Loss of insulating effect of insulation boards over time.

[mointainwalker]

From time to time there have been discussions on here about how/whether closed-cell foam insulating -boards ( PIR/PU and extruded-polystyrene ) lose part of their insulation value with time as the blowing-gas leaks out of the closed-cell structure.

This has mainly been about whether these boards are worth the significant premium they have if some of the extra insulation-value leaks away over the first few years,

Whilst looking at the Marmox website in connection with another thread, I noticed that for the first time I have seen, a manufacturer gave an initial insulation value and then a value at 5 years.

http://www.marmox.co.uk/uploads/product_images/47/MarmoxProductBrochureOct09.pdf see bottom of page 2

Thermal conductivity 0.027 watts/mK

Thermal conductivity after 5 years 0.032 watts/mK

So they reckon that their board loses almost 20 % over 5 years which is a fairly significant whack and as far a I have read, this continues until it* ends up at the same value as expanded polystyrene and fibre-wool. ( *talking about closed-cell boards generally, not specifically Marmox )

Obviously there are situations where those materials could not be used, but where they could, do you think it worth paying 3 to 5 times more for something that will disappear relatively quickly ?

 

[simonjay]

From time to time there have been discussions on here about how/whether closed-cell foam insulating -boards ( PIR/PU and extruded-polystyrene ) lose part of their insulation value with time as the blowing-gas leaks out of the closed-cell structure.

This has mainly been about whether these boards are worth the significant premium they have if some of the extra insulation-value leaks away over the first few years,

Whilst looking at the Marmox website in connection with another thread, I noticed that for the first time I have seen, a manufacturer gave an initial insulation value and then a value at 5 years.

http://www.marmox.co.uk/uploads/product_images/47/MarmoxProductBrochureOct09.pdf see bottom of page 2

Thermal conductivity 0.027 watts/mK

Thermal conductivity after 5 years 0.032 watts/mK

So they reckon that their board loses almost 20 % over 5 years which is a fairly significant whack and as far a I have read, this continues until it* ends up at the same value as expanded polystyrene and fibre-wool. ( *talking about closed-cell boards generally, not specifically Marmox )

Obviously there are situations where those materials could not be used, but where they could, do you think it worth paying 3 to 5 times more for something that will disappear relatively quickly ?

These boards enable you to "get past" building regulations, and as we all know that is all that matters.
Simon.

 

[wavetrain]

Obviously there are situations where those materials could not be used, but where they could, do you think it worth paying 3 to 5 times more for something that will disappear relatively quickly ?

I am aware of this issue with the foil backed 'Celotex' type materials. EPS does not have non air gas in its cells, so its R value does not change over time.

There is a school of thought that feels EPS is better value than 'Celtotex' type products.

Regarding your 3 - 5 times more... comment:- 3-5 times more than WHAT?

Perhaps you would like to provide the price/m2 (relative to an R value of say R=2) of different insulation materials taken from the Selco catalogue?

eg: 'Celotex type', EPS and a variety of mineral wool type products.

The best value insulation I know of is when someone else pays towards its cost, as is the case with the DIY-use-only subsidised mineral wool rolls that appear in some big shops from time to time.

 

[mointainwalker]

Wavetrain

Do you see EPS (expanded polystyrene ) mentioned anywhere below in the quote ? No you don't because the comments refer exclusively to closed-cell foams and EPS is an OPEN-CELL foam.

closed-cell foam insulating -boards ( PIR/PU and extruded-polystyrene

Or did you think expanded and extruded meant the same thing ? Try reading and understanding before making confused posts.

 

[wavetrain]

MW I think you may be the most rude/hurtful person on this building forum!

 

[tkmax]

EPS is an OPEN-CELL foam

The cheap white stuff is, but there's plenty of closed cell EPS around. Google it if you don't believe me.

Apology due to Wavetrain I think...

 

[mointainwalker]

@tkmax

I was surprised when I looked it up as I believed all PS was open-cell, however my thread - as shown in title - relates to insulating boards which is only the crumbly white stuff as far as PS is concerned.

The other thing that surprised me was that there seem to be two sets of abbreviations in use : I always used EPS for expanded ploy and XPS for extruded, however whilst looking at some sites it seems that PS for expanded and EPS for extruded is also, confusingly, used.