The Roof Cleaning Institute Of America Training & Certification Forum
"Find A Certified Roof Cleaner Directory"

Hey Doug, I've done a handful slate roofs over the years. I never had an issue with cracking slate from the ladder standoff. However, don't be surprised when you get up there up close you'll see pieces of slate scaling off. If you've ever done any old slate patios you'll know what I mean. Point being, just make the customer aware that there could be loose slate up there and it is pre-existing.

Aside from that, when I do slate roofs, I use a typical roof mix with the addition of Sodium Hydroxide. Just seems to give the mix some serious punch and "smokes" the moss.

If there are any copper gutters or anything else copper, be very careful when using hydroxide,...it will turn copper black instantly.

Are you going to be rinsing these to a finished roof, or allowing time to remove it? either way, when the moss is removed don't be surprised if you have to make another application or 2 to remove the normal discoloration that was under the moss and dirt. Just seems to go that way.

Jeff

We don't have a lot of slate roofs in MD do you guys not use tsp on slate?? I heard it leaves a film you can see.

Wholely Toledo,

We cleaned a asbestos roof in Little Rock that was original roof circa 1920's. It had moss, lichen, algae, etc.
Told client it would take three trip applications of chemical then rinse & lotsa ground work.
It came out like new... beautiful!
Client was Very Happy and we were too $$$
Chris

Chris, what was your mix for the asbestos roof?

Ray, you mentioned copper gutters.  Have you ever cleaned them?  If so, what did you use?

Here are the B4 n Aft pics of front
lotsa luck
Chris