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Thread: Expansion Joint

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    Join Date
    Jun 2011
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    Mississippi
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    Expansion Joint

    I am nearing completion of a pool remodel and trying to decide whether to use a semi-self-leveling caulk to fill the expansion joint between the coping and pool deck or to just grout it. As background, my coping is 12" by 24" bluestone and my pool deck is irregular shaped marble wet-laid on a concrete slab. I believe the marble is original to the pool. The bluestone is new. The builder did not do a very good job of preserving the expansion joint when the marble was laid. However, during the demolition process, I chipped away any mortar and grout that was filling the expansion joint and added deck-o-foam to preserve the joint when I re-laid the marble. So my question is. . . is caulking the expansion joint really necessary or can i grout it? I prefer the look of grout and have seen several pools around town that were built by very reputable builders that have a grouted joint. i realize caulk allows for expansion and contraction so if the pool deck settles or heaves, it does not apply pressure to the pool and coping. But how much resistance is a half inch deep and half inch wide grouted joint really going to offer?
    45,000 gallon IG old (1960s??) painted concrete pool; rectangular 20' by 40' with 12' deep end; one skimmer in deep, two returns in shallow
    1 HP Hayward pump; Hayward Pro Series 300 lb sand filter Model S244T
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    bmoreswim's Avatar
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    Re: Expansion Joint

    I would fill it with the appropriate flexible material and add sand to the top. It will look like grout and act like caulk.
    18'x38' Rectangle (3'-8 1/2' deep w/ diving board) - 27K gal. w/ gray plaster
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    Re: Expansion Joint

    +1 to above. It takes more abuse than you think.
    22k gallon IG pebblefina, Jandy 1.5 HP VS, Jandy CV Cartridge filter, Fafco solar panels, Polaris 360 supply side cleaner, waterfall

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    duraleigh's Avatar
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    Re: Expansion Joint

    But how much resistance is a half inch deep and half inch wide grouted joint really going to offer?
    You are missing the point of the caulk. It's job is to flex as the slabs move and keep the joint sealed. If you grout, there is no flex and the grout will crack (and allow water in) usually in a VERY short period of time. Caulk is the answer.

    You can get "sanded" caulk with sand mixed in it but it's fairly expensive and looks a bit better than plain caulk but not much.

    Use polyurethane.....and not self-leveling which is tempting but is suprisingly fickle....it goes where you don't want iot.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Expansion Joint

    Thanks for the replies. I usually err on the side of caution, so I will probably end up doing the sand over caulk. I will probably experiment on the deep end with a couple different methods and products.

    I get that caulk is designed to flex with any expansion/contraction and provide a constant water-tight seal. However, I have used caulk in many other construction applications and have been less than thrilled as to it accomplishing what it is designed to do (especially in outdoor applications), regardless of the quality. I am very curious as to why pool builders (at least around here) seem to have quit caulking the expansion joint. Perhaps it's because it is easier to simply grout the joint. If I had not seen friends' pools that are approximately five years old with grouted expansion joints and no cracks/separation, I would have never considered grout. But after seeing their pools I wonder, are they just extremely lucky and have experienced no movement and due to our mild winters the caulk has sufficed, or are the pool builders on to something.

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