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    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #1

    Dec 9, 2009, 08:21 PM
    How to Shore up floor Joists?
    My living room dining room have hardwood floors. When you walk across them, the furniture shakes. I though this was because the truss work underneath wasn't enough, I put another row of the X's about 4 feet from the other truss work. That shaking still happens. I realize now the floor isn't shaking side to side, it is shaking up and down.

    Does anyone think doubling up the 2x7 joists in the basement might stiffen the floor system a little more? The joist there are about 15 feet from the center heavy joist to the cinder block. I thought if I got the same joist wood and screwed the two together, tight up against the plywood subfloor, it would reduce the rumble effect.

    I am thinking doubling up 4 joists might solve the problem.
    JazMan's Avatar
    JazMan Posts: 219, Reputation: 14
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    #2

    Dec 9, 2009, 08:47 PM
    Hi Luke,

    Sistering the joists is one of the ways to stiffen the floor, and will make a big difference. Another way is to build a supporting wall under the room near the center of the span. Please double check the type and size of the joists. (You said truss a few times, and the two are not the same.) See if you can find a stamping that tells you the species and grade. Measure the o.c. spacing and measure the unsupported span of the joists.

    Jaz
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #3

    Dec 9, 2009, 09:15 PM

    Ijust re-measured the joists. They are 2x7. I assume they are really 2x8 because I have never seen 2x7 at Home Depot. I was looking today.

    The joists are branded on the ends. The name is Weyco. The house was built in 1969. One is split the long way, one of the others I would "sister" has a lot of knots in it.

    I would try to get the highest grade wood possible. Put that in, then put the truss back in.

    There was one set of truss work 9 feet from the center column. I put another set 5 feet, but it didn't do anything to stop the shaking. That's how I knew it must be up and down movement.
    JazMan's Avatar
    JazMan Posts: 219, Reputation: 14
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    #4

    Dec 9, 2009, 09:21 PM
    Are you calling the X bracing trusses? Trusses are something else. Yup those are 2x8's and should measure about 1 1/2 x 7 1/4". A split joist will make the floor feel like a trampoline. How about the other info I asked for?

    Jaz
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #5

    Dec 10, 2009, 12:04 PM

    X braces.. yes, I did refer to them wrong I guess.

    The joists only have the end stamping WEYCO on them. I am not sure what you mean by OC spacing.

    The joists I would be looking to sister are 17 feet long. I would probably sister at least 4 of them. Two I can't because of plumbing.
    JazMan's Avatar
    JazMan Posts: 219, Reputation: 14
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    #6

    Dec 10, 2009, 08:19 PM
    Those X thingys are braces. They help stabilized the joists from twisting and also transfer part of the load to the adjoining joists. OC is "on center", like in how far apart the joists are. 16" is standard.

    WOW....2x8's spanning 17 ft? Are you sure that is the span with no support? For tile work those joists shouldn't be spanned any more than 10' 6" or maybe 11' 6" depends on the species and grade. 17 ft. might be un safe, and one of them might crack... oops one already did. Is this a real old home? Was it built with permits and inspections?

    Jaz
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #7

    Dec 11, 2009, 07:43 PM

    I remeasured. They span 14'6" on one side, 12' on the other. I would be looking to "sister the 14" side. But if couple of joists shore things up, why not throw in a couple more.

    There is no chance adding about 6 or 7 sister joint add too much weight to the center column is there? It is 4 2X10's supported by the cinder block and 2 metal poles 7 feet apart.
    JazMan's Avatar
    JazMan Posts: 219, Reputation: 14
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    #8

    Dec 11, 2009, 10:28 PM
    14'6" is still not even close to minimum code, don't know how that happened. The 12' side is over spanned too. Sister all you can. If you find it difficult to do them all because of obstructions, you can use smaller size lumber such as 2x6 or 2x4's. You can even use strips of plywood. Even a 2x4 screwed to the bottom of the joists making an upside down T helps.

    Jaz
    mtconc's Avatar
    mtconc Posts: 119, Reputation: 9
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    #9

    Dec 12, 2009, 09:15 AM

    Is there anyway to get a pix or two?
    That would be very beneficial in the process..
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #10

    Dec 14, 2009, 09:37 AM

    I have been trying to upload pictures somehow... I haven't been able to figure it out... Does this let us share emails?

    Based on what I am hearing I am really concerned to the point where I have moved most of the furniture out of the room until I can figure something out.
    mtconc's Avatar
    mtconc Posts: 119, Reputation: 9
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    #11

    Dec 14, 2009, 02:42 PM

    Can you put bracing under the floor..
    Like a partition,just to see if you can stop the shaking.. maybe that will
    Answer some of the questions for you. Let us know
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #12

    Dec 14, 2009, 09:01 PM

    Lets see if this works...

    YouTube - Joists in the House

    I appreciate any feedback.
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #13

    Dec 14, 2009, 09:33 PM

    I have a video of the floor joists.

    I thought I posted it before. Maybe I am not allowed to do this?

    I appreciate any help anyone can give regarding the floor joists.

    YouTube - Joists in the House
    mtconc's Avatar
    mtconc Posts: 119, Reputation: 9
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    #14

    Dec 15, 2009, 05:57 PM

    The video was a great idea! It looks like there may be some dry rot or some damage to the joist that was "peeling". You should be able to sister the joists and make a big improvement to the bounce... that is a long span for those joists.it may be easier to get a glulam beam in there.
    Maybe that could be an option as well
    JazMan's Avatar
    JazMan Posts: 219, Reputation: 14
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    #15

    Dec 15, 2009, 08:31 PM

    Go ahead with your plan an you described in the video. Remember that the mid 2/3 of the span is the most vulnerable and so try to sister at least part of the joists of those that are difficult to get to. You can use smaller dimensional lumber than the joists.

    Also consider jacking up the joists about 1/8" while you laminate and bolt the new sister. I think that method will help the new joist bare its share better.

    Jaz
    mtconc's Avatar
    mtconc Posts: 119, Reputation: 9
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    #16

    Dec 16, 2009, 04:16 AM

    Jazman I agree with you... get at least some support help to all that you can
    Good luck with the project
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #17

    Dec 16, 2009, 07:03 AM

    Thanks guys.. I am going to try to tackle some of this today. I have the new joists and will at least get 4 of them up.

    I don't have a jack, what I will do is use a 2x2 post and jam it under each end while I laminate the sister.
    JazMan's Avatar
    JazMan Posts: 219, Reputation: 14
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    #18

    Dec 16, 2009, 09:17 AM
    You have a 2x2 or preferably a 4x4, you have a car, cars have jacks. No problem.

    Jaz
    Coolhandluke31's Avatar
    Coolhandluke31 Posts: 71, Reputation: 1
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    #19

    Dec 16, 2009, 06:43 PM

    Well... I am not sure how I made out.

    I ran 4 sister joists on 4 of the first 5. I jacked up both ends with a post and I know they were tight to the floor as could be. I shimmed the ends so I know they are tight as can be to the plywood flooring also. I braced them at 7 feet, the joist is 14 feet, save 4 inches at either end to sit on the cinder block and center column.

    Unfortunately the floor still shakes. I am so disappointed. At least I know the floor is strengthened, but the shaking is still annoying.
    mtconc's Avatar
    mtconc Posts: 119, Reputation: 9
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    #20

    Dec 17, 2009, 04:10 PM

    How much "bounce" is in the floor?
    Is it just the noise or are things walkin' around?

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