underlayment
 

I have the Avaire underlayment supplied by the retailer. It has a smooth side and a bumpy side. Which side goes up? Also, do the underlayment seams just butt up to each other or are taped together. Finally, how much gap do I leave at the perimeter and the closet flange.

Avaire underlayment
 

The smooth side goes up, but I don't think it would cause a failure if it's upside down. Tape the seams with duct tape and leave around a 1/4" gap around all obstructions. Good luck!