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My wavy slab.

blownonfuel | Posted in Construction Techniques on July 30, 2008 06:41am

Well I’m getting ready to start doing layout on my addition and was laying out my sole plates and butting them up to the existing sole plates.

It seems my existing slab is not very level. The new slab was poured to match the one corner that is lower than the rest. But now the new slab has about a 1/4″ hump about half way down the 43′ that it runs. The end of the slab is about level with the one corner that is down.

You can see on one of the pics the shim that was used to bring up the existing sole plate. I know I will have to shim up the new sole plate on one end but should I trim my studs at the hump or not even sweat it?

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Replies

  1. dovetail97128 | Jul 30, 2008 07:06am | #1

    Trimming the studs would have taken less time then taking and posting the pictures. How much time do you want to spend on the issue?

    ;-)

    They can't get your Goat if you don't tell them where it is hidden.
    1. blownonfuel | Jul 30, 2008 04:03pm | #4

      Hello DT. Well it is my house so I would like to take my time on it. Just don't know if it will cause any problems if I don't and leave it as is.

    2. brad805 | Jul 31, 2008 02:08am | #12

      Now that was funny.

      1. User avater
        Matt | Aug 03, 2008 02:57pm | #13

        We get a lot of that here.  Collectively we spend hours typing giving a person different solutions to resolve a problem that would other wise take about 15 or 20 minutes to resolve the obvious way.  That is the nature of the beast - helping someone is often 'more funner' than actually doing some work... 

  2. User avater
    shelternerd | Jul 30, 2008 08:21am | #2

    Trim them if your using trusses

    Don't sweat it if your stick building the roof.

    ------------------

    "You cannot work hard enough to make up for a sloppy estimate."

    1. blownonfuel | Jul 30, 2008 04:01pm | #3

      Thanks Shelter. Stick building.

    2. FCOH | Jul 31, 2008 12:03am | #8

      Seriously?  The other way around for me.  Stick build I want it perfect.  Trusses you can hide stuff.

      Trim the studs.  Do it right from the start and you'll have no worries.  $60 laser from Home Depot will be the best $ you've ever spent.

      1. User avater
        shelternerd | Jul 31, 2008 12:09am | #9

        Nah, I can frame a ceiling slightly out of level and shift my birdsmouths in and out as needed and snap a line on my rafter tails to tweak the fascia back into line but the bottom of those trusses is flat and a humped up interior wall will high center them and screw up the structure.------------------

        "You cannot work hard enough to make up for a sloppy estimate."

        1. FCOH | Jul 31, 2008 12:36am | #10

          Agreed with the hump in the interior wall but I thought we were talking about exterior walls.

           

          1. User avater
            shelternerd | Jul 31, 2008 12:52am | #11

            fair enough

            be well

            m------------------

            "You cannot work hard enough to make up for a sloppy estimate."

  3. splintergroupie | Jul 30, 2008 08:41pm | #5

    In pic 3100 and 3101, there are some nail heads showing in the end of the plate. Are they holding the plate to the slab?

    Is that untreated wood? Directly in contact with concrete?

    1. blownonfuel | Jul 30, 2008 09:50pm | #6

      Hello SG. The wood is a gauge block only to show the dry line difference from one end of the slab to the other. I will be using treated lumber for the sole plates.

      1. splintergroupie | Jul 30, 2008 10:29pm | #7

        Whew! I saw the nail heads and wondered...but i'll go back to my quilting now. <G>

  4. Piffin | Aug 03, 2008 09:32pm | #14

    call to wake me up in half an hour when those satanic 666KB files finish downloading

     

     

    Welcome to the
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    Knowledge FHB Campus at Breaktime.
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  5. Piffin | Aug 03, 2008 10:00pm | #15

    still waiting, but after reading this thru, wondering what you are meaning by 'level'
    Knowing that you have one corner low, and that there is a string line there for reference, do you mean flat plane by string or is the string itself set level?

    Is that 1/4" in middle actually high from level or high from a dot to dot string line that is low at one end?

    Generally, I want my top plates level and straight. Not doing so means harder to cut and place rafters and more work trimming. Much less work to correct things on the ground than while walking plates and working off staging up in the air. Deal with a quarter inch now and you only deal with it once. But let it go now and it will chase you all the way to the ridge, forcing you to deal with it again and agaain, in rafter length or set, in tails for fascia, and in shimming windows to set in line.

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
    Excellence is its own reward!

    1. Piffin | Aug 03, 2008 10:19pm | #16

      OK, Got them now. Looks like same test block in two photos - one high on the string and one low on the string, but no ref to what is where on the foundation. 

       

      Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

      1. blownonfuel | Aug 04, 2008 06:26am | #20

        Hello Piffin. That line is a flat line, it is running from the top of the existing sole plate (existing corner of slab that is low) to the end of the new slab and fixed to the top of a temporary sole plate.Between these two points there is a hump which is about 1/4" high.

        1. Piffin | Aug 04, 2008 04:20pm | #23

          So it is flat but not level.sounds like the 'hump 1/4" is closer to level point because one end of string is low.Which means you have top decide how you want the errors in the roof to happen - how does it tie into the existing - because if one wall runs off level while the opposite runs level, then the roof ridge is going to be???if a compromise between the two, it could throw rafter lengths off. I doubt it will show much in the angle of pitch cut, but length would vary one end of building to the other.But5 if you cut or shim the wall so that both top plates end up level and equidistant, you are dealing with the same triangle on all rafters. 

