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lifted laminate and i have a Damp concrete subfloor

Discussion in 'General Flooring Chat' started by thomo2710, Jul 16, 2012.

  1. Matt

    Matt Well-Known Member Staff Member

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    in old houses we never used to have products that was effected by moister and also adhesives etc was water proof.

    Now a days in old houses the floor should be dug up and replaced to meet regs. No different to having a new boiler fitted, you would use the correct flue to go with it or if you was to have your house rewired you wouldn't use the old fuse board.

    BUT, we have [products like NA and epoxy DPM systems. You use these! But you are relying on your subfloors bond to the product. Hence if you read the above Guidlines from ardex and follow them you wont have a issue. Its all down to how strong the bond of the old adhesive is and your concrete strength.

    Also please note that the tiles you have down may contain asbestos so seek advice on removing them safely.

    You have what is Bitumen down. Not a asphalt floor. Also note that bitumen was NOT used as a dpm. That was a adhesive that used to be used as it wasn't effected by moister. Asphalt was used as a DPM and you dont have this.

    PS, how old is your house?
     
    Matt, Jul 19, 2012
    #41
  2. thomo2710

    thomo2710 Active Member

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    These rh readings that are talked about, is this for the floor all of the time, or just at the time if laying the surface dpm?
     
    thomo2710, Jul 19, 2012
    #42
  3. thomo2710

    thomo2710 Active Member

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    1960s house, with a mid 80s kitchen extension.

    Is there any way of testing the concrete to see if it will make a good bond?
     
    thomo2710, Jul 19, 2012
    #43
  4. Matt

    Matt Well-Known Member Staff Member

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    Well that is again a issue with surface dpm's ! They say if the subfloor is below a certain rh then you can use. But with rising damp the rh will always be changing.

    Remember I asked you about the LANs levels outside your house ? This makes a big difference. As your land is not above the property then the rh should be pretty stable. But if you lived at bottom of hill you could get high peaks .
     
    Matt, Jul 19, 2012
    #44
  5. merit

    merit Well-Known Member

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    You have to get the reading with a hygrometer which has to be left for 72 hours. I like to put down a couple of hygrometers and leave them down for as long as possible
     
    merit, Jul 19, 2012
    #45
  6. Matt

    Matt Well-Known Member Staff Member

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    If you don't want to replace the subfloor then you have to go with Dpm system.

    They do work at end of day. As for testing, not really. Expensive test equipment and it will normally be done by cutting a section of floor out and sending off
     
    Matt, Jul 19, 2012
    #46
  7. tarkett85

    tarkett85 Well-Known Member

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    They won't cover it though, plus bitumen needs pulling up, the bitumen will fail before the screed does. If you're going with a non bonded flooring asphalt it costs around £25 m2 better safe than sorry.
     
    tarkett85, Jul 20, 2012
    #47
  8. thomo2710

    thomo2710 Active Member

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    Morning,

    I am going to lose the plot.

    My bath has decided to leak through the ceiling this morning. I cant take anymore!!! :(

    How/What methods are there available to scrape this thin layer of bitumen up?

    ignore that - just spoke to Ardex who said to scrape over the bitumen to make sure any loose bits are removed and that the Ardex NA product should fully bond to the bitumen and concrete.

    He said the slab doesnt need to be dry, upto 98% rh, as long as there is no visible surface water!

    I am still going to let me slab dry out for 3/4 weeks though, i have come this far so im not going to rush putting another floor back down just to please her indoors.

    I feel like every day is Friday 13th at the mo! :(
     
    Last edited: Jul 20, 2012
    thomo2710, Jul 20, 2012
    #48
  9. tarkett85

    tarkett85 Well-Known Member

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    The bitumen will fail before the screed mate, pull it all up, play it safe, latex based screeds aren't moisture sensitive, that's fine although the specs on surface membranes always state do not use over failed or missing Dpm.
     
    tarkett85, Jul 20, 2012
    #49
  10. dazlight

    dazlight Super Moderator

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    They might not cover it but it can be done.
    I know because ardex told me. Unless it's a high moisture reading you will be ok.
    Also I have done it alot with ardex dpm 1c and also f.ball F75.
    I tell the customer It's not fully guaranteed and I only do it in certain conditions as well.
     
    dazlight, Jul 20, 2012
    #50
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