Section 1809.5, Frost Protection. Except when erected upon solid rock or otherwise protected from frost, foundation walls, piers, and other permanent supports of all buildings and structures shall extend thirty (30) inches below finished grade and placed on undisturbed ground or compacted fill material, certified by a geotechnical engineer licensed to practice in the State of Maryland, and spread footings of adequate size shall be provided when necessary to properly distribute the load within the allowable bearing value of the soil, or such structures shall be supported on piles, piers or pre-approved methods of ground improvement when solid earth to rock is not available. Footings shall not be founded on frozen soils unless such frozen condition is of a permanent character.