I have an apartment complex that will have me pressure wash the entryways to the buildings once a year. They will also have me PW drives and garages occasionally on some houses that they manage too. I don't sell it, I just do it if someone asks. I also use a cheap home depot pressure washer. Nothing fancy. Easy absent minded work.
I offer pressure washing also. If you have not established enough carpet business to stay busy, then extra pw income can come in handy.
It helps to have a separate PW machine of at least 4.0 gpm. A pw with a burner for heat will give you an big advantage over cold units. You may also need other accessories like extra pw hoses, pw extension poles, and pw chems, so you will need a little extra room.
Carpet cleaning can be a little forgiving if you try to learn "on the fly", but trying to pressure wash without knowing the correct pressure ranges and chemicals to use for a given situation can get you in trouble very fast.
we've pressure washed and sealed a few decks.
PW'd the siding on a few rental houses and such .
anything big or serious I sub to a friend with a trailer mounted unit
Like Charles, i don't push it.
If they ask, or it's part of a rehab work scope , we'll do it or sub it
and if you intend to offer the service, I'm with Goomer, buy a decent pressure washer .
a decent contractor grade unit starts at around $7-800
I think that's what DeWalt's 3800 psi unit sells for at HD