dot and dab on non cavity external wall help on preparation please

Discussion in 'Builders' Talk' started by on-mrs-orders, Feb 28, 2005.

  1. on-mrs-orders

    on-mrs-orders New Member

    The back wall of my flat is non cavity, the room used to be a bathroom and having taken the tiles off the wall there is evidence of damp on very dodgy plasterwork.
    I plan to dot and dab plaster board on this wall but need advice on how i should prepare the wall.
    Should i apply sealant to this wall - can i use normal plasterboard or should i use foil backed?

    thanks for your help -


    ps -There is no rising damp
    PPS i did search the forum but could not find the answer.
  2. wood butcher

    wood butcher New Member

    what's the room going to be used for?
    If not bath room then you would be better of to insulate the wall including a membrane then baton and tack at most you will lose 3" of space but it will be dry.
    Or water proof render and skim. good luck.

  3. on-mrs-orders

    on-mrs-orders New Member

    hi wb

    The room will be a bedroom - being a DIY'r i get confused by the products on offer - can you suggest the insulation and membrane i should use.
  4. wood butcher

    wood butcher New Member

    there are several diferent types of membrane i would suggest a paint on type rather than mechanicle ie. thompsons water seal.
    insulation depends on which method you chooseif batons then rockwool or polystirean hope that helps.

  5. devil's advocate

    devil's advocate New Member

    Hi omo.

    There are a <u>few</u> ways you can insulate and finish your internal wall. 'Jewsons' do a freebee guide to Part L insulation requirements, although the Part L might not be relevant to you. It does explain very clearly, however, the different ways to tackle the job. (Order one on-line from their site).

    One of the easiest (and thinnest) products to use is 'Thermal Board', which is a plasterboard sheet with insulation <u>attached</u> - you just fix it directly to the wall (although if you had to comply with Part L, your minimum block thickness would have to be 190mm!). There are other ways, of course - it's a handy guide, worth getting.

    Please don't put plasterboard up without insulation - you'll have a really unpleasantly cold bedroom wall (+ all the moisture in the house will want to condense on it!)
  6. on-mrs-orders

    on-mrs-orders New Member

    Hi Again, struggling here

    I need to dot and dab the plasterboard as space is really tight for the bed.
    can i seal the wall (which sealant)
    can i buy plasteboard (thermal, duplex, foilbacked etc) that i can fix using the dot and bad method

    cheers for your help

    I looked at jewsons and got some guidelines from DETR but it did not answer my specific questions, i talked to Britsh Gypsum technical and they want me to use the thermal stuff but they said this cannot be done dot and dab blah blah blah
  7. wgr

    wgr New Member

    no foilbacked board cant be used with dot and dab, some people raw plug foil backed to the wall as a plasterer myself this isnt something i will unless specifically asked to do it that way...

    waterproof render is what you want really to be honest. which means knocking it back to brick
  8. Right heres the answer to your problem my friend.
    Firstly you absolutely need to address the problem of why and where any dampness is penetrateing through the wall in the first instance. When you say non cavity I assume you mean it is a solid 9" brick wall, perhaps you should check the pointing or at worse render the exterior in two coats with waterproofer and masonary paint. Once you have this problem solved you must determine whether it best to hack off the existing render or, board over this if it is stable enough. As an extra measure I suggest you paint on a couple of coats of Aquaseal damp proof membrane and dash the final coat with sharp sand when wet to give a key for the application of shelter boards (insulation backed plasterboard) dot and dab theese in the usual way or better still if you can, apply with slight pressure a thin smear to the positions of the dots on the insulation of the boards to get a good bond then the dabs of adhesive to theese and slap the boards to the wall. The reason I find to do it in this manner is that applying the dabs to the wallin the regular way you do not get the best of bond to the insulation itself as you would with a regular plasterboard. If you find it difficult this way then dab the walls harm! The next day you drill in plastic nailable plugs through the boards and into the walls... say a half dozen per board is ample. Skim over, job done and your sucking diesel and cooking with gas!!
    All the products you need are readily accessable from any decent merchants.
    Good luck.

  9. on-mrs-orders

    on-mrs-orders New Member


    i can follow your instructions with confidence.
    Thank you very much for the time you took to sort me out.

    (i am now surre that the slight damp damage came from within, the room was a bathroom and the flat had no heating. )

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