# floor joists butt ended over wall?



## Oldhouseowner (Jul 24, 2007)

Hi there everyone,

A question popped into my head about my never ending attic project. 

I am sistering old stock 2x4 ceiling joists with 2x10 to create a strong enough floor for a big funroom and eventually a bedroom (Can be fun too!).

The old joists are one continuous piece 2x4. Supported by a wall about half way. If I sister these I would need to splice the 2x10 above the wall by overlapping them. 

However is there anything to be said against butting them against each other directly over the load bearing wall, nailing it along the whole length to the old stock and strengthening this joint with a bolted on piece of 2x10 sandwiched at the other side?

I am thinking it must be stronger to have the sister directly attached to the old joist all the way then splicing it half way. Also I would keep to the 16"OC which makes it easier to layout my ply later.

Your opinions are greatly appreciated. Have a great day all.


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## skymaster (Jun 6, 2007)

Run em past the old ones and overlap on the bearing wall. Dont butt em, that will only get ya in trouble later on


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## redline (Mar 5, 2006)

Oldhouseowner said:


> ... Supported by a wall about half way.


Does this wall have support below it?


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## Oldhouseowner (Jul 24, 2007)

redline said:


> Does this wall have support below it?


Thanks for helping me out here. It sits on the floor joists with a girder running about 36" from it. Looks all original, House built in about 1912.


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## Oldhouseowner (Jul 24, 2007)

skymaster said:


> Run em past the old ones and overlap on the bearing wall. Don't butt em, that will only get ya in trouble later on


Appreciate the reply, thanks this is a great forum, even though of course sometimes we all hear things we don't wanna hear. 

The reason I was wondering was that it appears to be totally acceptable to splice ceiling joists that way provided you use a 2x minimum 24" long splice plate. Of course the load requirement is about double that which is why we use bigger joists to start with. 

Just a thought.


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## BigJimmy (Jun 30, 2006)

Oldhouseowner said:


> Hi there everyone,
> 
> A question popped into my head about my never ending attic project.
> 
> ...


I too am an owner of an old house (1911) that I am currently rebuilding from the inside out, one room at a time (looooove that plaster!).

First of all I am not a structural engineer (electrical) but I work with a group of them and I regularly consult them for business and personal issues. I've learned quite a bit about structures over the course of my career but by no means am I a professional SE. I do all my construction, including carpentry so I have some practical experience therein as well. That being said, here are a few pennies for your pocket.

First of all, you mention 2x4 lumber as being the existing _joist_ size? I've seen some very questionable things in my house which are totally code illegal by today's standards but 2x4 seems insane! You did mention that this are these are attic ceiling joists but still, they seem grossly small even for that application.

From your post, it appears that you are beefing up the attic floor to create a livable space. 10" lumber seems reasonable but you may want to check with a design professional to make sure. At the end of the day, it will be the 2x10's that transfer the floor load to the support walls and you want to make sure that the size will prevent excessive deflection. For this you'll need to consider the lengths of the free spans that they'll be subjected to.

My house is balloon framed and all the existing lumber is old growth (the wood is so hard I usually have to pilot drill before screwing into it to prevent cam out). The exterior wall studs extend continuously from the foundation sill all the way to the top plates on the second floor. The floor joists are continuous as well, spanning 36+ feet without break (there is a central load bearing wall running perpendicular at about 1/3 the span of the house for supplemental support). Last time I was at the lumber yard, I didn't see too many 40' pieces of lumber! Pretty interesting.

There is nothing wrong with splicing above the load bearing wall. This is done today, often to allow the use of standard length lumber. Usually though, the pieces overlap by a foot or two, i.e. they do not butt together. In your case, if you don't need to splice, then I wouldn't. Either way, once the new framing is in, take the time to properly block it over the L/B wall to prevent rolling of the new joists. If sistered to 2x4's, the blocks will need additional cuts to fit the 2x4/10 interface.

I tend to err to the cautious side when I'm doing something that is structural in nature. That being said, I often consult my SE pals or if not practical, go for something that I know will work (read: oversized!). At my work where the structures are for mass transit, those bozo's design with a 150% safety factor anyway!

Good luck,
Jimmy


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## johnrem (Feb 7, 2008)

If you butt them,just make sure you get 1 3/4 bearing on your wall from both sides.


