substruction

sub·struc·tion

S0853900 (sŭb-strŭk′shən)n. A foundation; a substructure.
[Latin substrūctiō, substrūctiōn-, from substrūctus, past participle of substruere, to build beneath : sub-, sub- + struere, to build, pile up; see ster- in Indo-European roots.]
sub·struc′tion·al adj.

substruction

(sʌbˈstrʌkʃən) n (Building) the act or process of substructing