Floor truss ?: BossHog etc. out there?
I have bad trusses: bouncy and likely too weak. The search here has fabulous stuff (especially in the Boss Hog and many of the other posts) so I see alot of what won’t work, but would it work to build my own truss in place?
Situation: We had a room built on, half of it over the garage built in 1990. The floor trusses are 20 foot long 14 inch 24″ o.c. that run perpendicular and unsupported by the 2×6 joists below, holding up the ceiling sheet rock and a whole bunch of nasty blown in rock wool black stuff (trusses clear 2×6 by 1/2 inch). The 2×6’s run parallel to how/if cars would be in the garage so the trusses are perpendicular, that is, parallel to the bumpers. The room above supports a 6×18 foot model railroad (dead weight with plaster, wood etc) but that’s over the room half with trusses both inaccessible but could be supported from below mid span by 2×12’s fixed into some reinforced walls so they’re not the problem. It’s the 3 trusses over the garage where people stand to view the trains that bounce and could be too weak. The underlying 2×6’s don’t help as the near ends go to a double 2×12 over the garage that can’t take more weight from those joists and roof. Flooring above the truss is 3/4 T and G glued to the trusses.
So, if I read Boss Hog’s posts correctly I conclude:
1. 14″ truss over 20 feet is the very bare minimum. Also, 1990 is prior to much of the truss research.
2. Sistering glued 3/4 plywood onto these truss turning them into box beams might increase the stiffness somewhat but neither the bounce or vibration that much (referencing Boss Hog post 21010.1 of 6/02) would be helped and sure would not be stronger, is that correct? Bridging or strongbacks ditto, right?. Did I get these conclusions right?
3. What I seem to need is deeper trusses but tearing down the 2×6’s, sheet rock, and dump all that nasty blown in insulation (which there is no easy way to collect that) that lies below the existing trusses. Can I build my own 24 inch truss that would be sistered to the 14 inch trusses? Is this the best conclusion?
-how good is a home built trusses IF I exactly copy the design of the other truss, for the metal connectors substitute 3/4 inch plywood glued essentially making it a box beam, and I can run the 2×4’s through holes in the sheetrock (perhaps too ambitious and crazy-which also serves as the definition of being a doityourselfer-but better than taking down all the sheetrock and rockwool or especiallycleaning the garage beforehand) and box the upper and lower cords in plywood and glue and then all I have visible is a nice little 6 inch looking plywood beam under the sheet rock.
Right, wrong, or better way please??? Thanks!!!
Replies
Trusses that are 14" deep and spanning 20' aren't really overspanned. I limit them to about 21' max span if I have a choice.
My first thought would be to wonder if there are 2X6 strongbacks in the trusses. Not really an easy fix, but they might do the trick. Is there any way to slip something in from the end?
I also wonder if the trusses have a duct run in the middle of them. As time goes on, I'm becomming more suspicious of them causing vibration problems. Don't really have any research to back me up - That's just a personal hunch.
Building DIY trusses isn't something I would even consider. That falls in the "you must be joking" category with me.
Some folks here think adding plywood on the sides of a floor member will make a great deal of difference, but I'm not one of them. It may or may not help.
If you end up tearing into the ceiling, you might as well fix it right. That may involve any number of things.
Any chance we could get some pictures?
This explains why Wile E. Coyote gets so many 'Get Well' cards.
Thanks much! Doesn't sound like bounce does not = weak so that's good.
No ductwork there. No strongbacks...sounds like that's the best bet if possible and + or - on the plywood glued to the sides before tearing anything out.
I'd have to read the instructions (is that possible with us men?) to try to attach a picture but will try.
I appreciate it!
what would gluing another bottom 2x4 to the bottom cord do? It essentially deepens the truss, right?
Don't really know - It might help and it might not.
I still think stongbacks are your best bet. Easy to install if you have access.
Here's a picture, just in case you aren't familiar with them:
View Image
Q: Who has the right of way when four cars approach a four-way stop at the same time?
A: The pick up truck with the gun rack and the bumper sticker saying, "Guns don't kill people. I do."
I'd agree with that. It increases the load sharing of the system
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
If I read this right, the same trusses that span the same distance =over new construction are fine, but where they are over the old garage, they bounce.
Is it possible that they are not supported at the neds the same way, or properly?
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
sorry, all the trusses date from 1990 and all are bouncy....it's just the ones over the garage that I'm scratching my head on how to fix and the ones over walls could get a mid truss support and be fixed (and that's were the railroad is so no one is walking there). Thanks