Large truss in attic not supporting roof

A very large, odd truss was observed in the attic of a very large old mansion, the function of which was unclear, as it was not supporting the roof to any significant degree (only attached to the roof at all by a small 1x6 board), and spanned from the front exterior wall perpendicular to the 2nd floor ceiling (attic floor) joists to more-or-less the center of the structure. A plumbing vent pipe passed through the center of the truss, but I did not observed any framing having been cut for the pipe below.

The attic was symmetric, and no similar truss was observed on the other side. There was a 3rd floor room in the center of the attic, with a small bathroom that was added on the side of the truss, the outer corner of which just overlapped the inside end of the truss.

The only purpose for this I could come up with was to stabilize the 2nd floor ceiling (attic floor) joists and/or walls below. Some sinking of the 2nd floor was observed on the rear of the structure, which the truss was obviously not intended to reinforce, but did not appear to be causing, either, no such sinking of the attic/3rd floor being evident.

Thoughts, anyone?

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Just curious as to what the large bolts were for in the lower half? Could that have something to do with it? And was this in the center of the room below? Looking at the pics I bet the ceiling joists run the other way so I don’t see how this could support much.

That truss is definitely supporting something below but of course can’t say what without more info.

I just looked again and I might be wrong on the ceiling joists its hard to tell, most joists go with the rafters but the flooring got me. :neutral:

It looks like the truss wood is newer than the rafters, if so it could be a retrofit to correct the 2nd floor sinking?

Did you notice anything odd in the basement structurally?

Wow, you guys are super! Where is Marcel???
Joking aside the “truss” is designed to allow for a greater open span across a large room, and still support or hold up the entire ceiling. Same as some bridges you drive across.
I take it the home is pre-1960?
This is of course speculative, since the pictures show very little.

Never have seen anything like this so just trying to piece it together.:wink:

Home is c. 1910. Additional support for the large bedroom ceiling below without having a noticeable beam “dividing” the room inside, as Sean suggested makes the most sense. Thanks.

Yes, this truss is holding up the floor below and the ceiling via the interior partitions. More pictures would help.
The threaded rods are picking up the load and transfering to the exterior brick walls at the exterior.
The threaded rod on the right appears to have the locking nut on the top not screwed down.

I did one similar to this 5 years ago enginneered by an SE.

This design transferred the load to the exterior wall without exerting any out ward force to the exterior wall using a beam below it and steel saddles.

Here are a few pics;

Thanks for sharing your expertise Marcel. I have never seen this before in a house and I would love to see something of this nature.

Cool pics Marcel!