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Dealing with a highly resonating 2"X4" stud easily???
Old 9th March 2008
  #1
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Dealing with a highly resonating 2"X4" stud easily???

I just built a wall in the living room of my house... 2"X4" construction with stringers. I added sheetrock to one side of the wall already but not the other. I happened to accidentally bang one of the studs in this wall and it created a TREMENDOUS ultra low frequency resonance... rang for several seconds. I then walked along the entire wall hitting each and every stud... seems that most of the wall is fine, there is resonance, but a "normal" degree and that's fine. But on the one end of the wall, there are two or three studs next to each other (one inparticular) that REALLY ring... like hitting a string on a giant bass guitar or something.

So I need to finish sheetrocking this wall but hate to leave this serious low-end resonance issue. This is just my living room, not a recording studio, however, there will be a TV and big speakers near this wall and I don't want to have any major low-end resonance issues.

My question... what is the quickest easiest way to keep these 2"X4" studs from ringing with low-end the way they do? If I hold one of the 2"X4"S with my hand and then hit it with the other, the stud does not resonante that bad. So I just need to somehow "dampen" these studs. Should I try to strap some bricks onto them, or...? Key words here: fast, cheap and easy. Any ideas, thoughts, tips would be welcomed.

Again, one side of the wall is sheetrocked already and I do not plan on removing that sheetrock. The sheetrock is screwed to the studs, not nailed or glued. I'm thinking I need to add some dead weight to the studs somehow... like put some sandbags in there or something... but whatever I do needs to be practical also... like, I can't really put sandbags in there because one day my wife will put a nail in the wall to hang a picture and all the sand will leak out, etc.

It's weird how I have this strange issue on just one end of the wall and not the other. All stud and sheetrock walls resonate at ugly low-end frequencies, but the few studs I have here are ridiculous... sounds like a giant concert bass drum or something.... like rumbling thunder with a long decay. The rest of the wall is somewhat similar but with a way shorter decay.
Old 9th March 2008
  #2
Gear Head
 

Insulation..... There is a crew building a studio in my basement, 5/8' sheetrock, 3/4" plywood, , staggard studs, insulation, 5/8" sheetrock.

Everyday I would go down there and bang on the walls and freak out at the resonance. When they put the insulation in everything tightened up. R-30 in the basement ceiling also tamed the main floor (hardwood) of a very resonant house.

I don't know if this is the answer for you, its just my experience.

Roscoe
Old 9th March 2008
  #3
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Rick Sutton's Avatar
 

Cross bracing, also known as fire blocking.
Old 9th March 2008
  #4
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Quote:
Originally Posted by Rick Sutton View Post
Cross bracing, also known as fire blocking.
Thanks for the replies, guys.

Yes, I already have some cross-bracing in the wall. I had referred to them as "stringers"... not sure if that is a correct term, but indeed I meant "cross bracng" or "fireblocking". Anyway, this didn't help much... surprisingly. And I did get the cross-braces very tight between the studs, screwed in well, etc.

I will indeed fill this wall with insulation. It's a 2X4 stud wall so I only have 3.5" of space in there, I have some R-15 3.5" insulation to put in, this is the heaviest 3.5" stuff at Home Depot. I know there are other "heavier" options perhaps like rockwool etc... never used it, not sure if this would make much a difference in my situation over R-15. If R-15 doesn't do the trick, I'll need something MUCH heavier.

This resonance is so bad, I'm thinking I may need like a 3.5" wide steel I-beam or something (if such exists), and bolt it right to the side of the offending studs (above and below the cross braces). It seems like I need some type of heavy dampening like this. Or perhaps the insulation alone WILL take care of this horrendous resonance.

Thing is, once I put the insulation in and add the sheetrock to the remaining open side, then I can no longer get inside the wall... so I'd like to try to do something inside the wall now that will make at least some noticeable reduction in resonance before putting in the insulation and sheetrock... this way once the rock goes up, hopefully I will not need to remove it.

I still like the idea of filling an area between the offending studs with sand... it's just that I can see a possible leak problem down the road. In theory though, lets say you could fill the entire cavity between two studs completely with sand... I think that would totally kill all resonances. But... it's just not very practical for a living room wall for multiple reasons.

The fact that I'm using just one sheet of 1/2" sheetrock on each side of this wall doesn't help. I can't go heavier though due to physical and cosmetic constraints... it is a living room after all.... this wall needs to mate up with another existing nearby wall, I'm trying not to turn this into a major project.

For the heck of it I had placed a few bricks on top of the cross braces, did not seem to help. But then again, the bricks were just sitting there, NOT tightly fastened.

Another thought is to strap some bricks all along the length of the offending studs using some metal pipe strapping... try to get the bricks TIGHT to the studs. Maybe enough bricks near the center portions of the studs (above and below the cross braces) would help...? (I happen to have a lot of extra old bricks laying around which is why I came up with the brick idea)
Old 9th March 2008
  #5
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Are your cross braces screwed to the sheetrock?
Sand can be very problematic, last resort type of stuff.
Forget the bricks, you've got panel resonances going on here. You need to break up the large panels and add limp mass to them.
Can you glue more sheetrock onto the existing rock from the inside of the wall? Extra blocking with two layers of 5/8 sheetrock sandwiched with a layer of celotex soundboard then stuff the cavity with insulation and that wall won't sing anymore.

