What is the longest 2 x 10 that can be placed beside the cracked joist, given wiring and plumbing that may be in place?

I would nail, not screw, the longest 2x10 I could comfortably sister next to this one. Use a tube of construction adhesive and a doubled 8" on center nailing schedule. If you could jack it into place before nailing, that would be really nice.

This post was edited by Trebruchet on Thu, Oct 16, 14 at 21:44

I secound the vote for 2x10 long as possible up to ends of scab resting on one or bothe joists. To properly load the new support, I would also raise the cracked joist before making the repair. 3/4" Plywood glued and nailed is equaly suitable or may be sandwiched to farthur increase load capacity. For laminations I use wood glue rather than construction adhesive.

I would also recommend that clamps should be used to draw the face of any sistered wood right up against the old 2X10, which will make the glue bond much more effective. If you don't have adequate numbers of beefy clamps, use construction grade (not sheetrock) screws to draw the faces together. Don't just drive in the screws: drill through the new material so the screws will have movement and drive them into the old 2X10. This will allow them to pull together. Doing this before any nailing will insure that the faces stay together during any subsequent hammering.

" For laminations I use wood glue rather than construction adhesive."

For shop made laminations where you can assure 100% coverage, I agree, but with cupped (trust me, they're cupped) 2x10s, the gap filling ability and driplessness of construction adhesive is the way to go here.

Trebuchet-
Good point. Regular glue would probably be ok if you were laminating 3/4" plywood to the face, but, overall, construction adhesive will insure that you will have decent contact coverage without having to worry about cupping.

The other side, closest to the wall, I could get a 6 foot section in.

No problem getting it to the rim joist.

I don't currently have any jacks.

"I don't currently have any jacks."
Most of this type jobs are done with 4x4 s sitting on bottle jacks. A single inexpensive 5 ton bottle jack will help immensely. Like bus said,just use your head in keeping things lined up so nothing slips out while under pressure.

If you don't have any jacks, pick up a 4x4 and cut it just long enough to drive it under the joist and sister with a sledge. Do the repair and drive it back out.

Why is everyone suggesting to jack it. It has cracked, but from the last photo it appears the displacement is horizontal. Also, it takes a tremendous amount of force to jack up and joist and copan sometimes cause more issues than you are solving.

You 7' lap piece should be enough, I would normally recommend about a 10' piece, but you should be fine. It does not need to go all the way into the bearing condition as that portion of th existing joists is still sound material, this is a banding issue, not a shear issue. Using adhesive is wise to make sure they stay acting together as they dry out. 10d nails at 6" on center top and bottom for the first two feet each side of the split then you can go to 12" on center if you want. Keep the nails about 1.5" from the top and bottom. I would also add a large bead of adhesive to the top of th new joist so it binds to the subfloor to help load transfer and minimize squeaks.

Jdubb

"Why is everyone suggesting to jack it."

Because that's the right way. Besides that, bus said so, I said so,everyone said so,so that's that and I don't want to say it again. LOL

So to the one who suggests that jacking is unnecessary, can we agree that some force caused the joist to break after the house was completed? And if the break is from displacement sideways as is suggested, from whence did that sideways force originate and how was it applied to just that one joist?

Glue should never enter into the calculations for determining the repairs, here's why: With old lumber that's cupped, warped, or degraded there is no way to quantify the effect of the glue, because you do not know how it will adhere. We could probably mix up a slurry of epoxy with the desired gap-filling ability, but this is a direct sistering operation, counting the load bearing capacity of the split joist as a 2x6, and using a well-established nailing schedule for the sister joist, which must be as long as possible to still give full bearing on the plate nearest the split, then you will have a suitable repair.
Glue-lam beams are only acceptable because they have been lab-tested to failure, and the manufacturer is standing behind them.
But anyway, this is not anywhere close to a catastrophic failure scenario, I just wanted to make a point about the engineering value of glue in a structural remediation project.
Casey

"Why is everyone suggesting to jack it. It has cracked, but from the last photo it appears the displacement is horizontal. Also, it takes a tremendous amount of force to jack up and joist and copan sometimes cause more issues than you are solving."

jdubb:

The cracked joist may have a dip. If you sister without returning it to flat, you've made the dip permanent. It takes little force to jack a joist or even several simultaneously. Of course you can't go crazy and replace a dip with a hump.

Casey:

I do know how construction adhesive, with its gap-filling ability, will adhere. That's why I suggested its use.

ohmmm: "I don't currently have any jacks."

Not a huge amount of jacking would be necessary. If you don't want to buy an inexpensive bottle jack, use the jack from your car and a 4x4; it would be better than nothing.

