Scozz - sent you a PM
JimM - Thanks for the info on the AdvanTech. Swore I would never use OSB, instead of Plywood. Although this appears to be OSB on steroids. Lumber salesman talked me into it , and it appears to be as advertised. Stays flat and true, easier to install than plywood tongue & groove. So far impressed with the product. Also feel free to steal any of devices/ideas that may work for you. I have about one or two original ideas every decade and some of them even work!!!