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-   -   Again with the sister joists . . . (http://www.diychatroom.com/f19/again-sister-joists-52017/)

benjamincall 08-31-2009 08:10 AM

Again with the sister joists . . .
 
Do you think a split running parallel to the grain compromises the strength of this sister joist? I really hate to start over now that I've come as far as I have. I will be putting in at least one additional sister for this joist.

Split at one end:



http://cambriaofcalifornia.com/ebay/DSC_0109.jpg


Split at the other end:


http://cambriaofcalifornia.com/ebay/DSC_0111.jpg

DangerMouse 08-31-2009 08:29 AM

i'd love to help you, but your pics are HUGE and i'm on dialup.... by the time they finished loading, i'd be on my lunch hour!
however... a crack can be repaired, and you can also drill through all of them and nut and bolt them together for added strength.

DM

benjamincall 08-31-2009 08:35 AM

Sorry about the pictures. I just resized them. The joist has about an inch to go before it's in place. You're saying that I should just slam it the rest of the way in and bolt it once I add the last two sisters? Would really like to add one on the other side as well, but the other side has the overlap.

Scuba_Dave 08-31-2009 08:38 AM

How long is the sister joist & how long is the split?

benjamincall 08-31-2009 08:47 AM

The joist is 12' and the splits are about 4' long at each end.

Scuba_Dave 08-31-2009 10:56 AM

With 2/3 of the wood split I'd have to say the sister joist is worthless

skymaster 08-31-2009 11:44 AM

Sorry but I agree with Dave, firewood. toss it. there is no structural strength of value left in it. IMHO

benjamincall 08-31-2009 12:17 PM

Next time around do you think I should take a circular saw to one of the corners? The main purpose of these sisters is to give the floor sufficient rigidity for marble floor tile.

Paragon 08-31-2009 04:16 PM

Okay Ben,

Here is some of the things I am wondering as well as some of my thoughts maybe even a question or two as well, lol.

Who was it that recommended adding additional framing in the form or sistering joist? Did you have or did you perform a flex test and did the floor fail? Second how from what I see the possible cause of the new floor joist splitting is that you used a regular framing hammer to beat the joist in place and the board was twisted and as it went in it did not make the turn and the incessant pounding on the floor joist caused it to split (hence the trimming of the corner question).

I am not there on site and I do not know the reason that this additional fraaming needs to go in but next time you need to tap a board into place use a scrap of lumber that you can use to take the abuse and transfer the force to the material you are trying to manipulate. In other words next time you need to shift a joist in place us a 2x6 or something like that and use a heavier hammer like a sledge, 4 lbs maul or another bfh and hit the 2x6 instead of the maaterial you are trying to preserve.

I am not sure how much this reply is in the DIY spirit but I saw your project but still wonder the why's and how's of what you have started.

Good luck and be safe

Paragon 08-31-2009 04:23 PM

ohh and yes I agree firewood because as others have said no structural integrity left what so ever over the areas where the support is most crucial. If the middle 4 feet is still in great shape however the portions of the new joist which are setting over the main support joist are split then the purpose of the new support joist is lost.

Just an idea if you have to place this new framing in can you elevate the rest of the framing ever so slightly with 1 or more hydraulic jack(s) a 1/4 or 1/2" via a VERY SLOW AND GENTLE lift so that you can place the new framing material without damaging it and then let the pressure out of the jack letting it down VERY SLOW and GENTLE as well? Might that work a little better for you to place that new joist material and then secure it to the existing framing that it is reinforcing?

Just food for thought.

!!!BE SAFE!!! good luck

benjamincall 08-31-2009 04:36 PM

Quote:

Originally Posted by Paragon (Post 321913)
Okay Ben,

Here is some of the things I am wondering as well as some of my thoughts maybe even a question or two as well, lol.

