Damp/wet concrete floor

Discussion in 'Floors, Stairs and Lofts' started by Jackal, 19 Mar 2008.

  1. Jackal

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    Hi,This question is probably boring the pants off people on here but I either can't find a question about exactly the same problem or I get lost in the jargon in the answers.
    Anyway,I have knocked through from the kitchen to the wash house to make a bigger kitchen and after lifting the old lino found that the concrete floor is wet in patches and also is not level,so is there a self leveling compound on the market which will do both jobs at the same time?
    I don't know if there is any sort of damp proof course under the concrete slab.
    Any help appreciated.
     
  2. alfiembra

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    Can you identify the source of the water, this would be your first step. It may be that the dampness is being caused by a roof leak what level is the outside ground compared to the floor level, if it's higher it may be coming through the walls. Is there any difference in floor level between the kitchen and the wash house? Need more information.

    Alan
     
  3. Jackal

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    Hi Alan,
    There's no roof leaks and the floor is at the same level as the kitchen floor at the joint where the wall used to be but it falls away to the other end of the wash house(only by about 3/4 of an inch.
    The floor level on the outside of the walls is at the same height as the lower part of the inside floor,the damp is all the way around the edge of the outside walls but not on the inside wall,the builder has blocked off an old door on the far end and he said that he didn't notice anything wrong when he took the old frame out,in one corner the damp patch reaches in about 3 feet and has had no floor covering on it for over a fortnight now and is well aired,what I would like to do is find out if there is a product which I can use that will level the floor and also stop the damp rising through it at the same time,is there such a product on the market?the tiler said that he'll just build the floor up with water proof adhesive as he's laying the floor tiles ?
    Is there any more info that you need?
    One more thing,the builder also said that the cavity in the wall may be full of old mortar which has fallen over the years and would have to take some outside bricks out to rake it out,is this right?
     
  4. alfiembra

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    If your outside ground level is more or less level with your floor level then it sounds like you may have a damp proof course problem or quite likely no damp proof course at all. The moisture in the ground is travelling through the brick work into the floor with no barrier in between.

    Generally speaking you would want to have your outside ground level at least 6 inches below your inside floor level with a damp proof membrane (DPM) below the concrete slab and turned up the wall to lap onto the damp proof course (DPC) in the brickwork.

    I would suggest, if it's feasible, try to lower the external ground level against the walls and see if you can locate a DPC it might not be obvious but it shouldn't be below the finished ground level, it's whole purpose is to stop damp rising up the wall. If you can't see one then there are a few waterproofing agents you can apply to the exterior of the brick, you could even paint on a thick layer of bitumen if you are going to cover it over again. This hopefully would stop the moisture penetrating the wall and getting inside.

    The contractor's idea of cleaning out the cavity has it's merits but if you are only getting dampness on the floor then I'm not sure this would cure the problem, I would expect to see damp in the walls too if the cavity was full of mortar droppings.

    HTH

    Alan
     
  5. ardvilla

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    I have just discovered the same problem. I had to lift my lino last night and discovered that the floor leveller had blown, there was water in patches on the surface and possible mould under the broken areas of the leveller.
    The pipes in the area are fine, there are no signs of water getting in from walls. The floor is higher than the outside. It is only in an area around a window about 3-4 ft sq.
    I left the lino back overnight and the floor has dried out.
    Is there a floor treatment that I can apply to stop this coming back?
     
  6. noseall

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    All the lino is doing is trapping moisture beneath, moisture that has condensed on the cold slab.

    Removing the lino removes the problem.
     

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