hoarding
n.— «The platform in question was partially draped by a large orange tarp, a technique known as “hoarding,” Hauser said. It’s a common and accepted way to shelter workers from the elements when working in winter.» —“Saskatoon construction worker falls to his death” by Jason Warick Financial Post Dec. 11, 2008. (source: Double-Tongued Dictionary)
This looks as though it’s merely a development of a older word: “hoarding” as a temporary fence used to enclose a building under construction or in repair, and regarded as a place where one would see posters–in particular, election posters. The OED takes it back to 1823.