I just built a house and I am noticing quite a spring in the floor system. I used Doug-Fir 2×10’s 16oc spanning 14 feet. The subfloor is 3/4 T&G OSB glued and nailed. I’ve found that even when someone as small as 100 lbs walks across the floor the bounce can be felt. I did not use bridging because I was told by a rep at the lumber yard that if I glued my OSB, bridging was not necessary. Any ideas? If I do need the bridging, what is the best type and installation method now that my house is occupied. My basement is not finished and I do have access to the floor.
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is it the first floor with a crawl space below? can you install a mid span beam? I have always installed solid blocking on floors every six feet. and squash blocks at all bearing points. hope this helps, good luck
Brett,
bridging, bridging, bridging. That said, I use a product called IBS2000. These are pre-made x braces sized for almost all layouts. They run about $ 7.50-8.00 each but they extend the span ratings and they really tighen things up. Follow the manf.'s recos.
http://www.luxorcorp.com
Curly
Restoring the past for the future.
Springy floors has been addressed several times in the past. Unfortunately the "search" feature seems only capable of finding an article about installing copper pipe... Some solutions proposed included adding plywood sheeting on the bottom of the beams to form a box beam of the entire floor, sistering additional boards to the joists, add a 2x4 along the bottom of the 2x10s with glue and screws (would increase the depth of the joists, however), and as mentioned above, extra beams or bridging. Of course, you could get really creative and you could also attach steel angles to the joists or epoxy some fiberglass to their under side...
Yeah, you are right about that search function. It sucks.
http://forums.taunton.com/tp-breaktime/messages?msg=36957.1.
Excellence is its own reward!
First of all your plans should have called for bridging mid span wether it was solid blocking (2x10's) or (5/4x3) cross briding not your lumber rep and how did it pass inspection?
All you need to do now is put solid 2x10 blocking at 7' since you said it is only a 14' span.
Joe Carola
Your joists are pretty much maxed out, but not grossly overspanned. You stand a good chance of stiffening them up some.
My first thought is to ask what the joists bear on? I assume they bear on the foundation at the exterior, but what about in the center of the house? What sort of beam do you have, and what post spacing? An underdesigned supprt beam can contribute to floor vibration.
The next suggestion I would offer is to add a couple of rows of 2X strapping near the mid span of the joists. It's cheap and easy, and might make a difference.
Next would be to add some bridging or solid blocking. Make sure it's glued well so it doesn't squeak.
Q: What's the difference between Mr. Potato Head and Michael Jackson?A: Michael Jackson has had more noses.
Edited 11/27/2003 7:11:49 AM ET by Boss Hog
thats what I thought to! so the only fix would be a mid span support, I dont think blocking will be the fix in this situation
What part do you agree with?
The part about the joists, or Michael Jackson's nose?Save water. Shower with a friend.
My joists span from foundation wall to a steel beam on columns. I may try the 2x strapping. I've done this type of fix before and it's cheap and easy.
What size beam, and what post spacing?I'm going to start a museum where all the work has been done by children. I'll put all the paintings up on refrigerators.
i'm pretty sure that FHB, or maybe TOH?, had an extensive article on solving this problem just in the last year or so. try searching their recent archives.
m
I have old 2x10's spanning 15' with two rows of blocking at 5' intervals. This floor is absolutely rock solid.
-- J.S.
Let me guess ... the lumber yard rep had a pimply face and a student bus pass right.Please due go back to this yard and make a formal complaint.Any truely experienced professional in the trade would have had many applications for your floor system.Glueing your floor ply would certainly not give reason to abort the use of cross bridging.So again please make the complaint .
cleric.... the bridging , or lack of it.. is not the problem.. the span for that lumber and species is the problem... if the subfloor is nailed and glued, soild bridging is NOT going to make much of an improvement...
so.. going back to berate the lumberyard clerk is not going to serve any prurposeMike Smith Rhode Island : Design / Build / Repair / Restore
Ok, this is going to seem like a really bumb question, but...
(and it should be obvious that the definition of a "bouncy floor" is subjective - one person will say it's bouncy if another person walks by and they feel themselves moving up and down, another person will say it's bouncy if the floor feels like anything other than a 12" concrete pad over granite)
...what, exactly is the harm of a floor that isn't rock hard? I mean, I know it's sort of a badge of honor, but 999 times out of 1000 it's in no danger of collapsing - ever.