"-----it appears the displacement is horizontal. "
No response yet from the one who suggested just clamping with glue. Really wanted to hear their further explanation as I am always eager to learn.
I do agree that the split appears to be horizontal. But the primary force that created the problem is vertical, not horizontal.
When a beam is loaded to the point of significant deflection, other forces come into play. "Precession" causes the beam to try to rotate. Thus the value of bridging. But jacking up the joist will help close the split as that split has both vertical and horizontal gaps.
Spending $200 for jackposts is not big money for dealing with such a potentially serious problem. The adjacent joists experience extra loads and will sag over time.

Even if somehow the force that cracked the joint was horizontal, the supportis now weak in that spot, and therefore would give to the preexisting downward pressure of the house as an after-effect.

Not that I know anything about construction, actually--just housewife common sense. (Not that I'm a housewife either. I just like puzzles.)

And in the interest of puzzles, I'm wondering: Would you suggest filling the crack with glue before jacking and sistering? To create a bond inside the crack, in addition to all the bonds on the outside, etc.?

When I first looked at the picture, it looked to me like that joist may have had a crack in it from the beginning, which could have gotten worse through natural warping and reaction forces in the wood. So I'm not convinced that the crack is resulting from other stresses. However, it never should have been installed in the first place, and it needs to be fixed.

Glue at the cracked place would not add enough strength to be worth the effort. But it will do no harm if one is comforted by adding the giue.

I had no intent of posting to this thread again after it turned into a "who can tinkle highest on the wall "race. Tally_sue's comments changed my mind. Note the logic and common sense applied,questions asked in the sprite of a student that others probably have but hesitate asking amid the back and forth.
Tally_sue,you are 100% correct on when,where,how and after effects of crack. As far as applying glue inside the origional crack prior to closing it. Same as everything suggested in addition to raising and nailing on a sister joist ,it may or may not help but certainly will not harm. IMO , raised to origional position and 8 or 10 ft sister nailed on is good enough. Spanning from nearest support to a few feet passed crack is simply insurance,spanning 13 feet resting on both end supports is farthur insurance,prefered and likly what a professional framer would do. Face glueing albeit redundant will in no way harm and possibly be important where soil srink and swell is a fact. It could be argued that filling the split adds a small increase in strength plus seals out insects and moisture. There is no limit to the extent of remediation of the problem because there are those who would add even more framing members based soly on evedince of overloading. Heck,I might reccomend painting bright stripes on it to draw attention 20 years latter so they can see how it's holding up.
Bus,I also considered jack posts before seeing secound pic and realizing this is suspended ceiling over living space. Will you point out where it was suggested clamping with glue and forego mechanical fasteners?
sombreuil_mongrel, I say shame on you for intering a discussion amoung self help diysers to sprinkle truistic statments engineer speak. That's commonly called mudding up the water. Do you realize 99.9% of projects undertaken here on GW never have nor never will require "lab testing" and/or "manufacture (diyers) standing behind them"?
Re; Those who feel the need for sweeping the legs out from under other ideas to make room for their own,grow up and get a grip on yourself. It is great that one usually gets various means and methods from which to choose but there is no need for attempting to blow holes in other opinions. UNLESS there is clear threat of injury or loss of life and property. To wit,using the automobile jack. If the inadvisability isn't obiovious,it's beound the scope of explaining here. Just don't try it unless you are certain about possible problems. In the absence of a suitable jack a far safer way was suggested useing a sledge hammer and sturdy beam. Yes we know it can destroy floor covering but eventhough True didn't say so,we know he intends placing bottom of beam on a 2x before hitting it.
If an inquirer is incapiable of sorting amoung suggestions,they will probably never try or wind up failing anyhow simply because they were not up to the task.

klem1:

This is nuthin'. You should see the threads regarding whether or not your contractor should be allowed to use your bathroom. They damn near max out.

"And in the interest of puzzles, I'm wondering: Would you suggest filling the crack with glue before jacking and sistering? To create a bond inside the crack, in addition to all the bonds on the outside, etc.?"

Klem, is this what you are concerned about regarding my post?

This post was edited by bus_driver on Mon, Oct 27, 14 at 19:59

Just to wet the wall a little, I have always understood that glue and adhesives have no strength in themselves. They are both unreliably brittle. Thick bodied adhesives are best used in compression, such as with all the weight bearing down to force (say) a piece of wood down against concrete, forcing it nearly completely thin, and glue is only useful if you also force almost every single bit of it out.

Houses move; glue doesn't. Can we say that any repair that relies on glue is a mistake? You can't say it'll be still reliable in twenty years, and everyone here has seen old brittle crumbling Liquid Nails. I wouldn't want that happening in my house.

Like already mentioned, no existing piece of framing lumber can be counted on to be flat. Neither glue nor thick bodied adhesives will have any effect on a repair unless extraordinary lengths are taken to really compress the wood surfaces together, and nails or screws ain't it. Save the laminating for the shop bench where you have full control.

