Unusal Attic Structure

1890 Build.

I am hoping someone can enlighten me on this type of truss like structure found in the attic.

It seems to be the back bone of the house but I am unfamiliar with this construction type.

Any help is much appreciated.

I have not seen that before. Looks impressive. They tighten down the threaded rod to tighten up all of the triangular bracing. Very cool.

Mike …Marcel Cyr built something like that on a commercial building He was working on some time back and He explained how it worked…He’s the guy to ask…I can remember the specifics…

I thought it was cool too but hope someone has more info or has seen it before.

I have done quite a few 19th century homes but this is new to me.

It was a very spacious attic.

12/12 pitch with 2 x 4 raters and completely open with high ceiling/roof.

I’m curios what those rods are supporting below and how far they go. Could they they carry floor load from somewhere down below? I would think it would be doing work that is typically done by load bearing walls or piers. Any unusually open areas below? It’s certainly interesting and definitely not new (I see ceramic knobs on it so it appears to be original). If there are no visible signs of distress, it has stood the test of time.

Report wise, I would comment that it was atypical framing using a site built truss and move on, but from a personal perspective, I would be curious to learn more about it too

Not concerned about them Chuck. Just curious how they work.

My client asked me about them and I said I would try to find out.

I even mentioned the MB and Marce. :wink:

If anyone knows where the thread Marcel talked about them, I would appreciated it.

Yes Mike, I did post about this system about 4 years ago in “A Little on The Commercial Side of Things” Thread I had going at the time.
Unfortunately, pictures there are no longer visible in the posts.

I did recover the pictures that I had posted in PhotoBucket.

These trusses were designed to pick up a floor load from the attic and transfer the load to the bearing walls at the exterior.
There is quite an assortment of design variations I have seen over the years.

Here are a few pictures of my project I was on.


Holes were drilled in the carrying beam to install a steel stirrup that will absorb the lateral pressures of the load transfer from the top chord where the threaded rod is and transfer that load down the bearing wall.




This last Picture shows you how it was simply done back in those years.
That system picked up the load from below and transferred it to the rafters and down the wall.
Unfortunately, in this building the walls were spreading out and a new system engineered.

In the case of your pictures, that truss design, is relying on the truss design to transfer the load straight down the exterior wall.

Both and most of these systems are designed by a structural engineer.






Thanks Marcel.

My photos do not show it well but both of these truss structures were on the centerline of the building and far from any exterior wall.

You can see one next to the attic access stair way.

The other is some 6 feet a way or so.

The first one I have seen in an older home.

It dosen’t have to be an exterior wall Mike.
The threaded rod is picking up a load from below and transferring that load to the end of the truss near the chimney, at which point there is some bearing structure at that point not visible.

I understand that Marcel thanks for your input.

So with that design the home was built with less load bearing walls on the interior of the home?

Yes it is probably what allows for this large room on the first floor

Yep, and I bet there are some nice hardwood floors under that pink rug. :mrgreen:

Yes there were indeed except in the servants quarters. Just painted in there.

Looks very similar to a house I saw that was built in the early 1950’s.
I was able to see one of the threaded rods going down a duct chase all the way to the footing. The owner said the original builder owned a lumber supply company. Looks like it was simply a way to make sure the top level did not come all the way off in a bad storm. I think the rods were thicker and the lumber also larger on the one I saw.

I have seen where they take out the load bearing wall in a Kitchen to expand it. This is not as complex as Marcel has explained but similar in design to transfer loads from the middle to the ends. Thanks for the pictures Marcel it reminds me of a flat roof design truss system in commercial.

reverse truss.