home that could cause this ' bang ' would be steel,,, i'd be checking the beam ( probably lengthwise w/2 adjustaposts or lally columns ? )
is there, by any chance, a manufactur'd steel beam originally 2 parts now 1 ?,,, could also be the lally's,,, imo, its exp/contr movement related to temp based on your inf,,, something's not compatible - tap on the lally's - should be conc fill'd for fire protection,,, if dull thud, ok - sharp ring, someone forgot
bldg inspector MIGHT be knowledgeable but i'd call a structural pe,,, is that beam sitting in beam pockets in conc walls ? ? ?
( ' lally column '
is an architectural term for a long, round, steel pipe [ 4, 5, or 6" ] oriented vertically on separate fndns [ not the bsmt floor ] to support beams stretching long spans. Lally column(s) is/are typically placed under beams to support the structure's weight reducing the tendency of the structure to deflect.
let us know what happens - this is interesting