Nope, they don't. They remain fully clothed at all points (and it has to be said, this is really a good thing...) and they don't even come into the house. Mum offered them tea once and they politely turned her down, so we just left them to it.

Apparently they're not real builders, then. :) But they have done a rather good job so far, all told...

And yes, the window washing is nice. They even did the outside of my window, which has never been washed in its poor little life, being so high up and awkward.