PIR quality

[Russell griffiths]

Evening all, I have had a load of 70mm pir sheets delivered, and I’m not happy ???

all the long edges seem to have shrunk back, leaving a reasonable depression in the pir material. 

As im going to want to butt these tightly together and then tape the joins im not thrilled that there will be a 10-12mm gap when you put two sheets together. Now I have thought of a couple of methods to overcome this problem, but why the bloody hell should I. 

 

Thought i would see if anybody else had had any rough stuff before I unleash the wife on the company I bought it from. 

 

Just as a side thought, the 50mm stuff is perfect. 

[Moonshine]

Picture?

[Oz07]

Reject it

[scottishjohn]

23 minutes ago, Russell griffiths said:

Evening all, I have had a load of 70mm pir sheets delivered, and I’m not happy ???

all the long edges seem to have shrunk back, leaving a reasonable depression in the pir material. 

As im going to want to butt these tightly together and then tape the joins im not thrilled that there will be a 10-12mm gap when you put two sheets together. Now I have thought of a couple of methods to overcome this problem, but why the bloody hell should I. 

 

Thought i would see if anybody else had had any rough stuff before I unleash the wife on the company I bought it from. 

 

Just as a side thought, the 50mm stuff is perfect. 

seconds?

not saying you bought seconds --but maybe you been given them 

Edited February 10, 2020 by scottishjohn

[Onoff]

Some Wickes 50mm I had was awful. +55mm at the edges. The 100mm bought at the same time was fine.

[Russell griffiths]

Tried to take a pic but the reflection from the foil just made them look crap. 

Seconds, I thought this so I did some subtle phoning around to find out if the manufacturer sold seconds on, The company that delivered the sheets said they never deal in seconds. 

 

 

 

[Patrick]

@Russell griffiths

Thought you wanted to go with EPS from up north. What company  did you use for the PIR.

 

[Ferdinand]

1 hour ago, Oz07 said:

Reject it

+1

 

You can foam it up to fill the gaps, but it could shrink some more potentially - which would just repeat the problem.

 

Best of luck.

[PeterW]

It could be older stock (70mm is an odd thickness) and that’s shrinkage as the foam ages. 
 

If it’s for a floor then I would ask the supplier to give a discount and spend the money on some low expansion foam and a decent gun, and you will be fine. 

[Russell griffiths]

27 minutes ago, PeterW said:

It could be older stock (70mm is an odd thickness) and that’s shrinkage as the foam ages. 
 

If it’s for a floor then I would ask the supplier to give a discount and spend the money on some low expansion foam and a decent gun, and you will be fine. 

No it’s going in the ceiling, under the rafters all taped to provide vcl as well as insulation. 

 

Thanks all I will start moaning and find out what they want to do, I’m prepared to run a saw down the edges to re square it up, but I will want some form of recompense for my time. 

[Russell griffiths]

1 hour ago, Patrick said:

@Russell griffiths

Thought you wanted to go with EPS from up north. What company  did you use for the PIR.

 

This is for the ceiling. 

[Ed Davies]

From what I've read elsewhere PIR tends to shrink anyway given enough time so it might actually be better for long-term lack of thermal bypass to have stuff like this if it's already done all the shrinking it's likely to do. This is a major reason I plan to have a separate airtightness layer rather than taping the PIR foil.

[SteamyTea]

PU keeps shrinking until it starts to crumble once the bacteria get into it. I am not sure if phenolic is better. Liquid phenolic resins seem to last well, better than polyester.

My one worry with SIP is the shrinkage of the core. 

[Cpd]

I have just been out To the shed and checked a whole bunch of PIR from 2-8+ years of age. My conclusion is that shrinkage is mostly batch specific as a lot of my old PIR (4-8 years)  is still within the mm of the right size yet a whole bunch of 50mm I got 3 years ago has shrunk to 45mm at the edges !!!! Boo hoo said piggy. I would personally get it sent back if it’s going to cause you grief in fitting but if not assume it’s now stable and hopefully finished it’s significant shrink !!!! 

[scottishjohn]

3 minutes ago, Cpd said:

I have just been out To the shed and checked a whole bunch of PIR from 2-8+ years of age. My conclusion is that shrinkage is mostly batch specific as a lot of my old PIR (4-8 years)  is still within the mm of the right size yet a whole bunch of 50mm I got 3 years ago has shrunk to 45mm at the edges !!!! Boo hoo said piggy. I would personally get it sent back if it’s going to cause you grief in fitting but if not assume it’s now stable and hopefully finished it’s significant shrink !!!! 

maybe if people could name the makes that have shrunk --could it be a price related quality problem 

[gc100]

10 minutes ago, scottishjohn said:

maybe if people could name the makes that have shrunk --could it be a price related quality problem 

Yes that would very helpful as I need to order many sheets soon

[Mr Punter]

I have not had issues with Kingspan or Celotex.  I have found some other makes have shrunk / warped but can't remember the brands and I don't want to accuse an innocent.

[epsilonGreedy]

17 hours ago, PeterW said:

It could be older stock (70mm is an odd thickness) and that’s shrinkage as the foam ages. 
 

 

Does this shrinkage characteristic rule out using PIR as underfloor insulation? I am imagining 50mm of flow screed sitting unsupported over shrinkage pockets and eventually giving way.

[Cpd]

I have mostly been dealing with Calotex and have seen some batches shrink while others have been fine.....  

 

[Onoff]

17 minutes ago, Mr Punter said:

I have not had issues with Kingspan or Celotex.  I have found some other makes have shrunk / warped but can't remember the brands and I don't want to accuse an innocent.

 

It was 50mm Celotex I had issue with being too thick.

[Cpd]

When one of my local BM we’re clearing up they gave me 4 sheets of 50mm PIR insulation, it had been out in the open for a few years and the foil was damaged so they wanted rid of it. I took it home and left it in the shed for 6 months to see if it misshaped or anything dramatic but it stayed the same, i only have a small bit left (5 years old in shed...) but just checked the edge and it’s still bang on 50mm and still super straight / no bending like what i get with off cuts of calotex. If you someone can identify it it from what is left of the manufacturer label it might be worth finding out a bit more about it. 

[A_L]

18 minutes ago, Cpd said:

If you someone can identify it

 

Xtratherm?

 

https://www.xtratherm.com/products/xt-tf/

[Declan52]

9 minutes ago, A_L said:

 

Xtratherm?

 

https://www.xtratherm.com/products/xt-tf/

I used mostly xtratherm in my build. At the time they had the best deal around and bought straight from them. They are based in southern Ireland.

[dpmiller]

19 minutes ago, Declan52 said:

I used mostly xtratherm in my build. At the time they had the best deal around and bought straight from them. They are based in southern Ireland.

 

@Declan52 they sell and deliver direct then?

[Declan52]

18 minutes ago, dpmiller said:

 

@Declan52 they sell and deliver direct then?

They did when I got mine about 5 years ago. I ordered a lot, all mine for my floor and for the roof in my room in the room build. It was a full 40ft lorry. I got the number from a sales rep at the self build show and ordered it the following week.