WW, the first thing I think of when I hear, 'hoarding', is a large (outdoor mostly) advertisement, like a billboard. Hoarding in the sense that wwh describes is much like the large sheets of tin or some other metal, tarp sometimes, that is used to seal off the area under construction. It is a protective measure instituted to prevent bodily harm to the public from hazardous construction materials and is a mandatory requirement for all construction in urban environments.