Need help taking the bounce out of my BCI floor system. What can I do to the existing in place joists to lessen the vibration ? Need to get from a 3 star feel to a four star feel. Can not add a beam under to cut the span. 2 x or plywood sister, 2 x on bottom cord, bridging, blocking ? Anything worked for someone else ?
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How about some details? Like the depth of the joists, spacing, clear span, what they're sitting on (beams or walls), and anything else you can think of.
There have been a couple of threads here about reducing vibration in floors, but I can't come up with one using the search function. Maybe someone else here will have better luck?
There's a thread on Floor Vibration which may help you understand what's happening.
In the beginning of a change the patriot is a scarce man, and brave, and hated and scorned. When his cause succeeds, the timid join him, for then it costs nothing to be a patriot. [Mark Twain]
More info:
11 7/8" BCI 600s @ 16" o.c.
20' 4 1/2" span between 2 x 4 walls
3/4 T&G fir Sturdi Floor sheathing glued & screwed
The floor is in, the problem is there, I'm looking for a "real world" fix
Spanning 20'+ with 11 7/8" I-joists is your basic problem. The joists simply shouldn't span that far, regardless of what the span charts say.
I've seen a lot of possible solutions proposed here. I can't personally say that any of them will work.
Adding another bearing is the most definite solution. Nothing else you do to them will ever make then as solid as a floor should be, IMHO.
Adding some sort of strapping on the bottom of the I-joists is fairly simple, and might make some difference. But no guarantees.
The other suggestions I've seen posted here involve adding plywood to the bottom or sides of the I-joists. Nothing I've seen has convinced me that any of those ideas have any merit.
Sorry - Wish I had better news for you.If all the nations in the world are in debt, where did all the money go?
Boss, a question for you. Would 1/2" ply 11 7/8" wide by 8' long, nailed to the top and bottom cords of each joist thus boxing it in,for say 16 feet,greatly stiffen the floor? Not suggesting, just asking. PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home
I've heard a lot of suggestions over the years about adding plywood or 2X lumber on the bottom or sides of joists to stiffen them up. But I've never seen any research that convinces me that it will work. And I've never seen for myself a job where it's been tried.
Since I won't recommend anything I'm not pretty sure of, I won't suggest it.My reaction to intelligence is the same as my reaction to pornography. I can't define it, but I like it when I see it.
Adding another bearing beam to split the span will be the most effective solution. Realize you don't have to split the span into two 10' spans...you could offset the beam to a 16' span and a 4' span. If done properly, it will improve the performance some, but again, nothing is guaranteed in a retrofit. And yes, I know you wrote that another beam was out of the question.
More wood may not neccessarily help, in terms of sistering to the existing joist. While it may improve things a bit, increasing depth of the joists is more effective than reducing the effective OC spacing.
Easiest is to strap the bottoms of the joists. The longer the lumber the better, glued and screwed to the bottom flange. It will help with the reverberation of the existing platform.
Less easier is to sheet the bottoms of the joists, with the ply glued and screwed. More work, and you lose immediate access to the mechanicals.
For anyone else out there, think L/480 as the absolute basic minimum for engineered joists. Think L/720 as a performance minimum for a good floor, and L/980 as a top performing floor. If on the edge of the envelope, increase the depth of the joist before you decrease the OC spacing.
Totally my opinion.
Ron
I'm spanning about 17' with 11 7/8 TJI's and feel no problem what so evers so far when I walk on it. One reason may be that I used PL Premium between the TJI's and the Advantech and blocked the joists less than 8' from wall to wall.
Feels sturdier (so far) than any floor I've ever walked on.
Even the 32' span over the garage I just framed with 16" TJI's feel sturdy (so far...lol). I swear its the PL Premium and Advantech.
Be sturdy
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
"I'm spanning about 17' with 11 7/8 TJI's and feel no problem what so evers so far when I walk on it."
That's 'cause you're a lightweight................(-:
Seriously - A 17' span is well withing the range I feel comfortable with. I wouldn't expect problems with that one.
"Even the 32' span over the garage I just framed with 16" TJI's feel sturdy (so far...lol)."
Honestly, I don't know how you got away with it. Maybe the blocking you put in helped - I just don't know. But you haven't changed my mind about what I recommend.There is an inverse relationship between reliance on the state and self-reliance. [William F. Buckley, Jr.]
Please describe your blocking at 8'.
