As discussed on our website, it is possible to make our bifold door and window flush with the floor or bench on both sides. If this is required we use our U channel sill. When this sill is used there will be a small gap between the bifold and the floor or bench as shown in the cross-section below. To help seal the bifold we can on request fit a snap on seal that helps seal the bifold. This seal is also shown below. It should be noted that this seal is inferior to our standard sill seal and if there is penetrating wind and rain there is a chance that some water may leak into the building. Usually U channel sills are only used when there is an eve covering the bifold or if water leaking onto a bench top/tiles in a storm is not an issue.