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Cavity Wall Insulation

  • 01-05-2022 10:30pm
    Registered Users Posts: 2


    I am building an extension. The now fired builder built up the 3 cavity walls but put no insulation in them. The walls are fully built but there are no windows in or roof on. Can I rescue it at this point, is it possible to put the insulation slabs in the cavity walls? I'm guessing I'll have to cut it in strips to work around the wall ties. Will this be OK and prevent the need for insulated plasterboard inside? I can get the cavity pumped also at the end to fill gaps.

    Thanks for any advice


  • Registered Users Posts: 1,182 ✭✭✭housetypeb

    Your last sentence is actually the answer to your question.

    No need to rescue anything -just pump it.

  • Registered Users Posts: 751 ✭✭✭C. Eastwood


    The incompetence of people in the construction industry is absolutely appalling. It was best to fire the muppet so as to prevent further damage.

    Its not possible to correctly fit sheets of insulation in to the cavity.

    Have the cavity pumped.

    You can also mechanically fix insulated slabs on to the inner face of the walls

  • Registered Users Posts: 79 ✭✭Shoco83

    Just a quick question on getting walls pumped, can it be done if the wall is red brick?

    Rear and gable are pebbledash finish, but front ground floor is red brick with upper floor being plaster.

    Mate told he though red brick can't be done as water could pass through to internal walls

  • Registered Users Posts: 1,326 ✭✭✭dathi

    took this from the agrement cert for kingspan beads . but most of the bead agrement certs have a similar line about brickwork or have a clause that only allows them to be used in areas of low exposure .

    "In the case of fair faced brickwork recessed mortar joints are not suitable for filling. Only tool flush joint brickwork"

  • Registered Users Posts: 751 ✭✭✭C. Eastwood

    You should get expert advice for this from a Construction Professional.

    If the cavity fill in the cavity inside the brickwork causes problems, it will cost approx €4,500 to extract the insulation fill.

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  • Registered Users Posts: 8,959 ✭✭✭tom1ie

    Hi all, dragging up an old-ish thread here but I’ve a 4 bed 1966 house semi d with cavity walls.

    Are there different types of cavity wall insulation? If so what’s the difference?

    I have the inside of the external walls slabbed with 50mm insulated plasterboard, will this give any issues?

    If I was to get external insulation a few years later would that give me any issues?

    The back wall is pebble dashed, the front wall is half pebbledashed and half red brick. The gable wall is actually the outside wall of the garage but I have the house wall of the garage slabbed with 50mm- but I’m looking to get that cavity done also.

    Is there anything I need to be looking for to ensure it’s installed properly?

    Any idea of cost? I’m in dublin area.

  • Posts: 0 [Deleted User]

    I would also like to know the risks & benefits of externally insulating a property that's already fairly well insulated internally.

  • Registered Users Posts: 751 ✭✭✭C. Eastwood

    You need to know the U value of a wall to decide if the Wall needs more insulation - which will lower the U value.

    We live in Ireland with mild weather.