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Old 10-16-2011, 02:22 PM   #1
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Second floor joists are horribly undersized.....options?


I live in a house that according to the city was built in 1920, however I am doing some work on it and had the walls and ceiling of the first floor stripped all the way down to the studs and the first layer of wall material was sackett board. I did some research and apparently sackett board wasn't made after the year 1916 so either they were using old inventory, or the city records are wrong.

Bottom line is that I don't know how old this house is but the second floor joists are way too small for the span that they are supporting. They are 2 X 6 rough boards (I guess they are referred to as full dimensional lumber as they are actually 2 X 6 rather than 1.5 X 5.5) and they are spaced 16 inches apart OC. They span 15 feet from wall to wall. I did some more research and I believe the minimum should have been 2 X 10's for that span but I don't know how they did things 100 years ago. 2 of them show some signs of cracking but for the most part the rest of them are fine except for a fairly pronounced bowing in the middle. The second floor is definitely very bouncy.

The contractor suggested sistering in some additional 2 X 6 boards to beef it up a bit but I am concerned that those 2 X 6's are still going to have the same problem of being undersized for that span. I have seen the process on television of using 3/4 inch plywood glued and screwed to the sides of each joist to stiffen them up and I also read about a process where a steel strap is run diagnolly down one side of the joist, crossed to the other side of the joist at its midpoint, and then run up the other side of the joist which serves to transfer the load at the center to the ends of the joist.

I am just wondering what the suggestions would be from the pros on here in terms of options. Oh and one other thing that I don't know if it is important or not is that the structure is I believe what is called a balloon framed structure whereby the wall studs span all the way from the sill to the roof line and the second floor joists are secured to the studs and to a ledger that is set in to the studs. This would be opposed to the more modern platform frame type of construction. The second photo is an image of how the second floor joists are supported to the wall studs.


IMAG0099 by jg1996business, on Flickr


IMAG0097 by jg1996business, on Flickr


Last edited by jerseyguy1996; 10-16-2011 at 02:28 PM.
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Old 10-16-2011, 04:09 PM   #2
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Second floor joists are horribly undersized.....options?


unless you plan on tearing the 2nd story off theres not much you can do other than sister to and add additional joists to the floor system, almost going 8" o.c. ive done it , its a bastard of a job but it worked, though not tile worthy

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Old 10-16-2011, 06:42 PM   #3
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Second floor joists are horribly undersized.....options?


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unless you plan on tearing the 2nd story off theres not much you can do other than sister to and add additional joists to the floor system, almost going 8" o.c. ive done it , its a bastard of a job but it worked, though not tile worthy
How would I figure out how many additional 2 X 6's to add for a 15 foot span? I have only seen sizing charts that go to 12 inches OC.
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Old 10-16-2011, 08:29 PM   #4
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Second floor joists are horribly undersized.....options?


There are a butt-load of things you can do. I guess which possibility you do depends on what you are trying to achieve.

Stiffer 2nd floor for tile?

Insulation? (I doubt that).

get rid of squeaks?

What is your budget?

Do you have time to do it?

Contractor?

Andy.
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Old 10-16-2011, 08:57 PM   #5
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Second floor joists are horribly undersized.....options?


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There are a butt-load of things you can do. I guess which possibility you do depends on what you are trying to achieve.

Stiffer 2nd floor for tile?

Insulation? (I doubt that).

get rid of squeaks?

What is your budget?

Do you have time to do it?

Contractor?

Andy.
Yes I am trying to make the second floor stiffer but more than that it is just to put in the amount of structure that should have been put in in the first place. My budget isn't huge but I know that could be a very relative term. I have the whole thing opened up right now so this may be the only opportunity to get this done. I have the contractor that is suggesting sistering every other joist with another 2 X 6.
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Old 10-16-2011, 11:53 PM   #6
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Second floor joists are horribly undersized.....options?


What you can do will be dependent on what your Local Building Depart will allow.
You could get engineering on this but I think there is a prescriptive solution to the problem. Prescriptive meaning, what your local code will allow without having to resort to outside engineering.
You could talk to your BD and see what they have to say about the situation and what they require.
HERE is a link to the New Jersey Building Code on-line.

Taking a cursory look at it, it seems that for your span you may be able to squeak by with 2 x 10s. That would stiffen things up well.
But if you intend to get permits they will want a plan of what you intend to do.

Andy.
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Old 10-17-2011, 11:40 AM   #7
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Second floor joists are horribly undersized.....options?


Jerseyguy,

I'm no engineer, my Dad was a very good one though, but have seen quite a bit of this having done construction for much of my life.

