Brian,
Thank you for your inquiry regarding AdvanTech subflooring. Although AdvanTech has superior water resistance, it is intended for interior use in conditioned spaces. AdvanTech is an exposure 1 rated panel which is not designed to be permanently exposed to the exterior environment. The water resistance is designed to prevent dimensional changes or structural degradation if exposed to weather during the construction process. For your application, we recommend the use of marine grade plywood. Marine grade plywood, or an otherwise exterior rated product, is designed to be permanently exposed to weather and moisture.
Please contact us with additional questions or concerns.
Nick Sabol
Huber Engineered Woods
Product Application Specialist
nicholas.sabol@huber.com
(704) 731-2673