Be prepared to spend some serious $$$ on the Raychem. I've made a few installations & it is great stuff, but it is not inexpenseive.
Here's another site to try, I can't verify the quaulity, but I've seen it mentioned (favorably) by other electricians. http://www.easyheat.com/roofgutter/
Good luck
Tom
Few things are harder to put up with than the annoyance of a good example.
