Sagging 2x6 joists on a 17.5' span


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Old 02-20-06, 10:12 AM
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Sagging 2x6 joists on a 17.5' span

I recently removed a water stained and ugly ceiling in my living room. The intent of this is to: 1) relace the ceiling and 2) prep the floor for a bathroom remodel. I intend to replace an existing fiberglass surround with a cast iron claw foot tub and tile the wall of the tub and floor of the entire bathroom. I have also removed the entire floor (except under the old tub and sink) from the bathroom all the way to the joists. So basically one half of the living room has a great view of the upstairs.

The tub sits in the dead center of the house parallel to a partition wall. I realize the existing 2x6joists are undersized. The floor has a serious sag, a couple of the joists were cut 2/3 deep from the top to make way for plumbing and one (at the opposite side of the room) was cut in half (missing an 18" peice) for no apparent reason. This last one is the major cause of the sag. I intend to sister these joists but would like to use 2x8 or use 2 laminated "I" beam to support under the main weight of the new tub and sister the rest. How can I jack the floor then intall larger floor joists? If I tack the new wood in then jack, it seems like this would only apply pressure to the new wood and not correct the sag in the old wood. Then the floor on the other side of the wall (which is still in place built with 1" T&G with maple on top) will basically just get tweaked. Can I attach the new wood at the low point of the sagging joists and jack staight up until the ends match? This seems kind of sketchy.

I do have the option of adding a cross beam to the floor to reduce the span but would rather not as this would not work so great with the layout of the brick hearth in the living room.

Do the sistered joists need to reach all the way to the outside load walls?
 
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Old 02-20-06, 02:33 PM
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There are several different ways to address this problem. First of all your 2x6 joists are way under the required strength. You are right on the edge of 2 x 12's being undersized. I am going to have Doug answer this for you since he is a Residential Building Designer, and I think that is what you need now.
 

Last edited by Doug Aleshire; 02-20-06 at 03:44 PM.
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Old 02-20-06, 03:20 PM
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sheamuson,

The problem, as I am understanding it, is that there is no way to just sister these existing 2x6' with larger stock and expect it to hold what you are intending for a load. This is just to high a risk for more issues to follow. Particularily with a claw foot bathtub - the load is not dispering laterally to avoid the point loads and there is nothing below to help in this endeavor.

As Jack mentioned, you are way over spanned for little 2x6s and even using 2x12's is at a point of its limitations. You definitely need a new plate line!

I only know one dimension of 17'-5" but what is it the other way? This is where you need to do some beam placement. Possibly install 2 or 3 beams - wrap them to enhance the appearance yet be sufficient to keep the floors level and solid. This is most important as you are mentioning tiling the walls and floor! You cannot have any movement within this room and if the bathroom is dead center over the living room, you have no choice.

Other option is to install TJI's - this would involve allot of work but these could be an alternative to using beams. Based on the 17'-5" span, you need to use 11 7/8" Series 210 MINIMUM for 16" O.C. placement. The issue here is that you would have to literately tear out all the ceilings and walls within the living room, create a new top plate at the correct level. This is the extreme case!

The beams would be better but depending on existing ceiling height, and the size of the beams used, it will intrude more than I care to say, down from the ceiling.

Another idea is to purchase TOP LOAD floor trusses - these could be done but issues as far as getting them into place can be an issue. I have done this but it requires some good planning nd manpower. It would provide great stability, would not be to intrusive from the ceiling down - meaning reduced ceiling height but minimal.

Finally, a ledger, placed within the living room perimeter - at least 2-2x10's bolted and nailed to existing wall studs, that could placed directly under the TJI's. These could have solid blocking placed 16" O.C. so you could nail the existing 2x6's to the TJI's. The TJI's would go from wall to wall. The 2x10's could be wrapped with drywall to create a small trayed ceiling look yet take care of the issues above. This method might be best of all. If you have any knowledge of baloon framing, this is a version of that. Difference is we are not notching the wall studs for a continuous let-in ledger. I am not recommending that due to current Codes and what may not be allowed. I am assuming that you have a 2 story and 2x4 exterior walls.

You have to make the choice of what you need to do here before going any further with you project.

I would suggest getting a building permit for this.

Hope this helps!
 

Last edited by Doug Aleshire; 02-20-06 at 03:44 PM.
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Old 02-20-06, 04:32 PM
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Sheamuson,

You have many options that have already been mentioned but the bottom line is that you need to have an Architect or Engineer to come out there and look at your house. Just have in mind that if you sister taller joists along side these that will raise your floor height and that means you will have to change your stairs.

There was a job one time when doing and add-a-level where the new joists were 2x12' and the existing ones were 2x6's and the stairs couldn't be changed so we made an area at the top of the stairs that was the landing when you walked up and then stepped up a 4" step around the perimeter to the hallway. It's just a solution if you can't move the stairs.
 
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Old 02-20-06, 09:54 PM
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sheamuson,

I just want to clarify something, as Joe mentioned something that I would not entertain.

I am not suggesting raising your second level floor. It is not an option I would entertain in your case at all.

I too agree with Joe that raising a floor leads to other issues that are not appealing and that you need a professional to look at what is there and get plans drawn for a building permit.

Just wanted to make it clear what I was referring to in my post.
 
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Old 02-21-06, 06:35 AM
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Originally Posted by Doug Aleshire
sheamuson,

I just want to clarify something, as Joe mentioned something that I would not entertain.

I am not suggesting raising your second level floor. It is not an option I would entertain in your case at all.

I too agree with Joe that raising a floor leads to other issues that are not appealing and that you need a professional to look at what is there and get plans drawn for a building permit.

Just wanted to make it clear what I was referring to in my post.
Thank you Doug, Joe and Jack all of your ideas are good ones. I have zero intention of raising the floor beyond original elevation. I am leaning toward using 2 cross beams. The room is ~12' across. One one side is my wood stove with a brick hearth (center of the wall) with the entrance to the kitchen to one side. This is the original outside wall of the house. I would put the beams to either side of the hearth. On the other side of the room is a partial funky faux brick wall with turned posts that basically divides the downstairs into 2 living rooms. This wall has a noticable sag in the center of it as well. It is built under the joists which was not doubled here either. But the celing in the other room is fine. Just a bedroom with new pine plank floors and seems ridgid enough.

My original intent was to lift the floor, sister it and replace this faux brick with an exposed 8x8x10 with 2 6x6x8 posts to support this portion of the house. Now if I put 2 beams (3 bolted 2x8x12) across the room how can I tie these into the dividing wall and 8x8? The crosses will not line up even with the beam supporting uprights.

The celings are 8' at bottom of joist so there is room for cross beams, but not lots. If I was to do this I could eliminate my worries of how to sister with larger lumber and just use 2x6, correct? and with this technique could I use shorter length lumber and join at the cross beams? This would make sistering a lot easier.

How would I install uprights to support these. There is a carrying beam below both of these locations in the basement. Do I set uprights on the floor and block in the basement or go through the floor onto the beam in the basement?
 
 

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