Noises in Floor System

[rheim]

At one of the residential homes I designed, TJI floor joists were installed with top flange hangers welded to a steel beam (no nailer used). All components are in accordance with the manufacturers recommendations, but we still have nasty noises, like metal on metal (it is not because of shiners).
Any ideas about what causes this and how to fix it would be greatly appreciated.

 

[rowingengineer]

can we get some details of the joist to steel beam connection as i am not familiar with this type of detail, I don’t even know what a TJ1 is, but I am Australian.

Also is possible to get a bit more of an idea of the type of noise, squeak, banging ect???




When in doubt, just take the next small step.

 

[Ron]

Generally, the higher the density of a material, the greater the sound transmission. You have steel supports for the truss joists, so any sound that is carried by the joints goes to the steel, unmitigated. Depending on the configuration of your connections, this can actually be amplified through a process called flanking.

This process is exacerbated by hard floor finishes such as tile. Most building codes in the US limit the sound transmission in wall-to-wall and floor-to-ceiling conditions. The construction method you described does little to mitigate such sound transmission.

You will need to either insulate the sound or isolate the sound. Insulation methods are obvious...batt, sprayed, or foamed. Isolation is a little less obvious. Rubber washers between the hangers and the beam would be one method of isolation...not great, but workable and provides some sound transmission reduction. Another is to coat all the hangers with a resilient coating (rubberized, urethane, etc.).

Filling the cavity with insulation will help. Placing a sound isolation membrane on the floor above will help also.

 

[ishvaaag]

Do not forget thermal adjustement. Whilst studying architecture in Madrid I lived in a college (Colegio Mayor Universitario, CMU heh) where transverse beams cantilevered on 2 colums at every frame and floor. According to much practice of the era stabilization likely was at the core of the building, maybe end of wings as well, and the transverse beams were (it seems) quite free to acommodate movement upon their seats at the columns. It produced nice and neat (non intimidating, it was obviously stiff enough) crackles and shrieks. It also was nice bouncing amidst the main beams, heh.

 

[hokie66]

rheim,

Firstly, although I think I have heard the term, I can't remember. What is a "shiner"?

Are you certain that the noise is from the joist to beam connections? If so, the information requested above by rowingengineer would help us to speculate. What time of day are the noises noticed? At what frequency?

 

[msquared48]

Hokie -

A "shiner" is when you have a nail showing above the plywood, that is slipping causing squeaking.

It got the term from reflecting or shining due to wear from traffic from protruding above the surface of the plywood sheathing.

This is not the Australian version of a black eye...

Confusing enough?

Mike McCann
MMC Engineering

 

[hokie66]

Thanks, Mike. We have squeaky floors over here, too.

 

[Ron]

A "shiner" is also a nail that missed its mark...didn't go into the sheathing support, so the sheathing at that point is not attached...causes squeaking.

That's why its a good idea to both nail and glue floor sheathing in place.

 

[msquared48]

True too. Thanks Ron.

Mike McCann
MMC Engineering

 

[rheim]

2nd Mike's statement about shiners.

rowingengineer: a TJI is a member looking like an I-beam, but made of recycled/engineered wood

The noises definitely occur at the connection between the TJIs and the steel beam, and they occur when somebody walks on the floor adjacent to the steel beam.
The building is still under construction, i.e. the framing is finished but still exposed, with no finishing work done so far. I.e., we can exclude any noise transfer from hardwood floors, tiles, etc.
The 2 main scenarios we are looking at right now are lackluster welding (which of course the manucfaturer denies) or the TJIs moving at the hanger due to inappropriate nailing, lack of adhesive, lack of web stiffeners, or any given combination of the above.
And of course our main problem is finding a way to fix it.

Thanks for your input.

 

[msquared48]

Is the nailing of the steel hangers to the side of the TJI slipping up and down on the hanger?

Mike McCann
MMC Engineering

 

[hokie66]

Where the TJI joists sit in the hangers, is there blocking on the sides to fill the hangers? What is the nailing arrangement?

Have you looked closely at connections from the bottom side when someone walks over the connections?

A link to the manufacturer's recommendations which were followed would help.

 

[msquared48]

I think that the link of the hanger nails,to the hanger, to the beam is the trail here, causing the beam to resonate like a tuning fork when the nails slip on the hanger.

This is one reason why I always use a nailer (3X) on the top of any steel beam when I use top mounted hangers. As Ron said, it is a sound transmission break. I always glue and screw, if possible.

Mike McCann
MMC Engineering

 

[rheim]

hookie:

no, they did not intsall blockings to fill the hangers. The bottom of the hangers does not touch the steel beam, but the wood does. The system is shown in the Simpson catalog 2009 on page 69 (with lumber joists, where we used TJIs). We used LBV hangers

Mike:

sounds logical to me, we will try to interrupt the sound transmission somehow in the next couple of days.
And yes, sounds like a good idea not to use welded hangers anymore in the future and go with a nailer instead.

 

[hokie66]

Are your joists on one side only as shown in the Simpson details? If so, twisting of the steel beam may be enough to cause some bumping noises against the joist ends.

 

[rheim]

hookie,

actually, there are TJIs on both sides of the steel beam, with equal spans, so rotation is not an issue. There is also a load bearing wall on top of the beam, supporting another floor, thus further restricting any rotation.

 

[msquared48]

In order to get a tuning fork to stop vibrating, you grab it to dampen the fork.

Is there a way, using power actuated fasteners, to anchor the wall/floor diaphragm to the beam by shooting through the wall plate into the steel beam flange? This might dampen the effect...some? Will not eliminate it though.



Mike McCann
MMC Engineering

 

[mudflaps]

You mentioned the sounds occur when you walk on the plywood ADJACENT to the beam. Is the depth of the hanger such that the top of the hanger is flush, or lower than the top of joist. If it's higher than the top of the joist the plywood will need to rise up to pass over the hanger top flange. Any nails close to the hanger may not be fully seated. In that case the plywood could be sliding up and down the nail making high pitched squeaking sounds. For this situation a screw nail BEATEN IN near the end of the joist usually takes care of the problem. You have to drive it in really hard because you need to deflect the plywood down closer to the top of the TJI. Or you could use a real screw.

 

[hokie66]

Mudflaps's post raises a good point, and by the OP's description we don't really the relationship of the plywood to the beam. Another thing we don't know is how the wall above the beam is supported. Does it start on the beam with the ply cut in, or does it start on the ply? If the latter, what fills the gap between the ply and beam, if any?

 

[rheim]

the problem finally is solved. The contractor installed shims between the bottom of the TJI's and the hanger, together with huge amounts of glue, thus restricting any rotation or movement of the TJI relative to the hanger.

The noises are gone.

Thanks for all your input