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-   -   Headering off a 2x6 floor joist (http://www.diychatroom.com/f19/headering-off-2x6-floor-joist-140502/)

Alan 04-16-2012 08:58 PM

Headering off a 2x6 floor joist
 
I'm swapping my tub out for a shower, and I have a 2x6 floor joist dead center on the drain.

2x6 joists are 16" OC.

If I cut the one in the way, would it be acceptable to run joist hangers with a single 2x6 in them to the two adjacent floor joists, and then hang the severed 2x6 joist in the center of the new perpendicular boards?

Do I need to use a 4x6 instead?

wombosi 04-16-2012 09:05 PM

2X6 is fine, but depending on the span of the joists, the adjacent joists should be doubled, as well as the header.

ninjahero 04-16-2012 09:06 PM

Can u draw a quick picture of what u mean I have an idea but just want to be sure

Alan 04-16-2012 09:15 PM

1 Attachment(s)
I think I see what you are saying about the span. The span is unknown at this point. Can you tell me what distance of span the joists would need to be doubled at?


Here's a picture just for G.P.


Red area is the area to be cut out.

Blue are the proposed headers.

cortell 04-16-2012 09:33 PM

Alan, your proposed solution is not structurally sound. You're looking to take the load of the middle joist and redistribute it to its adjacent joists. Those two joists will be in danger of being overloaded. This could lead to a sag, which could lead to cracked drywall and greater bounce in that part of the floor.

You should be doubling up the adjacent joists. The cross joists you drew in blue (these are called floor "headers") should be doubled, too, though I suspect some carpenters would argue that is excessive. For sure, though, you need to double up the adjacent joists.

Alan 04-16-2012 09:53 PM

Quote:

Originally Posted by cortell (Post 900635)
Alan, your proposed solution is not structurally sound. You're looking to take the load of the middle joist and redistribute it to its adjacent joists. Those two joists will be in danger of being overloaded. This could lead to a sag, which could lead to cracked drywall and greater bounce in that part of the floor.

You should be doubling up the adjacent joists. The cross joists you drew in blue (these are called floor "headers") should be doubled, too, though I suspect some carpenters would argue that is excessive. For sure, though, you need to double up the adjacent joists.

This makes perfect sense. Thanks for your input.


:)

hammerlane 04-17-2012 11:32 AM

1 Attachment(s)
For reference:

tony.g 04-17-2012 03:25 PM

[quote=cortell;900635]. Those two joists will be in danger of being overloaded. quote]

No, not necessarily. Whether or not the 2 adjacent joists will be overstressed depends on 1. their span and 2. the distance out from the wall of the new trimmer beam.
For example; if he only cut, say 9" off the middle joist and supported it with the trimmer, it would hardly make any difference to the bending stress in the remaining joists. However, if it was near the middle of the span, it could well make them overstressed.
If he's only putting in a shower, I suspect the new trimmer will not be too far out from the wall if its just to clear the outlet, and he won't need to double-up the joists.
If he gave an SE the figures, they should be able to confirm it would be OK without doubling, but in the end, that nagging little demon called 'worry' will make him double-up.

cortell 04-17-2012 04:03 PM

Quote:

Originally Posted by tony.g (Post 901079)
No, not necessarily. ...

Putting blinders on and trying to walk across a road puts me in danger of being hit by a car. It doesn't mean I will be hit by a car. Your point is obvious and applies to anything in life. You can always try to get away with something questionable. With a little luck, you can get away with it.

If you think given a safe and universally accepted framing solution to a problem, a plumber is going to hire/consult a structural engineer to see if he can safely get away without doing it, you're living in an alternate reality. I'd like to meet a plumber who, in the middle of a $500 job, stops what he's doing and calls in a structural engineer to tell him whether he can safely weaken the floor system.

Ralph III 04-17-2012 04:52 PM

I agree with Cortell and that is how I would do it in this case, especially for such a simple project with little additional cost.

Even if going slightly overboard you're assured of stability. Whereas, if you don't install adequate support you're guaranteed to have eventual issues.

Better safe than sorry....

God Bless

tony.g 04-17-2012 04:53 PM

I wasn't basing my argument on 'luck', still less on 'getting away with something questionable'.
From my own engineering experience, I know that if the trimmer is not too far out, he would not need to double-up.
I'm not living in an 'alternate reality' as you put it; an SE would probably charge more than the cost of putting in a couple of 2x6s, and there would also be the inevitable delay while he got the figures out. I was merely pointing out that, from a purely structural standpoint, he would probably not need to double-up (subject to what I wrote about the span etc).

"an engineer can do with a shilling what a fool can only do with a pound".

cortell 04-17-2012 05:21 PM

Quote:

Originally Posted by tony.g (Post 901150)
I wasn't basing my argument on 'luck', still less on 'getting away with something questionable'.
From my own engineering experience, I know that if the trimmer is not too far out, he would not need to double-up.
I'm not living in an 'alternate reality' as you put it; an SE would probably charge more than the cost of putting in a couple of 2x6s, and there would also be the inevitable delay while he got the figures out. I was merely pointing out that, from a purely structural standpoint, he would probably not need to double-up (subject to what I wrote about the span etc).

"an engineer can do with a shilling what a fool can only do with a pound".

My point is that advising him to double up the adjacent joists involves no guesswork. The result will be at least as structurally strong as what was there before. I think we also agree that bringing in a structural engineer in this situation is probably impractical. Thus hinting that it probably is OK to weaken the floor is well-intended but bad advice. When giving advice on matters where few details are known, one should always err on the side of caution.

Gary in WA 04-17-2012 10:02 PM

As you have the joists exposed to cut them anyway, just check if each header is within 3' of trimmer joist bearing, as per code:

R502.10 Framing of openings. Openings in floor framing shall be framed with a header and trimmer joists. When the header joist span does not exceed 4 feet (1219 mm), the header joist may be a single member the same size as the floor joist. Single trimmer joists may be used to carry a single header joist that is located within 3 feet (914 mm) of the trimmer joist bearing. When the header joist span exceeds 4 feet (1219 mm), the trimmer joists and the header joist shall be doubled and of sufficient cross section to support the floor joists framing into the header. Approved hangers shall be used for the header joist to trimmer joist connections when the header joist span exceeds 6 feet (1829 mm). Tail joists over 12 feet (3658 mm) long shall be supported at the header by framing anchors or on ledger strips not less than 2 inches by 2 inches (51 mm by 51 mm). From: http://publicecodes.citation.com/ico...002_par031.htm

Gary

cortell 04-17-2012 10:43 PM

Quote:

Originally Posted by GBR in WA
As you have the joists exposed to cut them anyway, just check if each header is within 3' of trimmer joist bearing, as per code:

Given the opening is small (it's being created for a shower drain), it seems unlikely. You'd be looking at joist spans of about 7'. More likely is that the joists might run over an interior non load bearing wall. This could give the illusion that both headers are within 3'. To rely on that would inadvertently turn that interior wall into a load bearing one.

sublime2 04-17-2012 10:57 PM

Quote:

Originally Posted by cortell

Given the opening is small (it's being created for a shower drain), it seems unlikely.

But possible......


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