If you can give up a little space on the finished side of the wall a layer of celotex covered by a layer of 5/8" rock will also kill it. Cheapest is just more blocking and insulation. If you ad more blocking make sure you add it randomly so you don't create multiple same sized panels.
Old 9th March 2008
  #6
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Quote:
Originally Posted by 666666 View Post
I can't go heavier though due to physical and cosmetic constraints..
What are the physical restraints that keep you from adding weight? Bricks and especially sand are God-awful heavy so you seem to be at odds with your constraints.
Old 9th March 2008
  #7
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Thanks Rick!

What I meant by physical restraints was, I did not want to add extra layers of sheetrock which would then make this section of the wall "stick out". This wall actually mates with other walling above and on side, so if I added say an extra layer of 5/8" rock or rock + celotex etc, I'd have to do the same with the rest of the walling in order to keep it all flat and smooth... and in this particular situation, covering the entire walling with an extra layer of stuff would be a lot of extra work. One side of this room has a high ceiling, so I'd have to rock up 16 feet or whatever, I'd rather avoid this if no necessary. The new wall that has the resonance problem is only 8' high,, it is a wall between a room with a low ceiling and a room with a high ceiling.

The framing is done, I'd rather not redo all the framing just to allow the addition of extra layers. If this was a studio room I'd do anything of course, but it's just a living room and I'm trying to keep the project as simple, cheap and easy as possible.

As for gluing extra sheetrock to the back of the existing sheetrock paneling, this sounds good, I was already thinking of trying this, but one thing I'll mention... I'm not sure how much of a "paneling" issue this really is because before I had added ANY of the sheetrock, the studs in question already had a specific nasty resonance. I was actually hoping that by adding the sheetrock the resonance would be cut down but it seemed to stay the same.

It's really weird. I've built many stud walls in the past, for general construction and also sound rooms and I've never run across such a strange and severe resonance in a local section of a wall like this. This must be a very specific perfectly disasterous combination of elements in a locaized spot. The most riniging stud is very dense and very green too. I wouldn't be surprised if a lot of this has to do with this stud itself. If I swapped in a lighter drier stud, perhaps it would not ring nearly as much....? Well, I'd rather not have to start pulling apart the wall if I don't have to.

I apologize for my approach with this... if I was building a true "sound room", I'd be very willing to rip everything apart and "do it right", but because this is just a living room (you know, my wife is forcing me to do this work and I can't wait to be done with it so I can move on and go make some music), I'm looking for a quick and easy way out... which I realize may not be possible.

If I cannot kill this resonance, hopefully the speakers that will be nearby will not cuase to much ringing. I'm sure the volume will never be up TOO high... and the speakers will not be touching this wall.... they might be say a foot away though on floor stands. The floor is very dense and solid so that's good... several layers of subflooring and then hardwood on top, all very tight.

Ok, I'll forget about the sand. It was just a thought. I've never used sand like this and realize it's not a very practical idea, it was just something that had come to mind.

I need to check to see if I had screwed the sheetrock to the stringers... perhaps I can help things by just adding some more screws in general. I had purposely not added too many screws in the name of reducing spackle work, this wall will be painted and will be the center focus of the living room, I want the wall to look really good, perfectly smooth, etc... so I was trying to keep the sheetrock as unblemished as possible... and cut down on spackling... but, I think I'll drive some more screws in anyway.

Perhaps I should have glued the sheetrock to the studs. Hmmm, I wonder if it would help at all at this point if I were to run a bead of construction adhesive from the inside of the wall where the studs meet the sheetrock. I'd pull the sheetrock down and glue properly but I already started spackling and sanding, the job is coming out nice, I really don't want to tear anything down now.

Rick, sorry for posting such a goofy situation here, I appreciate the help. Next time I post here it will be about something cooler and more interesting, I promise.
Old 9th March 2008
  #8
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Quote:
Originally Posted by 666666 View Post
Rick, sorry for posting such a goofy situation here, I appreciate the help. Next time I post here it will be about something cooler and more interesting, I promise.
Not goofy at all....actually very interesting! I've built many a wall and they all are different. the one thing I'm having trouble is understanding what your access to the back side of the wall is. Can you get behind it to work on?
Anyway, wall resonance can be tamed....you are not on a second floor are you? Beginning to wonder if you have a wall coupling with the ceiling and a resonant floor that turns the whole thing into a giant resonator.
If you can get behind the wall, damping and stuffing should kill it. If you really think a specific stud is a "rogue" (I think it more likely that it is at the "sweet spot" of the wall structure) don't try to pull it out, try scabbing another stud or two up against it like you would for window or door opening.
Screws are your friend and they are cheap, use lots of them.
2x4's are cheap.......blocking/scabbing quick and easy (if you have access).
The caulking idea may help a little but I think adding more mass or more blocking/scabbing along with stuffing the cavity is more effective.
Insulation is cheap. Put two or three layers of R15 in so it is compressed up against the sheetrock and dampens it.
Stuff the wall with an old mattress...........just kidding, it will solve your problem but has other safety/health issues.
What is the center spacing of your studs?


Just some random thoughts.

A little off topic but I recently installed a sliding glass door into an iso booth at the studio and it sang like a soprano. Bought some cheap carpet and glued some panels of it to the top and bottom of the glass, inside and out and now it's very quiet. Any port in a storm.
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