Structural cross joists and load-bearing walls (century home)

Question

I have a friend that recently took possession of a century home. Its a 4 plex and He was told it was an old school house (at least at some point in time). We’re experienced weekend warriors but definitely not experts. We’re doing some renovations to one of the units on the main floor, mainly looking to tear out a couple of walls that cut up the living space.

Anyways we have most of the demo work completed, opening up the walls/ceilings uncovered strange cross joisting unlike anything I’ve seen in my pervious experiences. The joist are true 2x4s and crisscross with each other. Hopefully the photos help.

The walls we’re looking to remove really don’t appear to be load bearing in anyway, as the majority of the studs don’t tie into the joists above. That being said with the cross joisting construction and the appearance that almost nothing is truly load bearing leads me to believe that everything is load bearing?

Its difficult to flush out a true question here but I guess I’m just after information about this type of construction, its name or any information I can get my hands on, and thoughts on whether these walls do provide any load bearing properties.

Answer 1

Pre-demolition, this could have been a "double floor" or "double framed floor". If you look up the wikipedia article on floor joists(I would link directly, but I don't have enough rep), it gives you a bit more context. The intention being one set is for the ceiling, and the other is for the floor above.

Alternatively, with century homes in particular, you can get quirks because of the wood sources - this could just be strapping with what was available. Modern buildings use 1x4 (or 1x3) ].

To answer the question "is this load bearing?", as with similar questions I think the best answer is get a professional in to determine that.

Answer 2

A floor made out of 2x4s would need all the help it can get. Leave it alone or sister it properly, preferably: fix it using sisters.

Consult span tables for what to use; I'd guess 2x8s or larger.

This isn't really a task for the inexperienced, unless you're willing to ask about 50 more questions and buy a bunch of stuff you're probably never going to use again.

If you have a friend in the industry who could come take a look, give you advice and borrow some tools from throughout the process, then have at it. Provided they're willing to outline the entire project for you (and answer daily phone calls of, what now?).

This is something that even I wouldn't undertake alone, myself. I would have another, competent person there to soundboard off of (IMO, it doesn't sound like either of you qualify).

PS, AFAIK, that type of construction is called BS.