# Help! Sagging Floor Joists-Second Story>>>Undersized!!!



## TazinCR (Jun 23, 2008)

Post some pictures if you can. Sistering 2x6 will do much more good than a 2x4.


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## Ron6519 (Mar 28, 2007)

Beams that old will not jack up and stay in place with a doug fir 2x6 sistered to it. I doubt it would stay up with an lvl 2x6. Those spans would require a minimum of 2x8(14' span) and 2x10(16' span). Unless you're going to remove all the second story floors and install lvl's next to the original beams, you're wasting your time.
Ron


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## II Weeks (Jan 6, 2009)

+1 what Ron said



> adding a header in the middle of the rooms is not an option!!


then your going to have to live with it or wait for someone to fall through the floor. If you want it done right, its going to be a monster job.

You could put in flush headers and then sister up the joists with 2X8 . . .


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## Maintenance 6 (Feb 26, 2008)

Can you afford to lose some ceiling height on the first floor? If so, then sister 2x10s to the existing joists. That will stiffen them, and will give you a flat surface for your new 1st floor ceiling.


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## red86yota (Nov 26, 2008)

our 1920's bungalow had just about the exact same condition. 2x6's 16" O.C. I don't think the upstairs was ever meant to be more than an attic, but the previous owner finished it off. we're adding a big dormer to the back, so i had to rip up all the flooring, put in 2x8's 12" O.C., and build a beam to span over the downstairs bathroom.

unfortunately, i agree with ron's comment. the only way you're going to get a proper level, flat, supporting floor is to replace with the correct sized joists.

see my post in project showcase...'dormer on a bungalow'


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## Scuba_Dave (Jan 16, 2009)

As Ron6519 said:
A 2x8 is the min for a 14' span, 2x10 for 16'

For LVL's I needed 11 7/8" to span 13', supoporting a wall above roof
Are the span distance measured from inside wall to inside wall?
Not that it will really make much difference


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## Termite (Apr 13, 2008)

You won't remove the sag on the existing joists, at least to any great degree. If the floor is bouncy, sistering some new 2x6's would help stiffen the floor somewhat. Sistering 2x10's would be even better, although it would cost you some ceiling height.

If you choose to sister the joists, use lots of construction adhesive and lots of nails.

A header really is your best bet. Headers don't have to be downset below the joists. An upset header (using a steel beam) might be able to be sized shallow enough that it wouldn't be much lower than the ceiling, if any. Might be worth hiring an engineer to come out and advise on the situation.


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## Danton84 (Jan 29, 2009)

Thanks everyone for the quick replys. A few of you mention sistering 2x10s or 2x8s to the existing joists. I can afford to lose some ceiling space since they are 9 foot. My question is how am I going to get a 2x10 or a 2x8 for that matter to sit on top of my supporting walls??...or do they need to run the full length?


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## Scuba_Dave (Jan 16, 2009)

You would probably need to notch them
There are restrictions on how much you can notch - 2.31" for a 2x10
To fit in with a 2x6 you would need to notch 3.75"
Possibly also put joist hangers on each side?
I would also use the same size in each room as that way the new ceilings will be at the same height


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## jogr (Jul 24, 2007)

Danton84 said:


> ...... farmhouse built in 1919..... I know its an old house and I can live with the sag, I just don't want it progressing. The floors do not squeek or make any noise when walking upstairs and they seam very solid. What I want to know is what I should do to reinforce the joists so that they do not get any worse?


I'll be the contrarian here. As you stated you can live with the sag (old farmhouses should have some character shouldn't they?). The floors seem very solid and don't squeek. So why mess with it? It took them 90 years to sag as much as they have so far. If the floor feels solid there's no reason to think it's going to sag any faster in the next 90 years. Will you care if they've sagged twice as much in the next 90 years? LOL

Now I understand the school of thought of "do it right" and usually subscribe to it. But a 90 year old house will be a mighty big money pit if you try to totally bring it up to todays building standards (you might as well tear it down and start with a new foundation). If the floors aren't solid and/or you hate the sag then yes fix it.


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## 4just1don (Jun 13, 2008)

If he doesnt do it now,,,throws a water bed up there,,or a dozen kids on a sleep over,,who knows what happens in there then,,,cracks a couple more,,,fixing at this time will look like a calk walk.

To save what a few hundred dollars??When it is open and EASY to do?? Its obvious something has to be done,,so the dif between least and BEST option is ONLY consideration. Lumber seems to be reasonably priced these days. Taking a 9' ceiling BACK down and doing it later,,,insult to injury!!