There are quite a number of things you can do but adding 2 x 6 sisters and laminated wood, similar to a header, would significantly improve your situation. You should also consider adding some cross bracing between the joists, especially at the middle. That will tie them all together in giving additional help in sharing the load.

I'm assuming you cannot add a perpendicular beam under the joists due to headroom issues?

You can read this "THIS OLD HOUSE" article on exaclty the same situation. They recommended 3/4 plywood in one suggested solution, but be sure to consider exactly what type you use, as per THIS similar thread.

Also you may be required, or at least should, add some blocking between your studs to create a fire block between the floors. A fire, God forbid, would be unobstructed otherwise.

Lastly, be sure to consult with your local codes/engineers as AndyGump stated.

Take care

Last edited by Ralph III; 10-17-2011 at 11:55 AM.
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Old 10-17-2011, 12:21 PM   #8
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Second floor joists are horribly undersized.....options?


Most likely the second floor was attic space. Can you post a picture of the outside of the home, to get a better idea of structure wise, how it looks.

Going back and looking at that, that is Balloon framing. That means that you have no choice but to get an architect or engineer to determine what is the best route. If it was me, I would consult with before mentioned, due to most contractors now days do not know how to work with Balloon framing, unless you get one, who grew up with a hammer as a rattle, due to their family has done carpentry for decades.
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Old 10-17-2011, 03:11 PM   #9
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Second floor joists are horribly undersized.....options?


you need engineering.

maybe you can sister in 2x6's.

maybe you can add wood I-beams

maybe you can cut the span in half and insert 6" steel i-beam perpendicular.

etc etc etc.

an engineer can tell you if it is currently safe (wont fall down, just deflect), unsafe (will continue to deflect and fail), or somewhere in between, and what the options are to be safe and have an acceptable amount of deflection.

that wood is considerably stronger than what you can buy today.
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Old 10-17-2011, 03:32 PM   #10
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Second floor joists are horribly undersized.....options?


I would recommend an engineer that understands the load capacity of "Light Gauge cold rolled steel studs/joists" Looking at some quick span tables for steel joists tells me that a 6" (it's actually 6" exactly) 14 GA joist set on 12" O.C. can span 15'9" with a 40# LL and 20# DL for a total loading of 60#. Should be more than acceptable for your situation. Might be cheaper than you think.
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Old 10-17-2011, 06:46 PM   #11
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Second floor joists are horribly undersized.....options?


Wow.....lots of suggestions here! I appreciate all of the advice. My father is a structural engineer so I will pass the question to him to see if he may be able to give me some insight. When you say that this wood is stronger than what you can buy now, does that suggest that this may have been sized appropriately in its time and now just due to age it is starting to have issues?
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Old 10-17-2011, 07:00 PM   #12
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Second floor joists are horribly undersized.....options?


I appreciate all that a licensed engineer can do for a home owner and or a contractor and everyone else that may be involved.
That being said, not every structural issue that comes up is in need of engineering, this job can be done using the prescriptive codes of the IRC.
Draw up a nice diagram (plan) of the existing condition then draw up a plan with a solution using anyone of the good ideas presented here.
Take it into the BD and see what they say. Most BDs are extremely helpful towards home owners, and for the most part will not steer you wrong if you are kind and courteous to them.

Andy.
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Old 10-17-2011, 09:50 PM   #13
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Second floor joists are horribly undersized.....options?


Andy, that is Balloon framing, which means they are going to need a engineer or architect to draw up the plans in the correct way to fix.
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Old 10-17-2011, 11:48 PM   #14
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Second floor joists are horribly undersized.....options?


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Andy, that is Balloon framing, which means they are going to need a engineer or architect to draw up the plans in the correct way to fix.
Not necessarily, I have done conventional (prescriptive) design for this myself here in the Old Towne Orange area.
Lots of older homes with balloon framing. Now the last one I did was back in '07 and i was the GC on the job.
Different locals sure but nothing ventured, nothing gained, as the old adage goes.
I find that invariably it is better to go the BD with some kind of plan in your hands that they can look at. They may turn the initial idea down but usually they give some guidance on what to do if they see you are at least spending some time and effort into getting a solution.

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Old 10-17-2011, 11:50 PM   #15
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Second floor joists are horribly undersized.....options?


For me, I would pull out the book I have downstairs that is dated, but it would help to fix the situation, due to it has some really descriptive info in Balloon framing. As for the OP, it could be done, but there is not enough info or visual as to what they are really wanting to do with the upper floors.

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