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

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

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

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.

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

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?

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 ......

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

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.

funnyname

Stihl waters wrote: »

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.

BryanF

Stihl waters wrote: »

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..

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?

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.

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

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

funnyname

furandfeather wrote: »

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.

funnyname

Calahonda52 wrote: »

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.

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.

funnyname

Calahonda52 wrote: »

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.

funnyname

Calahonda52 wrote: »

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?

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.

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.

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

funnyname

Calahonda52 wrote: »

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.

Calahonda52

funnyname wrote: »

No render behind the cut stone

Thanks, thats the problem right there.

funnyname

Calahonda52 wrote: »

Thanks, thats the problem right there.

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

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

Calahonda52

Stihl waters wrote: »

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

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

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to

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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?

hydrus21

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

upupup

build it with blocks and use one of these,very easy to put up and clean.
https://www.screwfix.ie/p/sabrefix-wall-starter-kit-stainless-steel/56037?gclid=CjwKCAjwq7aGBhADEiwA6uGZp7sXAOcvovcBj7iV_ihHISB_HyeDyACKDNXedvJpNzeIXHl4L050oRoCvyIQAvD_BwE&gclsrc=aw.ds

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.

funnyname

hydrus21 wrote: »

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.

What kinda movement are you thinking of and how would you fix the expanded metal?

sydthebeat

hydrus21 wrote: »

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.

You have to expect differential movement whenever you build an extension.

The starter rails are the correct method, but you need to incorporate movement joints at that point. The rails prevent the movement pulling away from the original, but yet vertical movement as the structure settles

funnyname

sydthebeat wrote: »

You have to expect differential movement whenever you build an extension.

The starter rails are the correct method, but you need to incorporate movement joints at that point. The rails prevent the movement pulling away from the original, but yet vertical movement as the structure settles

I've no background in this and am just trying to figure out as much as possible for my own curiosity and to be able to converse with the builder about the works that need doing.

So I'm a half if not a full block short on the inner leaf compared to the outer leaf of the house at the windows. When I take out the old windows, I need to build up either side of the inner leaf so that it matches the outer leaf. Then I'm in a position to get my new windows measured.

Wrt to the vertical movement joints are you talking about this remediated course of one block width (6 to 8 blocks high) having an issue because there's no wall ties in place linking it to the outer leaf?

Also how is it best tied in with the lentil above it?

hydrus21

"The rails prevent the movement pulling away from the original, but yet vertical movement as the structure settles."

There is no way these profiles would prevent pulling away movement from a new extension.
They were designed so that if movement occured between original and new work, building surveyors could determine whether it was
the new or the existing that was moving.
Their main advantage is to be able to join metric brick bond to imperial bond without toothing in.

sydthebeat

When used with movement joints, they do prevent pulling away movements. I've used them on extensions for over 20 years.
Essentially the two structures are designed to be constructed to be independent of each other.
Most cracking and opening joints occur where builders try to tie an existing structure to a new structure with no thought to differential settlement

hydrus21

What kinda movement are you thinking of and how would you fix the expanded metal?
__________________

Were talking hairline cracks from closing windows/slamming doors.
Metal lath is fixed with plugs and screws prior to rendering.

hydrus21

Essentially the two structures are designed to be constructed to be independent of each other.
Most cracking and opening joints occur where builders try to tie an existing structure to a new structure with no thought to differential settlement.

Correct.
40yrs ago, builders were bonding- in new work to old.
When there was subsidence/movement it difficult to determine what was moving.
In the cases i came across it was mainly the existing structure that was the problem.
Profiles were a result of numerous legal cases where homeowners were taking their local authority to court over movement/cracks issues.

funnyname

hydrus21 wrote: »

What kinda movement are you thinking of and how would you fix the expanded metal?
__________________

Were talking hairline cracks from closing windows/slamming doors.
Metal lath is fixed with plugs and screws prior to rendering.

So you tie in the new block to the inner leaf with the yokes (hope that term isn't too technical) from screwfix and then fix the the metal lath at the open cavity side that window will be fixed to? So basically the lath and the profile are the bread of the sambo with the new block the meat?

upupup

funnyname wrote: »

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

||||||
(||||

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?

Is the position of the new window going to change?ie moving back from the outside leaf.The windowsill position determines where the window sits.

funnyname

upupup wrote: »

Is the position of the new window going to change?ie moving back from the outside leaf.The windowsill position determines where the window sits.

Yeah, plan is to move the window closer to the inner leaf so yeah the position of the window sill is going to change, in fact going to to have to get new ones. Not sure if those will be traditional concrete ones or passive sills. Any suggestions there gratefully accepted as well.

funnyname

So windows have been loosened up and going to move in the existing sills as they are deep enough, hope to get windows measure next week with installation 4 weeks afterwards.

half of the insulation in the southern and western walls has been removed, want to get the rest of it done over the weekend, the pumped cellulose fibre is a pain in the hole to remove as it clogs up the filter in the vacuum cleaner, easy to take out in the more exposed area as the moisture that got in has it harden and clumped whereas in the dryer areas it's very fluffy and breaks up on touch.

funnyname

We're also going to spray foam insulate upstairs as the bedrooms don't hold the heat at all, existing rockwool has fallen out of shape and not keeping heat in or draughts out. There's only a tiny attic so going to take down the sloped slabs above the knee wall and the flat slabs on the ceiling and spray with open cell foam insulation so plan is this is create an airtight envelope from wall plate to the apex of the roof with a 50mm ventilation card between the felt and foam insulation so the roof can breath.

Question, no overall builder looking after this, just ourselves and the engineer with trades (unskilled and skilled) got as required, so just wondering what I can do with the old rockwool and slabs that are going to be coming out of the house, can they be recycled or do I just hire a skip and send them to the dump?

MicktheMan

Caveat emptor:

sprayfoam on its own will likely NOT airtighten your ceiling / roof.

funnyname

https://www.boards.ie/discussion/comment/117778822#Comment_117778822

We will be reslabbing the rooms again, is this not enough or should we also look at putting an airtightness membrane on after the spray foam so it's between the spray foam and slab?

funnyname

More questions of the top of my head

Would it be better to also remove the slab on the knee wall to make it a better/easier job when reslabbing?

When reslabbing should we go for an insulated slab or ordinary half inch one?

funnyname

So all the aeroboard and useless cellulose fiber has been taken out of the south facing cavity, most of the west facing cavity has been done.

I'm caught in the upper lower corners of the gable as there's only one centre window and I can't reach it as well as the other parts.

There's about 2x3 sheets left in place on both sides but with the wall ties and mortar it's fair stuck.

If the inner gable leaf was taken away I'd get it no bother but I don't want to go to that extreme.

Anyone have any ideas? Could I just leave that in-situ and pump the rest of the cavity and hope for the best?

funnyname

Photos to help

funnyname

View from below of top left and right corners.

10-10-20

Was it determined whether the dampness was interstitial condensation or the permeability of the external wall? If the latter, will this be remedied?

funnyname

It was interstitial condensation