All legal buildings, structures and uses existing as of the adoption of this chapter which become nonconforming by reason of the adoption of this chapter may continue; however, shall not be enlarged or altered in a way which increases its nonconformity, and shall not be enlarged or altered to occupy a greater area of land. However, as to a residence upon a lot which conformed to the zoning code in effect on October 26, 2011, a front porch, a deck, or an accessory building not to exceed 350 square feet may be constructed to the extent that it would have been allowed under the prior zoning code, provided that it is constructed on or before October 26, 2016.