The term "estimated cost," as used in this section, means the reasonable
value of all services, labor and materials and use of scaffolding
and other appliances or devices entering into and necessary to the
prosecution and completion of the work to ready a building or structure
for occupancy, provided that the cost of excavation or grading, and
of painting, decorating or other work that is merely for embellishment
or not necessary for the safe and lawful use of the building or structure,
is not deemed a part of such estimated cost.