I want to re do my handrail and I want the design below, a couple of things the balusters will be 66x18 primed treated pine and the rails will be 90x18 primed treated pine, the average distance between post is about 2750, I know I will need to put a block or something in the centre to support it but will the 3 lots of 18mm timber be strong enough outways, sideways (what ever you want to call it), the handrail top adds strength as well i suppose. What do you guys reckon.