Go to the current rules here:
https://www.des.nh.gov/organization/...env-wq1400.pdf
Go to page 13 and read Env-Wq 1406.04, (c), (3). When reading this and thinking about your project please keep in mind that the new footprint will be defined by the extension of the eaves. This will likely need to affect your design. You can also consider using the Shoreland Permit by Notification if extending the eaves and increasing the footprint a little is necessary. The PBN can't be used to expand living space in the water front buffer but it can be used for the construction of a deck or open porch as allowed under RSA 483-B:11.
D. Forst
Shoreland Section Supervisor
NHDES Land Resource Management Programs