Raccoons and other critters want in your house attic as much as they want in your coop. A nice attic is a great place for them to raise their young. I don't know how your husband plans to install that roof but if he follows the same basic construction techniques the roof will be fine. What materials are you talking about, covering and underlay?
Any roof needs to be firmly attached. The previous owners installed a metal roof with short smooth nails on an outbuilding. A strong straight-line wind ripped it off one night. Materials and construction techniques make a difference, but a proper roof properly installed will work great.
In my mind there is a big benefit in using materials you already have instead of spending money on something else as long as they are suitable. I don't know how that new coop is built of where it is situated, but the house and coop having the same type of roof may be more physically attractive.