Sistering in this case does not fix the broken joist. It replaces it in the area of the break, and once in place then you can ignore the break, and that break still exists.

Whew! Preparing to get yelled at...

Klem-
Please enlighten me about why a car scissors jack poses a risk. If it's such a risk as you imply, I truly want to know.

It's not like the floor is sagging significantly, or that the OP will be crushed if the jack fails. And a properly placed 4x4 with the base of the jack on a level surface is not going to become a giant spring that will come flying at the OP in this situation. If the floor is sagging at all, it's maybe 1/8". I was suggesting using a 4x4 and having one end of this beam under the joist and the other end sitting 4" off the floor on the jack. Raising the jack a tad to put pressure on the underside of the joist does not sound like a high risk activity to me. Maybe I've been lucky all these years, but I have often used a scissors jack to gently nudge something just a little further when it's seemed a better method than whaling away with a sledge.

So, I'm not trying to pick a fight...just trying to understand why you think this is so risky in this particular situation.

Just to clear the terminology, in this instance the joist is a beam, the 4x4 proposed for jacking is a column.
Using a 4x4 on top of a jack works well and I often use it when serious lifting is needed, sometimes with a 12 ton jack . Keep them in a vertical straight line and use a level to insure that the 4 x 4 is plumb. Just do not try to place the jack on top of the 4 x 4- it will be very unstable.
My copy of Wood Handbook, prepared by the Forest Products Laboratory, Forest Service, U.S. Department of Agriculture is from 1955 and is quite old, as is it's owner. If one undertaking this project will read and follow the information in such a handbook, the results should equal those of a an engineer-- because they use the same information for structural woods.
Agricultural Handbook No. 72

Here is a link that might be useful: Handbook

bus_driver-
I accept your terminology as more correct, although I was simply referring to the 4x4 in the Webster's Dictionary sense of the word:
"beam: a long piece of heavy often squared timber suitable for use in construction."
Ok...I feel better now!!!

(P.S.: Thanks for the Wood Handbook link: that looks like a valuable reference.)

This post was edited by kudzu9 on Mon, Oct 27, 14 at 21:33

Treb, I actually saw that when it begain but didn't comment because A. I believe snobs to be near impossible to reason with regarding respectful behavior B. I believe snobs are self pitying fools that consaquintly live a miseriable unforfilled life C. I don't comperhend snobery near as well electro and mechanical so I'll leave the subject to those better equiped to help.
Bus, No I credited that comment to Tally_sue and had no problem what-so-ever with it. Ironicaly my concern is that you are reading things on your screen that are not on mine.
Grubby,You are correct in respects to adhesives used alone being a poor choice for most framing work. On the other hand you are underestimating the incrediable streingth,durability and longivity of whatever total surface that happens to make good contact between the members. You may also be overlooking the benifits of preventing slight wiggle and domino effect wiggle can lead to. I take extra effort to help an apprentic understand effects small amounts of movement can have on an otherwise good assembly. I will speak only about glue which i happen to be a fan of and leave construction adhesive to be addressed by its fans. I rely on Franklin International products,Tite Bond family mostly and never experienced any failures you say are expected. Boats speak to water resistance and any wood long bow enthusiest will differ about laminated bows ability to flex without glue cracking,crumbling and falling out. To your question "Can we say that any repair that relies on glue is a mistake?" Absolutly not! Klem and furniture makers from centuries back have and still do rely on glue without a single mechanical fastener for both building and repair of pieces meant to last over several lifetimes. As they say "we arn't talking about your grandpaws glue here".
No yelling from here,feel free to drop in any time and join the wall wetting.
kudzu,I will tell you about lessons learned about car jacks over the years and you can choose to consider them enlightment or just ranblings of an old guy who hung out with clumsy people. Blanket statments #1. Every car has it's own jack that will not work on other makes or models much less do handyman work #2. The special jack is usually a pos at best if you can figure out how to operate it. Klem's opinion. I suspect manufactures intentualy desighn jacks so that drivers can't raise their car and risk law suits because car fell on them. To the delite of manufactures,most drivers become frusterated or nervous and call road service. Raising and lowering a scissors jack takes two hands when the object to be raised is motionless. A third hand is required to hold the 4x4 untile jack is tight under it. Not true with bottle jacks. Ahh yes,call the wife to lend a hand. NEVER! Aside to the damage done to a man's emage,it's another step on the path to quarreling or worse if she gets a splinter or makes a mistake. Don't ask how I know,you figure things like this out with experience. Ok so you get one of the kids to hold the post untile you get the jack good and tight. No use in having him help take the post out latter,just hope the thing doesn't fall over and break something while both hands are busy with the jack. Comparing scissors jacks to sledge hammers are about 3 to 1 ratio. I know 3 people who knocked out teeth,blacked an eye,blooded nose smashed fingers with jacks other than bottle for each 1 useing sledges. Most carpenters have a car and jack when time comes to do something like this. I can't say I ever seen a one go get the scissors if he didn't have a bottle. It is a common sight to see a carpenter nail a couple of 2xs togeather and drive them in with more 2xs or what is available.
How about you carpenters , carpenter's helpers and others who have to use presidential engineering take our poll. If only the two are available, we have always relied on scissors_____ / sledges_____

I know I sure wouldn't rely on glue alone in a structural situation!

