# Sister or Replace Floor Joists



## brando1118 (Oct 22, 2008)

Hello,
I need some basic advice. I live in a three story town home with a garage. It was built in the early 70's where as you can imagine, there are a lot of over spanned beams. I purchased the home on the cheap because it had some structural issues. The most noticeable was the 20' (two-2x12) beam that spanned my garage (lag bolted together) that failed and was sagging. It was supporting two stories and the roof line and was fractured years before I bought the place. It is now supported by a steal I-Beam that spans its entire length and is not an issue. What is an issue is the joists that were attached to the 2x12 beam for all those years while it was fractured. They are permanently sloped. This was not a real issue until I wanted to remodel the kitchen. Now I need to get the floor straight. My kitchen is directly above my garage so the photos are from the garage looking up at the floor of the kitchen and the subsequent joists. The kitchen floor joists are 2x10 boards and span ~14'. Some are doubled up because there is a load bearing wall in part of my kitchen. My question is this: Should I replace the joists or sister them? I want to replace them, but one end of the joists run over the garage door header and are part of the exterior wall. I realize that the bottom wall plate of the second story is probably nailed into these joists on the exterior wall so I'm hesitant to wrangle them out. Additionally there is blocking where the joists attach on the exterior wall for support(see pic with the white wall visible). I really want to remove the old joists and get some fresh, laminated 2x10's in there. What am I in for if I try to remove these joists while they are part of the exterior wall? Obviously I would replace one joist at a time. The other end of the joists are notched over a 2x4 and toe nailed into the old, fractured beam so that side will not be a problem. I've removed everything but the subfloor and will be removing the subfloor to do the joist work, so please consider your response with the subfloor removed. Thank you for reading my long post!!


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## Termite (Apr 13, 2008)

I say get them out of there since they're all warped. You're removing the subfloor, so you should be able to easily replace a couple at a time. Your walls are resting on the joists, but the rim joist will remain in place so it will provide adequate support while you're replacing the joists. Be sure to toenail the joists to the rim and to the mudsill.


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## brando1118 (Oct 22, 2008)

Thanks for the quick reply thekctermite. Is there a process or trick to removing the joists on the exterior wall other than yanking and cussing?


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## Wildie (Jul 23, 2008)

brando1118 said:


> Thanks for the quick reply thekctermite. Is there a process or trick to removing the joists on the exterior wall other than yanking and cussing?


 Chainsaw!:thumbup:


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## Termite (Apr 13, 2008)

I'd cut them off as much as possible using a sawzall. That'll leave a short block above the foundation wall (or framed wall below) that you should be able to pry out from the rim joist. Some coaxing with a hammer, chisel, sawzall, and pry bar combined with appropriate levels of profanity will probably make them come out pretty easily. You'll have to cut the nails that held the joists off because they'll be sticking out from the rim and will get in the way of the new joists' installation. There may be some nails from the wall above as well. Careful cuts with a sawzall with a long blade will cut any of the nails that get in the way.


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## Marvin Gardens (Sep 30, 2008)

I would be very careful in replacing the double joists since there is a bearing wall about it. Lots of weight there.

I suggest that you take one out at a time and have a temporary support on the other joist, then put the replacement joist in and repeat the process with the support moving to the new joist.

If you took them both out at the same time your kitchen wall might be the new garage wall.

So how bad are the door frames? Do the doors close?


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## brando1118 (Oct 22, 2008)

Wildie: Compressed air in the garage so how about an air chisel?
thekctermite: Thanks for the advice. I kinda figured as much, but I felt I needed to ask the question in case I missed out on some ancient framing secret.
Marvin Gardens: Thanks for that. Funny you should ask about my doors. When I first moved into the place with the fractured main beam, we had a really, really cold night for Atlanta. It was like 5 degrees ambient air temp in the morning. Well the whole place contracted and ended up shifting so much that the bedroom door frame settled onto my bedroom door. We were trapped! I had to break the door in half with my foot to get out of the room. Not something that seems too natural when you're in your boxers with bed head. Either that or start tying bed sheets together for the great escape out the third story window. An interesting way to wake up indeed. This was all solved with the 20' steel I-Beam that now resides directly under the still fractured, but very level, fractured beam.

Thanks all for the advice. I will post pictures of my progress, or of my house as a pile of rubble.
-B


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## Maintenance 6 (Feb 26, 2008)

Your sub floor is probably sandwiched between the floor joists and the bottom plate of the kitchen wall and runs out to the ring joist. I'd be really cautious about replacing joists. As long as they're structurally sound, I'd leave them and place new straight ones in between to level out the floor. A distance shot showing the whole floor system and where the warp is would be nice.


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## brando1118 (Oct 22, 2008)

Maintenance 6: That is correct. The subfloor is is between the bottom plate of the kitchen wall and is resting on the joists in the photo. That is why I was hesitant to just rip into it without asking questions. My plan is to cut the entire floor out all along the perimeter where the wall meets the floor. Obviously I can't get the entire subfloor off because, as you stated, it is sandwiched under the wall plate. I could sister them, but it would be great to replace them. With my configuration, is this not possible?


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## Termite (Apr 13, 2008)

It's possible and isn't all that big of a problem. Just cut the floor sheathing a few inches from the wall and leave it in place, because the floor was decked before the walls were built. You can piece in plywood as necessary after new joists are put in. Just do a couple joists at a time and you'll be just fine.


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## bjbatlanta (Jul 16, 2008)

I tend to agree with Maintenance6. The easiest and safest method is to jack up the sagged joists as best you can and add another on the side. (Glue and nail.) Two stories and a roof load above is a lot of weight to be playing around with.