OP---can you tell us how many of what length lumber it takes to sister up some good wood?? Figure pure lumber cost at your local dealer and see. Here any way,Menards had better lumber than a local lumber yard at 60% price. Some glue and a pneumatic nailer and your half done.

half of that conservative specs of old construction was due to single beds,one small dresser and a closet fit for 2 dresses,,,NOT waterbeds,massive heavy furniture and a dozen kids jumping up and down!! Who doesnt have more items with more weight than your great grandparents did?? times change,yes they do!!

Plus its hard to tell what those joists really are,,,,lots of houses in the country around HERE made with cottonwood lumber too.(NOT good stuff either) There are lots of substandard ramshackle houses of old as well as some VERY good quality. I know of a few that dont have over 4' length of lumber in them!! New Orleans shotgun houses were made of salvaged river barges,back then!!

I vote,,,if you couldnt tell,,,fix it RIGHT,,,NOW!!!


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## SNC (Dec 5, 2008)

II Weeks said:


> +1 what Ron said
> 
> 
> 
> ...


If it was built in 1919 i should be ballon frame, if there are no or few walls upstairs tearing up the floor is not that bad.


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## jogr (Jul 24, 2007)

Leveling that floor will not be "easy" which is why you shouldn't do it if you are ok with it the way it is and if it is solid which you say it is. 

If you want to level the floor you will need to tear up the floor boards because as someone else mentioned if you try to jack up the old joists and hold them level with sistered new lumber the new sistered joists will not win in a battle with the old joist. Instead you'll need to leave the old joists as they are and apply 2x10 sisters so that they provide a level surface above and below the old joists (hence the need to remove the old flooring).

Leveling the floor will be a lot more work than it sounds but if you want a level floor then it is worth it. If you are ok with the current floor then don't worry about it, you've given us no information that would suggest that it's going to fall in.


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## Danton84 (Jan 29, 2009)

jogr said:


> Leveling that floor will not be "easy" which is why you shouldn't do it if you are ok with it the way it is and if it is solid which you say it is.
> 
> If you want to level the floor you will need to tear up the floor boards because as someone else mentioned if you try to jack up the old joists and hold them level with sistered new lumber the new sistered joists will not win in a battle with the old joist. Instead you'll need to leave the old joists as they are and apply 2x10 sisters so that they provide a level surface above and below the old joists (hence the need to remove the old flooring).
> 
> Leveling the floor will be a lot more work than it sounds but if you want a level floor then it is worth it. If you are ok with the current floor then don't worry about it, you've given us no information that would suggest that it's going to fall in.


If I were to remove the floor and sister in new 2x10s do they need to sit on top on the load bearing walls?...or can they just butt up against them?


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## Timberwright (Jan 24, 2009)

Danton84 said:


> I just bought my first home that is a 1 1/2 story Bungalow-style farmhouse *built in 1919*. I am in the process of remodeling and am currently redoing the ceilings in the dinning room and living room. Upon removing the old plaster and lath boards, I confirmed what I already knew from the upstairs...my upper story floor joist are sagging. The joist *are 2x6(I believe they are oak)* and span approx. 16 ft. in the living room and 14 ft. in the dinning room. Some joist have have holes drilled in them where the wiring was ran and there are a couple that are cracked a little.


Something that people are not taking into consideration is the fact that these joists are oak (_if in fact they are_) and they are probably true 2" x 6". It that is the case this would change the load carrying capacity of these joists.


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## BJLower (Aug 2, 2008)

*Sagg strength from an old posting I remember*

An architect answered a posting a while back on someone asking if the could strengthen their floor joists by running particle board down each side of the joists under his floor.


The architect said the he couldn't use particle board because it's glued together and doesn't have a single direction that the grain runs in. He gave the formula that architects use for the “anti-sag” calculations.


The formula I remember to be something like the wider board minus the thinner board to the third power, but I know that isn't the correct one. I calculated the difference between a 2x4 and a 2x6 when I saw the calculation and it ended up 9.?? close to 10 times the “anti-sag”. The architect had a times something which equaled E (which was the “anti-sag”). The difference between what I recall was a 2x10 and a 2x12 was as I recall 177% increase. The increase between a 2x4 and a 2x6 was a much greater value that the difference between a 2x10 and a 2x12. I searched for the posting, but couldn't find it. 


The architect told him that running a 1 bye of real wood because of the grain down each side would give him the additional strength he was looking for.


The guy that made the posting did not have a sagging floor he wanted to prevent it.


