Partial fill cavity construction: dead?

Like last thread I would like to know if it is possible to fill existing cavity with polypearl given that 2 inch white board insulation is already in place for last 18 years.
 
Haille said:
Like last thread I would like to know if it is possible to fill existing cavity with polypearl given that 2 inch white board insulation is already in place for last 18 years.
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First off, I basically have no experience whatsoever in this but its never stopped me offering an opinion in the past!

Anyway, I assume the success would depend on how the original insulation was fitted. If it was fitted tight against the inner leaf leaving a 50mm cavity to the outside then I imagine it would be effective. If the insulation is zig zagging its way up the cavity you could end up with pockets where the pumping can't reach unless ALOT of holes are bored to ensure its effectiveness.

I'd talk to a company about it to be honest. The Gilmartin Group in Galway (093 52170) were the ones who put the Ecobead pumped insulation through IAB certification so I'm sure they'd be able to give you some idea as to what you could expect in performance terms.
 
sydthebeat said:
My preferred cavity construction is as follows:

external render
100 dense concrete block
50 cavity
100 AAC block
100 PU board mechanically fixed
47.5 Composite plasterboard
skim finish

With this relatively easy construction you are looking at a construction u value of 0.13. There are also added advantages of having the thermal insulation within the structure which i can go into later.
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Syd, would it not be better to pump the 50mm cavity with bonded beads? What is a PU board and how is it mechanically fixed? Tks
 
I was advised by someone in the full-fill bead insulation business not to dryline the walls. He said the u-value improvement would be very small.
I am building a cavity block wall with 150mm. Was this good advice ?
 
Birroc said:
I was advised by someone in the full-fill bead insulation business not to dryline the walls. He said the u-value improvement would be very small.
I am building a cavity block wall with 150mm. Was this good advice ?
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without being blunt, but sales speak is sales speak.....
fitting 47.5mm insulated plasterboard has the same effect in improving u values as increasing the EPS bead in the cavity by 50mm.
 
sydthebeat said:
without being blunt, but sales speak is sales speak.....
fitting 47.5mm insulated plasterboard has the same effect in improving u values as increasing the EPS bead in the cavity by 50mm.
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Thanks Syd, the question is, should I do both ?
 
Birroc said:
Thanks Syd, the question is, should I do both ?
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Birroc, the walls will be very thick... almost 500mm compared to 300mm normal. Are you prepared to lose more space? Perhaps leave the cavity at 150mm and don't dry line? Or use something like a 100mm or 150mm Quinn Lite block for the internal leaf?

Syd,

if both have the same U value potential surely the cavity option is more cost effective as dry lining is very labour intensive plus expensive for materials and can cause thermal looping?
 
Barney,
The lowest u value ive seen the 'pumped in' system quote is for a 0.2 wall... this was in a 150mm cavity... but did not state what type of concrete block is to be used. The extra width cavity raises its own issues.
the ecobead system quote a u value of 0.24 for a 100 cavity with 100mm AAC blocks on the internal.
I find it strange that its so hard to get an exact TC value for bead insulation that has the glue added. Have you got one barney?

My own calculations with 20 external render, 100 AAC, 150 bead, 100 AAC and 12.5 plaster only gives a u value of 0.23... so id love to see the calculations form ecobead.....

A 100 cavity with 60 PU, 100 AAC innerleaf and 35mm insulated 12.5 plasterboard can give you a 0.17 u value. Thats significant in my opinion, and cannot seem to be replicated by the 'pumped in' suppliers. So the extra work may be worth it. Thermal looping is caused by bad construction practice so its something to be avoided.
With this type of construction care is to be taken at details to avoid thermal bridges.

Im wary to give any opinion on what wall type to use without knowing many other particulars such as heating methods, floor + roof constructions etc.
 
Are these AAC blocks easy to source ? How expensive are they ?
Will blocklayers charge more to use them ?
 
Hi sydthebeat,

We had looked into using poroton on our build but come July the T10, T12 won't pass the building regs. T8 will work out quite expensive. So now we are looking at cavity construction as you suggested above but with the quinnlite block internally - what type of insulation would you suggest to bring down the u-value further. We are going to clad externally with a natural sone - donegal quartz which is about 9 inches deep - would this add to the u value of the wall in any way? We would consider using the timerframe internally with exterior block but we were hoping to go for concrete floors.
 
Haille said:
Like last thread I would like to know if it is possible to fill existing cavity with polypearl given that 2 inch white board insulation is already in place for last 18 years.
Click to expand...

