The best way to clean mold & mildew from metal siding & roof shingles?

Cheap shaving cream like barbasol cleans mildew and mold off of anything

I've heard great things about a product called Wet and Forget. I haven't had an opportunity to use it yet, but I feel it is worth giving a try.

I have the same problem, and I use bleach. It yields excellent results, and it requires no scrubbing. I use a cheap paint sprayer that I bought for another job, and it cost me less than $100. Just try the bleach out on a small area first. I use regular bleach instead of ‘outdoor’ bleach because it is a little cheaper.

We've got vinyl siding and a metal roof and do the same...bleach and water in a sprayer and let it dry before applying again as needed.