Setbacks, Lot Area, Floor Area, Street Frontage, Useable Open Space, Building Separation. A modification of setbacks, lot area, floor area, street frontage, useable open space or building separation is permitted provided the modification is consistent with the purposes and intent of this title, and is necessary to: a) secure an appropriate improvement on a lot; b) prevent unreasonable hardship; c) promote uniformity of improvement; or d) the modification is necessary to comply with the Americans with Disabilities Act and/or California Code of Regulations, Title 24, requirements.