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Hairline grout cracks

WillieWonka | Posted in General Discussion on February 10, 2007 04:15am

I’ve not had a tile job before where the grout lines hairline cracked….until now. I did a very large floor, it had oak floor joists (2×8) that spanned 12 feet 24″ o.c.. Over top the floor joists it had 3/4″ TG floor boards (original to the house). I put over top of these floor boards Luan in order to even out the floor some, then I put 3/4″ Advantech on top of that followed by 1/4″ Hardibacker. The floor was solid to me. The floor is rectangular shaped at 12′ x 22′. The floor was fine back in October when I did it. There was no heat in the house until December and there were a number of cold snaps that occurred in between. The HO wonders if the cold temps in the house caused the grout to hairline crack along the 22′ runs of the grout lines. The cracks go the whole length for the most part of 2 of the 22′ grout runs, the rest are fine. The cracks occur along the sides of the tiles where it meets the tile, it “separated” from the tiles is kinda what it looks like. In a few places the crack traverse the grout line and then cracks on the other side of the adjacent row of tile, making the grout appear to have a crack across the width of the grout line. It is sanded grout with 1/4″ grout lines.

I don’t want to think of chipping out the grout, I’d be there foreever. I am wondering if I get the same grout and literally water it down so it’s nice and runny if it’d be enough to cause it to flow into the cracks and close them up. The grout was sealed by the way with the Spray and Seal sealer. Or what else would work to make the cracks go away?

If at first you don’t succeed, try using a hammer next time…everything needs some extra persuasion from time to time.  -ME
Reply

Replies

  1. User avater
    EricPaulson | Feb 10, 2007 05:40am | #1

    The cracks are there to stay,

    I think the floor is over spanned for the size and length of the joists.

    I also believe that you put a whole lot of useless material on top of the joists, but according to some, that may be debatable.

    I would have put 3/4 cdx, yellow glued down, with about 5000 screws. Tile over that with top shelf Mapei thinset.

    Conditions may have also played a part in it as well as you suggested. Cool for so long then the shock of heat and lower humidity.

    Scratch it out. Use latex additive and make a thick strong mix, pack the hell out of the joints and hope for the best.

    [email protected]

     

     

    It's Never Too Late To Become What You Might Have Been

     

     

     

    1. DanH | Feb 10, 2007 07:29am | #5

      Yeah, using a good additive might have prevented this. And the grout may have been a hair too wet.
      So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin

  2. User avater
    BillHartmann | Feb 10, 2007 06:30am | #2

    Good excuse to get a Fein Multi-master.

    I only got to remove a couple of inches of grout with one at a company demo, but it really took it out quickly.

    .
    .
    A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
    1. andybuildz | Feb 10, 2007 07:18am | #3

      and if he can't afford the Multimaster ...Rotozip makes a grout remover too for a lot less $$$$$.

      Greek poet Archilochus said: "The fox knows many things, but the hedgehog knows one big thing"!  From The Hedgehog & The Fox ~~~~ An essay on Tolstoy's view of history ~~   by Isaiah Berlin

       

      http://WWW.CLIFFORDRENOVATIONS.COM                                   

       

  3. andybuildz | Feb 10, 2007 07:21am | #4

    You sure you didn't make the grout mix too watery to begin with? that'll make for cracking more times than not. Too much water is what weakens any mix.

    Greek poet Archilochus said: "The fox knows many things, but the hedgehog knows one big thing"!  From The Hedgehog & The Fox ~~~~ An essay on Tolstoy's view of history ~~   by Isaiah Berlin

     

    http://WWW.CLIFFORDRENOVATIONS.COM                                   

     
    1. WillieWonka | Feb 10, 2007 08:43pm | #12

      I made the grout like wet sand. It wasn't runny or anything like that and it was stiffening as I went along. The occasional stir loosened it up some but it wasn't runny at all.If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME

  4. User avater
    SamT | Feb 10, 2007 08:44am | #6

    2x8x12' (oak) 24" OC

    Topped with

    • 3/4" (oak?)
    • 1/4" ply
    • 3/4" Advantech
    • 1/4" CMU
    • 3/8" tile

    Dead load of just the flooring feels like about 30# to me. I dunno, it sure seems overspanned, which will crack grout in a heartbeat, not to mention popping tiles. Even if that's 2 full inches by 8 full inches.

    SamT

    Anyone who doesn't take truth seriously in small matters cannot be trusted in large ones either. [Einstein] Tks, BossHogg.

  5. IdahoDon | Feb 10, 2007 08:48am | #7

    The joists may or may not be a factor, but what caught my eye was the 22' run without an expansion/contraction joint.  The tile will expand and contract at a different rate than wood does so something has to give.  The comment confirming a wide temperature swing prior to the cracks adds fuel to that idea.

    Had there not been a wide temp swing, the grout may still have cracked.  Regardless of what else is done, adding a sanded caulk joint matched to the grout color halfway across the longest run is a good idea.  You'll want to take out all the grout along the caulk line.

    Unfortunately, if it's been sealed there is very little that will stick to the surface.  However, you don't have anything to lose by going over the grout lines, although it's probably delaying the inevitable.  No need to water down the grout, simply rub it into the cracks with a good deal of pressure.

    It would be much better functionally to open up the cracks with a grout removal tool of some kind and regrout from there.  Of course the ideal situation, and probably the only thing that will result in good cosmetics, is to clean out the cracks and reduce all the grout to well below the surface and regrout.

    Good tiling

     

    Beer was created so carpenters wouldn't rule the world.

