[おくじょうおくをかす, okujouokuwokasu](exp, v5s) (See 屋上架屋) to do something useless; to paint the lily; to gild refined gold; to build a roof atop the roof[Add to Longdo]
[かける, kakeru](v1, vt) (uk) (sometimes written 掛ける) to suspend between two points; to build (a bridge, etc.); to put up on something (e.g. legs up on table)[Add to Longdo]