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Comp. roof showing signs of moss

Looking at the roof you are starting to see signs of moss. There are some spots

where it looks like the moss is starting to distort some of the shingles. Like,

raising the edges.

Can the roof be pressure washed?


Can it be sprayed with anything that would kill the moss?



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Posted 2011-01-30T13:12:29+0000  by julesybugs julesybugs

Hi julesybugs. I want to welcome you to the community  - it's good to hear from you.


I noticed a couple of other recent questions you posted, and it looks like you in DIY mode for 2011. We will tackle together any question you have as you go along your way.


   Pressure washing roof shingles can be done, but with cautious safety in mind. I have personally fallen from those kind of heights and you really are at the mercy of whatever "gravity" wants to deliver to you. So, an ounce prevention goes a long way.


   Depending on how high up the affected area is on the roof - you need to actually get up on the roof. The reason why is, that when using a pressure washer you do not want to spray upwards into the shingles. You always want to spray in a downward direction over the top of the shingles. So, positioning yourself above the area or to the side is advisable.

There are several ways to accomplish this:


  •    place a single section of  ladder (remove the two sections of an extension ladder) running flat on the angle of the roof. This can be achieved by using a "ladder hook" attached to the top of the ladder and hung over the peak.

                     ladder hook.jpgroof hook.jpg 

  •    Another way to support the ladder is with several "roofing brackets" secured to the lower section of the roof with a board attached. The ladder rests on the board/brackets and can be moved across the surface as needed.

roof hook.jpg


   SAFETY: always have a "back up" plan when working on a roof. Try tying a long rope to a solid object like a tree on the opposite side of the section you are working on to act as a safety harness. Remember that if you should loose your balance, that rope will prevent you from falling off the roof. It is very important that you attach it directly behind the section you are working on - not off to the side.


safe ladder.jpg


Once you have the "how" down, get ready to become very wet and very dirty. 


   You will want to treat the surface with a chemical that will loosen up all that moss and algae (as well as prevent it from growing back).  My two favorites are JOMAX and M-1 ROOF CLEANER. Soak the areas that you want to clean with these chemicals - following the manufacturers instructions. This step will ease the removal of the moss, and make cleaning the shingles a much quicker task.

jomax.jpgm-1 roof cleaner.jpg 


After you have let the chemicals do their job; its time to pressure wash. 


   SAFETY: A lot can happen when you are precariously perched on a roof -  at an angle that most people are not used to, while operating a heavy high pressure hose. So have an assistant on the ground, and make sure that the area is free of any other people. I have had situations where someone on the ground accidentally  tripped over the hose and pulled me off balance. Also, the roof surface will be very slippery - so stay on the ladder.


   Start from the top and move your way down. Keep the spray about 10 - 12 inches away from the surface and constantly moving. If you allow the spray to "linger" too long, then you run the risk of slicing through the shingles. Always point the wand  downward according to the angle of the roof and moving across. Stick to this process until you have a new looking roof. 


I recommend that you stay off the roof and hire a professional to do this work.:smileywink:


Please let me know if this helped you at all, and if you have any further questions.

Posted 2011-01-30T15:10:51+0000  by Kevin_HD_ATL

Thank you so much for taking the time to help me.

Your advise sounds excellent.

Safety first... Especially

if you are disabled or elderly... Like we are.





Posted 2011-01-30T21:47:37+0000  by julesybugs

I appreciate your kindness...


   Thank you once again for stopping by the community and becoming a part of it. There are a lot of ways we can help you DIY anything - regardless of your ability. The community is made up of many members from lots of places with as many skills to help.


See you soon.

Posted 2011-01-31T12:58:24+0000  by Kevin_HD_ATL

I have a small area above my porch, approximately 100 square feet, that I plan to clean using the m-1 roof cleaner concentrate with a garden sprayer. I will get on the one story small roof section with a ladder.  I have three tab shingles.  I am not comfortable using a pressure washer; can I use my garden hose for the rinse and get the same results?

Posted 2012-06-03T11:55:28+0000  by peggysam100

Although the product does very well loosening up the growth on the shingles - it may not rinse off with just a garden hose.


Try using a stiff bristle scrubbing brush that attaches to an extension pole to see if you can remove additional dirt from the roof.  You may reach most of the roof right from a ladder leaning up at the roof line.


Please be careful and wear protective eye wear, gloves, etc.


Hope this helps.


Posted 2012-06-03T18:08:54+0000  by Kevin_HD_ATL
The American Roofing Manufacturer's Association has addressed this:
You really should hire a pro, because there is a learning curve that could cause you to fail several times before getting it right. You can buy all this stuff at HD, but be safe. I have been cleaning roofs since 2004 and I get advice from guys who have done it for 20 years or so. Happy New Year!
Posted 2013-01-01T07:40:50+0000  by OutdoorProWash
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