Moss Removal from Roof

[Mike]

I live in the PNW close to the Puget Sound. I have moss on the north side of my house and garage roof. It's an asphalt shingle roof so I'm not pressure washing it. Being close to the water I'm cautious of the chemicals I use. I'd like to hear recommendations for killing and removing the moss.

Thanks

 

[poncho62]

I would power wash it...................I don't think it would damage the shingles more than the moss does in the long run.

 

[timgr]

There was a "ASk This Old House" segment about moss or lichen on a roof. IIRC they used dilute bleach in a pump sprayer to kill the growth, then added copper strips to the roof to retard further growth.

http://www.thisoldhouse.com/toh/asktoh/question/0,,401167,00.html

 

[mhoffm911]

I have NEVER tried this, but I have heard that oxygenated bleach (such as Oxi-Clean) can remove such moss. Again, I have no proof of this.

Do some research on Google and I am sure you can find a viable solution at a reasonable cost.

 

[mhoffm911]

more info here:

http://www.askthebuilder.com/B374_Cleaning_Shingles_-_Algae_Mildew_Oxygen_Bleach.shtml

 

[Franz©]

Find the neighbor with a pool and leftover HTH. Mix up some strong solution (sodiumhyperchloride) and stand UPWIND while you apply the solution with a garden sprayer. It will KILL the mold, and you can flush the dead mold away with a garden hose.

May need to do second or even third aplication in the case of heavy mold.

Once the mold is dead and gone, install ZINK strips along the bottom edge of the caprow. The ZINK will generally keep the mold from coming back.

If you insist on power washing, especially in cold season, turn the pressure down LOW.

 

[crowldawg]

50-50 bleach and water in a garden sprayer .Then wash off with a garden hose. Bleach is bleach. get the cheapest you can buy .

 

[Rickster]

OK, I just did this! Went to local ACO hardware and got this Oxyout Algea Remover ($11) cleaner stuff. A powder cleaner in a smaller blue plastic container and a larger preventitive in a gallon sized clear container with blue liquid inside. I have not yet applied the preventitive because we just got hit with a snow storm. I also had to buy a small garden sprayer. Total cost was around $60. I have this one section between the main house and garage that the north side of the roof never gets sunlight and it was really looking bad with mossy mildew. Says to mix the cleaner 3 cap fulls to a gallon of hot water and up it to 4 capfulls for tougher areas. I started with the 4 cap fulls mix. First application the stuff foams up and then you hit it with the hose. I used a driveway sweaper nozzel and washed quite a bit of the growth off the shingles. But when I was done, it still had a lot left. Second day I hit it again with the same 4 cap full per gallon mixture. This time I washed it off with the hose and driveway sweeper nozzel but worked each shingel with the hose and was able to get 98% of it off. From the looks of the mess on the ground it doesn't look like I tore up the stone on the shingel face too badly, but my roof is about 6 years old. I'm still waiting for a clear day to apply the preventitive. They make a zinc strip (found in a web search) that can be applied to the roof about a foot down from the top to stop the mold build-up, but I thought I'd try the spray-on application. Hope this helps.

 

[Dustoff 35]

I have the same problem on my roof, algae and moss. I heard about a product called Roof Reviver on a local home improvement radio talk show (Gary Sullivan). It is a oxygenated bleach specifically designed for removing algae and moss from your asphalt/fiberglass shingles. Here is a link; click on "Cleaning the fungus from your roof".

http://www.local12.com/content/mediacenter/homeworx/homeworx.aspx

Apparently, you can apply it and wash it off or you can apply it and let nature wash it off over time. Watch out for cleaners that contain potassium hydroxide (sp?) as they can pit the insides of your gutters.

I would avoid a pressure washer on the shingles, my 2600psi unit would take the granular substance right off of my shingles if not tear off the shingles altogether.

Good luck

Duane

 

[Bevis]

I've got a 7-8 foot section under one of my double windows that has a green/black algae moss, on the side of my house. Bleach slowed it down for a bit, but it's back.

 

[Mike]

Thanks all, I think I'll start with the bleach then if necessary move up to the more $$$ products.

 

[gotta56forme]

To help the bleach stay up there a bit, I was told to use TIDE brand powder detergent w/ BLEACH. It worked OK, but it is an ongoing battle here in our damp climate.

 

[crowldawg]

You can get bleach for a buck per gallon .If you look at the label on many of those house or deck cleaners .they all use the same ingredient -Sodium Hypochlorite .I haven't done too many roofs but I always bleach a house before I paint or stain it . I spray it on to a dry surface let it sit for about 15 min and then wash it off with a hose. If it doesn't remove the moss or mildew I wait till the next day for it to dry and hit it with straight bleach.
Be careful where goggles , gloves and a long sleeve shirt you don't like. That stuff can burn you .Especially you eyes

 

[amg1678]

I live in the PNW close to the Puget Sound. I have moss on the north side of my house and garage roof. It's an asphalt shingle roof so I'm not pressure washing it. Being close to the water I'm cautious of the chemicals I use. I'd like to hear recommendations for killing and removing the moss.

Thanks

scrape the moss off using a roof scraper or moss removal tool and then apply a chemical such as bleach (sodium hypochlorite) or a biocide to prevent the moss from growing back, these chemicals will act as a preventative and stop the moss from growing back for a couple years, it will also clean the roof slowly over time as the moss and lichen die off. when applying these chemicals ensure you collect all runoff from the gutters as you dont want it going into the drains. also make sure it does not go near any ponds/wildlife

 

[Zeke]

This thread is 16 years old! And that is not the correct answer.

 

[K'ledgeBldr]

I’m pretty sure Wet&Forget was around 16yrs ago- surprised no one mentioned it.

And I saw no mention of Zinc strips either!

 

[jkuro]

The Zinc strips will also prevent the black streaking caused by an airborne fungus, traveling from roof top to roof top.

 

[yhprum]

Sprinkle oxy clean type detergent in it regularly and let nature do the work. Bleach is a short term fix.