Bouncy Floors

greenley

I recently built my own house operating as owner-builder. I'm an electrician by trade, so please forgive my ignorance in advance... We used trusses for the floors and they span 22' while being spaced 19" on center. It seems like my floors bounce more than any other house I've been in, and I've been in a lot. The kitchen cabinets shake, and all these heel-walkers (my wife and kids) sound and feel like a stampede going by. Are there any easy fixes or ideas for getting rid of the bounce???

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neolitic

Assuming that they are
properly sized, I would have
two rows of bridging for that
span.

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greenley

Need more input... remember I'm an electrician, so I need answers in layman's terms...

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neolitic

Let's start with dimensions
and pix.
Specifics will help get specific
answers.
Bridging on truss joist would
probably look like "X's" between
the joist.
Meantime Google bridging.

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SelfContract

Also, pix of column supports too, if any or lack of??

critter

Hey, Greenly!
A frustrating problem to be sure. If you go the bridging route, you will improve (lessen) the bounciness, but it will probably still not be acceptable to you. If this is a first floor over a basement area, your best fix may be to install the support girder that you were trying to avoid by using trusses.
Another possibility (check with manufacturer) is to plate the sides of the trusses with osb, glued and nailed as per their suggested nailing schedule for such a reinforcement. Make sure your fix does not conflict with their engineering in any way and direct these questions discussed to the truss manufacturer. There is where your safest, surest answers lie.
If you used I-joists, there is some possibility of adding material to the web (center vertical) section of the I-joist. Again, refer all these ideas to the manufacturer - don't take our word(s) for the best fix.
-Best Wishes.

neolitic

The only thing that stops horizontal
defection is bridging.
Whether truss, I-joist, or dimensional,
The strength is vertical, not horizontal
(side to side).
If he knew what he was looking for
he might be able to see them twist
under load.
I have.
Bridging may not get all the vibration out
of a huge membrane, but it will stiffen it
and make the joist work as a unit.

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rbsremodeling

Every time I read one of your posts. I get the impression you've done this carpentry stuff a few times before

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neolitic

Sometimes I think most of
what little I know comes from
fixing other people's ups.

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Paulie

I got to diagree. Bridging is not the ONLY THING that stops deflection. I agree bridging is a solution that couldn't hurt without more info. A support truss is another possible solution. The bouncy floored electrician said his kitchen was a problem, not to get down on the plumbing trade but I've seen more than one plumber sawsall a knotch or two in the floor joists.

loneframer

I agree with the double row of criss-cross bridging. I would use 1x3 or 1x4 clear pine. Before installing look for sag in the joist, if there is,according to whats above you may be able to take some of the deflection out.Don't attempt this if there are tile floors or cabinets above, only if its open space.Otherwise I would spread the rows of bridging 2 feet each side of centerline of span,keeping them in a continuous line the entire width of the building, this should help tremendously. You may still feel a spounginess to the floor which may be due to 19.2 inch centers, the subfloor is probably deflecting between joists. The bridging will help with the bounce because it forces all joists to share concentrated loads.When attaching bridging in this situation I would hold bridging flat against side of truss and fasten top through short point of angle cut, then fold up to contact other joist, tap up to snug it in and fasten securely, being careful not to split.

neolitic

We are talking about two different
kinds of deflection here.
The beam deals with one,
the bridging another.

If he has a 22' span, it needs
bridging.

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D.Foster

A plumber shouldnt need to notch a floor truss, he doesnt have joists.And i think bridging is the way to go, esp for head room too. Another truss will be a head target

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Paulie

Fair enough, my bad I jumped over the horizontal part. My other question would be of the code man letting a 22' span with a 19" OC go with no bridging.

Mike772

I build with floor trusses, maybe I can help.

22' should be no problem for floor trusses. I've clear spanned 32' with no problems and zero bounce. Granted I had them at 16"oc, but the original plans had them at 24"oc, my point is they will be engineered for your application to work. By me reducing the spacing, I reduced the bounce.

Floor trusses don't require "x" bridging, atleast in my state. They do require strongbacks. Continuous 2x6's nailed to the vertical member (inside the trusses) of the floor trusses. So from truss to truss and so on, from one end of the house to the other a 2x6 nailed to the vertical member with a minimum of (3) 16d sinkers on each vertical. Check the paperwork that came with the trusses, there is usually an explanation and some graphics of what they want and what is required.

Now, on my larger spans I increase the the strongbacks to every 5', which is every vertical member in the truss. I'm told by engineering that will decrease deflection. And it does. I've noticed that any bounce or deflection to be almost completely gone when I add that many.

The real trick is to not let the other trades notch or cut up those strongbacks. Depending on the height of the trusses, it usually isn't a problem.

loneframer

Strongbacks are the production answer to bridging. Without opening the side of the house up, strongbacks won't be continuous. The goal in either case is loadsharing of the joists. I would however recommend that any bridging should be inline with vertical members of truss. I won't build a floor system of any type without wood x bridging. It is tried and true.

MBS

I have to say that loneframer is right on the money here with the proper way to frame floor trusses. Strong backs will make a huge difference and is often overlooked as unnecessary framing to the novice framer. Or they are planned for installation on a rainy day, then they are forgotten and the trades get in there and run their goodies which makes putting the strongbacks in almost impossible.

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cleveman

Original Poster:

Out of curiosity, were the floors bouncy when the house was stocked with sheetrock?

greenley

You carpenters are a loquacious bunch - thanks for all the feedback. I think I'll try the strong back idea first, it actually falls within my limited carpentry skills. If that doesn't work, then on to the bridging. In regards to the strong backs, do they need to be nailed to each truss or did I read every five feet? Thank you kind sirs...

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Warren

Strongback needs to be nailed to every truss. Only problem is if the house is done (it is) then you will have trouble getting long lengths of 2x6 inside the webs. We generally slide them in prior to decking before we install our end band board. If you cant wiggle in at least 10 foot sections it probably wont help. Might have to try the bridging and maybe strap the bottom chords with a couple of 2x6 running across the bottoms. This will at least tie them together .