The National Flood Insurance Program (NFIP) requires that if the cost of improvements to a building or the cost to repair damages (from any cause) to a building exceeds 50% of the market value of the building (excluding land value), the entire building must be brought up to current floodplain management standards.
In addition, the Kane County Stormwater Ordinance stipulates that the substantial improvement can be reached by the cumulative reconstruction or repair of a structure; not each expenditure. Building improvement projects include exterior and interior remodeling, rehabilitation, additions and repair and reconstruction projects.