Tapered insulation board, at sufficiently high enough density, can be used very effectively in upper level parking decks. With concrete installed over continuously tapered areas, the resulting effect can provide a good drainage solution. This option needs to balance weight and void fill requirements carefully. To see a project being carried out take a look at the online slideshow here
www.universalconstructionfoam.com/products/tapered-eps.php . EPS is one of the most popular tapered insulations available with a wide range of densities available for the commercial design and construction sector.