If you have a new account but are having problems posting or verifying your account, please email us on [email protected] for help. Thanks :)
Hello All, This is just a friendly reminder to read the Forum Charter where you wish to post before posting in it. :)
Hi all, The AutoSave Draft feature is now disabled across the site. The decision to disable the feature was made via a poll last year. The delay in putting it in place was due to a bug/update issue. This should serve as a reminder to manually save your drafts if you wish to keep them. Thanks, The Boards Team.
Hello all! This is just a quick reminder to ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere.

Another cavity insulation wall thread

  • 28-02-2022 10:24pm
    Registered Users Posts: 3,085 ✭✭✭ stevek93

    Hi all,

    I am getting cavity wall insulation installed but I didn't apply for the grant because I want to get external insulation.

    It is possible to installed both of these together?



  • Registered Users Posts: 490 ✭✭ mike_2009

    It's possible but a bit overkill? Are you going for 100/150/200mm external insulation? You may find you'll have to use different companies for each due to specialization. Plus figure out a suitable time gap between them. Not heard of this being done before.....

  • Registered Users Posts: 290 ✭✭ Biker1

    Yes, best practice is to pump the cavities to prevent thermal looping. Then get the grant for external insulation.

  • Registered Users Posts: 1,535 ✭✭✭ Dudda

    Agree biker above. Get the cavity pumped if you intend on external insulation. You can get the same company to do both. The company that did external insulation also pumped cavity but this probably isn't the case for all contractors.

    As well as preventing thermal looping you don't have to paint or tidy up the holes drilled on the external wall to pump the cavity if you're going to externally insulate the shortly after.

  • Registered Users Posts: 4,426 ✭✭✭ maestroamado

    I was told that cavity insulation effects airflow in the cavity and may cause mold or something like that...

  • Registered Users Posts: 1,535 ✭✭✭ Dudda

    In a timber frame structure yes you need a ventilated cavity. A blocked cavity could cause mould or rot.

    For a blockwork or concrete this isn't an issue

  • Advertisement
  • Registered Users Posts: 439 ✭✭ divillybit

    Just a side question on this topic, but I was thinking of getting the cavity pumped on my 2015 built detached house... if I did get the cavity pumped with insulation, is there anything to stop the insulation from coming out if I were to upgrade the windows at some stage in the future to triple glazed? Or is it a case of replace the windows first, then pump the cavity?

  • Registered Users Posts: 2,707 ✭✭✭ MicktheMan

    An adhesive is applied to the bead (insulation) when it is being injected into the cavity so that the beads bond together when the adhesive cures. Therefore, you should be okay to replace your windows after the cavity is pumped.

    But if I were getting both the windows and insulation done, I would first replace my windows and then pump the cavity.

  • Registered Users Posts: 439 ✭✭ divillybit

    @MicktheMan thanks very much for the reply

  • Registered Users Posts: 96 ✭✭ Skill

    is there any way of knowing if the cavity is already pumped, or not? this is a second-hand house, pretty chilly, but i don't know if the cavity wall is filled or not

  • Registered Users Posts: 2,707 ✭✭✭ MicktheMan


    If the meter box enclosure is in the external wall, open it and have a look. Generally there is evidence of pumping to be seen.

    Look in the attic around the edge for evidence of "spilled" bead.

    From the outside have a good look at the walls. If the cavity was pumped you should see regular small circular deformations along the tops of the walls and under the window cills.

    Failing all that, you can have a borescope survey done by the cavity wall insulation company to ascertain the suitability of the cavity for pumping.

  • Advertisement
  • Registered Users Posts: 290 ✭✭ Biker1

    In theory if the correct glue to bead ratio is added at the correct temperature this will ensure the bead is "bonded". However all too often this does not happen as the glue is the expensive part of the process and is sometimes spared.

  • Registered Users Posts: 96 ✭✭ Skill

    Brilliant - thanks a million

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


    many external concrete block walls will need ventilation of the cavity

    2 million home owners in UK will agree with that.

    see this article:-

    Cavity Block constructed Walls must never be pumped with cavity fill insulation.

    The cavity of a Timberframe house must never be filled with insulation

    a ventilated cavity is brilliant at preventing ingress of rainwater, and also allows rising dampness below the DPC to escape out of the cavity. Most cavities will be ventilated.

    Since the mid 70’s - in Ireland most houses with external concrete block walls are cavity constructed walls. (excluding Dublin).

    In most houses if there are gable walls, the cavities are vented at the gables where the cavities are not closed, so as to allow ventilation of the cavities. Fresh air is excellent at preventing damp problems.

    when the external insulation is applied on the outer face of a cavity constructed concrete block wall, where the cavity is vented (which is the situation in many homes in Ireland since 70’s) - the external insulation will be waiting in vain for ever for heat to come near it, because the heat from the house will pass through the inner concrete block leaf (by conduction) and in to the cavity, and because heat must rise up (by convection) it will rise up and escape through the vented cavity.

    BER Assessor will give a A(?) certificate for the external insulation and the warm air in the cavity will still be escaping from the vented cavity because it is a warm gas, and will always choose to escape by Convection from the vented cavity rather than Conduction through the externally insulated external concrete block outer leaf.

    there are thousands of houses in Ireland externally insulated with vented cavities, which have good BER Certs

    FAS are now ReSkilling and UpSkilling many of the Insulation Experts that will be Fitting insulation with the new SEAI Better Energy Homes Scheme and of course will tell the home owners that the external insulation in best for their house, and explaining about the grant of over €25,000 to help pay for deep retrofit insulation of their homes

    wonder what percentage of these Experts insulation installers and BER Assessors will know about the heat loss from the Vented Cavities.

    Tonto and Loan Ranger and Co, Expert Insulation Installers. (501/2 year guarantee).

    Palladin Expert Insulators Co. (have insulation, will travel), (200 year guarantee)

    Trotters Independent Insulation Co. (Double your money back Guarantee)

    In the UK article above re the terrible debacle of problems with external wall insulation fill in the UK - most of the Contractors (with no insurance) and 25 years guarantee are gone Pufff, and the UK Government must pick up the tab, in the meantime families must go through mental stress and have damp houses and other issues for many years.

    I wonder what will happen in Ireland with the new Insulation grant. (Oh Rodney, where is my Fairy Godmother)

  • Registered Users Posts: 439 ✭✭ divillybit

    Good article there @C. Eastwood

    I had looked at several other threads on here about potential problems with getting cavities pumped. I'm thinking it's best to leave my house as it.

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


    I always recommend fixing thermal insulation to the inner face of the external walls.

    it will also be necessary to fit some insulation to any block partitions which are built in to the external walls.

    I am aware of all the Pros and Cons.

  • Registered Users Posts: 439 ✭✭ divillybit

    The inner face of external walls? Never heard of that practice. That would only ever be feasible for new builds. That would be in addition to the insulation already attached to the inner leaf right? How much of an air space would that leave? 10mm?

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


    I always use insulation fixed to the internal face of the external walls for renovations of old buildings.

    many old buildings constructed in Ireland before the 60’s are solid concrete block walls or solid stone walls

    In solid walls there are no cavities.

    I always specify a chemical fix and a mechanical fix as per manufactures instructions with existing walls.

    Therefore your heating system does not have to heat the huge mass of the walls.

    This also allows the fitting of new electric fittings and plumbing and heating pipes etc within the insulation.

    also fix new slabs to the ceilings and re plaster the entire rooms