I am planning to insulate under floor of my cold bedroom which is right above unheated garage. I will be using ultratouch batts but I think it may not be enough to keep the bedroom warm. I do not want to use a spray foam.
Can I install rigit foam board first and then add the batts on top? I think I will need vapor barier as well (I live in Seattle). Can the rigit board substitute the polyethylene plastic sheet? If so, how and what kind of board should I use?