Cedar tends to be toxic, esp the oils that deter insects and prevent rot. Although there are some recipes for cedar tea for a few medicinal purposes, it can cause allergic reactions, spontaneous abortion in pregnant women, seriously low blood pressure and convulsions.
You wouldn't want to make a rain barrel out of it, either.
Sue
I am planning to build a garden building, and thought about putting a Cedar shingle roof on it... just for the experience of doing it {and I think Cedar roofs look nice too}.
I also wanted to collect rain water from the roof, for garden irrigation, etc... is that a bad idea?
In other words, would that collected water be toxic or harmful to the garden soil and veggies?