I have a double decker 10 x 20 screened in porch to build,the framing already exists, we have to install the decking, trim, rail/spindles and screen. The lumber salesman mentioned using mahogany T&G for the floor and use clear cedar for the rail work and trim. I can only pitch the existing joist 3/4" to 0 in 10' and that is perpendicular to the decking (V-goove). And there is no knee wall, its an open rail design so 2' around the outside will receive NE Ohio weather. We were originally going w/ redwood but the prices......... WOW! The numbers are: 1x4 mahogany = $1200. / 5/4x6 cedar select knot decking = $1200. / 5/4x6 clear cedar = $3000. / 5/4 x6 Trex = $1600. We were originally putting screen over the joist and using EP-TY hidden fasteners, but now this salesman has me thinking about mahogany. Anyone w/ expirience w/ mahogany on an exterior application?