Install Timbertech Tropical or Azek Arbor Collection decking.
Install White PVC clad on the existing on the existing rim board and rim joist. Reface the existing arches with Hardi backer board and prep for tile installation (assume the existing structure is adequate to support the installation. Install tile on both sides of the archway corner finishes TBD (not mitered). Install Timbertech / Azek Composite Radiance (White) railing using structural 4x4 posts with composite post sleeves and composite rail kits and ¼” glass panels approved for use with the Azek rail system in lieu of balusters installed per manufactures requirements and in compliance with the International Residential Code (2015) or local municipal requirements. Block and fasten the flat post caps so the existing light fixtures can be reinstalled. Install matching railing on the stairs.