<https://www.youtube.com/watch?v=6J6LBOA5qVM>
<http://schema.org/description>
"Draining a flat roof with a channel leading the water oof the road. This is what we mean by a channel to a drain on a roof. This way water can flow easily. Notice that the drain and the top of the strainer is almost level with the roof.\nhttp://www.commercialroofusa.com"
<https://commercialroofusa.com/flat-roof-drains-location-installation/>