           

          Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          1. Jim_Allen | Aug 04, 2008 05:12pm | #25

            In our system of presheathing, that 1/4" hump would make the far end flyup quite a bit. It wouldn't be possible to ignore it. If it was perfectly centered, it might not be real bad but if it's slightly offcenter it can really cause some problems. Bob's next test date: 12/10/07

          2. blownonfuel | Aug 04, 2008 10:48pm | #26

            Well after double checking the new slab it is neither flat or level. I took a string and ran it from the existing wall, top of the last stud (bottom of the d.t.p.) in the wall, and built a 3 stud corner at the far end of the new slab and tied the string up on top of the new 3 stud corner.I made sure the string was level from point to point. About a 1/3'd of the way down to the other end the slab is raised about 1/2" then drops back down at the far end.So here is how my slab is. At the existing wall the slab is low and the previous framer stuck a 1/4" shim under the sole plate to bring it up to the rest of the existing slab. The new slab had to be low in that one corner so there would not be a lip from old to new. The new slab should be low in that one corner then rise up gradually to the end, but it does not. it rises too far about a 1/3'd of the way down then drops back down so there is a hump. I will have to trim some studs so my top plates are flat and level.I'm thinking of making another 3 stud corner for the other corner and run lines all the way around and back to the other existing wall that I will be tying into.I posted some pics. First one is the shim under the existing sole plate. Next is the string line I ran. Next is a pre cut stud under the string at the existing wall, next is the high spot in the slab which is 1/2' high and then the last pic is at the far end corner of the new slab.

          3. Jim_Allen | Aug 05, 2008 05:05am | #27

            Don't ya wish you had checked the forms as closely as you are now checking? Keep up your program. The little bit of wasted time in the beginning will save you hours and hours later. How will you justify all this if someone measure your ceiling to floor and complains because it's a half inch less though? Maybe you should grind the floor level...then go underneath and add another 1/2" to make the slab 4" again. Just messing with you. Carry on. Bob's next test date: 12/10/07

          4. blownonfuel | Aug 05, 2008 05:21am | #29

            I just wish I had one wall up Jim. I get discouraged sometimes because I don't see stuff going up as fast as I would like.Someone on this forum once said, " if something is off and you fudge it to make it work, keep it so yourself". I'll never tell.I ended up using a water level to confirm that my string was indeed level and not sagging. The water is one great tool.

            Edited 8/4/2008 10:24 pm ET by blownonfuel

          5. Jim_Allen | Aug 05, 2008 05:25am | #30

            Well then quit fussing around and stand a wall up. Then shim everything. The results will be the same. 99 times out of 100, I've done the shim thing. If I'm locked in between two fixed concrete walls, I'll string a line...only because it only takes me one minute to do so. Anymore than that and I'm committed to shimming, which takes only minutes after everything is standing and there is weight on things. Bob's next test date: 12/10/07

  6. Jim_Allen | Aug 04, 2008 01:54am | #17

    You're just beginning to see how much fun it is merging old unlevel stuff with theoretically level stuff. It's more art than science.

    The answer might depend on how you frame. If I were doing it, we'd probably frame and sheath it all with the same length studs. When we got around to setting the wall, all the variations would expose themselves and we'd shim it where necessary to achieve a level and plumb wall.

    This might cause the entire wall to be too high in relation to the existing roof and fascia lines. Since you are conventionally cutting your roof, the adjustment is simple, just subtract some from your heel.

    Occasionally, we have been forced to use several other options. Certainly, custom cutting each stud is one of the option. I'd probably just use your string to eyeball whatever amount I needed to cut off at each stud layout and just walk down the wall taking off and eigth or a quarter or three sixteenths or whatever.

    Enjoy the ride and don't let anyone talk you out of doing it as perfect as you see fit.

    Bob's next test date: 12/10/07

    1. blownonfuel | Aug 04, 2008 06:28am | #21

      Thanks Jim, as always I appreciate your help.

  7. Jim_Allen | Aug 04, 2008 01:55am | #18

    I forgot to mention something. The fact that you are suggesting two appropriate options tells me you understand enough about what you are doing to effect a quality product. Good for you....a lot of novices wouldn't have a clue.

    Bob's next test date: 12/10/07

  8. User avater
    Timuhler | Aug 04, 2008 03:19am | #19

    Your situation has a pretty easy fix, if I'm understanding it correctly.

    We always assume on basement foundations that the concrete isn't accurate.  So we set corners shot in with a laser and then run a chalk line and cut all the studs to get a flat topplate.

    Here is a slideshow of the process http://picasaweb.google.com/TimothyUhler/Lot36Muirkirk and an article that explains it in more detail http://www.jlconline.com/cgi-bin/jlconline.storefront/489646610ec70c7827170a32100a0633/Product/View/0806fram

    1. blownonfuel | Aug 04, 2008 06:39am | #22

      Thanks Tim for your help and you understand my problem correctly. Since my slab is low on one end, a hump in the center, and "level" at the end where one of my exterior walls will run, I think the laser or chalkline method is just what I need.You web album is a big help. As they say, " a picture is worth a thousand words".BTW, i'm reading your "Plumbing and Straightening Walls" article. More great info.Thanks again.

      1. User avater
        Timuhler | Aug 04, 2008 05:11pm | #24

        I'm glad it helped.  I was taught this method with a builders level by my mentor Dave years ago.  The laser just makes it a one man job. 

         

         

  9. blownonfuel | Aug 05, 2008 05:16am | #28

    Thanks John.

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