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## skymaster (Jun 6, 2007)

Johnrem: I respectfully disagree on this; He is actually building a new floor system that will be taking the total load. With only 1 3/4" of a joist to take this load is a disaster waiting to happen. A joist will DEFLECT under load, If you can picture that bending moment it WILL tend to pull the ends of the joist towards that bending moment and location. That is why you overlap those joists and nail em together and toe them into the plates.
I am willing to bet a case of beer on the fact that if you just butt those joists IT WILL FAIL INSPECTION AND CODE.:whistling2: And BLOCK EM to prevent twisting


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## johnrem (Feb 7, 2008)

If he does butt them ,and the wall is 3 1/2 ",he must be careful to to have these joists meet in the center. Any less could be a problem and possibly fail inspection.I don't have code book in front of me but this is something I seem to remember from the past. agree about solid bridging to prevent twisting,among other things ,such as framing(2x4)directly below new joists to transfer load down to a solid footing,but I'l leave this for the engineer. Maybe some here could help us with the facts on the codes.


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## PKHI (Oct 23, 2007)

johnrem said:


> If he does butt them ,and the wall is 3 1/2 ",he must be careful to to have these joists meet in the center. Any less could be a problem and possibly fail inspection.


You would NEVER EVER EVER but two joists together like that. You always run past.


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## johnrem (Feb 7, 2008)

I do wonder what the code book would say about that situation.


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## Oldhouseowner (Jul 24, 2007)

johnrem said:


> I do wonder what the code book would say about that situation.


Not a lot that I could find. You can apparently butt CEILING JOISTS over a bearing wall if you use a splice plate. However I can't find any info doing this to FLOOR JOISTS, but I can't find anyone forbidding it either. My thought was lining up the 2x10 and the old stock ceiling joist as well as a splice plate for the butt ends would make for a very rigid floor. 

Skymaster, very good point with the deflection pulling the ends together though. That is about the most logical explanation I have heard about it.

Jimmy I hear you with the old house! I agree - I wish drywall had been invented 60 Years or so earlier. As an added bonus the old owner had screwed drywall over the old lath which made for an interesting new bathroom reno a few years ago.

The old stock 2x4 were quite a common way to frame the ceiling in the old days here allegedly. They span about 30" with a bearing wall in the centre. 2x10 are sufficient for the span I've got with a ceiling finish attached to them. It's quite beautiful what kind of wood they had in the old days - 2x4 that are actually 2x4 in 32 foot or so lengths?

Thanks for your help folks :thumbup: any more feedback is of course appreciated


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## johnrem (Feb 7, 2008)

ok.FYI.this is what I found.This my not be true everywhere but this is what Ohio says:OHIO BUILDING CODE,THROUGH APRIL 2006,chapter 5,floor framing,R502.6 bearing,"the ends of each joist,beam,or girder shall have no less than 1.5" of bearing on wood or metal and not less than 3" on masonary or concrete ,ect..."also R502.6.1 floor systems "a wood or metal splice with strenth equal to or greater than that provider by a nailed lap is permitted". I guess you could think of the splice being similar to a bottom cord of a roof truss.They always have seams like this.Old house owner's idea would work and pass code in Ohio,and big jimmy's post was right on all the way.I am sorry but a floor joist that is sized correctly ,would NEVER deflect so much as to fall off a bearing of 1.5" or more.What I was referring to in post #7 was that if he ended up with less than 1.5" bearing,because of sloppy work,then he would fail inspection.If I were you,oldhousebuilder,I would check with your local inspector.They won't tell you how to build,but they will answer specific questions.Now I do believe skymaster owes me a case of beer but one problem,I don't drink(diet soda only) so give the brew to your crew on me.


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## johnrem (Feb 7, 2008)

FYI.this is what I found.This my not be true everywhere but this is what Ohio says:OHIO BUILDING CODE,THROUGH APRIL 2006,chapter 5,floor framing,R502.6 bearing,"the ends of each joist,beam,or girder shall have no less than 1.5" of bearing on wood or metal and not less than 3" on masonary or concrete ,ect..."also R502.6.1 floor systems "a wood or metal splice with strenth equal to or greater than that provider by a nailed lap is permitted". I guess you could think of the splice being similar to a bottom cord of a roof truss.They always have seams like this.Old house owner's idea would work and pass code in Ohio,and big jimmy's post was right on all the way.I am sorry but a floor joist that is sized correctly ,would NEVER deflect so much as to fall off a bearing of 1.5" or more.What I was referring to in post #7 was that if he ended up with less than 1.5" bearing,because of sloppy work,then he would fail inspection.If I were you,oldhousebuilder,I would check with your local inspector.They won't tell you how to build,but they will answer specific questions.Now I do believe skymaster owes me a case of beer but one problem,I don't drink(diet soda only) so give the brew to your crew on me.[/quote]


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## Oldhouseowner (Jul 24, 2007)

Thanks Johnrem, that's very interesting. Finally a code which mentions it. I guess plugging the inspector is the answer.