The architect told him for the maximum strength to glue the sisters and put a lot of nails in to hold the sisters good an tight while the glue sets.


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## Tonglebeak (Dec 28, 2009)

Timberwright said:


> Danton84 said:
> 
> 
> > I just bought my first home that is a 1 1/2 story Bungalow-style farmhouse *built in 1919*. I am in the process of remodeling and am currently redoing the ceilings in the dinning room and living room. Upon removing the old plaster and lath boards, I confirmed what I already knew from the upstairs...my upper story floor joist are sagging. The joist *are 2x6(I believe they are oak)* and span approx. 16 ft. in the living room and 14 ft. in the dinning room. Some joist have have holes drilled in them where the wiring was ran and there are a couple that are cracked a little
> ...


I really wish there was a span table for a true 2x6 made from old oak that is much harder than anything you'll ever find today.


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## brons2 (Jan 25, 2010)

that's a tough problem Danton84. Makes me glad my floor joists are 2x12 in my 1964 built house. Let us know what you decide, and take pictures of the work.


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## COLDIRON (Mar 15, 2009)

Back in 1919 2x6 is probably a true 2" x 6" and oak they probably are stronger than 2x6 of today.

So even if the floor sags a bit it don't squeak and seems strong if I was concerned about the sag and wanted a level floor I probably would level it from the upstairs.


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## stubborn1 (Oct 24, 2008)

I ran into the same situation last summer when I was remodeling our 1920s bungalow. I did a combination of all of the suggestions above. I ended up cutting in a double LVL header under my attic knee wall. Existing 2x6s supporting the attic floor behind the knee wall were sistered with 2x8s as shown. In the living area, I ripped out the sagging 2x6s and replaced with 2x8s. It's the only way I could guarantee it would come out level. See the attached photo for a general idea.

I had thought about living with the sag, but now that the project is done I'm very glad I took care of it.


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## Scuba_Dave (Jan 16, 2009)

stubborn1 said:


> I ran into the same situation last summer when I was remodeling our 1920s bungalow. I did a combination of all of the suggestions above. I ended up cutting in a double LVL header under my attic knee wall. Existing 2x6s supporting the attic floor behind the knee wall were sistered with 2x8s as shown. In the living area, I ripped out the sagging 2x6s and replaced with 2x8s. It's the only way I could guarantee it would come out level. See the attached photo for a general idea.
> 
> I had thought about living with the sag, but now that the project is done I'm very glad I took care of it.


Why did you run them the "long" way instead of the shorter distance across the room?
Or is that a multi-2x beam in the middle that the 2x8's are hanging on ?


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## Snav (Aug 20, 2009)

A note about repairing sag - any methods that involve jacking up the floor (sistering, bracing, etc etc)

If your floors have sagged for quite some time that means your flooring on top of the sag has also relaxed down into the sag (it's warped, crowed, etc, to fit the dip). For some flooring it doesn't matter (carpet, laminates for example - they are flexible)
But others that are solid or less flexible might have problems when you go to fix them:
If it's hardwood - the slats have taken a new shape they might not "relax" when you fix the floor.
Any repair jobs that previous owners have done to the floor might be "popped" loose when you jack up the floor - you'll have to fix it.
Tilework and bricks might crack. . . etc.

In my kitchen the floor sagged considerably - we had to sister in new beams to fix it. In the process of jacking up the floor to install the new beams the sagged portion of underlayment was no longer held down with pressure like: \__/ - so nails started to pop up, they eventually popped through the flooring in the room. . . and eventually the top underlayment separated from the bottom underlayment and the floor "jumped" up - so there was a crack in the floor.

I had to remove the old flooring, level it off and readhere the underlayment (I used screws to pull the separated sheets together) and so forht - it took extra time and work but eventually I got the floor evened out. It's not perfect, you can still feel a rise where the sag use to be de to the previous owners repairing the area with too thick of underlayment - but it'll be ok until I rip it all up.

So - if you have a sag just be aware that other problems might come around after you fix it. But after the effort to fix the sag these little problems might seem like small beans.

Further note - if it sags because your beams are undersized then *yes* fix it - don't just leave it alone. A little sag due to settling is one thing but sag due to undersized beams can put too much pressure on the beams - eventually causing them to break. I've had to sister countless beams under my entire house because sag lead to breakage.

If it's lasted for 90 years, you're lucky - but I wouldn't bet on it going for another 90.


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## stubborn1 (Oct 24, 2008)

Scuba_Dave said:


> Why did you run them the "long" way instead of the shorter distance across the room?
> Or is that a multi-2x beam in the middle that the 2x8's are hanging on ?


