In one of the other threads here the topic of convo crossed to changes in board insulation post install, and I noted that I had some PIR/PUR based insulation board (75mm) that had contracted a considerable amount. I said I'd post some pics when I got the chance but I'm not sure which thread it was so I thought I'd make a new one

The attached pic shows the gap that opened up between board ends; it used to be 5mm and was foamed up (no idea where most the foam went).

The boards have not only shrunk but curled too. For scale the battens are 25mm ish so in some places it looks like a shrink of 2 inches, though interestingly seemingly only on one dimension)

These boards were tissue faced seconds and may have been stored outside - hopefully dry first grade foil faced boards wouldn't suffer to the same degree..

I have had reputable boards delivered that have distorted and shrunk giving concave edges which I rejected. Had 2 different makes from 2 different merchants that had done the same thing. I also had a several packs of 8x4 bent with pooled water between the sheets. I suspect that merchants do not keep them under cover that is the evidence I have from 3 merchants near me. When you raise this with the BM they claim they are ok as they are shrink wrapped except that the manufacturer's label clearly indicates they should not get wet. When I was building I had ordered t&g cavity boards that the BM could not deliver from their yard for several days. I collected as rain was imminent. As I have mentioned previously a builder reported to me how he came across a job he had done 10 year previously that had shrank considerably. My experience is that the BM do not take care of anything.

I have just taken a look at what I have left in a few boards a mix of full sheet and thicknesses in a range between 150 and 25 mm thick with foil, and 50 mm K5 boards without foil facings. They have been stored on top of my workshop roof making it effectively a mezzanine level. Some have been there since 2011 The workshop is in an agri building and the mezz level gets extreme of heat and cold as the agri building roof is cement sheets. From about 35C to -3c over a year. Not one is showing any signs of distress but then they are exposed to the same temperature all around so maybe it is a differential temperature between face that it the issue in roof and wall use and possibly moisture content if they have got wet before installation. Wonder how good a SIP panel is at a join between panels.
A thermal camera might tell us that.

Posted By: revorI have mentioned previously a builder reported to me how he came across a job he had done 10 year previously that had shrank considerably.

I bumped into the builder yesterday morning and mentioned to him about this thread and me went on to say that it was Kingspan he had insatalled.