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Is this a sand/cement render or just a plaster base coat

Discussion in 'Building' started by SJRSJR, 2 Oct 2016.

  1. SJRSJR

    SJRSJR

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    Hi, can anyone tell from this photo what materials have been used on my internal party wall? It's at the base of the wall where it meets the floor.

    I've posted about damp on it and have been told by a damp specialist that the grey is carlite plaster which has been wicking up moisture and I need to hack it off, get a chemical DPC plus waterproof sand/cement render. However I have pulled a chunk out and wonder what the yellowish material is above/behind it (which he didn't see - he said the whole wall was carlite)

    Is it just a plaster base coat or could it be a sand and cement render and might it have previously been applied to the walls to hold back damp? The carlite plaster only seems to run to the height of the lowest brick so might it just be there for the old skirting to attach to?

    I can't knock picture hooks in up above holes have to be drilled so surely that wouldn't be the case if it was all carlite?

    I've had the house 24 years and had the walls skimmed 10-12 years ago. The damp is manifesting itself as a dark patch - no salts, no yellow stains so I'm wondering if it's coming through the carlite up the face of the plaster skim without touching the assumed sand/cement render below? Might it explain why there's no damp on the other side in my neighbours house?

    If so, could I avoid the need to have it all hacked off if the origins of the damp was resolved (currently assumed to be damp in the hearth/chimney breast and it was allowed to dry out? Thanks.
     

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  3. SJRSJR

    SJRSJR

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    So I had a plasterer round who said it is a sand/cement render and could be tough to remove. Do I really need to get rid of it only to re-do it?

    With the 3month drying out time plus the minimum 2 month notice for the Party Wall Act, would it make more sense to do a chemical DPC then batten and plasterboard the wall?
     
  4. John D v2.0

    John D v2.0

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    You won't need a party wall agreement for replating the wall. Cutting and inserting a dpc, yes, but not plastering.
    Also you needn't wait 2 months, on the template letter there's a clause they can tick so you can start straight away.
     
  5. SJRSJR

    SJRSJR

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    Even if my neighbours save me the 2 months on the Party Wall notice I'd prefer to avoid 3 waiting months before being able to redecorate. Is the idea of plasterboarding feasible? Thanks
     
  6. tomfe

    tomfe

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    It's funny how all these damp specialist say the same thing....
    I don't believe in rising damp, I've never seen it. There has always been another issue that has caused it.

    Was it wet when you hacked the plaster off? Did it smell damp? I hate the smell of damp plaster.
    Have you got a suspended floor or is it solid on batons embed in concrete then chipboard?

    Looking at that wall I think a couple of hits with a hammer would take it off with little effort.
     
  7. vinn

    vinn

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    FWIW, I've seen rising damp umpteen times.
    To deny rising damp is to deny capillary action.

    Hold two off-cuts of sheet glass together, and dip one edge into water - watch what happens?
    Against gravity the water will rise between the two sheets of glass - thats capillary action, sometimes known as rising damp.
     
  8. vinn

    vinn

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    OP,
    FWIW: since June you've been more or less ducking and diving with the advice you've been given, and now you raise a new post separate from the same subject older posts.
    You now mention for the first time, as far as I can recall, the Party Wall Act.
    For myself, there's no problem with advising you over a period but when the goal posts keep changing its very difficult.
     
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  10. If you've got bonding on the lower bricks, then yes, it's crept up the bonding, and then up the plaster. But did he damp specialist do a drill test to determine if the bricks above the normal dpc level were dry or wet, because if the damp is coming up through the bonding, the DPC may be fine.

    If you knock off the bonding, then apply sand and cement with a waterproofer in it, you may find that that's all you need to do.
     
  11. tomfe

    tomfe

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    I just said I don't believe in it, not that it does not exist in some unique situation. I bet 9 times of of 10, no 99 times out of 100 that so called rising damp is no but is due to something else.
    Try placing a brick in a tray of water, see if you can get the damp to track up to the top of the brick.
     
  12. John D v2.0

    John D v2.0

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    I think there's a lot of disagreement of rising damp but I think it's more to do with the balance of capillary action and evaporation.
    I never heard anyone saying they got rising damp in an unpainted bare garden wall, but render both sides and acrylic paint your house wall and then form a pond at the base and it'll track up the wall as far as gravity will let it if the bricks are porus.
    There's never one factor, you have to look at the whole picture.
     
  13. SJRSJR

    SJRSJR

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    Thanks for the replies.

    Vinn - there's nothing incompatible with this and my other post and I'm not 'ducking and diving'. As I previously said, the myriad of opinions does make me wonder who to believe, especially as the quotes are between £2550 and £5000. Not sure why mentioning the Party Wall Act annoys you, I hadn't factored that in but it is what it is. I've taken the advice on this forum, done most of it other than excavate the fireplaces, which is not practical right now but will be done. I raised this as a separate post because it was specifically to do with the sand/cement render. But thank you for the helpful advice you've previously given.
    Doggit - no, no drill test, but in other more saturated areas the brick dust seemed moist so that probably closes that avenue.
    Tomfe - it's been pointed out that there's a damp course on the front external wall and also under the floor on the other party wall. Also they are not the original joists and they're also on hangers. The conclusion was that the house has had a damp problem which has been treated, presumably more than 25 years ago as I've had it that long.

    A plasterer not a specialist pointed out that there's no through ventilation from front to back of the house because my front garden is only a brick lower than my living room so I understand that a French drain will be needed. Another thing to factor in...
     
  14. vinn

    vinn

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    tomfe,
    Stop wriggling. You know what "I dont believe in rising damp, I've never seen it" means. Playing with words to escape the consequences of what you said is wriggling.
    So is all of a sudden raising the"unique" situation claim - where did that come from? I didn't mention any thing about unique situations? I've dealt with rising damp in all kinds of situations.

    You even resort to that old and long ago rubbished red herring about the brick in a tray of water.
    That was disproved & refuted many times in many experiments. Read the whole story not just the bit that a journalist wrote.
     
  15. You're completely right, but add some mortar and plaster, and that's where you'll find the water creeps through; and this can be verified by the capillary action of silicone based DPCs
    The damp specialists don't tend to do a proper inspection because they might find the problems localised, and they'd lose work. If there's been a problem in the past, then it may well have been eradicated, but someone just messed up putting bonding behind the skirting boards. A drill test uses isolated probes, so avoids picking up moisture from the plaster. It might be worth getting a couple more companies in, and ask a few more searching questions to show you can't be bulsh1t.

    My partners house was built 1930, and has cement rendered walls, and it seems to be a common way of doing things back then, because it's upstairs in the bedrooms as well.

    You'll also need a few telescopic airbricks to get the airflow through, as this was very likely why the old joists needed replacing. If the joist end rot due to damp walls, you tend to cut out the joist end, and bolt a new piece on.
     
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