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Wide cavity . Effect of blown in insulation?


Moggaman

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Hi all.

Something mentioned to me today about the negative effect blowing in beads under pressure can have on a block cavity wall and that it caused cracking of wall?.

seems unreasonable to me ?.

I have no evidence of this but the posters here might give there view. My build is 200mm wide cavity with 100mm inner and outer leaf block with extra ties 

thanks

 

 

 

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Also , the same blocklayer said to me that blown in beads into a cavity isn’t really done on new builds where I’m from( west of Ireland).. however, I’m not reinventing the wheel here? ... my design ie 200mm blown into block cavity is quite common amongst houses built in block now isn’t it?... I mean structurally and thermally?. Just looking for reassurance.. my engineer will be involved of course . 

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@Moggaman, multiple holes are drilled at the same time, IMHO any slight positive pressure used to inject the beads would escape through these and any significant pressure build up impossible. I have seen cases of fibre cavity fill accidently injected into timber frames and the plasterboard buckle as a result.

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I very much doubt blown bead insulation could damage a block wall in the way described. Arent the beads already expanded before they are blown in? I guess it might be possible with foam that expands in place but I've never heard of that cracking blocks. I have had an issue with a stud wall and expanding foam blowing out plasterboard but that was my fault.

 

I think the person you spoke to was confusing it with another issue..  Fully filled cavities can cause water to bridge the cavity causing damp inside. For that reason its not recommended in exposed lolocations. The problem is that bricks are porus. Would your location be considered exposed? Installers that fill cavities on old houses are meant to decline if they think this is a risk on houses they have been asked to quote on. I suspect many dont. My understanding  is this is not an issue if your house is rendered. I have heard that the grey "platinium" coated bead system is also at less risk. Pick a good installer and perhaps check if the warranty covers this issue. 

Edited by Temp
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West coast of Ireland + severe exposure + full fill insulation = probably not a good idea. Check MIs, Certification and additional requirements for protection of the wall from wind driven rain (render, tile hanging, rainscreen).

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1 hour ago, Temp said:

I very much doubt blown bead insulation could damage a block wall in the way described. Arent the beads already expanded before they are blown in? I guess it might be possible with foam that expands in place but I've never heard of that cracking blocks. I have had an issue with a stud wall and expanding foam blowing out plasterboard but that was my fault.

 

I think the person you spoke to was confusing it with another issue..  Fully filled cavities can cause water to bridge the cavity causing damp inside. For that reason its not recommended in exposed lolocations. The problem is that bricks are porus. Would your location be considered exposed? Installers that fill cavities on old houses are meant to decline if they think this is a risk on houses they have been asked to quote on. I suspect many dont. My understanding  is this is not an issue if your house is rendered. I have heard that the grey "platinium" coated bead system is also at less risk. Pick a good installer and perhaps check if the warranty covers this issue. 

I am 30miles from the west coast. Yes it rains a lot here! And technically falls within that severe exposure area.However, these beads it claims can deal with some moisture coming into the Cavity. My west , south and east facing (the direction all the weather comes from) have no brick and will be finished with sand/cement render. 

The north face which very rarely would be subject to driving rain has some brick on it. I really want to avoid thermal looping so I reckon the bead was the workable solution.

 

 

89D9B243-F281-4433-9DA5-9431ABA0578E.jpeg

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1 hour ago, ADLIan said:

West coast of Ireland + severe exposure + full fill insulation = probably not a good idea. Check MIs, Certification and additional requirements for protection of the wall from wind driven rain (render, tile hanging, rainscreen).

What do you mean check Mls?

 

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4 hours ago, TonyT said:

https://www.mikewye.co.uk/wp-content/uploads/2016/01/GEOCELL-Foam-Glass-Bubbles-brochure.pdf
 

i was thinking about using them subject to availability locally for insulating behind Victorian lath and plaster wall

 

Lambda value of 0.07 W/(m·K) compared to 0.02 for PIR?  You would need three times the thickness to achieve same result.

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Thanks A_L. I’ve read these documents before, when I was in the planning stage, now my extension is finished, I’m looking at further thermal improvements on a room by room basis.

 

trying to get motivated to do the work is another matter...

 

 

 

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We have a 250mm blown bead cavity in SW Ireland. No issues with cracking due to the beads but as the cavity is wider and less stable than standard you may get more settlement cracks. 

 

As mentioned above most installs are only compliant with plastered external leafs so you may need to change your brick.

 

Here is a list of approved operators. As usual the key is avoiding the cowboys. 

 

https://www.nsai.ie/search/insulation/eyJyZXN1bHRfcGFnZSI6InNlYXJjaFwvaW5zdWxhdGlvblwvIiwia2V5d29yZHMiOiJCZWFkIn0/

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4 hours ago, A_L said:

 

How about Perlite/Vermiculite (Silvapor). As mentioned in the second pdf? Thermal conductivity 0.05W/m.K

 

https://www.dupreminerals.com/wp-content/uploads/perlite/Silvaperl-silvapor.pdf


 

yes, I’ve used vermiculite when I first bought the property and found a ,dead space between the vestibule cupboard and lounge cupboard, poured a few bags in

 

Im going to go under the floor next week and stiff glass wool in the gap where the ground floor boards wall junction to stop anything falling out!

 

 

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4 hours ago, Iceverge said:

We have a 250mm blown bead cavity in SW Ireland. No issues with cracking due to the beads but as the cavity is wider and less stable than standard you may get more settlement cracks. 

 

As mentioned above most installs are only compliant with plastered external leafs so you may need to change your brick.

 

Here is a list of approved operators. As usual the key is avoiding the cowboys. 

 

https://www.nsai.ie/search/insulation/eyJyZXN1bHRfcGFnZSI6InNlYXJjaFwvaW5zdWxhdGlvblwvIiwia2V5d29yZHMiOiJCZWFkIn0/

Thanks @Iceverge . i will talk to the company for advice. Looks like i might have to plaster and then brick over that for same effect. Can I ask, did u have precast in your build and what did it sit on at the external leaf.. 100mm, 150mm or block on flat?

Thanks

 

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Internal leaf you mean? 

 

215mm block on flat downstairs and 100mm upstairs. Talk to the precast floor suppliers. They'll let you know as it's dependant on ceiling height. I seems to remember something about 12 courses of 100mm block being OK for first floor with precast floors. 

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3 hours ago, Iceverge said:

Internal leaf you mean? 

 

215mm block on flat downstairs and 100mm upstairs. Talk to the precast floor suppliers. They'll let you know as it's dependant on ceiling height. I seems to remember something about 12 courses of 100mm block being OK for first floor with precast floors. 

Yes internal leaf..sorry!

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