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Thread: Expansion Joint vs. Control joint between cantilever coping and pool deck

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    Expansion Joint vs. Control joint between cantilever coping and pool deck

    Is it ok to use a sawn in control joint between cantilever concrete coping and the rest of the pool deck instead of an expansion joint?
    Thanks! Tim
    Tega Cay, SC
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Any concrete pros in here? Pool will be enclosed by screen, need to know best place for deck drains as well.
    Thanks! Tim
    Tega Cay, SC
    2016 build 16x32 polymer IG-Speck BaduMV 2.4 hp variable speed pump-individually run 2" plumbing-4 returns-1 skimmer-Doheny Discovery robot-
    jetted bench-Pentair Clean and Clear Plus 420 cartridge filter-Circupool RJ60+ SWG-Hotspot FPH heater

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    Mod Squad pooldv's Avatar
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Edit: I would prefer an expansion joint with some Sikkaflex in it. Just to minimize movement across the top of the bond beam and the top of the tile line. But, I'm not sure it is needed on a cantilever deck. Deck drains depends on elevations and grade. We'd need more info or pics to help on that. I'm sure some more folks will be by.
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Whoa Nelly!!!!!!

    Generally a poured cantilever deck is poured over the bond beam in such a manner that it moves freely. That way it does not need an expansion joint. around the pool. One would cause more problems than it would solve. Have you talked to a structural engineer or a concrete pool deck guy about this or are you doing this yourself?

    Generally you want the soil and rock under the deck next to the pool to be well compacted to the same level as the bond beam so the deck structure will slide over the bond beam.

    Read this article:

    Problems Due to Concrete Decks
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    Mod Squad pooldv's Avatar
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    That's a nice article.
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Quote Originally Posted by gwegan View Post
    Whoa Nelly!!!!!!

    Generally a poured cantilever deck is poured over the bond beam in such a manner that it moves freely. That way it does not need an expansion joint. around the pool. One would cause more problems than it would solve. Have you talked to a structural engineer or a concrete pool deck guy about this or are you doing this yourself?

    Generally you want the soil and rock under the deck next to the pool to be well compacted to the same level as the bond beam so the deck structure will slide over the bond beam.

    Read this article:

    Problems Due to Concrete Decks
    I have seen that article but it appears confusing. You say no expansion joint is needed but the diagram appears to indicate an expansion joint between the coping and the deck.
    My PB wants to pour once and cut control joints, including one where an expansion joint might go between the coping and the pool deck. I want to use 6" concrete with rebar in the deck
    which would be thicker than that of the coping.
    Tega Cay, SC
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Doh! Just noticed the CANTILEVER diagram...
    So control joint after cantilever coping? Or just normal control joints in the deck? Pool is Vinyl liner.
    Tega Cay, SC
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    An expansion joint is not a control joint. Control joints provide weak spots in the slab to allow cracks to occur (control cracking). An expansion joint or isolation joint provides an area of "cushion" to allow movement of the slab through expansion/contraction to not push on the structural pool shell.

    If you do typical coping, the expansion joint must be between the deck and coping for the entire vertical distance between the two. If you go with a cantilever deck (no coping), the expansion joint is between the deck and top of the bond beam for the entire horizontal distance.

    At no time should the slab extend below the top of the bond beam, and if it does, the expansion joint needs to extend into that area as well.
    -Brian-
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    /\/\/\ What Brian said
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Quote Originally Posted by gwegan View Post
    /\/\/\ What Brian said
    Thanks, Guys! How far apart should the control joints be cut? Do you have recomendations on the thickness and strength of the concrete? Rebar or mesh?
    Pool will be cantilever concrete with vinyl over polymer walls.
    Thanks again.
    Tega Cay, SC
    2016 build 16x32 polymer IG-Speck BaduMV 2.4 hp variable speed pump-individually run 2" plumbing-4 returns-1 skimmer-Doheny Discovery robot-
    jetted bench-Pentair Clean and Clear Plus 420 cartridge filter-Circupool RJ60+ SWG-Hotspot FPH heater

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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    Placement of control joints has a lot more to do with the contours and shape of the slab then actual spacing. Cracks always occur at the weakest point with is the thinnest and narrowest portion of the slab.

    3.5"-4" is typical thickness for slabs and should never be less than that. The thicker the better, in fact I'd opt for a thicker slab with a lower PSI mixture than a thin slab with a high PSI mix.

    Rebar is required in a 12x12 grid in the immediate area 36" around the pool as an equipotential bond grid. Beyond that rebar can be spaced 24"-36" if at all. Rebar does not prevent cracks in slabs (sometimes it causes them) but does prevent the slab from separating and/or rising from hydrostatic pressure. Some like to use wire mesh, I do not.
    -Brian-
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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    I'm thinking about 5-6" of concrete around the deck with rebar supported to the middle of the slab. I'm concerned,however, that the cantilever mold is only about 3.5". Would this create a weak point between the cantilever and the rest of the deck?
    PB told me that the pour would be done all at once and everything tied together and not moving. He said there is no bond beam since this is not a gunite pool (has polymer walls). Need advice, know just enough to be dangerous...

    QUOTE=bdavis466;1143069]Placement of control joints has a lot more to do with the contours and shape of the slab then actual spacing. Cracks always occur at the weakest point with is the thinnest and narrowest portion of the slab.

    3.5"-4" is typical thickness for slabs and should never be less than that. The thicker the better, in fact I'd opt for a thicker slab with a lower PSI mixture than a thin slab with a high PSI mix.

    Rebar is required in a 12x12 grid in the immediate area 36" around the pool as an equipotential bond grid. Beyond that rebar can be spaced 24"-36" if at all. Rebar does not prevent cracks in slabs (sometimes it causes them) but does prevent the slab from separating and/or rising from hydrostatic pressure. Some like to use wire mesh, I do not.[/QUOTE]
    Tega Cay, SC
    2016 build 16x32 polymer IG-Speck BaduMV 2.4 hp variable speed pump-individually run 2" plumbing-4 returns-1 skimmer-Doheny Discovery robot-
    jetted bench-Pentair Clean and Clear Plus 420 cartridge filter-Circupool RJ60+ SWG-Hotspot FPH heater

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    Re: Expansion Joint vs. Control joint between cantilever coping and pool deck

    That would be a weak point since the slab thickness is essentially being cut in half.

    While you don't have an actual gunite bond beam, all pools have extra reinforcement at the top of the walls. View a pool no differently than a paper cup... The walls are thin but extra reinforcement is placed at the bottom transition between the bottom and wall of the cup and a rolled top lip is added (bond beam) to the uppermost portion. Unroll that top lip and the cup losses all stability. Those two areas are where the pool will see the highest stresses.
    -Brian-
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