You’re reading that correctly – find a venue that’s currently undergoing renovations. Now, why would I recommend such a ridiculous idea as to find a reception hall that’s being worked on? It’ll be covered in plastic sheets, plaster, and all sorts of construction goodness that will prevent you from really seeing what the end product will be. You’ll have to worry that the place won’t be complete in time to actually hold your wedding or your reception, you’ll have to worry that it won’t even really look like what their plan says it’ll look like, and you’ll have to put down a sizable deposit even though all those concerns are still plainly visible.
So, why would I even recommend doing such a thing? Because no one else will and a hotel loses money whenever its rooms go unused, conference and dining rooms included (if not especially). So, by looking past the scaffolding, you can snag yourself a really good deal by looking at venues under renovation. There is risk with this strategy but you can we rewarded for taking that risk.