FromCase Study: Tulsa, Okla., Loft Townhomes A ship’s ladder leads to the deck and buffalo-grass roof, where Navarro installed the Garland GreenShield layered roof system. At its base is a multi-ply, modified bitumen waterproofing membrane. Specially engineered layers on top prevent roots from penetrating the membrane, draw moisture away from the roof’s surface, and keep soil from clogging the drainage system. 800.321.9336.