Let me try an idea on ya..once did this on an old farmhouse..grossly undersized and spaced joists. If you screw a 2x4 flat at or near mid span perpendicular to the joists, then screw a 2x4 16' on edge 8' away to the side if yourjoist or bottom chord then bow up the other end and glue screw it as well you have a sort of "bow string truss"..it worked wonders for a place that was like a tambourine. the flat 2x4 MAY have to be a rip @ say 2" or more if the 1 1/2 thickness does not give enough ummphh factor in bending the 16 ftr.IT should not be a one hand bend in the 16, but require a fair amount of force to flex it up. If you are in a low crawl space on your back good luck, I was able to jack mine up far enough to get decent pattern of gunnails in the connection.
Without using another beam to split the span, your best choice is to run strapping on the bottoms perpendiculat to direction of the I-Joists on 16" centers.
This makes the floor system a sandwhich. It is more effective than blocking, I swear. It is the recomendation from some of the manufacturers also.
I agreee with Boss on this. 20' is a long span for these babies. If I had to deal with that minimal elevation, I would have gone 12" oc and used strapping below.
BTW, a beam under to split span is not always the answer either. I have one where a beam was used but it lets the floor ripple over it with kind of a teeter-totter action
Excellence is its own reward!
I had a conversation with a structural engineer about this. He suggested a plywood sandwich glued and nailed to the top and bottom chord as Paul Hayden suggested. Also you could install bridge blocking mid span. I think BCI makes a pre fab bridge block. A layer of gypcrete on top for a radiant floor could also help stiffin it up.
Are you sure about the orientation? Paul H has described a vertiucal sandwhich of each individual joist. The I joist companies describe sandwhiching the entire floor system by the top slice of bread at the subfloor and the bottom being either strapping or ceiling plywood on the bottom, both in horizontal oreintation.
Haydens thought will slightly stiffen each individual joist while adding weight to them, conteracting some of the gain. The horizontal sandwhich doubles the diaphragm resistence and makes the whole floor system act more as one instead of a group of individual members.
To substantially add strength to the designed and engineered I-Joists, the plywood laminated into each would need to reach from one end to the other. In most floors the eight foot lengths would break the integrity of that design, IMO
I am sticking with the strapping because the recommendation comes from the company, it is the easiest and cheapest solution, and because I know from experience that it works.
Excellence is its own reward!
" The I joist companies describe sandwhiching the entire floor system by the top slice of bread at the subfloor and the bottom being either strapping or ceiling plywood on the bottom, both in horizontal oreintation. "
Just curious where you've seen this recommended. I've never seen this from an I-joist manufacturer.
"I am sticking with the strapping because the recommendation comes from the company..."
Again, I haven't see this from an I-joist manufacturer, and am curious where you got it from.Funny that government can never afford to cut taxes or reduce spending, but taxpayers are never asked whether they can afford higher taxes. [Cal Thomas]
Somebody else here posted a link to a study they recieved from a manufacturer a couple of years ago. I read it, but didn't keep it because it simply agreed wioth my experience and substantiated what I already knew. I didn't need convincing. Since then, I have seen this same discussion here every couple of months and made basicly the same comment..
Excellence is its own reward!
Piff & Boss,
I've posted this several times. On a new computer so I don;t have all my bookmarks. HTML version is on TJIs site, this is a PDF version.
Direct from TJI, for strapping recommendations see page 8, the bullet just below Figure 22.
http://www.ki-lumber.com/engineered/TJI/2065.pdf
OK, I have saved that this time - remember seeing it before relative to squeeks or repairs but not the one I'm thinking of that I first saw here. It was more one of those dry textual reports and the I-joist companies had refered people to it..
Excellence is its own reward!
Mongo
I just bookmarked that as well.
Same joists I'm using now. First time for me and I had a lot of questions.
Tried just using common sense cause its hard to reach tech support on the phone when you need them.
For instance I wasn't sure if I should add a piece of 5/8 ply in the web area when using a teco. I did though with few screws and some PL Premium.
Another question I have is about those knock out holes. They don't seem to line up no matter which way you turn the TJI's...Whats up with that...what am I doing wrong?
Also the Advantech sucks tring to get the T&G together.
Why notr invent a steel piece with like a T&G that you can bang em together with? I've been using some left over crappy T & G wainscott planks I saved (thank god). I get through about two Advantechs before the wainscott plank become splinters.
How does anyone else deal with this issue????
Swim across? OK see ya in a few. I can walk to the sound in about ten minutes from here so add ten minutes on.
Be well
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
I don't even mess with the knockout holes. I ignore them and later drill what I want where I want it.
Never used Advantech, so I'm not sure how the T&Gs register. I'm still stuck in the land of 3/4" T&G CDX.
TJI has done a better job with on-line troubleshooting and recommendations. When I first used the product there was virtually nothing. They now recognize the limitations of the product, and the I won't say the common installation errors...more like ideas on how the product can be installed better...because who knew back then? Now they address them on-line, which is nice.
