If there’s an opportunity to support a floor truss midspan: (20 foot span with 14″ truss with no strongbacks or lateral bracing bridging, bouncy floor) with a perpidicular supporting wall that supports midspan at a verticle member of the webbing and not just the bottom chord in between webbing:
what is bad or can go wrong about doing that? (It would seem that suddenly it’s a 10 foot span far exceeding specs re strength/bounciness, etc)
THANKS!
Replies
^
If I'm understanding your situation correctly, then the support wall will take away your bouncy floor problem and would possibly be less expensive than strapping the existing.
Any wall built under the 20' span would change the span characteristics and give a stiffer floor. Two 10' wide rooms would seem to me to be narrow. I am assumming there is a basement!
Building even a 4' closet/storage area on one side will reduce the span to 16' and achieve the floor stiffening plus leave you a room that is 16' wide.
.................Iron Helix
"Building even a 4' closet/storage area on one side will reduce the span to 16'..."
With trusses, it isn't that simple. You can't just stick a bearing under one anywhere and expect it to work. That's O.K. with solid lumber and I-joists. But trusses are a different animal.
I can take a shot at posting some examples if you're interested.
I'd kill for a Nobel Peace Prize.
The man with the sharp eye takes the prize!
I jumped to I-Joist...not truss joist!
I retract my statement...and I'd like my crow medium well, Thank You! ;>)
............Iron Helix
PS....I would still propose a storage closet set at 5' out from one wall thus leaving a nice 15' room and still reduce the bounce problem.....will it work with those floor trusses?
Edited 4/23/2005 7:41 am ET by Iron Helix
"I would still propose a storage closet set at 5' out from one wall thus leaving a nice 15' room and still reduce the bounce problem.....will it work with those floor trusses?"
Yes and no.
It probably would reduce the vibration. But it also introduces a whole different set of forces into the truss with an off-center bearing. You would get uplift at the end of the truss nearest the new bearing.
If he wanted to do that, I would suggest having the truss reviewed to see if it needed some reinforcement at a couple of the joints.
I that doesn't make sense let me know and I'll try to post an example.
Broken promises don't bother me at all. I just wonder why they keep believing me.
Makes good sense...now that I know what I'm talking about........Thanks
...............Iron Helix
Any good engineer will tell you that you can't do that without seeing how it will affect the truss overall. Adding a bearing reverses the forces in some of the webs, and may require different plate sizes on some of the joints.
But - I'm not a good engineer. (I'm not really an engineer at all) So I've given you the "official" position, now I'll tell ya what I think.
My first thought would be to say are you SURE you need the bearing wall? A 20' truss 14" deep should perform O.K. You said there's no strongbacks in the truss. How about putting some in? That should make a significant difference.
If you do put the wall in, I'd say it most likely will help and won't cause problems, with one exception: Is there a duct chase (rectangular opening) in the floor truss?
If there is, I wouldn't add the bearing. That could make for some interesting bending loads in the chords, and I don't really know what it would do. But it bothers me enough that I wouldn't recommend it.
Any chance you could post a picture of the truss?
In the absence of getting quick pictures, I tried to find an example on the internet but guess they don't make this kind any more.
Picture a triangle within a box, apex up: the vertical sides of the box occur at five feet intervals. The triangle base, then, is about 5 feet so the apex of the triangle is a 2.5 feet. That's all, nothing else: no squares in the middle for venting etc. There's 4 of these in the 20 foot span.
Thanks
So it looks like this?
View Image
And he disappeared in a puff of logic.
Exactly that. The verticals 5 feet apart so it's repeated 4 times over a twenty foot span. Thanks
Well, if you wanted me to stake my life on it being O.K. I probably wouldn't. But I don't know any reason it shouldn't work put O.K.I'd still suggest trying some 2X6 strongbacks first. There's a good chance that would do the trick and you wouldn't have to mess with the bearing wall.
Any twelve people who can't get themselves out of jury duty are not my peers.
If the pic is what you have, and you can put a bearing wall directly under the center, you will remove bounce.