I had this situation on an extension to my house and went ahead with Warmfill beaded pumped insulation, which I imagine is very similar to polypearl. It has made a difference to the warmth of the room. The installers told me that since the beads were pumped in under pressure they would push any boarded insulation that had moved away from the wall back against the inner leaf, and fill any holes or gaps.
 
moved in to my house last week but still alot to do, i built using standard block on outside,100mm cavity-put 60mm kingspan in this,and b5 quinnlite as inner leaf, used mortar for the quinnlite which is slow as mortar goes off quickly-today i would use glue to join them as it would be quicker and stronger.the house is very warm with ufh and rads upstairs-we have no curtains on and are walking around in t-shirts(we have no sense of shame).i put 250mm insulation in attic and 150mm under ground floor screed.
 
anglea, FBT seem to be pricing themselves out of the market.... plus, i havent heard good things about the workmanship on site of the poroton blocks.

Every material has a thermal conductivity value which insulates, some obviously superior to others. Natural Stone (quartz) typically has a thermal conductivity of about 3 w/mk

a quick calculation of a construction......

225 natural stone
100 dense concrete outer block
40 cavity
80 PU board
100 AAC block
50 PU insulation fused to
12.5 plasterboard

this typical gives a u value of 0.14.....

if the insulation behind the plasterboard was 35mm then typically 0.16, 45mm typically 0.15..... etc

But the most important factor with 'open' construction such as this is that the workmanship is top notch and all best practices are adhered to.
 
Hi Sydthebeat,

Thanks for that. Hoping to use Homebuilder have seen a couple of their houses, workmanship looks good but then I was looking at tiling, tidyness of site general things but I will be getting it checked at various stages. Do you think the external render stucco (hope that's how you spell it) would have a better insulating effect perhaps than the stone?

Thanks

Angela
 
To be honest, whats external to the cavity doesnt really matter from an insulating point of view... as good as the workmanship is there will always be points of air ingress into the cavity... thus it will be semi-vented (if theres such a term)... so any heat trapped at this point (cavity) will eventually be vented out to the external anyway. the most important thing is to worry about what happens from the first line of insulation inwards. The only reason ive turned to a drylining type is because so many people are now installing UFH... and drylining is a good method to increase the responsiveness of this systems.

I certainly wouldnt sacrifice any aesthetic external finish for the sake of minimal insulative properties.
 
Hi Sydthebeat,

Thanks for all your advice, it really is invaluable. Now next step is to get it priced - well let you know how things proceed.

Many thanks

Angela
 
sydthebeat said:
anglea, FBT seem to be pricing themselves out of the market.... plus, i havent heard good things about the workmanship on site of the poroton blocks.
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Couldn't agree more! You would think Poroton was made of gold, the price of it and even if constructed properly only achieves modest U values (0.27, 0.25, 0.23 for the common type blocks). I've seen a few houses and looks like there are a lot of gaps!!! Forget about air tightness with the houses I've seen so far.

sydthebeat said:
a quick calculation of a construction......

225 natural stone
100 dense concrete outer block
40 cavity
80 PU board
100 AAC block
50 PU insulation fused to
12.5 plasterboard

this typical gives a u value of 0.14.....
Click to expand...

Syd, as you say you've changed from the full blown in insulation option. Can you help with the following questions please??

To achieve the 0.14 what specific product is used for the 80 PU board and 100 AAC block. Would Kooltherm and QuinnLite satisfy respectively? Likewise what about the 50 PU? I would just like to start working out the cost of this (materials only for now).

Also, sorry for being a pest but can you calculate the above with 150mm AAC block and see what u value can be achieved. I realise the wall will now be quite thick!! Thanks for all your help!!!!
 
any example of the 80mm board insulation could be Kingspan Thermawall TW55 zero ODP (this is polyisocyanuate)... another suitable product would be Xtratherm Thin-R/CW (T+G).... this is also a polycyanurate material with the added feature of a special corner piece.

Quinnlite B3 is best (TC = 0.12)
Quinnlite B5 (TC = 0.17)
Quinnlite B7 (TC = 0.19)

the revised calculation using quinnlite B3 150mm (rendered external) would give a u value of 0.13.....
have a look here for the html file of this calculation
[broken link removed]
 
Thanks so much Syd!

So the u value difference in the 150mm and 100mm B3 block then is only minimal (0.14 v 0.13) and the 100mm block will leave more internal space - will have to look at costs and see what it works out at. Cheers, BarneyMc
 
dont mention it barney....

When you get down to figures such as 0.14 etc its much more important to get your details correct to avoid thermal breaks. Plus, the standard of care and attention by tradespersons is paramount....
 
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