Biggest thing I can advise is any time you're going to mount something to the web of a TJI that could cause any vibration...a RFH pump, for example...do something to offset the reverberation characteristics of the TJI. Like you did, PL/screw something to it, a chunk of 2-by, something to add mass to it. Plus, it gives a little more meat to attach things to.
I was told by a TJI tech that adding too many nails to the edge like where you add the 5/8 by tecos or squash blocks makes more of a possiblity of squeeks.
Personally, squeeks never bothered me...and on TJI's I doubt that'd happen all that much anyway.
Advantech.......never thought I'd like something as much as I do that subfloor....try it. Incredable stuff especially with PL and screws...You'll never go back to cdx again....
I'm tempted to use Advantech for the wall sheathing. Kinda sucks cutting it and its real heavy but I spose thats what makes it super solid.
Cutting cdx sure feels like dem ol' daze compared to this stuff but.....time to move on.
I also think its less expense as well as better IMSHO
Also....I hadn't paid attention to those knock out holes other than just wondering what they were thinking when they put em' in.
One other thing....I have a feeling you need to put all the TJI's the same way.....letters up or down....unless I got a weird batch it seemed unless I had all the letters facing in the same direction (up or down) they didn't end up level/flush. MAybe my imagination.
We'll have to discuss this further on the next P&A HBO Special......lol...we're allowed to talk like real builders on HBO.....lol
BE well
andy
Be well
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
Totally misread a part of your post.
Saw "tecos" and read "taco", as in a water pump. I'm too used to RFH.
Apologies all around!
Andy,
I would think that using a steel tamp-in tool for seating the Advantec T&G would be likely to break it up more since the steel is harder than the wood. I just do the same I always have with the 3/4" ply - take a 3-4 foot long 2x4 from dunnage and place it along the grooved edge. I stand on it with my heels on the sheet and toes or balls on the 2x4. Then I swing a sledge hammer and the sheet slides right into where it needs to fit with 2-3 taps. Were you installing with tongue out instead of sliding tongue into the previous?
I use the knockouts for wireing. Wire doesn't need to line up.
Excellence is its own reward!
I tried the 2x method before anything else but it seemed to crush the groove a bit and made the next piece harder to slide in. I thought that possibly my shipment was hanging out in the lumber yard too long and got a bit funky.
It was incredably hard for me to even get the order. I needed almost a hundred sheets give or take ten or twenty....I over ordered just in case out of paranoia.
I figured I could use the left over somewhere at some time.
Donno, but I still think my steel T&G is a good idea.....I'm kinda stubborn as you know, but open minded.
I may just need to buy a piece of steel at my iron shop and try it just because! lol
I'll let ya know what happens.
Be well bro
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
I don't know if I mentioned it or not, but Advanteck makes 7/16" for sheathing - lighter to handle.
Excellence is its own reward!
yeh, I know. Considering it.
Ever use it?
If its as water resistant as the subloor I wonder if I really need plastic bag wrap....lol....around the house which I'm not inclined to use anyway. Something about it bothers me..Kinda like wrapping your body in a plastic bag......do you know what I mean.
Felt paper's been used for so many years and all the houses I've done demo on.....well, the felt was always in good shape no matter how old the house was.
Advantech seems to serve the same purpose IMO. Water has puddled up like a swimming pool now with all the plates around the perimeter and when it dries out days later the stuff still looks perfect.
Kinda scarey actually....What the hell is in that stuff and do I wanna wrap that around my entire house....yehhhh, probably..after all, how much time do I have left anyway?????lol
BE a wall
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
ply, osb, or advantec are all VBs to some degree, it is the joints where transmission and drafts occour.
I wouildn't think of doing a job without TP or Tyvek but I see even in Hw To videos shot out west in dry climates, that they are installing windows directly to the advantec sheathing. I cringe at that..
Excellence is its own reward!
my thoughts are to use TP not house wrap..something about house wrap bothers me...I could be wrong (its been known to happen....lol) but my gut usually is right.
I'm not concerned about air infiltratin but more about poisons getting locked into my breathing area.
Air infiltration is fine with me as long as its not blowing major breezes...I want my home insulated properly but not overly...after all some people lived in tipis........right?
