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concrete new slab and addressing existing existing slab with no vapor proofing...

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  1. #1
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    Default concrete new slab and addressing existing existing slab with no vapor proofing...

    Hi all,

    We are converting a 30sq metre garage to a granny flat, existing slab is concrete, no moisture barrier - can you recommend something making it habitable but not taking more than 1mm height as we are at 2.4 and a smiggin now and council needs a floor to ceiling ration of 2.4, I am told epoxy moisture proof barrier to existing slab is the way to go?

    Also any recommendations with the new slab extension on joining them up? how thick to make it to keep council happy?

    cheers
    coastal

  2. #2
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    Quote Originally Posted by Coastal View Post
    Hi all,

    We are converting a 30sq metre garage to a granny flat, existing slab is concrete, no moisture barrier - can you recommend something making it habitable but not taking more than 1mm height as we are at 2.4 and a smiggin now and council needs a floor to ceiling ration of 2.4, I am told epoxy moisture proof barrier to existing slab is the way to go?

    Also any recommendations with the new slab extension on joining them up? how thick to make it to keep council happy?

    cheers
    coastal
    G'day Coastal,
    Properly prepared and applied Epoxy will do a pretty good job but it will also be expensive.

    I had a call from a client who had water coming through his slab under the bedroom.
    Turns out this was part of the double garage before extensions were done.

    With the carpet removed about 17 damp spots were identified and some minor cracking with only one large crack through one corner on the end of the slab.

    I treated the area with C1 also known as Krystol, this stuff looks like pure cement dust in the drum and mixed to a slurry consistency is applied with a sponge.

    Now for the clever bit, the layer of wet product soaks into concrete and forms tiny crystals in any tiny voids and cracks, the formation of the crystals takes about 7 days, and you need to apply it at least 3 times/coats a week apart.

    The advantage of this over epoxy is price, application time reduced and the fact that the slab ends up with waterproof layer 'in' the slab not 'on' it where it's prone to damage.

    Any wide cracks can be filled but will need ramming to get the product to tightly fill the void, this a simple procedure, fill and hammer it into the gap.

    I have also used this on exterior wall to path/plinth joints that leaded to the internals with great success.

    Good luck.
    Growing old is compulsory, growing up is not.
    http://www.wet-seal.com.au/waterproofing/locations.html

  3. #3
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    mate thanks for the quick response, would council accept this krystol solution?

    And re Properly prepared and applied Epoxy - is that painted on? or how does it go on?

    Are you interested in the job?
    Juan

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    Quote Originally Posted by Coastal View Post
    mate thanks for the quick response, would council accept this krystol solution?

    Can't answer this as the rules change depending on your local council, obviously the local council up here in Central Qld had no problem when this bloke added 2 extra rooms to the house, despite the fact the slab was an old car port, so no need for the builder to have laid any plastic.

    However the fact that stopped all the leaks must count for something; the same stuff stopped a dam leaking on the dry side of the wall, so it can't be too bad.


    And re Properly prepared and applied Epoxy - is that painted on? or how does it go on?

    Properly prepared as per the manufacturers instructions, this might mean a light grinding and pressure wash, best done before you apply the C1/Krystol, then apply the epoxy.
    Normally applied with a special roller on the end of a long handle, if the epoxy in one of the newer water based ones a standard roller can be used.

    Are you interested in the job?

    I am confident anyone could do this work, there are a couple of things to look out for, but nothing worth noting here till you find out a bit more from the council or your builder.
    Good luck Juan.
    Growing old is compulsory, growing up is not.
    http://www.wet-seal.com.au/waterproofing/locations.html

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