You using a mixer? Get a quote on pumped delivery... you will age otherwise :-) Open window, pump it in, then notice it is the wrong room but you had a Saniflo in there anyway so no harm done.
If adding fibre reinforcement by hand to a mixer, make sure they mix properly rather than gloop together. The fibre is re thermal cycling, and the foam around the edge re expansion and thermal dam.
Foiled over
Do you really think that gas cant migrate out of even a tiny crack over time?
If the foam cells themselves cant hold the gas then nothing around them, will.
I recall the german research "found" the following:
- Foam cells suffer degradation over time.
- Cells are closed, but suffer damage by sunlight, cutting & aging.
- Pentane can migrate out over time, diminishing performance.
I also recall substantial confounding factors to the research:
- Sheets are foil faced not bare, with only edges (lower area) cut.
- Insulation is not installed in a manner subject to continuous sun.
- Insulation edges are foil taped, installations are substantially air tight, so convection is avoided and air interchange with the outside environment is negligible so reducing environmental attack of the cell walls.
In summary the german Accelerated Aging tests were not representative of the usage environment, they had very poor efficacy and thus a poor predictor, sensitivity analysis would throw out the test methodology.
Lets assume despite this the foam cells deteriorate throughout. Over time that means pentane can migrate out - it is not pressurised, it is not like a balloon, it just migrates. The faces are foil covered. The edges could be foil taped. So the available area for pentane to migrate out can be significantly reduced - PUR/PIR boards in general are not "bare boards".
I suspect the german tests were erroneous. Unfortunately though, I have seen no data showing the deterioration in R value of PUR/PIR foam over 25-50yrs. Likewise I have not seen the deterioration in Argon filled DG over 10-15-20yrs. Likewise Accelerated Aging is met by the difficulty in maintaining efficacy of the test method. So I suspect we will just have to wait for some to age in a lab, which the industry is not likely to sponsor - indeed it would counter-sponsor.
The BIGGEST problem with insulation is the skill level of the installer. Poorly fitting boards & incomplete fitting is going to cost a whole lot more in thermal element U value than comparatively trivial "will the pentane migrate out over a few decades". I have seen some try foil taping to battens to make up the gaps in miss-cut boards, this does not work - the foil tape will not bond to wood reliably at all.
Uneconomic re time.
Digging...
University of Stuttgart did research on the thermal conductivity of artificially aged PUR/PIR.
1 - Insulation was applied to 80oC hot water pipework & tanks. Unrepresentative of temperatures & duration experienced by domestic wall insulation.2 - Aging was via EN & DIN methods. Aging methodology unrepresentative of temperatures & duration experienced by domestic wall insulation.
The results were 18% of thermal insulation loss due to pentane migration, which when combined with shrinkage the the loss of thermal insulation was 38%.
Now... If we take domestic loft insulation, the maximum temperature is likely to be 45oC? If loss of performance is not linear, the observed losses at 80oC could take decades at 45oC because such temperatures only experienced for comparatively brief periods of the year.
Here we go...
So basically they state the gas does migrate over time. A pity there is no timeline & percentage given.
The german study, however, is only useful for environments where the test & accelerated aging has efficacy (which is not domestic wall insulation).
Scouting around...
PIR PUR PET off-gassing reduces insulation value.
- Off gassing occurs more rapidly in the early years.
- Insulation reaches 25yr average in year 7.
- UK BR443 2006 requires for foamed plastic materials blown other than by air, the declared value represents the AVERAGE OVER 25 YEARS.
Losses can be greater in high temperature applications; lagging hot water pipes & tanks, where insulation is not foil faced, where foam is soft fill. In some instances the initial figure may decline by 38-44%, but the standard under which they are certified may well reflect such (not really relevant to domestic insulation so not looked).
Is any of this important?
- No, because installer skill is far more important.
- PIR etc boards inserted into framing or between joists with edge gaps, or inserted incompletely into framing with spaces, results in vastly greater losses from thermal looping.
- PIR etc cavity boards not held tightly against the inner leaf result in vastly greater losses from thermal looping.
So focusing on quality of installation is far more important.
Some claim the off-gassing occurs more rapidly, well what if it does? The vast majority of the insulation value is not down to the gas, the curve pretty much flatlines. One could argue hot water pipes should be insulated in foamed nitrile rubber armaflex rather than just chucked in a wall full of PIR etc - but that should be the case anyway.
Not in my case .... screeder didn't want a pump ... screed was delivered by the skip load, (4 skip loads in fact) barrowed in and laid ... Did it on 2 Saturdays.
It came with retarder & fibre already mixed in, I was amazed how fast he laid the stuff.
I wandered into this thread by mistake... and saw this.
Pentane? In foam insulation? But... it's a liquid...
I think its something that ends in -pentane.
Not pure pentane
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