  6. mattt19 | Feb 10, 2007 09:59am | #8

    Check out the deflecto at -http://www.johnbridge.com/vbulletin/deflecto.pl

    1. User avater
      EricPaulson | Feb 10, 2007 04:16pm | #9

      Sam T mention an expansion joint which possibly would be called for given the long run of 22ft.

      One thing I forgot in my post last night was to verify the location of the crack.

      My guess is that the crack runs perpendicular to the joists, somewhere about midspan.

      You didn't spec tile and grout size either did you?[email protected]

       

       

      It's Never Too Late To Become What You Might Have Been

       

       

       

      1. andybuildz | Feb 10, 2007 04:21pm | #10

        My guess is that the crack runs perpendicular to the joists, somewhere about midspan.<<<<<<<My guess is its over a crowned FJ...Loveeeeeeeee TJI's and Advantech. Glued and screwed....30' over my garage..oh yeh..sorry to change the subject...welll.I didn't change it that much : )

        Greek poet Archilochus said: "The fox knows many things, but the hedgehog knows one big thing"!  From The Hedgehog & The Fox ~~~~ An essay on Tolstoy's view of history ~~   by Isaiah Berlin

         

        http://WWW.CLIFFORDRENOVATIONS.COM                                   

         

      2. User avater
        SamT | Feb 10, 2007 05:54pm | #11

        Idaho Don mentioned the expansion joint, and I believe the OP said sumpin 'bout the crack being perp to the joists and about midspan(|:>)SamT

        Anyone who doesn't take truth seriously in small matters cannot be trusted in large ones either. [Einstein] Tks, BossHogg.

      3. WillieWonka | Feb 10, 2007 08:47pm | #13

        The cracks run perpendicular to the joists as you suspect, almost the full length of the 22' run of the lines.

        I've never seen an "expansion" joint in a tile job before. I've walked in on a lot of huge tile jobs bigger than this, never saw one and never heard of having to add one. What would it look like for a tile job?If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME

        1. User avater
          EricPaulson | Feb 10, 2007 08:55pm | #14

          I've never seen an "expansion" joint in a tile job before. I've walked in on a lot of huge tile jobs bigger than this, never saw one and never heard of having to add one.

          What would it look like for a tile job?

          Butt ugly if you ask me. Not sure one is needed here as you crack is perp to the short dimension.

          Go to a mall or a large supermarket with a tile floor and you wil likely see one.

          Not typical for residential use.

          I think you just have and overspanned joist issue.

          If you cleaned out the joint thoroughly and put in a flexible matching caulk instead of grout would they buy it?

          Maybe the only way out.

          Can you add support midspan under the joists?

          Eric[email protected]

           

           

          It's Never Too Late To Become What You Might Have Been

           

           

           

        2. User avater
          BillHartmann | Feb 10, 2007 10:23pm | #16

          Here are some types of expansion joints..
          .
          A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

        3. IdahoDon | Feb 12, 2007 09:12am | #21

          I've never seen an "expansion" joint in a tile job before. I've walked in on a lot of huge tile jobs bigger than this, never saw one and never heard of having to add one. What would it look like for a tile job?

          You don't see them because if the sanded caulk is well done it blends almost perfectly with the other grout.  If you've never heard of one, well, I can't help you there other than to say you should have.  It's basic tiling.

          Good luck. 

          Beer was created so carpenters wouldn't rule the world.

  7. user-69050 | Feb 10, 2007 09:46pm | #15

    Don't mean to step on any toes, but since this is my trade I feel I need to mention this.

    Was the Hardibacker bedded in thinset and the joints tape per manufacturers specs? Expansion joints have always been called for in a tile installation. If the room is small, then a 1/4" gap along the room perimeter. When the room becomes larger, then every 20' to 25' in each direction. Interior tile work exposed to direct sunlight or moisture is 8' to 12' in each direction. the other change lists for it to occur in the backing materials. These were taken from the 2005 TCNA Handbook that shows the only changes made in that year were to the expansion joint distances. This is the latest handbook published. The next one is due this spring.
    Jim Carlin

    1. WillieWonka | Feb 10, 2007 11:52pm | #17

      The backer was set in thinset.If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME

      1. user-69050 | Feb 11, 2007 12:42am | #18

        Thanks, it sounds like movement to me. I had a similar incident with hairline cracking as you described. I was attributed to underlayment movement along the edges of the panels. Had to remove the tiles and correct the problem. Hope this is not the case for you.
        Jim

        1. WillieWonka | Feb 12, 2007 05:46am | #19

          FYI, I found the problem tonight and it's pretty ugly. I had the HO walk around on the floor while I went in the basement and watched the floor joists. Stupid me, this is my fault. the joists are in an old home and they were set on top of a stone foundation wall with a few rock shims or wood shims underneath the joist bottoms to level out the floor. The joists range from 2x8 to 2x10 full dimension. Well the shims aren't doing the job they need to do. I saw joists deflecting on top the stone wall almost a 1/4" if not  more. No wonder there were cracks. The HO is going to put a post under each joist to stabilize it and sit the post on a concrete pad. This will prevent the deflection on the ends of the joists.

          When I inspected the floor before the job I never thought to look at the ends of the joists to be sure they were properly secured. If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME

  8. User avater
    Fonzie | Feb 12, 2007 06:36am | #20

    I'm asking not teaching - would this have been a place for the isolation membrane Detra?

    We used it once when tiling a small area over treated wood on a screened porch floor - worried about excessive wood movement. Could that be it here?

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