Who was it that recommended adding additional framing in the form or sistering joist? Did you have or did you perform a flex test and did the floor fail? Second how from what I see the possible cause of the new floor joist splitting is that you used a regular framing hammer to beat the joist in place and the board was twisted and as it went in it did not make the turn and the incessant pounding on the floor joist caused it to split (hence the trimming of the corner question).

I am not there on site and I do not know the reason that this additional fraaming needs to go in but next time you need to tap a board into place use a scrap of lumber that you can use to take the abuse and transfer the force to the material you are trying to manipulate. In other words next time you need to shift a joist in place us a 2x6 or something like that and use a heavier hammer like a sledge, 4 lbs maul or another bfh and hit the 2x6 instead of the maaterial you are trying to preserve.

I am not sure how much this reply is in the DIY spirit but I saw your project but still wonder the why's and how's of what you have started.

Good luck and be safe

The need for the sister is to achieve l/720 for 12" marble tile. 2x8s floor joists spanning 11 feet need a lot of help to attain that kind of deflection, especially since the two neighboring joists were notched like crazy by the plumbing and HVAC subs back in the 50s.

At any rate, I used a 16 lb. sledge, a column jack, and a bar clamp to rotate that guy into position. You're right, I should have used scrap lumber to the protect that joist. It was a slippery slope. I started out banging with the flat side of the sledge, but I ended up flipping it around in frustration (tired shoulders). :no:

benjamincall 08-31-2009 04:39 PM

Quote:

Originally Posted by Paragon (Post 321917)
ohh and yes I agree firewood because as others have said no structural integrity left what so ever over the areas where the support is most crucial. If the middle 4 feet is still in great shape however the portions of the new joist which are setting over the main support joist are split then the purpose of the new support joist is lost.

Just an idea if you have to place this new framing in can you elevate the rest of the framing ever so slightly with 1 or more hydraulic jack(s) a 1/4 or 1/2" via a VERY SLOW AND GENTLE lift so that you can place the new framing material without damaging it and then let the pressure out of the jack letting it down VERY SLOW and GENTLE as well? Might that work a little better for you to place that new joist material and then secure it to the existing framing that it is reinforcing?

Just food for thought.

!!!BE SAFE!!! good luck

Do you think that would do have an impact on my masonry shower pan and marble shower?

Paragon 08-31-2009 04:51 PM

Shouldn't if you give it slight lift and when I mean slight I mean if the new joist is 3/4" tight (exageration I know) lift is 7/8" and lift VERY slowly, have someone planted upstairs to see if anything changes (you are going to hear groaning, crackling and other scarry nerve wracking noises) and VERY gently. And again lets say the lift is 3/4" you could lift 1/4" per day and let things settle down a bit if there is a big lift involved but I am guessing that the lift required would be more like 1/4" or so and a tthat little of a lift then I think you could do it in one lift very slowly very gently and it SHOULDN'T affect the materials above it but it is a crap shoot but it SHOULDN'T but then I could be wrong. I just know if you need the extra framing and you don't have any other choice that to shred another joist is not the best option and this will give you a little breathing room to get the sistered joist in place.

Just my .02 worth and others may have a better solution that I never thought of.

Good luck, be safe

Gary in WA 08-31-2009 08:07 PM

Cut the joist 6" longer than outside-outside bearing. With more than code for waste hanging over, -- inches past bearing of size depth of joist = 2x10 = 10" max. past bearing.
Cut 3/4" x 12" rip off each end's bottom edge, roll the joist into position, install wedge cut-back under same ends, use a wood (ply or similar)driver to push joist up tight to take the load. Remember the saw cut thickness, the end will need to go past flush of joist end. This is a much gentler and safer way to get the exact load needed (fine-tune). Code allows 1/4 of size of joist removed, but don't go anywhere near that.

Other possible help: http://www.finehomebuilding.com/PDF/Free/021184090.pdf

Be safe, G

Scuba_Dave 08-31-2009 08:15 PM

Is the marble already installed ?


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