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100mm block cavity - insulated 60mm aeroboard & 40 mm cellulose fibre

  • 27-03-2021 11:58pm
    #1
    Registered Users Posts: 1,633 ✭✭✭ funnyname


    Seeing a lot of bubbling of the plaster on some parts of the western walls and bad mould around the internal window reveals.

    House was built in 2001 and all the windows and doors are attached to the outer block, something I hope to get help for in another thread.

    I did some investigative work and found that the cavity has the spec above with the spec being; inner block - 60mm aeroboard - 40mm cellulose fibre - outer block.

    The cellulose fibre is wringing wet so much so that when you squeeze that lots of water is released and the aeroboard isn't tight against the inner block.

    This leads me to believe the cavity insulation isn't working and it would be best to remove and then pump it with an insulation water resistant bead.

    Now the €64,000 question, we will be replacing all windows and doors so while they are out will there be enough access to the cavity to be able to remove all of the existing insulation and will the wall ties be a major obstacle to this?

    Thanks for looking

    FN


«1

Comments

  • Moderators, Home & Garden Moderators Posts: 10,101 Mod ✭✭✭✭ BryanF


    I think your figure above is in the ball park of what it might cost...

    If I was you, probably for external wall insulation


  • Registered Users Posts: 605 ✭✭✭ upupup


    The main problem is that the moisture is getting to the cellulous fiber.The exterior plastering or the brick exterior needs to be fixed/waterproofed.


  • Registered Users Posts: 715 ✭✭✭ Stihl waters


    BryanF wrote: »
    I think your figure above is in the ball park of what it might cost...

    If I was you, probably for external wall insulation

    If the op went for external insulation would the wet fibre have to come out or would it dry out eventually


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    Thanks for the replies, apologies but I forgot to include one crucial piece of info the house is fully faced with 200m of stone so EWI isn't going to be an option.

    So back to the big question, is it possible and also cost effective to remove existing insulation and then pump the cavity?


  • Registered Users Posts: 3,704 ✭✭✭ Metric Tensor


    I think you are correct that you've no choice but to take it all out.

    However you have a major problem with water getting through that stonework and you need to solve that or whatever insulation you pump in will end up in a similar mess.

    It's not easy to make stonework water proof after the fact and the best way is one that you won't want to do ......


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  • Registered Users Posts: 605 ✭✭✭ upupup


    funnyname wrote: »
    Thanks for the replies, apologies but I forgot to include one crucial piece of info the house is fully faced with 200m of stone so EWI isn't going to be an option.

    So back to the big question, is it possible and also cost effective to remove existing insulation and then pump the cavity?

    If you can remove the cellulous fiber then that may solve the damp but if you pump it again it may get wet again.
    remove the fiber first to get a 40mm cavity and see does that solve the dampness and insulate internally if needed


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    upupup wrote: »
    If you can remove the cellulous fiber then that may solve the damp but if you pump it again it may get wet again.
    remove the fiber first to get a 40mm cavity and see does that solve the dampness and insulate internally if needed

    Trouble is accessibility, not sure how we can get at it to remove it all.


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    If the op went for external insulation would the wet fibre have to come out or would it dry out eventually

    Yeah I think it would eventually dry out however to install the EWI we'd have to take down the stone work to do the instillation so costs would be very high.

    Bought the house 7 years ago, had it surveyed and all came back ok but living in it is when you find out all the issues that the original self builder baked into the house by accident or incompetence.


  • Moderators, Home & Garden Moderators Posts: 10,101 Mod ✭✭✭✭ BryanF


    If the op went for external insulation would the wet fibre have to come out or would it dry out eventually

    you might drill a few weep holes late spring and wait until late summer to do the ewi.

    OP,
    I have zero clue how you get the insulation out of the cavity.. hence EWI might be your best option, followed by dry lining as a distant 2nd..


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    BryanF wrote: »
    you might drill a few weep holes late spring and wait until late summer to do the ewi.

    OP,
    I have zero clue how you get the insulation out of the cavity.. hence EWI might be your best option, followed by dry lining as a distant 2nd..
    Internal dry lining with what kind of board and skim would you suggest?


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  • Moderators, Home & Garden Moderators Posts: 10,101 Mod ✭✭✭✭ BryanF


    funnyname wrote: »
    Internal dry lining with what king of board and skim would you suggest?

    Personally it would be my last resort. Dur point calc required, but maybe 30-50mm Insulated slabs, taped and jointed or skimmed depending on how good they go in.


