I have this seasonal home that was built in the 1940’s. The upstairs floor joists are spaced about 21″ on center and are exactly 2″ x 6″ x 13’8″. The floor is supported in the corners (no other support posts along span). Width of room is approximately 14′ (don’t have exact measurement). There is no sub-flooring. Planks are nailed directly to the joists. The floor has a noticeable spring to it. There are no cracks or other defects that can be seen. The house has been in the family since it was built and from what I can remember the bounce has not being getting worse. My question is what can be done to eliminate the bouce? In the next several years I plan to have some major renovation work but until then I am looking for a stop gap. Will sistering similarly sized joists work?
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Questions similar to this are asked quite a lot. If you use the search feature at top or bottom of the list of discussions and put in a key word like "sistering" you can get a list of previous discussions about this. The usual argument seems to be that sistering like-sized joists has a minimal effect. Some recommend putting new joist between old ones, others say to use blocking, others talk about strongbacks and so forth. Many will tell you the real solution is to put a beam and posts under the center of the floor if possible. Anyway, if you look at past discussions, it'll start you out. Probably others will answer you directly too. Welcome, and good luck!
Thanks Danno. I'll look into it.
Danno makes some excellent points.
What sort of access do you have to the floor joists?
If they are open, how "open" are they (open everywhere but the kitchen & bathroom can sometimes not be open "enough")?
While we're cogitating on this, what sort of "stuff" is is in the existing joist bays? It will not help if there's half a house's plumbing or hvac work to move to get a stiffer floor in.
Now, looking here: http://www.southernpine.com/pdf/table01.pdf, just to pick a span table, doubling your 2x6 (so you have about 10-11" O.C.) is still "short" of your 14' span, and that's at a relatively light 30# live load. That suggests (to me) that you may need a bit of engineering. It's that, or lose a couple or three inches of headroom, possibly.
The house is rustic (read as uncovered walls) and access is clean. The house was built in pieces so the kitchen has no upper floor to support. It was added as separate addition years later. Also, there is minimal "stuff" in between the joists. There is some wiring but it is contained at the ends.
What do yo mean by lose a few inches of headrom? Apply a couple of layers of subflooring upsatirs or adding wider joists and lose the headroom downstairs? FYI, the joists aren't 2x6. They are literally 2" thick and 6" wide. They are rough sawn so I guess he may have cut them himself.
You didn't ask this of me, but I think you'd be ahead to add deeper joists (whatever the span table says--2x8 or 2x10) rather than add more weight by adding more layers to the second floor. Just "gut level" feeling says that whatever stiffness you might gain by adding layers, you will lose because of the additional weight. If you won't be bumping your head, I would think adding deeper joists between, or sistering deeper joists would be good--but you will have to notch the ends of deeper joists to fit between the existing floor and the top of the wall and I'm not an engineer, but others may be able to tell you if that could be a problem. You are allowed to notch to a certain depth by code and I'm not certain what it is at the moment.
lose a few inches of headrom
Well, if the answer is to add 14' 2x10 and sister them to the existing joists, then you'd have a 1.5 wide by 9.25 tall (not entirely "pretty") structural member fastened to the side of your existing 2 wide by 6 tall hewn joists. Since the floor is fixed, the difference in height, 3.25" in this example sticks "down" into the headroom below.
If the joists are 144" (12') above the floor, not a big deal; if they were 92, 93" up, though, could be an issue. (And that before havign to notch them to sit on the existing top plate.)
Adding flooring above is not likely to take the bounce out, you'd need some sort of stressed skin on both sides to do something like that. Which would also necessitate an answer I was trying to avoid for you--pulling up all of the existing upstairs floor.Occupational hazard of my occupation not being around (sorry Bubba)
clout-
That subject has been addressed here on Breaktime a number of different times in the past.
In the event you fail to receive the information you desire, you might find it in the archives.
If you scroll down in the lower left corner of your screen there is a search function that will take you to previous threads dealing with whatever you type in the search bar.
If you type in 'bouncy floor' or other keywords of the subject matter you'll get a supply of data from those old threads.
Cheers
oughta be 2 x 10s at 16" oc. Might get by with sistering 2x8s to what you have, but better try to find room for 2 x 10 sisters
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Where are you located? I have worked on three rustic cabins in Michiana Shores, Indiana. New wood will never look good if you want to keep the rustic look. I used rough sawn cedar for repairs and it looked OK. I would leave the bounce. Around here we call that character. Like squeaky floors and stairs. If you have headroom and really don't like the bounce you could put a timber beam under at midspan.
Exposed rafters, joists, studs like a timber frame?
Located in Southern NH. That was one of my concerns--having the wood contrast so much.
A beam is a possibility. Thanks.
You can see one of the ones I worked on. Go to http://www.seemichiana.com. click properties, click michiana log cabin, click view details. let me know if it resembles yours.
Yeah, it is quite similar although mine is a cedar-sided house. Central air?? What, open all the windows?? :)
Here is mine.
http://members.cox.net/cathyabb/index.htm