Our small village's zoning permits nonconforming preexisting uses to be expanded up to 25%. However, the zoning does not elaborate on how to calculate the baseline. We now have before the planning board a mobile home sales operation, which includes an office, a storage building, and a sales lot with several mobile homes and trailers on it. The use was grandfathered since it predates zoning in our village, but is nonconforming. The owner wants to build an additional storage building, and is arguing that the baseline - the size of the use from which to calculate the allowable expansion - should be calculated as the total lot area used for mobile homes sales, including the area used for displaying mobile homes and trailers as well as the existing buildings. He then argues that he should be permitted a building with a footprint of up to 25% of this total area. I think that the reasonable way to interpret the zoning is that the owner would be permitted to expand each element up to 25% - so he could add up to 25% more square footage of building and up to 25% additional lot area for display of mobile homes. However, this does seem to be a tricky issue. I would very much appreciate any thoughts on this one.