Hey shouldn't any Beer here go to the guy who started this tread?:laughing:

Have a great day Guys,


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## johnrem (Feb 7, 2008)

thats right oldhouseowner.It really is about how your inspector interprets the code. Forget about the beer,I doubt that that case ever leaves the beverage store.


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## Oldhouseowner (Jul 24, 2007)

Ah, never mind, I'll have to drink the old homebrew again.

Thanks again for all your help everyone. You rock!

:thumbsup:


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## skymaster (Jun 6, 2007)

Johnrem; As you said Ohio might allow it but NJ sure doesnt. Also My comment about MAYBE the reason for no butts was that the loads tend to pull those butts apart did not say it would pull the joist off. That said a question for ya.Say you frame floor with standard code approved lumber and have that 1 1/2 Minimum Dimension. Tell me what dimension you will have in about 3 years once it is enclosed and heat has been applied to the structure?
You are still entitled to the soda tho for your diligence for going to the code book. Next time I am in Mentor I will let ya know,
However answer the quiz if you please :}:}:}:}
Old house make me feel better after your home brew by telling me you will overlap those joists


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## Oldhouseowner (Jul 24, 2007)

skymaster said:


> Johnrem; As you said Ohio might allow it but NJ sure doesnt. Also My comment about MAYBE the reason for no butts was that the loads tend to pull those butts apart did not say it would pull the joist off. That said a question for ya.Say you frame floor with standard code approved lumber and have that 1 1/2 Minimum Dimension. Tell me what dimension you will have in about 3 years once it is enclosed and heat has been applied to the structure?
> You are still entitled to the soda tho for your diligence for going to the code book. Next time I am in Mentor I will let ya know,
> However answer the quiz if you please :}:}:}:}
> Old house make me feel better after your home brew by telling me you will overlap those joists


Skymaster, appreciate your concern. Yes, I'm overlapping. There was only one Joist in question where I was tempted to not, as after doubling around the staircase opening that I had no room as the rafter was sitting on the part of the plate where the overlapped joist would go. 

It's good to clarify things here in the Forum, I like the fact that we generally find good reasons for what is done.

And thanks for letting me finish my beer. It was delicous. Gulp. You should have one too!


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## oldfrt (Oct 18, 2007)

skymaster said:


> Johnrem; As you said Ohio might allow it but NJ sure doesnt. Also My comment about MAYBE the reason for no butts was that the loads tend to pull those butts apart did not say it would pull the joist off. That said a question for ya.Say you frame floor with standard code approved lumber and have that 1 1/2 Minimum Dimension. Tell me what dimension you will have in about 3 years once it is enclosed and heat has been applied to the structure?
> You are still entitled to the soda tho for your diligence for going to the code book. Next time I am in Mentor I will let ya know,
> However answer the quiz if you please :}:}:}:}
> Old house make me feel better after your home brew by telling me you will overlap those joists


 We had this discussion with the local building official and it became a matter of personal preference.
We posed the question as a comparison to a floor joist which has been boxed on the perimeter of an exterior 2 x 4 wall.
This floor joist only extends over the plate a min. of 2",the 1 1/2 band joist making up the remainder of the space.
It seems that butted joints properly done would suffice.
My personal preference is to overlap for the pure ease of getting some decent nailing into the plate.


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## skymaster (Jun 6, 2007)

Olfrt; WE know you are still a kid:laughing: I agree with you the only thing i would like to repeat is this particticular situation we are talking is NOT the normal rim joist ,floor joist setup. It is an interior partition where Oldhouse wants to add a heavier set of floor joists and one suggestion was to just sister them and only butt the ends giving ONLY 1 1/2 - 1 3/4 bearing. :}:}:}:}:}:} 
The consensus is to NOT do that and overlap them. 
The only other choice I see is if a whole buch of us go to his house and fix it for him. OF COURSE food and beer and lodging will be on his tab ROFLOL

Oldhouse: WE are expensive but we are worth it LOL LOL Have anudder brewskie


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## johnrem (Feb 7, 2008)

