ivy (lichen)
Whoever suggested a turbo nozzle is a bit reckless (in my opinion)! Ivy is typically going to be found on a residence which would not be condusive to aggresive cleaning with a turbo. MAYBE on a concrete block wall (retail or commercial setting) where possible minor damage may outweigh the result the owner is looking for!
This is not a "quickie" fix-it job. We usually pass on requests to remove ivy suckers from vinyl or other synthetic siding, unless it's a very small area. However, on brick, (which is more typical in our area) it's usually worth it to the client to have it removed. Typically, we end up with a complete exterior restoration job on the brick.
The first thing you need to do is cut away all of the vine and foliage so all that's left are the suckers. The more excess material you remove, the easier it will be to approach the real problem, which is the sucker (lichen) attachment. You can suggest the customer perform this part to save them on $$$. Otherwise, charge on T & M, or a liberal quote. Unlike dirt or other carbon attachment, these suckers are organic material. So use an organic solvent to break down & loosen them. We typically us ABR Fast Finish Remover (same product we use on decks to remove old stain & fungus), diluted 5 or 6:1. You have to test to see what you need. Agitate the solvent & allow to dwell. Use a 40 degree tip and adjust your pressure accordingly.
If this is a textured brick face, it's gonna' be a bear! If it's a smooth brick, you'll be more successful. If it's soft like cream city or chicago pink, you better know what your doing! In either case, you'll want to let the client know you may not get every single sucker, but can effectivelly remove enough to restore the aesthetics. However, depending on how long the suckers have been there, even when fully removed they may leave a "shadow". Especially on smooth, colored brick. If you're doing a chemical restoration after the ivy removal, the shadow will be removed.
Either way, not a fun job. Good luck!
