Pumped cavity Bead Insulation

M

michaelg

Registered User
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About to do some insulation work and trying to figure out if it would be worth pumping my cavity walls with beads ?

I live upstairs in a (2004 build) Duplex apartment, Concrete slab floor, I have been told by an Engineer that its probably 100mm cavity and 50/60mm expanded polystyrene insulation inside, pumping would give me an extra 50/40mm of insulation. Roughly double the insulation.

Worth it ? I heard the outer leaf can remain wet once the cavity is gone ?
 
Hello,

We had our walls pumped with beads, over ten years ago... To this day, they are still coming out through every vent etc. A complete pain and I honestly don't think they helped with heat retention.
 
MrEarl said:
Hello,

We had our walls pumped with beads, over ten years ago... To this day, they are still coming out through every vent etc. A complete pain and I honestly don't think they helped with heat retention.
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How can you tell they didnt help - have you a pre/post thermal imaging result . That said, something with your vents may be an issue too.

Have beads installed in a brick outer-leaf cavity construction along with the loft it made a difference. Pay attention to heat loss & ventilation too!.
 
MrEarl said:
Hello,

We had our walls pumped with beads, over ten years ago... To this day, they are still coming out through every vent etc. A complete pain and I honestly don't think they helped with heat retention.
Click to expand...
How old is your house ? did it have any insulation previously ?
 
clinteastwood said:
How can you tell they didnt help - have you a pre/post thermal imaging result . That said, something with your vents may be an issue too.
Click to expand...
No, I don't, tbh.

Would you be happy with me saying that it doesn't feel like it made any difference?
 
There are both bonded and loose bead options, the loose will move and leave voids if disturbed by later works or there are unsealed gaps around services or vents.

@michaelg, the first thing you need to establish is whether you would be permitted carry out such works. Depending on the ownership structure of the building or development, you may not be permitted carry out any works affecting the structure of the building without explicit permission. Is there a management company in place?
 
The management company have been made aware and there are no objections.

As there is a concrete slab between floors which likely reaches across the cavity to the outside leaf.
I am curious to how the cavity wall is vented, especially given that there are no visible weep vents on the upper floors.
How does the cavity manage moisture and ensure proper ventilation?
 
If there is indeed a 50/60mm board installed in the cavity during construction and you have high heat loss at the moment then having the residual cavity pumped subsequently will unfortunately likely yield little if any benefit.
The reason for this opinion is that if the original insulation was installed properly by the blocklayer (a rarity) then you should already be benefitting from this insulation and adding more will make little noticeable difference. If, on the otherhand, it was installed poorly then adding insulation behind it will not change the fact that the original insulation boards are not insulating the internal concrete block leaf thus leading to little in any change in conductive heat loss through your walls.

A 2004 build might also have internal insulation installed (does the wall sound hollow if tapped with your finger). If this is the case then I would recommend you have a proper air tightness test done first (maybe as part of an overall heat loss survey) because air leakage may well be you main issue to address for significant heat loss reduction.
 
Thanks for that.

The heat retention I think is actually fairly decent, Its definitely not a cold apartment, We are just looking to maximize its potential.

I would have thought doubling the 50mm to 100mm insulation would make a difference.
Doesn't the pumped beads fill in any empty spaces and help reduce air gaps and voids ? I also thought they can be beneficial to help reduce thermal bridging particularly around windows and doors?

The walls are definitely not hollow sounding when tapped , sounds more like solid concrete.
 
michaelg said:
I also thought they can be beneficial to help reduce thermal bridging particularly around windows and doors?
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The beads will only get into voids. They will not physically disconnect elements like the cills, lintels, or frames that might cross the cavity providing the bridge.
 
If the heat retention is good and you have internally plastered solid finish to the inside then you could get the residual cavity pumped which may save you somewhere between €50 to €100 euro per year on your heating bill. Not sure what your payback would be but might be pretty long. As @Leo has said it will not improve any thermal bridging already present, in fact, it might make them more pronounced. Also, don't forget, you will be increasing the risk of penetrating damp across the cavity which currently the residual cavity is preventing. The level of this risk is generally low but would be dependent on your location / exposure to driving rain.
 
Thanks.
With the grant it would be virtually free.
Thankfully I'm not in a costal/hilly area so I don't think driving rain is a problem, but damp is still my only concern , for example what if the cavity is less than 40mm in places (the minimum required for beads).
 
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