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Can I dot and dab Kingspan K17 to existing plaster?

Discussion in 'Plastering and Rendering' started by Darren9571, 19 Aug 2014.

  1. Darren9571

    Joined:
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    Location:
    Birmingham
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    Hi,

    I am planning to dot and dab Kingspan K17 insulated plasterboard in a bedroom. Originally I was going to knock off the existing plaster back to brick but the plasterer has just told me to dot and dab onto the exiting painted plaster.

    The existing plaster is pretty solid but I didn't know whether the adhesive would bond to the painted plaster?

    Is it OK to stick the boards to the existing plaster?

    Thanks in advance
     
  2. Micilin

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    I would pin it after the dabs are set.
     
  3. kingspandirect

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    Kingspan Kooltherm K17 Insulated Plasterboard is the primary component of The Kingspan Kooltherm K17 Insulated Dry-Lining System. It can be bonded over existing plaster using gypsum adhesive so long as the plaster is sound / solid and dry.

    However, in order for Kingspan Insulation Ltd to confirm the suitability of an adhered / bonded Insulated Dry-Lining System, we would need to know the following:

    • What type of wall it is e.g. cavity or solid
    • Whether the wall is an existing cavity wall e.g.the Kooltherm K17 Insulated Dry-Lining System can be used to internally insulate the existing cavity walls if the construction comprises a 100mm blockwork inner leaf, 25 mm + drained residual cavity, 102.5mm facing brick externally and internally lined with a solid plaster finish.

    If the wall is of a solid masonry construction, then in order for Kingspan Insulation ltd to confirm the suitability of an adhered system we would need to know the following:

    • What the external finish is (if any)
    • The masonry type & thickness
    • The inside finish (which, you have stated is solid plaster)
    • The geographical area of the country in which the project is located
    • Whether the site is exposed or sheltered / protected e.g.is the building situated on a hill top, near to the coast or is the site protected by adjacent buildings?
    • Whether there is a Damp Proof Course (DPC) running around the perimeter of the building (this should be situated 150mm above external ground level), and if so what type of DPC is it e.g. rigid DPC or chemical DPC?

    Once we have this information, we can advise on the suitability of using an adhered system on a solid masonry wall construction.

    Regardless of wall type, if the inside finish is painted plaster, then the plaster would need to be solid / sound and dry. If an adhered system is to be used, the paint would also need to be removed from the existing plaster otherwise this can affect the bond. Gypsum adhesive needs suction in order to create an adequate bond / key. The easiest way to remove the paint would be to sand the walls down to the existing plaster finish. Once this has been done, all wall surfaces receiving the Kooltherm K17 Insulated Dry-Lining System are to be clean, dry and free from dust in order to provide a good bond for the gypsum adhesive.

    There are many different types of masonry, therefore a bonding agent maybe required on some substrates in order for the adhesive to key. Plaster would be one such substrate / finish that would require a bonding agent if you were to use gypsum adhesive to attach the Kooltherm K17 Insulated Dry-Lining System. Therefore you would need to use a proprietary bonding agent such as an emulsion of PVAC to BS5270-1 or equivalent. Some manufacturers produce their own alternative for high or low suction backgrounds. The bonding agent is to be applied to the background in bands corresponding to the gypsum adhesive dab / band location.

    Once the above preparation has been carried out, The Kooltherm K17 Insulated Dry-Lining System can then be adhered to the background with gypsum adhesive dabs. Once the dabs have set, add no less than 2 gypsum nailable plugs per boar. Increase this figure to 9 if The Kooltherm K17 Insulated Dry-Lining System is to receive ceramic wall tiles.

    We hope you find this helpful.
     
  4. Darren9571

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    Thank you for the responses. What kind of pins or nailable plugs do I need? Are the Gyproc nailable plugs the ones? These only seem to come in packs of 100 and I can't any similar product in smaller numbers - I only need about 10.

    The walls are 2 standard bricks with no cavity but a layer of slate between the two brick walls. The plaster is a sand/cement with plaster skim. The external wall is bare brick and has just be re-pointed. The site is not especially exposed, it is in a built up area of Birmingham. There is a slate and chemical damp-proof course, but this work is in an upstairs bedroom.
     

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