Brown patches on roof


Hey all,

Still fairly new to soft washing, have done multiple brick houses and other exteriors walls, all have turned out excellent. Starting to practice on friends roofs to really tone my craft. I am just not getting the results I want, attached is a photo of a roof I did today, I used a 4% pure CH mix with surfactant. You can clearly still see brown patches. Does anyone have advice on 1) what these patches are and 2) how to properly remove? This is the 2nd roof I have done with same result.

Thank you for the help in advance.


What are you using to apply it


Using a variable spray gun meant for fertilizing.


Is it 12 volt or more like a pump up sprayer?


Yes 10gpm gas pump sprayer.


Try putting another coat.


Awesome I’ll try it and let ya know! Thanks for the advice.


What is a CH mix. I would use a 50/50 mix of water and 12.5 bleach and spray with a dedicated 12v or air pump.


Calcium hypochlorite. It’s just another form of bleach. Trying it over SH on roofs to see how it works.


You need sodium hypochlorite.


That will leave white residue, is not recommend by ARA for shingles, and does not clean effectively. Try SH and you will be much happier


Will do guys, thanks for the info!


Stupid question… has it been rinsed with water at all? Rain… low pressure … water balloons?


Yes rinsed with low pressure water.


Ok just checking. Kinda looked like leftovers and since it was near the bottom of the pitch I figure I would ask. Cant go wrong with 50/50… we tend to tweak it down for roofs with discoloration and no moss.


With CH need to make it about 20% stronger. Can be done, key is getting it to stay blended. but using SH a lot easier.


“If it’s brown it’s coming down - if it’s black you’re going back.” Should rinse off with rain eventually.