[jyl]

I can put in a gutter. That part of his property is a 4' wide planted strip along the side of his house, the strip is invisible from his house and I maintain it for him anyway - prune the roses, water the plants, pull the weeds, lay down the mulch, etc. So he won't have a problem with some runoff, but you are right, a gutter is the way to go - if only to avoid drowning the plants that I am tending.

As for the City of Portland, well, I am hoping to avoid inviting them to my house, because my treehouse was built, shall we say, without the benefit of municipal services. And I am a big believer in screws over nails.

Good point on the architect and safety. I have some close friends who are architects and will run this by them. But, as usual, I want to try to figure it out for myself first. Of course I'm perfectly willing to cheat by asking PPOT . . .