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Dampness in conservatory dwarf walls

Discussion in 'Building' started by mr_chaela, 27 Nov 2019.

  1. mr_chaela

    mr_chaela

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    More damp problems with the bungalow renovations.
    The conservatory dwarf walls are very damp. The problem appears to be that the path/patio area outside is too high, approx 2" below FFL.
    Are there any ways to alleviate this other than lowering the path/patio? Perhaps a chemical dpc injected into the walls.
    The owner or the property is a very active and sharp 84 y/o lady but with limited funds.
    Any suggestion welcome.
     
  2. Notch7

    Notch7

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    Are they cavity walls?

    Do you nean the interior walls are damp - if so where is the damp showing.....
     
  3. mr_chaela

    mr_chaela

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    Single skin brick, inside has minimal render thickness and painted with sandtex. Exterior just the facing brick.
    Dampness is worse at bottom, some paint has flaked off and with some dampness showing on top of interior quarry tiles along where wall meets tiles.
    None of this was really noticable until carpet lifted and rain started.
     
  4. Notch7

    Notch7

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    It does seem the high path patio is causing some of the damp -rain splash could a cause, or dpc is being bridged. Single skin walls might get damp if the brickwork is porous.

    You could try a water repellent -stormdry or a silane based product.

    https://www.amazon.co.uk/Stormdry-M...61&hvtargid=pla-421621383520&psc=1&th=1&psc=1

    https://www.amazon.co.uk/Microshield-Masonry-Water-Repellent-5L/dp/B0785JB17H

    Ideally apply when the wall is dry so the damp is not sealed in -say after a period of dry, windy, sunny weather.

    I suppose a channel could be cut around the outside and put in gravel -like a french drain
     
  5. mr_chaela

    mr_chaela

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    Thanks for your reply Notch7, the Stormdry looks interesting and its BBA certified. Have you used it or know anybody who has?
     
  6. bobasd

    bobasd

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    unless you know the cause of the damp it can sometimes be difficult to treat it?


    when was the conservatory built?
    do the knee walls definitely have DPC's?
    does the solid floor have a DPM?
    how secure is the sealing of the bottom rail or plate sitting on the knee wall?
    single brick wall is very poor practice.

    why not post photos of inside & outside the conservatory?

    fwiw: is the main house DPC at the same level as the conservatory DPC?
     
  7. mr_chaela

    mr_chaela

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    Sorry for delay. I will be at the bungalow tomorrow.

    when was the conservatory built?
    Probably 15 years ago.

    do the knee walls definitely have DPC's?
    Can't see anything inside or out, there is a cement plinth on the outside so that is possibly spanning the dpc.

    does the solid floor have a DPM?
    Again can't see. the floor has red quarry tiles, no sign of damp in the cement grout.

    how secure is the sealing of the bottom rail or plate sitting on the knee wall?
    Upvc cill under upvc window frames - all looks OK.

    single brick wall is very poor practice.
    Agreed.

    why not post photos of inside & outside the conservatory?
    Will take photo's tomorrow and post them.

    fwiw: is the main house DPC at the same level as the conservatory DPC?
    Not sure, cement plinth hiding any dpc.

    This is the first time the conservatory has been decorated in 14 years, since the owner bought the place. It all appeared dry and sound when I started, so I just scrapped off the few small areas of loose paint (all just above the floor) and decorated, that evening the rains started and the full extent of the problem became noticable - the water based paint wa still wet 2 days later.

    Thanks for the help.
     
  8. bobasd

    bobasd

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    use a small screwdriver to scratch out a little mortar in the lower beds and any DPC will be revealed.
    except in historic/conservation houses its the usual remedial practice to totally remove plinths because they bridge DPC's and wick up plinth ground contact water.
     
  9. mr_chaela

    mr_chaela

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    1 RHS.jpg 2 LHS.jpg 3 Int Tiles.jpg 4 EXT - LHS.jpg 5 Cill.jpg 6 EXT - RHS.jpg 7 EXT - RHS End.jpg 8 Cons Side.jpg

    Some pics of the problem. Unfortunately I forgot to check for dpc in the brickwork, will do so in the morning.
     
