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Thread: Gap between concrete and pool border

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    Gap between concrete and pool border

    This pool was built by previous owner about 5-6 years ago. This is going to be my 2nd summer.

    I have this gap around the whole pool and I believe this gap is getting bigger(or may be I just started paying too much attention to it). Guys who closed my pool last fall said they have never seen a gap like this and it must be filled otherwise pool surface my start falling. What do you guys think? Does this gap need to be filled and if so, what does it need to be filled with?

    Thanks
    Attached Images Attached Images
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

  2. Back To Top    #2

    Re: Gap between concrete and pool border

    The gap is supposed to be there. It is an expansion joint. It protects the coping from being damaged when the concrete deck expands and contracts. It should have been filled with caulk to prevent water from going through the crack.

    Based on the way the foam is not filling the entire crack, it looks like the expansion joint has gotten bigger, probably due to the deck settling due to water getting in the crack.

    All of the foam should be removed and the crack should be filled with caulk.

  3. Back To Top    #3

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    Re: Gap between concrete and pool border

    Fill it with the right size 'backer rod' (looks like there is some too small backer rod in the 2nd pic) and use a weatherproof caulk to seal the gap while still allowing for deck movement.
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  4. Back To Top    #4

    Re: Gap between concrete and pool border

    Caulk or silicone? any particular kind? do I need to get one from pool stores or home depot will do?

    Also, would there be any reason why it wasn't caulked in the first place?

    Thanks.
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

  5. Back To Top    #5

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    Re: Gap between concrete and pool border

    They make special caulks for pools (often available in different colors to better match the deck) but anything that is weatherproof and durable should work
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    Re: Gap between concrete and pool border

    Caulking comes in several viscosity grades or "thicknesses" depending on the intended use. There is "gun grade", which is intended for non-level joints. There is a Semi Self-leveling, which in thinner and flows more readily. And, there is self-leveling, which is intended for very level joints and flows easily.

    BASF/ SONNEBORN SL-1, Sonneborn NP1 Polyurethane Sealant and Vulkem #45 are some example of caulking that can be used.

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    Re: Gap between concrete and pool border

    Judging from the pixs, it looks like the original pool builder didn't finish his job. The PB didn't apply any mastic material in the expansion joints...Water has been 'pouring' in the gap for 5 or 6 years.

    A typical gap is about 1/2", but your pixs show about an 1". It looks like your deck is moving away from the pool. Is this portion of the deck adjacent to any other concrete slab/structure? What is the deck's sq. ft?

    You definitely need to seal the gap asap and prevent further movement of the deck.

    PM
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  8. Back To Top    #8

    Re: Gap between concrete and pool border

    Quote Originally Posted by JamesW
    Caulking comes in several viscosity grades or "thicknesses" depending on the intended use. There is "gun grade", which is intended for non-level joints. There is a Semi Self-leveling, which in thinner and flows more readily. And, there is self-leveling, which is intended for very level joints and flows easily.

    BASF/ SONNEBORN SL-1, Sonneborn NP1 Polyurethane Sealant and Vulkem #45 are some example of caulking that can be used.
    Thank you.

    Vulkem 45 is significantly more expensive then the other two. Is there a reason why?

    Also, I have no idea how many OZ I need and wonder how to figure that out.

    Thanks
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

  9. Back To Top    #9

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    Re: Gap between concrete and pool border

    BASF SL-1 and NP-1 are not made for high chlorine concentrated areas like pools. Read here for SL-1 http://www.basf-cc.com.sg/en/products/W ... L1_PDS.pdf and here for NP-1 http://www.basf-cc.com.au/en/products/J ... P1_TDS.pdf

    Try Sikaflex 1CSL (self leveling) or Vulkem 45 for pool coping.

    Doug

  10. Back To Top    #10

    Re: Gap between concrete and pool border

    It looks like part of my deck has moved, but I can't say when it started moving and whether it's still moving.

    This deck was build about 6 years ago.

    Attached are some more pictures with questions embedded.

    Thanks
    Attached Images Attached Images
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

  11. Back To Top    #11

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    Re: Gap between concrete and pool border

    Yup, the deck has been moving.

    The areas you point to aren't an issue, for now. The deck seams (control joints) are supposed to do that , or, at least, that's why they are there and the skimmer gap is a result of the deck moving and is above the water level, so isn't going to cause you issues at this time.

    Would it be better if this wasn't happening? - YES! But, I think your builder didn't let the ground reach ~ full compaction before pouring the deck While it's not a problem now, the freeze/ thaw cycle will only exacerbate the cracks as the years go by
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  12. Back To Top    #12
    maxepr1's Avatar
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    Re: Gap between concrete and pool border

    Looks like damage from winter heaving? Is it just that one area? Or all the way around?
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  13. Back To Top    #13

    Re: Gap between concrete and pool border

    Quote Originally Posted by maxepr1
    Looks like damage from winter heaving? Is it just that one area? Or all the way around?
    a couple sections - only what's on the attached pictures
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

  14. Back To Top    #14

    Re: Gap between concrete and pool border

    Another question - the joint on the first set of pictures is about 3-5 inches deep, filled with the backer rod or whatever that foam like material is called.

    I read somewhere someone fill it with sand. Is that the right approach, maybe with backer rod on top?

    Or should I just get backer rod about 25% wider then the gap and stick it in on top of existing one pushing existing one down?

    Also, I guess the backer rod should be about .25"-.5" below the surface, leaving that .25"-.5" space for the caulk. correct ?


    The areas I point out with arrows on the 2nd set of pictures - Will the water getting behind the deck seam cause a problem?
    If so, should I could vacuum around the deck seams and caulk there?

    Thanks.
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

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    XsAllOverIt's Avatar
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    Re: Gap between concrete and pool border

    On the bottom of this page:

    http://www.poolcenter.com/service_suppl ... pplies.htm

    There is a good explanation on how to caulk. Get rid of all of the material in the cracks, place backer rod and caulk.
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    CUTiger78's Avatar
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    Re: Gap between concrete and pool border

    Here's what I'm going to try this year - Natural Pool Masticâ„¢ AKA Santastic.

    Here's the web site - http://www.santasticpoolmastic.com/

    Looks like it's easier to use than caulk and you fill most of the gap with sand instead of backer rod. I've got a friend who went the traditional way last year (backer rod, caulk) and he's had some failure, with caulk pulling away from the sides in less than a year.

    Haven't done it yet - just recovering from knee surgery, so I'm not up for a lot of kneeling yet. And this is a down on your hands-and-knees job....

    I'll report back after I've done the work.

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