The existing condition of distinctive historic features shall be evaluated by the code administrator to determine the appropriate level of intervention needed. Where the severity of deterioration requires repair or limited replacement of distinctive historic features, the new material shall match the old in composition, design, color and texture, and shall not, in any way, damage original parts, features or materials of the building or structure. Fifty percent (50%) or more of the original materials must be unrepairable in the written opinion of the code administrator in order to be replaced, provided that the new material matches the old in composition, design, color and texture, and shall not, in any way, damage original parts, features or materials of the building or structure;