Lime Washed Engineered Oak Prime Grade – 21 mm x 240 mm – Luxury modern design project. This project showcases some of our finest bespoke staircases. Firstly a White Cantilever Staircase with wall anchored floating treads and White Balustrade, create a high- end contemporary finish. The second is made using Prime Grade Lime Washed Engineered Timber for the Seamless Treads and Risers.