You will need a cherry picker, we use the nifty lift 120t (or the 170 which is bigger)
We hire it from our local plant hire.
You can pressure wash it, we’ve done many that way, but these days soft washing is safer, although I still prefer pressure washing depending on the roof tile.
Be prepared for a lot of mess, and I mean a lot. You’ll fill the gutters with moss and dirt, and the surrounding area around the house will be absolutely filthy with moss and dirt
We don’t do do as many as a few years back, purely because of the shear mess involved!
If you soft wash it you’ll get less mess, but you will find it hard to get the lumps of moss off etc.
Price wise you need to factor in the equipment needed, the plant hire, and the time. It’ll probably take 2 days, so you’ll want to go in around £950 (2 workers) Most people won’t pay it, and you won’t get the job. Our cherry pickers are only £110 a day to hire, but you might find where you are it’s substantially more.
It’s a messy job, hard work, and dangerous. So if you do go for it, don’t say you weren’t warned! However the results do look great in the end, and the nive chunk of money is always good!