We live in an older bungalow (1 1/2 stories, with partially finished basement, dusty cement floor, "freeflow" through stone foundation, 1920's house).

The house currently has several main 8"x8" beams (16" o.c.) traversing the original 20'x20' cellar, which beams then rest on the side stone foundation. Each beam is supported about every 10' with either a tree trunk, or iron lolly column. The house was sagging slightly in the middle, around a central stairway...since 1920, it has been added onto in 1947 (basement extended to accommodate), and 1987 (attached room over a higher floor grade than basement due to ledge under--essentially a 4' high crawl space).

However, one 1920 center beam is cantilevered (i.e., beam is split in two, one portion resting on the other), with a nail plate joining the two on both sides. This particular beam is supported by a lolly column permanently attached in the basement cement to the "upper" beam, and 10 feet away is a tree trunk attached to the "lower" beam, which slips out now and then. It is truly not safe in my opinion.

In addition, nearby (4') from this beam is a 1920 stairway, originally very steep and in disrepair. I replaced that with pressurized 4x4's, supported that framing underneath with 2x4's (so that if the bolts and nails tied into the framing I used failed, the stairway would still retain support). This had a net effect of ratcheting up the main floor above by a quarter inch.

I would like to move the lolly columns more convenient to basement traffic patterns --washer/dryer, etc.), join up the cantilevered beam, and permanently remove the tree trunks as support. The movement and placement of the new lolly columns I believe would require accurate timing and placement.

Should I get a structural engineer involved, or would a typical house contractor suffice? Would love any and all opinions...thanks

Structural enginneer.