I’m a homeowner and we’re building a poolside pavilion at our place, roughly 31’x12′ that’s enclosed with full height walls on the back and one side (bathroom&storage room on that side) and open in front and eventual outdoor kitchen counter on the other side.   Shed style roof with 2×12 rafters 24″ OC.    Trying to determine what to do for a ceiling in the open area…ceiling area is appx. 23’x11.5′

At first we were thinking T&G cedar but after pricing it out that quickly was shelved.  Then was thinking painted pine T&G (windsor one boards) but we recently came across Hardie’s new Architectural 4×8 panels, namely the grooved fine sand version as the grooves would could hide seams on the 8′ edge.  I would need 9 panels to cover our ceiling so i’d have two rows of seams on the 4′ end but I saw some pictures online and the seams looked fine due to the perpendicular grooves.

Anyway, just wondering what to look out for if we did use these panels on the ceiling.   The bottoms of our joists aren’t super level so I thought I’d put up some 1/2″ CDX first to eliminate potential for waviness.    Should I glue the hardiepanel to the CDX in addition to fasteners (nails or screws?) when installing?  Is there something else I’m not considering that should cause me to abandon this idea?