I use wfp, I make up a bucket of gg4 dip my brush in it and with low water otput scrub all along gutter and fascia and everything comes away very easy, When every part of the house is done I wack up the flow rate and rinse evrything off, comes up a treat.
I also use this method for realy dirty first cleans on windows.
Sometimes if fascias are realy dirty directly behind gutters where you cant get the brush, I will offer the customer the option of removeing the guttering and cleaning for extra cost, but as you only see this area if you stand directly under the guttering very few have this done.
I have been on the look out for a long bristled brush to enable me to get behind the guttering, but have as yet not found anything suitable, anybody know of such a brush? If so where can i get one.
The above method I use I got of this forum but cant remember who it was that posted It.
Drew