Is this acceptable?

[ryder72]

So I visited site today and found this. This is one of two layer of PIR insulation being fitted between timber studs. The height between studs is around 2.6m so it is inevitable that there is atleast one join and perhaps sections where 3 or 4 pieces make up the insulation but 20-25 pieces doesnt sit well with me.

 

Your thoughts?

[ToughButterCup]

Not acceptable.

Ian

[Jeremy Harris]

The short answer is, no, it's not acceptable, but it is probably as good a standard as the builders know how to build, and almost certainly better than a lot of mass-produced new houses.

 

Right now, there will be convection through all those joints which will reduce the effectiveness of the insulation, and may well introduce a condensation risk as well. 

 

You can fix things by going around and sealing all those joints with low expansion foam, and that's good practice with even a reasonably good fit with rigid insulation fitted between studs, as it's hard to get a good seal otherwise, anyway.

[jack]

Sorry, is it like this everywhere or just in a couple of sections?

[ryder72]

Thanksfor your replies.

 

I have seen this in only 1 room. The insulation is two sheets of 70mm PIR and most places (5) where the inner layer was visible was in this state. There may be more but i didn't have time to check today.

 

I will be asking all secondary layers to be stripped back to inspect, something I wasn't expecting to do.

 

I will obviously report tomorrow.

 

My concern lies around the fact that i have uncovered this and I wonder what else lies hidden. 

Edited March 14, 2017 by ryder72
typo

[Mr Punter]

Looks pretty crazy, but if one of the layers is in a single piece I doubt it will make a great difference.  The gaps seem fairly small.  Liking the mixture of brands (Kingspan & Recticel?)  If it is like this for more than 15% I would say no good.  On the upside they have reduced the amount going to landfill.

[ryder72]

Thing is, no matter how finely its cut and butted, multiple pieces are not the same as 1 piece and a stack of 30 pieces is never going to perform as well as a single piece, leave alone one made from 3 or 4 offcuts.

 

I hadnt paid any attention to the use of mixed brands but thats a good point that will need addressing too.

 

Appreciate its not going to landfill but at the risk of being called a nimby, 'not in my house'.

 

Very disappointed.

[jack]

Do you think that these are the offcuts from the layer behind?

[Oz07]

Seen it from a decent sized tf manufacturer here before. Probably not ideal. 

[AliG]

Any reason for 2x70mm vs 1x140mm? It is more expensive and more labour surely. Also more cuts and joins.

Edited March 14, 2017 by AliG

[CC45]

Weve got 140mm frame and since the pir (supposed to be 140mm) is rather variable in actual depth we have some places, well quite few actually, where it sticks out beyond the frame.  Never again will I use 140mm pir in a 140mm frame. Lot of pain to come.

 

That install looks like a bodge.

[ryder72]

11 hours ago, jack said:

Do you think that these are the offcuts from the layer behind?

 

What you are seeing is the outer layer. The inner layer is better.

 

10 hours ago, AliG said:

Any reason for 2x70mm vs 1x140mm? It is more expensive and more labour surely. Also more cuts and joins.

 

NO idea. It didn't make sense to me.

[AliG]

2 minutes ago, CC45 said:

Weve got 140mm frame and since the pir (supposed to be 140mm) is rather variable in actual depth we have some places, well quite few actually, where it sticks out beyond the frame.  Never again will I use 140mm pir in a 140mm frame. Lot of pain to come.

 

That install looks like a bodge.

 

That's a fair point, my PIR is in the cavity and a lot of the pieces aren't quite flat so the thickness varies. You can get away with this in the cavity but it would be a problem inside a timber frame. Not sure if 2x70mm would help this though. It is probably easier to bend back into place.

[CC45]

Id just use 120mm. Not much difference in u value but a lot less issues.

[Simplysimon]

not acceptable, and one of the reasons i'm going for blown cellulose even though i would have been fitting the insulation myself had i gone for rigid

 

simon

[ryder72]

2 minutes ago, Simplysimon said:

not acceptable, and one of the reasons i'm going for blown cellulose even though i would have been fitting the insulation myself had i gone for rigid

 

simon

 

Granted that blown cellulose will most likely eliminate any voids but there is surely a proper way to fit PIR insulation.

[Simplysimon]

2 minutes ago, ryder72 said:

 

Granted that blown cellulose will most likely eliminate any voids but there is surely a proper way to fit PIR insulation.

 

yes, but it takes accuracy and therefore more time and also a willingness to do a good job

[ryder72]

4 minutes ago, Simplysimon said:

yes, but it takes accuracy and therefore more time and also a willingness to do a good job

 

Yes agreed and that has been a consistent weakness.

[CC45]

I put all our pir in, every piece was measured and carefully cut to fit tight. Then spent hours with expanding foam.  Now the vcl in on Im very surprised how much it billows out when we have a breeze. Clearly air gets in somehow.  Got a plan for that.  It does take time but hopefully we will have a warm house.

[Construction Channel]

1 hour ago, AliG said:

Any reason for 2x70mm vs 1x140mm?

it is easier to keep the cuts square on thinner boards. but that is the only reason i can think of. unless you are using a table saw which will have to be very big to cut 140mm

 

and no its not acceptable, possibly if they had used a few larger off cuts just to fill the last few studs but those 25mm strips really are taking the piss.

[Crofter]

20 minutes ago, CC45 said:

I put all our pir in, every piece was measured and carefully cut to fit tight. Then spent hours with expanding foam.  Now the vcl in on Im very surprised how much it billows out when we have a breeze. Clearly air gets in somehow.  Got a plan for that.  It does take time but hopefully we will have a warm house.

 

Ah good, glad it's not just me! I was fitting the VCL to one gable yesterday; the wind was howling outside and clearly air was getting in somewhere because the whole thing blew up like a balloon. At least the VCL seems pretty airtight, I could not press it back against the wall at all. This morning the wind had changed direction and it was flat as a pancake.

Expanding foam just isn't airtight, not 100% anyway- that's my conclusion.

 

What's your plan, by the way?

[ryder72]

I have attached two more photos showing rather large gaps (as much as 8-10mm) which I assume are not acceptable either? The proposal was to foam fill them. Is that acceptable or should every piece be carefully measured and cut to suit?

 

I am so glad I notice the original bodge. This has opened another can of worms.

[jack]

If the frame gaps are consistent, why would these all be (badly) hand cut?  Surely you'd set a table saw up, or even a circular saw and straight-edge, and spend some time up-front banging out what you need at consistent widths with straight edges?

 

It's difficult to know with this one.  "Acceptable" probably means something different to us compared to the average British builder.

 

One trick I did use once or twice where we weren't happy with trades was to go back to the manufacturer's instructions.  If they say things like "cut with a straight edge", "leave no gaps" and "interference fit is important", then you have some objective evidence to beat the builder with.

[Declan52]

I would foam and tape the larger gaps if they won't redo it properly. 

I would agree with jack that it's probably what the guy has done before and had no issues but it's your house your rules your standards  so it's your way or on your bike. That's how I would say it.

[ryder72]

Jack/Declan52 -thanks for your inputs.