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## brando1118 (Oct 22, 2008)

thekctermite: I was planning on cutting the sub floor out flush with the wall because I was going to replace the subfloor with a thicker plywood. The builders went cheap and the subfloor wood used currently is thin and flimsy. So you recommend to leave a few inches of the old plywood throughout the perimeter of the kitchen, or just on the wall where my joists are joined? Should I leave a small gap beetween the old and new plywood to prevent squeaks? 
Thanks,
-B


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## Marvin Gardens (Sep 30, 2008)

brando1118 said:


> thekctermite: I was planning on cutting the sub floor out flush with the wall because I was going to replace the subfloor with a thicker plywood. The builders went cheap and the subfloor wood used currently is thin and flimsy. So you recommend to leave a few inches of the old plywood throughout the perimeter of the kitchen, or just on the wall where my joists are joined? Should I leave a small gap beetween the old and new plywood to prevent squeaks?
> Thanks,
> -B


You can cut right up to the edge of it.

As for squeaks you should glue and screw it to the diagonals. Use lots of glue and make sure the screws are long enough to get through the subfloor and the diagonals. Short screws will only get a little bite and will not do the job.

This will create kind of a plywood with many different layers of wood all glues together.

I have an old creaky home with lots of squeaks and this has worked well and I no longer have squeaks in rooms that I have redone.

Just be very careful when working around the bearing wall and the joists below it. I can't stress how dangerous this can be if you don't do it right. There is a lot of weight on there and if it fails it could be a catastrophic failure if you are not careful.


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## Termite (Apr 13, 2008)

I agree with Marvin Gardens about the plywood. If it is a different thickness than the 3/4" you'll be putting down, cut it flush to the face of the studs. 

As for weight, loads, and danger...
I'm always an advocate for safety and prudence when doing work on a structural element of a home...
But...
Your rim joist isn't being removed, and it is sitting on the foundation and your walls sit on it. It will adequately support the loads from above for the period of time you'll be doing this, and should have no trouble doing so, provided you only remove and replace a couple joists at a time. Your rim is 2x material. Removal of your joists for a short period of time is no different than a house framed with I-joists and a rim board...The I-joists have basically no resistance to loads from above (they crush), so the rim joist does all the work of supporting the loads from the walls. Sometimes squash blocking (vertical 2x4's) is added to beef things up, and you could certainly do that as a precautionary measure during demolition.


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## brando1118 (Oct 22, 2008)

Thanks guys,
I' going in this weekend armed with knowledge and extra caution. I will be very cautious with the area of the floor that has the load bearing wall. I will be using plenty of wall jacks and 4x6's to support the surrounding areas.
Thank you all for your time and advice. I will post pictures of my progress.
-B


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## brando1118 (Oct 22, 2008)

Hi guys,
Well, I got the first joist out. 
thekctermite: You were right. It was not difficult at all and the house is still standing.
Marvin_Gardens: I've got wall jacks under the remaining joists that have the load bearing walls. 
I am going to double up the 2x10 non load bearing joists and triple up the 2x10 load bearing joists. I would like to use the bracket in the photo below to mount my joists to my beam. I would be using the double bracket, I just had this laying around. Will a double bracket like the one if the photo be strong enough to support the joists? I also included so other pics. 
Thanks again for all the advice.
-B


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## Marvin Gardens (Sep 30, 2008)

Joist hangers will do the job. Just make sure you get tico nails because they have more sheer strength that regular nails and are designed for hangers. You can mix those with regular nails.

I suppose there is a thing as having too many nails in a hanger nails but lots is good in my book.


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## brando1118 (Oct 22, 2008)

Thanks MG,
Didn't even know Tico nails existed. Will do exactly as you stated. Checked out your photo of the beautiful addition you built. Really really cool.
Thanks for the response and the advice!
-B


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## Termite (Apr 13, 2008)

If your joists are sitting on the mudsill (the plate that sits flat on the foundation) then joist hangers are unnecessary. If the joists have a couple inches of bearing then a few nails is all that's needed. 

If the joists don't have adequate bearing in some places then joist hangers are appropriate. 10dx1-1/2" tico nails are appropriate for use in the face nails, but the toenails that go in the side of the hanger diagonally through the joist must be full length 10d nails, not tico's.


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## brando1118 (Oct 22, 2008)

Thanks thekctermite. Understood!!
-B


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## brando1118 (Oct 22, 2008)

Hi guys,
Built and installed my first beam today. Only 10 more to go!


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## Termite (Apr 13, 2008)

Isn't working with wood fun?!?!? Looks like you had pretty good success. :thumbsup:


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## Lansing (May 8, 2008)

This is your proof that doing a job right the first time is the way to go...

I can see this one is going well and when its finished you will never have to break your bedroom door down to escape the ...wife ? as it looks from your pictures that you got things going right and level...Good advice here and good luck on the project...Just carefull cutting/nailing near the electic wires...


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## davitk (Oct 26, 2008)

You likely already completed your project, but I just wanted to point out that that original subfloor was also a membrane, tying the outside garage wall to the house. During re-assembly, bear in mind to adequately fasten that new assembly to the old wall(s). :thumbsup:


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## Termite (Apr 13, 2008)

davitk said:


> You likely already completed your project, but I just wanted to point out that that original subfloor was also a membrane, tying the outside garage wall to the house. During re-assembly, bear in mind to adequately fasten that new assembly to the old wall(s). :thumbsup:


Can you elaborate a litte? The 3/4" floor sheathing somehow ties the garage wall in?


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## brando1118 (Oct 22, 2008)

Hi all,
Another newbie question: Do they make triple board joist hangars? I plan on tripling the joists under my floor where the load bearing wall resides. What would be the best way to attach a beam of three 2x10's to the 2x12 beam if there is no such thing as a triple board joist hangar?
Thanks,
-B


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