I don't mean to deny that tight floors CAN be one, among many, signs of good craftsmanship. It's just that of the hundreds of houses I've been in, and the many characteristics each house has had, I've never been struck by the tightness of the floor one way or another. There are just too many other things to appreciate or be critical of, IMO that affect everyday life and/or aestetic values more than this topic, yet this is a topic that gets discussed here fairly often.
Just curious.
...what, exactly is the harm of a floor that isn't rock hard?
You can't tile it..... the tile will crack at the the grout lines or throught the tile...
It will squeak (a lot) later
, but 999 times out of 1000 it's in no danger of collapsing - ever.
maybe...
in a new floor install it probably won't fail.....
in an old floor install..... hmmm, dryrot comes to mind..
just a thought
christmas is coming..... should I buy the wife that new tablesaw ....hmmmm
Another "problem" is when you have china cabinet and as you walk by all of the china rattles.
If you look at Boss's posts, probably within this thread, he links to some articles on floor bounce and one of them list the range of motion that people complain about as a "bouncy" floor.
Yes, the gist of it is that a floor that vibrates at a low frequency makes people uncomfortable. Stiffen it up to get a higher frequency and it's OK to let it move a little.
-- J.S.
Thanks for responding (and not saying it was a dumb question).
I know about tile problems over wood, but I'll bet at least 95% of floors over wood are not tiled.
Hearing the china tinkle a little doesn't seem like a big deal to me. I used to play a lot of LP records and the skip would be very annoying I'll admit, but those days are long gone.
The issue of perspective is what interests me. I'll grant you that anyone who builds for a living is going to notice any less-than-ideal characteristics in any building - including the level of deflection in any floor. But most people don't build for a living and I can't recall a single instance where anyone outside construction commented at all on the stiffness of a floor unless it was truly in danger of collapsing underfoot. And this includes people who it might be said had better than average taste or perceptiveness.
No disrespect to Boss or anyone else, but any reading on the subject written by or sponsored by the truss industry would be suspect, IMO.
I'm not suggesting anyone ignore span charts or anything like that. But when I hear someone suggest (as I did on another thread) that deflection levels really should be 2-3 times less than span charts allow for, I have to wonder why they don't just pour giant concrete slabs.
nanny... when floor trusses first came into use.. i remember lots of non-trades people commenting on the "trapeze" effect of the floors..
i think what was happening then was they were specing trusses that were fine as far as load ability, but the deflection was enough to give people motion sickness..
most of the ( hell, make that ALL) truss and i-joist mfrs now spec stiffer systems and people pay more attention to the deflection ratings ( 1/280, 1/360.. etc )
floor stiffness is often a mentionable "selling Point " with realtors.. particularly when the one across the street is a trapeze..Mike Smith Rhode Island : Design / Build / Repair / Restore
"when floor trusses first came into use..."
Maybe the problem had a lot to do with folks using the new product to stretch the practical span limits. I rarely come across instances of more than 20' of span, and in any case, the question here was about a 14' span with conventional lumber that falls well within standard limts. I've never seen a span chart that allowed anything more than 1/280 and I would stick to nothing more than 360, but then I read comments from others that scoff at such lax standards.
I've never felt a "trampoline" effect, but I'll take your word for it. Just seems odd to me that I've never felt it either on floors that were either likely underbuild or likely overbuilt.
"No disrespect to Boss or anyone else, but any reading on the subject written by or sponsored by the truss industry would be suspect, IMO."
What kind of stupid comment is that? If you would actually READ the info I've posted, it applies to wood webbed floor trusses, I-joists, conventional joists, and the beams that support them. Not just trusses.
It's not like my suggestions were something that would make the industry as a whole more money. My advice was actually in the vast majority of cases to NOT decrease spacing, but to INCREASE it. That would basically result in selling less pieces, and theoretically making less money as a result.
The research documents I referenced were done at a university anyway - NOT by anyone in the truss industry.
Remember that the vast majority of people don't share your low standards, and WANT floors with a good "feel".It's as bad as you think, and they are out to get you.
Hi again,
It is a little hard to interpret some of your comments because there is a difference between vibration and deflection but you seem to be using the terms interchangeably.
All of us find our decision making processes based on prior experiences and presumptions or assumptions. Your experiences are quite limited if you have never known anyone to have a problem with either bouncy or sagging floors.
I work on plenty of houses over a centruy old, built more by rules of theumb and economy than on span charts and engineering. Most of them have experienced sags in the floor center from over spanned framing. Some have vibration and some don't.