Be well
Namaste'
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
Now since you asked, I googled "I-Joist + Vibration" and found a lot of stuff you would enjoy for your hobby reading.
http://www.luxorcorp.com/subpage/technical.htm
scroll down on this one to the chart and tables for vibration controled. AndyC will enjoy seeing how much better the chart shows things when glue is used in addtion to nailing. Now look at the notes under that span chart, "All spans assume the use of strapping drywall equivalent"
http://www.woodmags.com/wlb/magazine_rack/2003_summer_42/ijoist/
"Vibration
Vibration performance is one of the most complicated serviceability criterion for wood-frame floors. Often felt as bounciness, vibration is affected by construction quality and subjective opinions on acceptability.
http://www.woodmags.com/wdb/magazine_rack/2000_fall_13/tech/
"Laboratory studies showed that gluing sub-floor to joists increased composite action between the two, therefore enhancing floor serviceability. Blocking/bridging/strapping/strong-backs restrain joist torsion and increase floor stiffness." [This one is old and goes on to point out that they were just beginning to work up formulae at that time. The context points out that they say one row of bridging, blocking or strapping cannot be expected to overcome bad design, as we will agree. My recommendation is for full bottom strapping as later studies did show.
Lateral bracing, such as strapping, bridging and blocking, dampens vibration by providing transverse floor stiffness. Many I-joist manufacturers recommend specific methods of cross-bracing in their literature, rather than conventional cross bridging that may not be installed properly in the field. Gluing increases floor stiffness further by creating composite action at the intersection of subfloor and joists."
http://www.alpeng.com/pdf/dolan.pdf
This PDF report shjould be interesting to you in the way it adresses vibration. They conclude - last page - that depth to span ratios should be greater as span increases, especially once it is over 22' at which the chart shows an acceptable ratio of 15/1 compared to your 18/1, if I read it right.
http://www.sbcmag.info/past/2001/01jun_jul/serviceability.htm
" one of the most effective ways to increase damping in a typical residential floor system is to add a layer of sheet rock or other heavy stiff panel product directly to the bottom of the floor. This helps stiffen the joists and adds a component of friction shared by all joists and thus helps to increase the rate at which the floor system dissipates vibration."
Now look at this one pertaining to open web floor trusses which are subject to the same kind os stresses in the real world...
http://www.centralfairbank.ca/floors.html
"Strongback installation is recognized as the most effective bridging method for vibration reduction because it introduces a continuous stiffness in the transverse direction of a floor system."
It is this continuous nature of displacing the vibrations and inducing load sharing that the strapping does in I-Joists.
I'm sure you'll enjoy all this, but not necessarily on a friday night, right?
.
Excellence is its own reward!
Jump to the post above. Lots of references for the I-joist thingy you've got going on.
;).
Excellence is its own reward!
dude.....no one home tonight or sumpin......lol....
I do have to take photos and explain how intense a newbie TJI dude feels with this stuff......
PL Premium is most definatly the key!! No doubt
Be super solid......wahhhhhhh how come I cant do the fest this year...I needed to be goofed on for my work.......ok ok so what.
Fine.....I'll fly down to southern California and help Ram Dass out.....got a letter from his helper a bit ago
NAmaste
andyMy life is my practice!
http://CLIFFORDRENOVATIONS.COM
C'mon, swim across the sound for a bevy at my place (by August it'll be almost plenty warm), then we'll tool over to Mike's for some bocce and quahogs.
Thanks for looking up the info. I worked from 5am today until 5pm~ so I'm not much in the mood for reading tonight. But I'll check it all out.Just when you think you've won the rat race along come faster rats
Understand, Enjoy.
Excellence is its own reward!
I read through all of those that would load. But none of them really give any specific info about when and where the specific recommendations would help, and when they wouldn't. Or how MUCH any of them will help.
That's why I don't make specific recommendations about stiffening floors - There's no way to know if, when, and how much any of them will help.Microsoft's Bill Gates' $12.9 billion fortune makes him the worlds richest man, fulfilling the biblical prophecy: the geek shall inherit the earth.
I retrofitted an old floor a few years ago but the joists were 2' high with 2x4 struts. The engineer called for 3/4" ply glued and nailed each side and staggered joints. I jacked up the whole floor with a temporary girder and screw jacks before applying the plywood. It seemed to hold. The floor later had a gypcrete pour and plywood skin under a chestnut floor.
I can't say if that method would have much effect for an 11.875" I joist..
Sorry to ask a stupid question. (amature) What is PL Premium?
If I used Advantech for wall sheathing, I would treat it as a Vapor Barrier. That is, only use one VB per wall. (no plastic sheeting between studs and drywall). To do otherwise would trap moisture.You get out of life what you put into it......minus taxes.
Marv
PL Premium
Not a stupid question. Remember...
"Knowledge is good."<g>
Edited 11/25/2003 3:05:02 PM ET by Mongo
Try taking your situation to a lumber yard that has "TJ Beam" - it's a program designed to maximize the stiffness in the floor using options ( blocking, strapping, drywall etc) and let them play with the situation. It's very enlightening and will give you some options not only for your current situation but for any building that you have in the future. The TJ program has had tons of R & D.