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Fibre Batts or Blown Beads


MortarThePoint

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Well I thought I knew exactly what we were going to do for cavity wall insulation years ago, but just before placing the order for the fibre batts I (re?-)discovered blown beads (Ecobeads). I don't know if the Ecobeads have got better in the last 2-3 years since we decided on Knauf Dritherm Ultimate 32, but they look quite attractive. I got some quotes and the price for Ecobeads installed is essentially the same as the Dritherm material cost. I'm finding it difficult to make up my mind now.

 

Some pros / cons:

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Kingspan did a white paper on fibre batts and, whilst they have a commercial interest in knocking full fill insulation, they do make some good points. I haven't seen many sites, but I don't think I have ever seen people installing fibre batts as set out in their BBA documents. Outer leaf first, snot boards and properly orientated batts. I have seen loads of YouTube videos of clearly skilled brickies who don't follow much of this and if you look carefully are dropping and leaving snots on the batts. I don't want to be a nightmare for my brickies breathing down their necks and insisting they work in a way they don't normally, but I'd want fibre batts installed as per the BBA certificate as otherwise there can be a loss of performance even if not an actual damp problem.

 

There were loads of bodged blown bead installs for retrofit, but I'd expect that is due to narrow cavities as well as other unsuitability issues. I don't like the thought of them and any future work could mean beads blowing about for years to come. I also worry about insects living in them as I have seen that with PIR insulation. There is also a lot of faith in that one day of install. If the installer is a joker then you're stuffed whereas a more gradual install can be understood and rectified much more easily.

 

We're building in East Anglia so it's the best part of the country for fibre batts, but still.

 

Blown beads feel like a no brainer for large cavities (e.g. 200mm or more) but I'm not so sure for us (100mm cavities).

 

Your help and experiences please making this decision would be massively helpful.

 

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I was originally going to use blown beads in a timber frame, but changed to Frametherm 35 instead.  They both essentially give the same U values.  So it came down to cost.  I would have had to pay for the hire of a machine and a team to blow in the beads.  The frametherm was DIY installed so cost £0

 

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19 minutes ago, ProDave said:

I was originally going to use blown beads in a timber frame, but changed to Frametherm 35 instead.  They both essentially give the same U values.  So it came down to cost.  I would have had to pay for the hire of a machine and a team to blow in the beads.  The frametherm was DIY installed so cost £0

 

 

I was surprised, but the beads installed seem the same price as just the material cost of fibre batts.

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Beads could also potentially settle over time ( I know they are coated in PVA or something to help them bond). Personally I feel batts are a more reliable method, and I'm doing a 300 cavity, but it's certainly attractive to simply blow in beads  at the end and not faff around with batts.

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Did a 150mm cavity with blown bead and worked really well - they got everywhere ..! They set after about 3 hours as they are glued together when installed and I’ve core drilled sections through so know that they don’t really move about much once installed. I’d use them again over batts which are a pain as they are bulky and get in the way. I’ve also seen batts get soaked on site and still used - they are not cheap to chuck in a skip. 

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12 hours ago, Miek said:

Beads could also potentially settle over time ( I know they are coated in PVA or something to help them bond). Personally I feel batts are a more reliable method, and I'm doing a 300 cavity, but it's certainly attractive to simply blow in beads  at the end and not faff around with batts.

 

I've seen videos of installers tweaking the glue recipe, so it doesn't seem an exact science. Voids and or settlement are concerns and you wouldn't be able to see if they had happened.

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I'm still pulled in two ways on this. If I could be certain they were installed correctly, I think I'd go with the Knauf Dritherm Ultimate fibre batts as they are more 'normal'. Blown beads could give a possible future purchaser concerns since there have been horror stories associated with their retrofit use. I like the labour saving of the blown beads and the fact that it wouldn't need the constant monitoring of how the insulation is installed that fibre batts would require. That said, if they mess it up on the day of blown bead install then it would be a nightmare.

 

These decisions often come down to minimising the downside rather than optimising the upside. Maybe that sounds a big 'glass is half empty', but you don't get giddy about your cavity insulation being slightly better than it could have been, but you would get sick of it being a lot worse.

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I went full fill batts but 300mm wide cavity. No way would I let brickies install it, I did it all myself. They did try to fit some but I took it out and re did it. 
 

beads are great but I think you will find they work out too expensive. If you do for them go for platinum ones. 

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16 minutes ago, tonyshouse said:

I went full fill batts but 300mm wide cavity. No way would I let brickies install it, I did it all myself. They did try to fit some but I took it out and re did it. 

 

Did you worked along side the brickies then or did they build up the walls to the point ready for you to install in the evenings?

 

17 minutes ago, tonyshouse said:

beads are great but I think you will find they work out too expensive. If you do for them go for platinum ones. 

 

It would need to be the platinum ones to give equivalent Uvalue. The price seems to be the same as fibre batts 32.

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Well we've surprised ourselves here because we think we will got with the Ecobeads. The U-value is essentially unchanged (Ecobead platinum lambda=0.033W/mK vs Dritherm Ultimate lambda=0.032W/mK) and I have quotes for confidence on the price. We talked to some insurers to see if there were any concerns, of which there was none.

 

I think the factors that swayed it were:

  1. Intrinsic water handling - drains rather than dries.
  2. No on site storage - I would have worried about the fibre batts getting wet and they would have taken up space as well as being a marginal theft concern.
  3. Ease of wall construction - No fibre batts to put in correctly.

I'm going to get guidance from the installer about how to build with beads in mind to make sure that things like cavity trays fill up with beads nicely.

 

We are trying to build with a low chemical (VOC) approach and liked that the Knauf Dritherm used their Ecose technology that was Formaldehyde free. We ruled out PIR for chemical reasons. I will double check with Ecobeads that they are equally good in that regard. We're far from obsessive about this sort of thing, but would like to preserve air quality in the house as we are reasonably rural.

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1 hour ago, MortarThePoint said:

I'm going to get guidance from the installer about how to build with beads in mind to make sure that things like cavity trays fill up with beads nicely.

 

Make sure they lay the DPC flat on the lintels, and they will drill either side, above and below to ensure they fill the whole wall. Internal walls were fun - I did one between an internal garage and a lounge and we had to make sure as it was a single skin above the first floor we plugged the top of the cavity with rockwool.

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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.  

Edited by Iceverge
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1 minute ago, 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.  

 

Good to heat Iceverge! Please let us know how you get on with the trial holes if you do those.

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  • 2 months later...

@MortarThePoint

 

Apologies for late reply. 

 

My observations on Full Fill Bonded blown Beads,

 

Are they Full Fill: Yes very much so, in our wide cavity at least. I drilled a few trial holes around windows and doors to check in awkward to reach places. All full with beads.

 

Are they Bonded: Kinda, a little hit and miss really as i found out when coring ventilation holes and lost a few buckets. 

 

The remaining question: Will they settle.......? Time will tell. 

 

Would I use them again? Yes, but I would core all holes in the wall first.

 

 

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