  10. bobasd

    bobasd

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    there's been obvious, previous damp issues.

    remove the entire sand and cement plinth - its part of the problem & could be bridging the DPC.
    the flags have raised the original ground level too high, and caused ignorant "builder's" to install the Aco drainage and the plinth.
    whats the purpose of the white Pvc pipe that ends in the Aco drain? is there a waste pipe connection behind the black down pipe?
    does the Aco linear drain discharge into the manhole?

    the interior shows damp signs below the bottom Pvc rail - check the silicone sealing of the door.
    and damp signs on the lower walls - hack off 300mm beyond damp signs and render back with sand and lime (never gypsum plaster).
    after hacking off, look for the edge of any DPM?
    the wall plaster should not be in contact with the solid floor or the quarry tiles - the abutment of the tiles to the wall has had an attempt to seal with silicone or something - its not working.

    fwiw: on the last pic your main house wall shows an air vent/brick thats set too high in the wall to be much useful for any suspended floor.
     
  11. mr_chaela

    mr_chaela

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    No. The Aco gulley is a recent addition, apparently water was pooling outside the french doors when it rained so the owner had it installed last year. The aco drains into a sump pump loacated in the manhole and is pumped thro' the blue flexible hose which runs back along the gulley and up into the pipe you mention in order to discharge into the drain at the other end of the pipe. Not sure about the legality of installing a sump pump in a manhole.

    Had a poke around looking for the dpc. On the right of the french doors (viewed from outside) there is a dpc is in the joint above the brick that shows above the cement plinth, thats about 6" above FFL. On the left of the doors I couldn't find anything - unless it's behind the plinth. The bungalow has had a lot of work done to it by the previous owner and judging from what I have seen they had very little diy skills. I couldnt find the dpc in the main bungalow, It is I believe a 50's build so should have one, probably beneath the plinth.

    The air vent you mention was originally for a pantry cupboard in the kitchen. The bungalow has solid floors.

    Would your suggestion of using lime render be sufficient, does the dpc problem need addressing first, perhaps with a chemical dpm?
     
    Last edited: 3 Dec 2019 at 8:49 PM
  12. bobasd

    bobasd

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    so the mysterious unprotected, white flex(?) is feeding a pump - well wrong wiring. have it checked by a sparkie.
    it should be a protected, dedicated cable, and RCD side in the c/u.
    why not ask on the sparkie's forum?
    its an unusual drainage set-up but maybe there are few alternatives?

    having the DPC's so high wont protect the FFL. DPC's should typically be at the same level all around the conservatory.
    the damp shadow on the plaster is now well defined
    does the conservatory floor flow through into the main house or is there a step-up?

    is there a piece of wood acting as a "threshold" filler near the bottom Pvc rail?
     
  13. mr_chaela

    mr_chaela

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    The white cable is a tv aerial cable. There is an rcd spur in the opposite corner of the conservatory to feed the pump but how the cable gets to the manhole is a mystery. Can only assume it goes thro' the rear wall and is buried between the aco and the wall. The armoured cable by the white downpipe is the garage feed.

    The conservatory floor is 3" or so below the bungalow floor.

    Don't think there's any timber under the threshold, outside the plinth is up to the cill and it appears solid, would expect it to sound hollow if on wood.
     
  14. bobasd

    bobasd

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    i'm referring to the sprig of white flex that shows going into or coming from the plinth - is that the same TV cable that shows inside the room?

    without knowing all the circumstances - why build a step into any extension?
    inside the conservatory, are there visible air bricks, set in the main house wall?
     
  15. mr_chaela

    mr_chaela

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    i'm referring to the sprig of white flex that shows going into or coming from the plinth - is that the same TV cable that shows inside the room?
    - Thats the coax aerial cable that shows inside the conservatory

    without knowing all the circumstances - why build a step into any extension?
    - Good question. I said the previous owners knowledge and skills were limited.

    inside the conservatory, are there visible air bricks, set in the main house wall?
    - No. The bungalow has solid floors.
     
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