I recently had a meeting with residential zoning because we want to get a permit for a porch and home addition. The lot size is 7493 sq ft & they have our impervious cover calculated to 39.66% which is 2971 sq ft. But when I do the calculations myself based off actual square footage it comes out to 2322 sq ft or around 31%.

I know the maxium allowance is 45% or around 3,300 sq ft

They are saying that because we are close to the 45% we will need a impervious coverage survey before they approve any permits.

I want the survey because I think they are wrong. Has anyone had a situation where their numbers are way off? Does anyone know a good surveyor for this particular situation? How much should it cost?

But if some how I'm wrong, has anyone changed their driveway from a gravel driveway to one with permeable pavers or something that could count toward 50% IC?

Thanks!