When i go to remodel an area of the house, one of the things highest on the list of "We wants" is to fix the floor so it is straight and solid. I think owners don't point out the problems of their homes to visitors and that most visitors would be too polite to point out flaws in your house to you, so that could explain why you have never heard of such a complaint. But it does get under people's skins enough to want to correct the problem.
It is also unsafe in some situations, to have too much deflection. Bookcases falling over when the kids are rough-housing is one example that comes to mind. 'Course, it's easier to mop up the spilled blood when it all puddles in the center of the room..
Excellence is its own reward!
Boss and Piffin are correct (as usual). I live in a 100-year old house, and while the floors are not going anywhere, or even deflecting noticeably, I cringe when anyone walks near the sideboard and the china starts rattling. I have experienced this in new homes, 70's homes and office spaces. It is one of the many subtle differences between Fine Homebuilding and Adequate Homebuilding....that's not a mistake, it's rustic
Hi again.
"there is a difference between vibration and deflection but you seem to be using the terms interchangeably. "
Granted, and I understand that there must be a difference, but I'm a little puzzled by the vibration part. I've been on plenty of floors that flexed noticably due to deflection (and that seems to be the factor that created this thread) but I can't say that I have felt any other phenomenon in relation to floors. Maybe that's because I don't have occasion to be on many floors with exceptionally long spans. Maybe that's because I'm just not sensitive enough to it - but if a person not looking for it doesn't sense it, is it a problem? (if a tree falls in the woods...) Added to my experience is that I've never witnessed anyone else complaining of a "trampoline effect". This does NOT mean it doesn't exist in my mind, it simply means I suspect it may be more rare and/or less noticable than other posts suggest.
"...if you have never known anyone to have a problem with either bouncy or sagging floors."
Your wording here suggests that "bouncy" has to do with "vibration" and "sagging" has to do with "deflection". If so, then that's different than my interpretation. To me a sagging floor is one which cannot hold true under its own weight while a bouncy floor is one which deflects under the relatively small added weight of a person moving across it - and then bounces back. It seems to me both issues are about deflection, simply to different degrees. The "trampoline effect" would seem to suggest one of two things; either you actually experience an upward thrust, as you do on a trampoline, (I've never felt that) or you experience a brief, rapid up and down sensation like the vibration of a guitar string (I may have felt that to a small degree - certainly not enough to consider distressing).
But again, that doesn't mean I'm denying it exists. Is it possible that the vibration may be noticable mostly only during construction, before carpets, rugs, furniture and other deadening factors are in place?
I've already made clear I'm a fan of sticking to standard span charts at minimum. But whenever this subject comes up (not just on this thread) there is this undertone that I detect that goes something like this: If a sturdy floor is a sign of good craftsmanship, then a "studier" floor is a sign of better craftsmanship and and even sturdier floor is a sign of even better craftsmanship, and so on, and so on. In my opinion, there has to be some point along that line where it just becomes a waste of good wood.
Given the thread parent's information in the opening post, I would guess he's more sensitive to movement than most people. It also seems to me the blocking solution several others suggested should improve things quite a bit. For the average person, under average circumstances, I don't think the floor he described was fundamentally underbuilt, though others seemed to suggest it was.
Have a good holiday!
Blocking, bridging, strapping or midspan beams will help.
Strapping is easiest and least expensive and as effective as blocking.
Beams do the best, but are more expensive in terms of both cost and space taken.
Blocking or bridging uses least space and can often be done with scrap but it most expensive in terms of labor and sometimes conflicts with utilities.
Multitude of solutuions, some better for one job and some for another..
Excellence is its own reward!
Hey Piffin.
You said that blocking and strapping are equally effective in improving a floor system.
While I don't know, never having worked on two identical floors, one with blocking and one with strapping, and not being trained to do the engineering math, it seems to me that a 2x block, with a good friction fit and 3 or 4 nails per joist, will couple the forces from one joist to another better than a 1x3-4 nailed across the bottom.
I am open to convincing otherwise if you have the time to explain it to me.
Thanks,
SamT
sam... you assume one row of blocking , right ?.. or maybe two rows ?..
but strapping is typically 16" OC.. that's why it's just as effective , or even more so that blocking or bridging..
it's also why we don't use blocking or bridging.. since we strap all our ceilingsMike Smith Rhode Island : Design / Build / Repair / Restore
OK, You win the speed typing award.
;).
Excellence is its own reward!
