Jimmy_Cason]

I searched and searched for a good anwser to this.
I  found a product that can only be shipped to a New Zealand address.

One message board said the only way to keep moss from growing on a north wall is to REMOVE the north wall..    Heh ...    Not an option Huh?

[trish]

I checked the link above and the zinc product is for roofs.  My roof is moss-less; its the back exterior wall of the house that is the moss magnet.  That is made of stucco.  Currently the house is painted yellow--maybe I should just re-paint it green so the moss doesn't show.  We all know I'm kidding---right?

[spinnm]

You're in Southern CA.  Inland or coast?  Green moss?  The kind that grows on rocks and trees other places?

Is it possible that you have a water issue of some sort?  Either a leak or a drainage thing?  Doesn't sound right to me.

[Amanda_931]

How much harm will it do a stucco (concrete?) wall?

How much harm will removing it do to the ground below?

Probably need to balance the two.

Will pressure washing work?  (will it damage the surface?)

quote from a restoration project (marble, I think)--(sounds to me like they are talking about sandblasting with silica sand--sometimes a right destructive process, e.g. on soft brick):

http://www.capitol.org/preserve/masonry.html

"Removing the organic growth blackening the facade will involve the application of a biocide to kill the micro-organisms. Then a process of "facade gommage" will use air-driven glass powder to clean the dead organisms from the surface of the building. Once the accumulated algae and moss growth has been removed, it is anticipated water cleaning of the building will be done every 40 to 70 years as new growth requires."

[Amanda_931]

Found a (roof) site that swears that the oxygen bleaches--OxyClean is one--kept as wet as possible for twenty minutes or so, and followed by brushing, does as good a job as anything, without killing plants, bleaching your clothes etc.

He recommends copper instead of zinc, not, as prescribed for roofs, suitable for the wall.

Aren't there some exterior paints that contain copper (or maybe even an additive)?

http://www.askthebuilder.com/539-Removing-Moss-and-Algae-From-Roofs.shtml

[trish]

Many thanks to all who replied.  In reading the links some of you thoughtfully provided, I saw the word "algae".  I'm not sure what the difference is between algae and moss. Maybe we have Algae?

I will be showing all the info from your responses to my husband.  Using the input the Forum has provided, between us both we should be able to come up with a resolve to the situation.

Again, many thanks to all who replied.
Trish

[DavidLeBlanc]

Chances are you have algae and not moss. Moss would stand out from the surface an inch or so and have a soft, feathery appearance. Algae will look like a stain on the surface.

Chances are you also have some sort of water accumulation on/in that wall. Is the wall regularly hit by spray, like from watering plants?

Neither moss or algae will grow without a fairly regular application of moisture from some source - and the wild rainy season you guys had this year is over, right?

I wonder if "CLR" would help....?

[jb]

I had the algae problem on the inside of my bermed concrete structure that I am remodeling...every so often I sprayed it with just Windex with ammonia in it, or an ammonia product....it went away....