Home / What is ‘overlay’ in sports grounds? What is ‘overlay’ in sports grounds? Overlay is the term used to describe the use of temporary installations (such as ‘fan zones’,seating decks, tents, kiosks, bridges and generators) for specific events. It can also includethe provision of new roads or routes. Some of these installations may be built to the samespecifications as permanent installations and may even, in time, become permanent.