I'm not getting why 14' is to long of a span for 2x10's 16" o.c. I've framed alot of houses and additions over the past 20 years and we've always maxed 2x10's out at 16' sometimes doubling up every other one or going 12" o.c where there's tile above and always using 5/4x3 cross bridging mid span. Anything over 16' we use 2x12's and anything over 8' we put cross bridging.
No one uses strapping around here and we never have problems with beams twisting and sheetrock popping.
Joe Carola
Edited 12/4/2003 4:33:06 PM ET by Framer
Generally, when you do blocking, you aim to split the spans roughly in half to about 6-8', and place a single line of blocking in that position. With a strapping method, you place the strapping at 16"oc so you have much more than a sigle attachment point and the entire frame system works as a sandwhich, almost as though there is another sheet of plywood fixed to the bottom of the joists, but open enough to allow access for utilities. You are right that if one relied on a single run of strapping the strength would devolve soley from the shear strength of the few nails holding it up.
Sorry not to be more explicit, I should have anticipated this misunderstanding knowing that strapping is not practiced throughout the land..
Excellence is its own reward!
hah... yur slowing down pard !Mike Smith Rhode Island : Design / Build / Repair / Restore
This is getting weird - now I'm responding to anticipated thoughts you haven't posted yet and still can't get ahead of you.
Excellence is its own reward!
"...blocking and strapping are equally effective in improving a floor system...."
Might as well throw another opinion in the pot here.
It seem to me that they do 2 different things.
Bridging transfers some impact load from one floor member to the adjecent ones.
Strapping keeps the bottom of the floor member from flexing sideways, creating "Torsional vibration".
Seems to me they both solve different problems. But the problems also frequently overlap. So it's almost impossible to figure out which one will help in any given situation. But either one would probaby help some regardless of what the problem is.
The whole floor vibration thing needs more R&D done on it. I figure it will be 10 years or better before we see specific guidelines on floor vibration performance written into building codes.A man on a date wonders if he'll get lucky. The woman already knows. [Monica Piper]
PiffinMike Smith
Thanks Mike, forget Piffin, he's just too slow. (I think it's age related. shhh, don't wake him.)
Ok I can see where the worst case of blocking (8'OC) is about the same as strapping.
But, I gotta go with the Boss on this one, there is a whole lot that blocking addresses that strapping doesn't.
If the floor design is so poor that blocking @ 8'OC doesn't fix it, but 4'OC might, strapping will never be enough.
Blocking is much more effective against rolling.
Blocking helps against cupping.
Blocking is usually of the same material as the rim joists which keeps seasonal dimensioning the same across the depth of the floor. Oh sh!t, now I gotta worry about the expansion effects of the floor sheathing!!!
On the other hand, strapping can be done after the floor is sheathed and you've received the phase payment, whereas blocking must be done as the joists are laid.
Reminds me of when I worked on the Ventura, CA based Broken Arrow/Patagonia factory.
The second floor framing, 2 ?/? X 21" glulams, were to be the 1st floor ceiling. 30' span. The GC wanted to get paid for sheathing the second floor fast so he blocked (2 rows) after the floor was skinned. All the joists had rolled, some as much as 1 1/8". No way to roll 'em back, every block had to be hand cut to fit. Wasted all the precut blocks, about 160 linear feet. Pennywise, pound foolish cheapskate.
SamT
i don't know , sam.. obviously you've installed bridging on your share of floors...
i've done a fair amount ,too... 1x4 X-brace, 2 8d nails top & bottom, solid blocking offset, metal x-brace bridging...
it never showed me much .. the solid blocking was cool , if it also fell out on plywood end joints..
but, given the choice.. i'll take strapping any day... and we don't have much problem with rolling joists.. until you get up to 2x12's... but they're going to get strapped too ....Mike Smith Rhode Island : Design / Build / Repair / Restore
> All the joists had rolled, some as much as 1 1/8". No way to roll 'em back, every block had to be hand cut to fit.
I've had pretty good luck using a little 2 ton bottle jack to take the twist out of existing joists and make the blocks fit snug. It is time consuming, though, as is carefully custom fitting each block.
-- J.S.
Bar clamps work too.
Excellence is its own reward!
My sister used to work in an office building that had very long spans, and a very low frequency floor vibration when anybody walked around. A lot of people found that very annoying, including some of the upper management types. When they did a merger and needed to rearrange things, that location was the first thing they dumped.
-- J.S.