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    OP: is this the buildup of the wall
    from inside

    gypsum plaster
    100mm block
    60 mm XYZ
    40 mm sodden cellulose
    100 mm block
    - no outside tender
    200 mm stone facing
    .
    There is zero prospect of getting out the wet cellulose?
    eg in corners maybe 1.8 m from the window/door

    Is it wet all the way around, including the sheltered side of the house?
    Is there stone all the way around?

    In any event you are not addressing the fundamental issue here which is that the house is shipping serious amounts of water the source of which is unknown for definite so until you solve that problem you are pi$$ing time and money away in the wind.

    As MT has intimated, the obvious solution may not be palatable.
    You could take done the stone facade, put on breathable insulation, with a breathable wind barrier on the unrendered outer block leaf and the fit a cement board rain shield on a metal framework, leaving a ventilated cavity behind.
    You could then face the cement board with 10mm slices of the stone facade.

    Budget unknown but the wall will dry, eventually


  • Registered Users Posts: 389 ✭✭ furandfeather


    I worked on a house a couple of years ago that had fibre glass used for cavity insulation on a brick fronted house. Same as yourself it was absolutely saturated. Some company from up donegal side I think, were able to suck all the insulation out, they had to open up a few holes but nothing major. I can try find out there name for ya if you want


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    I worked on a house a couple of years ago that had fibre glass used for cavity insulation on a brick fronted house. Same as yourself it was absolutely saturated. Some company from up donegal side I think, were able to suck all the insulation out, they had to open up a few holes but nothing major. I can try find out there name for ya if you want

    Yeah that would be brilliant, organising a survey from a Kerry based company, hopefully they will be able to visit soon.


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    OP: is this the buildup of the wall
    from inside

    gypsum plaster
    100mm block
    60 mm XYZ
    40 mm sodden cellulose
    100 mm block
    - no outside tender
    200 mm stone facing
    .
    There is zero prospect of getting out the wet cellulose?
    eg in corners maybe 1.8 m from the window/door

    Is it wet all the way around, including the sheltered side of the house?
    Is there stone all the way around?

    In any event you are not addressing the fundamental issue here which is that the house is shipping serious amounts of water the source of which is unknown for definite so until you solve that problem you are pi$$ing time and money away in the wind.

    As MT has intimated, the obvious solution may not be palatable.
    You could take done the stone facade, put on breathable insulation, with a breathable wind barrier on the unrendered outer block leaf and the fit a cement board rain shield on a metal framework, leaving a ventilated cavity behind.
    You could then face the cement board with 10mm slices of the stone facade.

    Budget unknown but the wall will dry, eventually

    Thanks, that's a very detailed approach to take, i appreciate your time to go through all the steps.

    I'm trying to find out as many remediation solutions as possible so we can get the best bang for our buck.

    I saw a thread on Walltite and I'm wondering would this be any good as it seems to fill all available spaces as it is an expanding foam. So that the wet cellulose would then be trapped between the Walltite and aeroboard and the aeroboard would then be tight against the inner leaf and any breaks in the aeroboard would also be filled.



    The sheltered sides of the house (north and east) are fine, thankfully the cellulose is dry.

    Is there any reason for the cellulose fibre to be used as insulation in a block cavity? I don't understand why it would have been used in the first place.


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    My guess is that the cavity was pumped post construction to boost the U value, common nigh and not a wrong idea except when the external facade is incapable of stopping the driving rain into the cavity.

    Over zealous application of walltite has been know to crack walls....
    not being harsh here: your theoretical description of the wall lite getting between the outer block and the wet cellulose is just that, even fanciful: it just wont work that way.
    However it raises the question, is it cellulose or some sort of a fibre.
    cellulose is chopped paper: can you post a picture of the wet cellulose please

    The dry walls are key to pointing to where the problem is, are the sheltered walls stone clad or rendered.

    AS I said before you must solve the water ingress problem first.


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    My guess is that the cavity was pumped post construction to boost the U value, common nigh and not a wrong idea except when the external facade is incapable of stopping the driving rain into the cavity.

    Over zealous application of walltite has been know to crack walls....
    not being harsh here: your theoretical description of the wall lite getting between the outer block and the wet cellulose is just that, even fanciful: it just wont work that way.
    However it raises the question, is it cellulose or some sort of a fibre.
    cellulose is chopped paper: can you post a picture of the wet cellulose please

    The dry walls are key to pointing to where the problem is, are the sheltered walls stone clad or rendered.

    AS I said before you must solve the water ingress problem first.

