Common open space. The minimum open area required for common use of the residents in the development shall not be less than ten percent (10%) of the gross area of the development. Common open space shall be calculated as any open unoccupied area remaining after the dwelling spaces, buildings, roadways or streets, parking areas, general storage areas, and the ten (10) foot permanent perimeter area have been deducted. Said open space shall be sodded and/or landscaped or otherwise designed and made available for recreational use.