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Old 08-22-2011, 08:51 AM   #1
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Floor Joist Whacked Off At The End


I decided a couple of weeks ago to remodel the master bath and as is always the case a huge can of worms was opened. I found substantial water damage that was covered up by the previous owner and in the end required removing not only the master bath floor, but the floor in the adjoining main bath. I've also found that the rot has extended into the master bedroom floor in various places and into another bedroom on the other side of the main bathroom wall. It's a freaking mess to say the least.

I also found that when the previous owner did their own remodel on these bathrooms they moved the main drain for some reason. Well, when they did this it appears that one of the floor joists was in the way, so they just hacked it off about 2 feet of it and then nailed a piece of old 2x6 to the end of it I guess thinking it was going to support the weight. It of course didn't support it and everything in that area has dropped by about 2 inches. If this weren't bad enough, now that the floor wasn't level they built the floor back up with self-leveling concrete so they could lay the tile.

So, what was supposed to be a weekend project has turned into 2 weeks so far of sheer aggravation and the sincere desire to track down the previous owner and beat him on principle.

Anyway, the real dilemma is how to deal with the joist. Splicing I know isn't really an acceptable solution, but replacing the entire joist would be an absolute nightmare. Yesterday I put a 7 foot 2x8 along side the hacked off joist and considered bolting the two together with two 3/4 bolts every 16 inches. But, I don't believe this will be a long term fix and have pretty much convinced myself that my only real options are to replace the entire joist (not my favorite choice) or put a column under the spliced area to support it, which I believe is the required method in most locales if not replacing the entire joist.

Any thoughts, other than to burn the place down and leave the country?

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Old 08-22-2011, 09:09 AM   #2
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Floor Joist Whacked Off At The End


Post a picture----not all 'whacked' joists are repaired the same way.

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Old 08-22-2011, 09:26 AM   #3
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Floor Joist Whacked Off At The End


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Post a picture----not all 'whacked' joists are repaired the same way.
I'll see if I can get a good picture of it. Kinda hard now that I have the new piece of 2x8 in there, but should be able to get something that shows what it looks like.

In short though, the joists to either side of this one are intact. Picture a block foundation with the joists resting on top of it. This particular one was cut off about 2 feet from the block wall. This joist also supports a wall above it.
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Old 08-22-2011, 09:47 AM   #4
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Floor Joist Whacked Off At The End


Do you have access from below?
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Old 08-22-2011, 10:18 AM   #5
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Floor Joist Whacked Off At The End


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Do you have access from below?
Yes, it's over the garage so I can get to the area pretty easily. Can get to it from the top also since I have the floor cut out.
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Old 08-22-2011, 11:26 AM   #6
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Floor Joist Whacked Off At The End


There is nothing wrong with bolting, nailing or screwing and gluing a joist to the existing joist as a fix. The key is to get adequate overlap, an adequate number of fasteners in the proper pattern, and make sure the far end of the spliced joist is properly supported. Often the far support can be done with a bracket (see Simpson catalog).

The most accurate way to determine the number and pattern of fasteners requires pretty advanced mechanical analysis of the joint, therefore is never done in practice for residential work. Carpenters have developed rules of thumb, or they just do it the way they were taught. Here is a simplified analysis procedure, by no means rigorously accurate, but good enough for residential work.

Compute the total load on the beam or joist. This is typically done using the tributary area of the floor above, and the nominal pounds per square foot loading from code. For example, if the joists are spaced 16 inches on center, and the total load by code is 40 psf (30 psf live, 10 psf dead), and the joist is 10 feet long, the total load is going to be 40 * 10 * 1.33 = 525 pounds. The maximum shear is going to occur at the supports, and will be half the total load, or approximately 265 lbs.

Since you are not going to splice the joist right at the support, the shear at the splice point will be a little less, so you can assume 265 lbs to be conservative. Look up in tables the allowable shear for the type of fastener you are planning to use. You can usually get this off the web, for example nail shear values can be found at http://www.uspconnectors.com/nails.shtml

For example, 16d common using 14 gauge steel has an allowable shear of 140 lbs/nail, so in this case you would need only 2 nails to carry the shear. However, you also need to carry the bending moment at the splice, and it is tricky to calculate the stress on nail patterns from bending moment, so in this case I would use at least 6 16d nails, spaced approximately 12 inches apart horizontally, placed approximately 2 inches from the top and bottom of the splice, and no nail should be closer than 3 inches from the end of either beam. The top and bottom nails alternate in 6 inch increments, so the pattern looks like a series of V shapes.

Furthermore, nails are dirt cheap, so you can certainly use more nails over a wider splice if you can fit them in. You can also glue the splice using industrial adhesive, this will add additional strength. Make sure the splice occurs over undamaged wood. You can remove damaged wood if it is rotting, however if you elect to leave it in place, make sure you do not count any fasteners you put into the damaged area as part of the minimum fastener total for the splice.
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Old 08-22-2011, 11:50 AM   #7
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Floor Joist Whacked Off At The End


Did it look something like this?



That 'was' my bathroom a few years ago...cracked shower pan....etc...over 2" of drop....

Your doing the right thing by pulling it all out and doing it right. That was what I did.



As Daniel said, a lot of variables and then there is "Carpenters have developed rules of thumb, or they just do it the way they were taught."

In my case....the overlap was 4'...a crap load of nails....but I also used some bolts.

Daniel.....please confirm one way or the other....I was told that bolts are better than lag screws in that you can get more force with the bolt.....so I used 4 3/8" bolts on each overlap....two at the end...2 near the splice....rest with nails using the patern you described. I did not use glue.
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Old 08-22-2011, 12:16 PM   #8
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Floor Joist Whacked Off At The End


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Did it look something like this?



That 'was' my bathroom a few years ago...cracked shower pan....etc...over 2" of drop....

Your doing the right thing by pulling it all out and doing it right. That was what I did.



As Daniel said, a lot of variables and then there is "Carpenters have developed rules of thumb, or they just do it the way they were taught."

In my case....the overlap was 4'...a crap load of nails....but I also used some bolts.

Daniel.....please confirm one way or the other....I was told that bolts are better than lag screws in that you can get more force with the bolt.....so I used 4 3/8" bolts on each overlap....two at the end...2 near the splice....rest with nails using the patern you described. I did not use glue.
Holy crap! No, not quite like that. Most of my damage is in the floor itself and some studs. Also a lot of mold in the walls of one bathroom because the previous owner simply covered an already damp wall with drywall and tiled over it. There's no appreciable damage to the joists, just the one they cut the end off.

My overlap is about 5.5 feet and I was going to use 3/4 inch bolts, 2 vertically roughly every 12-16 inches. I think last night when I was looking at it this ended up being 10-12 bolts depending on how I space them.

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