    See attached for some of the pumped material, i took that bit out of the sheltered side of the house.

    The house is in a very unforgiving spot in North Clare so driving rain is a big issue.

    Also there might be issues wrt how the lintel cavity trays were applied during the build, might be none or retro fitted poorly. Also the application of the vertical dpc could be another issue.


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    My guess is that the cavity was pumped post construction to boost the U value, common nigh and not a wrong idea except when the external facade is incapable of stopping the driving rain into the cavity.

    Over zealous application of walltite has been know to crack walls....
    not being harsh here: your theoretical description of the wall lite getting between the outer block and the wet cellulose is just that, even fanciful: it just wont work that way.
    However it raises the question, is it cellulose or some sort of a fibre.
    cellulose is chopped paper: can you post a picture of the wet cellulose please

    The dry walls are key to pointing to where the problem is, are the sheltered walls stone clad or rendered.

    AS I said before you must solve the water ingress problem first.


    See attached for some of the pumped material, i took that bit out of the sheltered side of the house.

    The house is in a very unforgiving spot in North Clare so driving rain is a big issue.

    Also there might be issues wrt how the lintel cavity trays were applied during the build, might be none or retro fitted poorly. Also the application of the vertical dpc could be another issue. Need to do some more investigations, any suggestions how best to do this?

    548566.jpg


  • Registered Users Posts: 605 ✭✭✭ upupup


    funnyname wrote: »
    See attached for some of the pumped material, i took that bit out of the sheltered side of the house.

    The house is in a very unforgiving spot in North Clare so driving rain is a big issue.

    Also there might be issues wrt how the lintel cavity trays were applied during the build, might be none or retro fitted poorly. Also the application of the vertical dpc could be another issue.

    The damp around the window reveals can be fixed when putting in the new windows.The new windows should be fitted in the middle and not to the outside block.You can easily put in new dpc but you need someone that knows exactly what he is doing.


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    I believe the pumped material could actually be

    InstaFibre White Wool


    This insulation comprises granulated glass wool fibres manufactured from silica sand and treated with an inert water repellent during manufacture. It is a new generation product developed specifically for use in cavity walls. InstaFibre Cavity wall insulation.


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  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    https://www.savingenergyuk.co.uk/wp-content/uploads/2017/03/Cavity-Wall-Insulation-Spec.pdf
    from UK
    You never said is the outer block rendered behind the cut stone.
    Given where you are, its a must


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    https://www.savingenergyuk.co.uk/wp-content/uploads/2017/03/Cavity-Wall-Insulation-Spec.pdf
    from UK
    You never said is the outer block rendered behind the cut stone.
    Given where you are, its a must

    No render behind the cut stone

    Yeah I'm always surprised to see new houses with cut stone around this way not having the block work rendered before stone is added.


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    funnyname wrote: »
    No render behind the cut stone
    Thanks, thats the problem right there.


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    Thanks, thats the problem right there.

    Thanks, but wouldn't rain just get through that as well?


  • Registered Users Posts: 715 ✭✭✭ Stihl waters


    If everything is done correctly then the blocks shouldn't need to be rendered, theres obviously something wrong with dpc or dirty wall ties


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    If everything is done correctly then the blocks shouldn't need to be rendered, theres obviously something wrong with dpc or dirty wall ties
    Depends on the exposure as per the attached


  • Registered Users Posts: 1,633 ✭✭✭ funnyname


    So after a bit more investigation and consulting we've come up with a plan.

    First a bit more info tho.

    The windows cavities present an additional problem as the inner cavity is tapered away (probably a half block less) from the outer to give curved effect on the revels so more light comes into the room.

    The windows need replacing anyways so plan is to get new ones and remediate the inner cavity so that it is flush with the outer cavity and make the placement of the new windows as normal across the cavity. Basic example of what the current window situation looks like within the limits of keyboard characters available :D

    ||||||
    (||||

    to

    ||||||
    ||||||

    The trickiest part of the job seems to be the block work to remediate the half block missing from the inner leaf.

    Any suggestions on what the easiest method for this is?


  • Registered Users Posts: 25 hydrus21


    My solution would be to tooth-in the new 1/2 blocks to avoid a straight joint.
    Materials = cheap
    Labour =not so.


  • Registered Users Posts: 605 ✭✭✭ upupup




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  • Registered Users Posts: 25 hydrus21


    Those profiles will create a straight joint which will be subject to cracking if there is any movement.
    If the op uses them, I would suggest fixing expanded metal over the joint to reduce the chance of cracking.


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