I have no formulas for the quiz but what I know is....lets assume joist is 14'x2"x10"...with tape measure,it would be exactly 14' x 1 1/2 x about 9 3/8. The shrinkage on the length is minimal (if any).this is never an issue.The width will also not change much to notice.Now I have seen the hight of joist to shrink down to about 8 7/8. Around here we see alot of vinyl siding popping loose at the rim joist hight because of this,(houses about 3 years old) I agree that butting in this manner is not the best,but on 90 year old houses you sometimes have to wing it.And it will work.Just want to add..If you do bolt the wood or metal splice,you must drill the holes the exact size to where you have to tap the bolts with your hammer.You do not want any slop in these holes....I hope I pass the quiz...and skymaster,look foward to seeing you in Mentor. I used to down a few at the old depot at RT615 and tyler .(probably why it's soft drinks only now)


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## skymaster (Jun 6, 2007)

ROFLMFAO OK John you win!!!!!!!!!!!!!! All I was getting at is with normal lumber and its moisture content within 3 years it will shrink at least 1/4 to maybe 3/8 therefore if you start with that 1 1/2 minimum in 3 years it will NOT meet minimums. :}:}:}:} Sorry but here in NJ if we did that the first thing an inspector would do is shoot our ass then hang a red sticker on it :}:}:}:}:}:}
You are on tho for that iced Tea I will give ya a heads up when we are going out to visti grand daughter and family.
Hell I feel generous 2 yeah give ya 2 big ones LOL LOL
Jack


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## js2743 (Feb 13, 2008)

ok you guys are worried about butting the floor joist but i would think the LB wall under neath isnt strong enough to hold the weight. if its just 2x4 and im betting its not load bearing its just a wall. shouldnt there need to be a header across there like 2 2x6's together to give enough support. also better check under neath the wall, if that is supported to the foundation. sounds like a disaster waiting to happen, i started to say accident but if something is built wrong then it cant be a accident when it fails.

here would be a news article local family trapped when floor falls and fold up like a book.


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## Joe Carola (Apr 14, 2006)

js2743 said:


> ok you guys are worried about butting the floor joist but i would think the LB wall under neath isnt strong enough to hold the weight. if its just 2x4


Why isn't a 2x4 wall strong enough? 2x4 walls can handle 2 and 3 story houses. If that wall is the center bearing wall sitting on top of the main girder, he's fine. If there are any openings in the wall below and he's adding weight , he has to make sure the headers in that wall can handle what he's putting on above. I'm just saying that there's no need to be concerned if a wall is a 2x4 wall.


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## AtlanticWBConst. (May 12, 2006)

It's a common misconception that many people with minimal framing/building backgrounds have. 

They often think that 2x6 framing is based on structural load requirements, when it is based on greater wall-depth to achieve a higher R-Value when using fiberglass batt insulation. As Joe already stated, 2x4's are perfectly sound for carrying several floors of weight.


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## johnrem (Feb 7, 2008)

post #1 states that it is load bearing wall. Post#4 states wall is offset 36".Post #9 suggests to leave load bearing requirments for an engineer.(other things involved sush as first floor construction).2x6 studs will increase the load carrying capacity of the wall,(but doubtful that it is needed here).It would give you more bearing for end butted joists but I think we're done with that. Unrelated,,another time to use 2x6 studs is in a tall wall (up to 16'),to limit in and out movement.


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## crecore (Nov 2, 2005)

I would dare say that 1.5" is a general min case rule. I guarantee that somewhere else there is a joist chart that substantially reduces the allowable loads with such application. This would be similar to hanging a joist from the side of a beam with a hanger as a opposed to sitting it on top. From what I read in this post I would certainly not recommend this method.


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## Oldhouseowner (Jul 24, 2007)

skymaster said:


> Olfrt;
> The consensus is to NOT do that and overlap them.
> The only other choice I see is if a whole buch of us go to his house and fix it for him. OF COURSE food and beer and lodging will be on his tab ROFLOL
> 
> Oldhouse: WE are expensive but we are worth it LOL LOL Have anudder brewskie


:laughing:
ROFLMAO - I dunno we have to get some jello so you guys can wrestle out the Joist issue. So here we are beer, food, lodging and Jello.

No worries! When are you coming? - I've got to tell the Canadian border guards!


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## AtlanticWBConst. (May 12, 2006)

My Vote: Overlap them. That's how we would do them.

(FWIW: It's standard building practice with every builder, GC, & framer I know...)


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## oldfrt (Oct 18, 2007)

skymaster said:


> Olfrt; WE know you are still a kid:laughing:


This is the *kid* my wife sees!


Valentine's Day brings out her best humor!


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## skymaster (Jun 6, 2007)

Oldfrt ROFLMFAO what a GREAT disguise!!!!!!!!!!!!!!!!!! EH!:thumbup: :laughing:


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