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Fibre Batts or Blown Beads


MortarThePoint

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  • 2 months later...
On 12/06/2020 at 14:50, Iceverge said:

We've had a 250mm Cavity done this week with blown eps bead. 

 

I climbed into the attic earlier to have a look as I was sceptical the beads would fill right up to our cavity closer (450mm DPC).

 

I checked the entire perimeter of the house and was pleased to find the beads had billowed up the DPC everywhere.  Its given me confidence that around the windows and doors there's a tight fill as well. I may do some trial holes if I can find the time but thus far I'm more impressed than I thought I'd be.  

Did you have a cost per m2? toying between 200mm or 250mm cavity and cost will swing it ?

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  • 2 years later...

The beads haven't settled in the least. 

 

They bowed up the 450mm DPC cavity closer when they were blown in. 

 

Earlier this year I climbed into the attic and did a few spot checks to see if any settling had occured. None had. Similarly when I checked with a thermal camera there were no voids. 

 

We've used about 17kWh/m2 over the last 2 years in heating bills. A bit more than PHPP predicted but I'm not sure why. I don't think it is the beads. One thing that I think is important is getting wind tightness very secure as the nature of them is porous and susceptible to wind washing. (Where heat is lost by blowing through the insulation)

 

If you are building a cavity wall I would recommend them or full fill fiber batts. 

 

 

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5 minutes ago, Iceverge said:

The beads haven't settled in the least. 

 

They bowed up the 450mm DPC cavity closer when they were blown in. 

 

Earlier this year I climbed into the attic and did a few spot checks to see if any settling had occured. None had. Similarly when I checked with a thermal camera there were no voids. 

 

We've used about 17kWh/m2 over the last 2 years in heating bills. A bit more than PHPP predicted but I'm not sure why. I don't think it is the beads. One thing that I think is important is getting wind tightness very secure as the nature of them is porous and susceptible to wind washing. (Where heat is lost by blowing through the insulation)

 

If you are building a cavity wall I would recommend them or full fill fiber batts. 

 

 

Yes building a cavity wall and now final choice is between beads (cheaper) or the Celotex Thermaclass 21 T&G (expensive) but is also full cavity fill “according to manufacturer”. 
Setting the financial aspect of things aside, and based solely on other numbers which one to go for to guarantee longer term? 
 


 

 

Celotex_Thermaclass_Cavity_Wall_21_Install_Guide.pdf

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1 hour ago, Iceverge said:

One example of many posts about this. 

 

PIR boards in cavity block walls is idiocy. 

 

 

 

 

 

Yes saw it earlier. 
i am wondering if we do it right from the start. Inner block leaf then T&G PIR, then outer leaf. 

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