I have only used bitumen based products on the roof of a hutch to make good leaks, I would be reluctant to put any thing like bitumen inside a hutch.
If you are looking at preserving a hutch you would be better to use something like roofing felt on the roof, back and sides. It is better to prevent the water entering the hutch rather than protecting it once it has got inside and started to rot the wood, or coat it with a preservative or varnish. You can help protect the base from rotting if you use a marine varnish on it when it is perfectly dry. Having the hutch riased off the ground will protect the bottom from rotting as well.
Janice