Aeroboard EPS

Starting our build in January and still confused by the insulation combinations. judging by whats been discussed for a standard block build there a few options

A: cavity 100mm with 80mm board
b: cavity 100mm with 80mm board plus dryline internal wall
c: cavity 150mm with 140mm aeroboard
d: cavity 100m with blown beads

While they all have issues looping, potential water ingress, etc I am erring on option c to give a calc U value of 0.19. Is there anything else i need to consider - I am aware that 150mm cavity may require some careful detailing for the opes. All comments appreciated!

you could use 140mm cavity and 100mm of either kingspan/xtratherm to get around 0.19.xtratherm have the corner piece which folds around the corner instead of 90 deg. butt joint and the reveal panel but maybe better use an insulated cavity closer or rubberoid's insulated phenolic dpc at the openings.kingspan also have the phenolic cavity board which around 90mm would give same u-value as 100mm polyiso.you could add 25mm insulated plasterboard internally to get an instant heat response still have a thermal store in your block and 100mm insulation behind that,all in theory should get a u-value of 0.15.either way if the theory is not really true the proof is in the heating and if you've a good level of airtightness with the insulation "theory" i mentioned it really shouldnt be that much more expensive a year to heat than the more proven (and most times a lot more expensive to build)methods of reaching very low u-values.not so gone on the aerobord platinum 140mm board if a block layer puts 1 board out of them all in upside down the little water direction finns wont work properly and could lead to damp crossing to the inner leaf.the 100mm polyiso etc doesnt have these and the retaining rings are a better system to hold tight against the inner leaf.polyiso a lot dearer but that few extra thou could be cheaper in the long run.just my opinion hope it helps

Seriously thinking of using 140mm aerobord in a 150mm cavity. it achieves .19 u value and appears to be good value. Little worried that it may weaken the structure of the house. Has anyone used this ?

cw2p said:

Seriously thinking of using 140mm aerobord in a 150mm cavity. it achieves .19 u value and appears to be good value. Little worried that it may weaken the structure of the house. Has anyone used this ?

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Your certifying engineer will be responsible for the stability of the structure. If they say it's ok then it's Ok.

Incidently, the point above about water ingress if one of the boards is put in upside down is plain wrong. The tongue and grove on the vertical edges of that product are wedge shaped (so you can't have put in a board upside down and properly butt it up against the rightway up next board) and there is also a tongue on the top and a groove on the bottom of the panels. The insulation will have to be all the rightway up or all upside down. Even with the appaling levels of workmanship displayed by the irish building trade I would doubt they'd manage to get this wrong.

cw2p said:

Seriously thinking of using 140mm aerobord in a 150mm cavity. it achieves .19 u value and appears to be good value. Little worried that it may weaken the structure of the house. Has anyone used this ?

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140mm of standard expanded polystyrene with a thermal conductivity value of 0.04, in a standard block cavity wall construction, will only give you a u value of 0.28.....

sydthebeat said:

140mm of standard expanded polystyrene with a thermal conductivity value of 0.04, in a standard block cavity wall construction, will only give you a u value of 0.28.....

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I assumed he was talking about AeroMark Platinum cavity fill which doesn't really require the cavity i.e. only 10mm. It does come in a 140mm version for 150mm cavity. Don't know about the u-values.

yes, i forgot about the full fill.....

i have seen this used once since the upgrade of the regs in 2005, but it lost popularity since the same u value could be met by much thinner PU or PIR insulation......

2 different u value calculators are giving me widely varying different u values so ill withold comment until i figure out why theres such a difference....
one gives me 0.17 for 140 MM at 0.03 TC... the other is giving me 0.23 for 140mm at 0.027.... somethings up...

sorry about the dismissal in my first post... edited to suit... SAS can you do the same please

Was thinking of the full cavity fill syd.
Got a great Quote on this! Check out the aerobord website I think it gives all the details. What are the other cavity options to achieve the same u value ? Not keen on the slab drylining system, it leaves the walls surface very prone to damage and dificult to fix objects to.