(I've read that in things like furniture construction or repair, wood glue creates a bond that's stronger than real glue, and if a repair re-cracks, it'll crack -beside- the glue. I've seen that happen, actually. Though yes, I've seen glue dry out, too.)

But I'd probably squirt a bunch inside that crack just bcs it makes me nervous. (Though I so totally see the logic that once you've sistered it, the crack is immaterial, and the glue in it even more so. I just, well, I'd squirt glue inside. It would make me feel better.)

(off to google "bottle jack"--not that I ever think I'll need one, but I love gadgets. and puzzles.)

Holy toledo, a 6-ton bottle jack is $30!! a 12-ton one is $50. Why don't I own one? (and they're cute)

That's pretty cheap! And now that I look at one, I can see why a scissors jack from your car might be a little iffy.

This post was edited by talley_sue_nyc on Tue, Oct 28, 14 at 20:41

"Holy toledo, a 6-ton bottle jack is $30!! a 12-ton one is $50. Why don't I own one? (and they're cute) "

When it comes to bottled jacks , I prefer Single Barrel Select but will settle for Old No.7 .

talley_sue-
It may seem counter-intuitive, but glue in that crack would do next to nothing. It's true that, in a well-glued joint, the wood will fail before the glued surface does. However, a well-glued joint is one that has the tiniest amount of glue between the surfaces. That's why, when one builds high quality furniture, the unglued joints are almost a friction fit, the glue is put on sparingly, and clamps are used to force the wood surfaces together so that excess glue is squeezed out and the remaining glue works at almost the molecular level. Glue itself is not very strong, so, if you were to "squirt a bunch inside that crack," it might sound good...but it would add little or nothing to the strength. Only if you could get glue inside and along all the inner surfaces of the crack, and then force the two sides back into near perfect contact, would you add anything to the repair. And that can't be accomplished with this type of problem.

This post was edited by kudzu9 on Tue, Oct 28, 14 at 22:13

Oh, I totally believe you that the glue would be a placebo. It would just make me feel better (like a placebo--but without the placebo effect).

And I do know that you have to have full, solid contact; I've done that kind of gluing successfully now and then (but boy, it can be tough to get that "near perfect contact").

Ok...I think it would work perfectly as a placebo!

I am the original poster.

Wow, lots of discussion on this. I took more photos. It will be one of my winter projects here.

As to why it cracked, my hunch is that it was just a crappy piece on site and they used it anyway. I don't see any smoking gun that could have caused it after the fact.

The flooring above in the master bedroom is carpet. Nothing in the bedroom area of the cracked joist that is of significant weight.

I could run a string line on either side of the crack to see if it is dipping significantly versus the other joists.

I managed to get a straight 2x10x8 for the job. Actually got four, just in case I find other spots as I remove dropped ceiling tiles to do other work.

So I could shove the new joist all the way to the rim, but there is no way to get it tight up against the left side as in the photo, because of that "peel" coming off.

So I guess the plan is to jack it up slightly, use clamps, construction adhesive, 10d nails 6" on center.

I imagine marking a "crack path line" in pencil on the new joist would allow me to keep the nails 1.5" away from the crack lines on the damaged one.

I do have a palm nailer to use as well.

Would ring shank/spiral nails be better to use, or makes no difference?

Using some 3" screws will help draw the faces together.

I'd cover the floor, inject two tubes of 5 minute epoxy into the crack, jack it together and forget about it.

Photos of the repair below. Worked out ok. Got a couple of shorty screw jacks. Put some doubled 2x4s together and used those as jack posts. Used a level across the bottom of the joists and got it close. Not perfect, but better than it was.

The 2x10 I sistered on was 8 feet long and straight with not much cupping. Used 1.5 tubes of construction adhesive. Got the 2x10 in place with clamps on it. Then proceeded to nail it every 6 inches. Smooth shank nails. Air operated Bostitch palm nailer made quick work of it.

The lines on the new joist are the approximate positions of the cracks on the old joist. Wanted to keep the nailing outside of those areas. Used a full pound box of nails.

Let it set for 24 hours and removed the jacks. Should be good for another 30 years.

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Interesting nailing schedule, but you got 'er fixed. Good job.

Structural repairs are not for amateurs. Proper bolting pattern and overlap are essential for a worry-free repair