A quick question about the best way to put the layers of plywood and roofing felt together. Are they simply glued? What is the best glue to use? Is it better to put the 2 layers together first before attaching to the frame or attach each sheet of plywood separately? I do plan to glue and screw to the frame as has been recommended many times. Thanks for all the help in this forum. What a great resource for newbies like me.