"Moss" On House Siding ?

[Bob]

Hello,

Live outside of Boston. Typical Colonial, with white painted clapboards.

Lots of big, green, what I will call Moss (but may be wrong term for), spotted areas on one side of house.

Really don't want to re-paint the house at this time.

Is there any "good" product that I can perhaps attach to my hose and just spray the "Moss" ? Would it kill it ? Just remove it ?

It is way too high up for me to consider getting up there and doing any hand scraping, etc. Would have to be from ground level.

Would be concerned about the safety of the product in that it doesn't do any additional discoloring of the white paint, or cause peeling.

What about "Pressure Washing": Something to consider ? Just water, or some mixture ?

Would be very worried about pressure washing causing peeling of the paint; house hasn't been painted in a very long time.

Product to use or other opinions ?

Any thoughts on any, or all, of this would be most appreciated.

Thanks, Bob

[(PeteCresswell)]

Per Bob:

...

We have our entire house pressure washed every couple years. The "moss" is especially prevalent on the North wall of the house.

But ours is vinyl-sided, so I can't say about paint considerations.

[Mayayana]

If it's actually moss you need to scrape it off. If you mean algae then the best method is strong ammonia solution and a scrub brush. (Moss has height. It's a recognizable plant. It will occasionally grow near the ground on siding. Algae shows as a green stain. It can build up fairly thick, but appears as a coating rather than stems and leaves.) Bleach will work, but not as well as ammonia. Bleach is also more damaging to both the siding and your skin/eyes.

You might have good luck hosing it down, but it's hard to get algae off without a scrub brush. The ammonia turns it to mush but then it needs to be loosened. If there's too much to scrub you might try wetting it with ammonia so that it's well soaked for a few minutes, then try a powerwash fitting to wash it off.

If you actually have mildew (blackish spots) that requires bleach.

[dadiOH]

Water + bleach. About 3/4 water, 1/4 bleach IIRC but Google it. The bleach won't hurt the paint, plants either. It will kill the existing moss or algae but won't prevent it coming back. It is on shady areas of your house? Places where dampness prevails?

If it is thick - as opposed to thin, superficial spots - you may have to scrape it off. For roofs, you can prevent it by afixing zinc strips near the peak of the roof...rain water dissolves a bit of the zinc and that zinc laden water kills/prevents the growth. Hard to do that on a vertical surface though...you might try spot painting with a paint to which a mildew/fungicide has been added. The best cure is to arrange things so that it doesn't stay shaded and damp.

[clare]

Bleach and TSP in warm water, spray on, soak, and hose off.

[gonjah]

It could be an area where water collects after a rain and it's splashing up on your siding. You can make a grade or put in gutters if that's the case. Be careful if you use a pressure washer, It maybe too powerful for your siding and it just makes it wet again too. It was happening to me and I made a grade away from my house and put pavers in to guide the water away. Worked great. Gutters probably would have worked too.

[micky]

That's what it says on the bottle of bleach and in google, but when I tried to kill green things growing on my unpainted wooden picket fence to go away, a mixture like that did nothing. I finally used 100% bleach.

Do I have Super-Moss, or what?

[Mayayana]

| >Water + bleach. About 3/4 water, 1/4 bleach IIRC but Google it. The bleach | | That's what it says on the bottle of bleach and in google, but when I | tried to kill green things growing on my unpainted wooden picket fence | to go away, a mixture like that did nothing. I finally used 100% | bleach. | | Do I have Super-Moss, or what? | You need to distinguish between moss, mildew and algae. Ammonia is best for algae. Bleach is the only thing for mildew. TSP is often recommended, which is very good for cleaning but won't actually affect algae or mildew. Only mildew can be cleaned with little or no scrubbing. It can often be treated with bleach in an insecticide hose spray attachment. algae requires a scrub brush and a bit of elbow grease before it can be rinsed away. If you actually have moss you should start with scraping.

[micky]

It was only the fence, so I wasnt' interested in cleaning or in removing it, only stopping it from growing. 100% bleach didn't clean it either, but I think it did stop it from growing. (Can't remember details now, but I was pretty happy at the time.)