Mainly so I could sister the 2x8s onto the existing 2x6s left behind. Also - the wall on the right wasn't originally load bearing. I had to add the doug fir 4x4 in the wall to take the load from the double LVL directly to the timber beam in my basement.


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## Gary in WA (Mar 11, 2009)

ll you need to do is ask! And some math....... Table #7, page 643: http://books.google.com/books?id=DW...m=4#v=onepage&q=drilling wood columns&f=false

Flitch plates: page 655--------------then the spans and math per inch, starting on page 717. Three kinds of oak, page 651. 

Are we having fun yet? Lets put 50 men in one room,elbow room only, to test the floor: you find it. 

Be safe, Gary


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## Snav (Aug 20, 2009)

Stubborn, That makes sense - if you ran them the other way the wall on the right with the 4x4 would then be pulling the load for the entire overhead - which would have made more load for you to direct to the basement beam.


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## Scuba_Dave (Jan 16, 2009)

stubborn1 said:


> Mainly so I could sister the 2x8s onto the existing 2x6s left behind. Also - the wall on the right wasn't originally load bearing. I had to add the doug fir 4x4 in the wall to take the load from the double LVL directly to the timber beam in my basement.


I see it now, I thought they might be LVL's in the middle
Also missed the sistered joist on the back side
If I ever rip the ceiling down in my main room I'll be sistering 2x8's to the existing 2x6's too


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## COLDIRON (Mar 15, 2009)

stubborn1 said:


> I ran into the same situation last summer when I was remodeling our 1920s bungalow. I did a combination of all of the suggestions above. I ended up cutting in a double LVL header under my attic knee wall. Existing 2x6s supporting the attic floor behind the knee wall were sistered with 2x8s as shown. In the living area, I ripped out the sagging 2x6s and replaced with 2x8s. It's the only way I could guarantee it would come out level. See the attached photo for a general idea.
> 
> I had thought about living with the sag, but now that the project is done I'm very glad I took care of it.


"NICE WORK":thumbsup::thumbsup:


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## scott j (May 4, 2009)

I have an old house also (1925 American Four Square) with 2x8 floor joists throughout. In the 2nd floor Master bedroom, the floor joists span 16 ft. and it sags in the middle. I was told by a few General Contractors that that's the way it is and it is not critical to replace since the wood used is much stronger than todays pine. I agree, when I try to nail or drill into a joist in the basement. It is very hard. 

However, I did add 2x8 blocking in the middle of each joist in the basement for the 1st floor. The blocking seemed to help with the bounce but not the sag.


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## Tonglebeak (Dec 28, 2009)

scott j said:


> I have an old house also (1925 American Four Square) with 2x8 floor joists throughout. In the 2nd floor Master bedroom, the floor joists span 16 ft. and it sags in the middle. I was told by a few General Contractors that that's the way it is and it is not critical to replace since the wood used is much stronger than todays pine. I agree, when I try to nail or drill into a joist in the basement. It is very hard.
> 
> However, I did add 2x8 blocking in the middle of each joist in the basement for the 1st floor. The blocking seemed to help with the bounce but not the sag.


I have 1907 2x6s 24-32" OC that span 14ft in one room, and 16ft in the other (they also used 2x6s for the floor joists, and amazingly they do not bounce worth a damn). The 14ft span bounces, and the 16ft doesn't. Go figure. I did find the culprit joists and need to sister them sometime (one joist is bowing from the side, the other seems to have water damage of some sort). I was also thinking of bridging the joists with solid 2x6 (although they're be smaller than the true 2x6 used back then). Glad to know that newer wood is able to help out older wood.


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## HooKooDooKu (Jan 7, 2008)

Danton84 said:


> If I were to remove the floor and sister in new 2x10s do they need to sit on top on the load bearing walls?...or can they just butt up against them?


Because the purpose of sistering a joist is to strenghten the joist (i.e. make it harder to deflect under weight), you do not have to have the new joist sitting on top of the wall. And since it's all about strenghtening the existing joist, notching rules do not apply. That would only be the case if you were replacing the joists. 

If you do notch the joists, then you have to account for the sag. If you notch the ends such that the ends are exactly the same 6" height of the original joists, the center of the new strait joists will ride above the existing sagging joist.


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## HooKooDooKu (Jan 7, 2008)

One other thought. Keep in mind that by sistering the existing joists, you are adding dead weight to the existing structure. If your walls were sized marginally as well, you might have to look into sistering the wall studs as well.


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