ADLIan

Sorry but denser does not necessarily mean better in term of acoustics. Just about any mineral wool, at a set thickness, will have a similar acoustic absorption figure, perhaps lower than 0.4 at frequencies below 500 Hz, increasing to 0.8-1.0 at higher frequencies. However any slight difference in performance between products is lost once installed in a wall or roof - the plasterboard, tiles, slates, timbers etc having the biggest impact, swamping any difference in the mineral wool. Denser slabs may also 'couple' each side of the construction and actually make the performance worse! The only difference a slab at 100kg/m3 would make would be to your wallet!

The Building Reg classification is 'Class 0' (number zero, not letter O). This is a Building Reg classification only based on BS 476 tests - it is not a true BS 476 classification however (that only goes to Class1). I don't think Class 0 is referenced in England & Scotland Regs anymore. Most building materials are covered by harmonised European Standards (that the UK will keep post Brexit) and these do not use BS 476 but instead use the Euroclass system under BS EN 13501.

A drawing would help. Be aware that having the insulation at rafter level but with a horizontal ceiling has a major negative impact on the calculated U-value. You may think you are getting say 0.18 W/m2K but due to the correction factor it may be nearer perhaps 0.22 W/m2K!

+1 on Moonshine's info. Note that to comply with the AD E you will either have to adopt the RDs and register them with Robust Details Ltd or undertake acoustic testing on completion of the units to show that the required insulation levels are achieved. Note the insulation in the cavity here does very little acoustically as it is there to avoid cavity wall thermal bypass - standard spec is mineral wool with a density of at least 18 kg/m3

Under current fire testing regime there would be little difference in fire performance between a PUR (PU?) and PIR - something like Euroclasss D and C respectively, both still combustible.

Plus client, specifiers, cladding manufacturer, insulation manufacturer, sub-contractors, specialists.... Some of it downright untruthful, a lot of ignorance on fire testing (fueled by certain industry sectors) and a mad series of contractual relationships where everyone thought everyone else was responsible for the design.

You cannot tell the difference between pir and pur just by looking at them as they both look the same, the difference is in the chemistry. Normally a yellow/cream foam with foil, bitumen felt or glass tissue facings. The material used in packaging is expanded polystyrene, EPS, (you can normally see the individual beads that have been fused together). EPS is even more combustible than pur/pir and tends to shrink away from fire but does create molten droplets which can spread fire further. Rock and glass wool products are classed as non-combustible.

PUR or PIR doesn’t really matter as both come under the above Standard and both still combustible. Difference is in the chemistry, PIR slightly better thermal and fire performance compared to PUR but still burns..

BS EN 13165 which covers the manufacture of PUR foam was introduced in early 2000s and referenced BS EN 13501 for the assessment of the fire performance. Both Kingspan and Celotex continued to use BS 476 data (which was no longer relevant) hiding behind the Class 0 surface spread of flame rating. Note Class 0 is not even a BS 476 rating! Hence the issues at Grenfell. Finding the Euroclass fire rating for these products was not made easy simply because the D or E rating would have revealed them to be combustible. From memory the other PUR foam manufacturers did use the Euroclass system as soon as it was introduced.

It’ll be fine. Crack on. £600 extra??? No wonder we’re cynical!

Don't see what the problem is - if its OK to be used vertically why not at an angle? Only has to support itself until the ceiling finish goes in as ProDave says. Perhaps they make more money on the Metac!! I also doubt lack of BBA certification will be an issue and never had a problem with this construction as the application is covered in the Appr Docs and relevant British Standards

Also add the chemicals they (may) use to deter insects and improve the fire performance

See BS 5250. If a suspended floor it requires ventilation. At a stretch a ‘suspended’ floor could be designed to have insulation pumped in afterward but it would then effectively become a ‘solid’ floor requiring a dpm (correctly joined to dpc) and positioned to protect the insulation. Probably simpler to build it correctly. I’m sure the bba certificates for these flooring systems will require ventilation without exception.

The gshp and pv will keep the co2 emissions down but there is also a fabric energy efficiency standard and if other U-values are not up to scratch you may have problems. U=0.2 in a floor is not good. Have you had a SAP assessment done as this will give insulation requirements and fabric efficiency numbers. Does your bco have the sap numbers to confirm compliance with Regs?

Mineral wool roll or batts with a conductivity o 0.035 W/mK or better are normally rigid enough to be self supporting as ProDave says (to do with density). I think we all know of the fibreglass you refer to - probably made not a millions miles from you!!

75mm PUR sounds to be the very minimum to get through Building Regs - would expect at least 100mm and as above 150mm+. I'm not aware of U=0.20 being against any flooring requirement, 0.25 is the worst acceptable. What does your SAP report say? Normally PUR in a floor requires a dpm below and another membrane above - check with manufacturer instructions and BBA certificate install instructions

The test method for thermal conductivity accounts for thermal drift and worsening of lambda over time often found with PUR, Phenolic and XPS foams. Declared values should reflect long term lambda (20-30 years)

DS(TH)4 and DS(-20,-)2 are short term (48hr) dimensional stability tests at elevated temp and RH or at low temp (-20) as spec. Has nothing to do with long term shrinkage often associated with pur products, newer chemical formulations may have cured this problem now (???)

I still cannot find any reference to differentiate single dwelling or multi storey/multi dwelling

Thanks Dave. Can you reference that statement please?

The NI Regs and technical documents are woefully out of date. Post Grenfell. England, Wales and Scotland quickly updated the guidance and I do not think Class 0 is now referenced. Class 0 is not a BS 476 classification but a ‘made up’ classification within the Approved Docs. Both Celotex and Kingspan hid behind this classification despite the manufacturing standard for PUR foam not referencing BS476 at all - should be BS EN 13501 but this would have shown their products to be combustible (Euroclass C or D?). Hence the post Grenfell sh*t storm. Note that many building products are now manufactured to harmonised European standards (BS ENs) which do not use BS 476 fire tests.

Thanks PeterW. Beat me to it with that reply. We need WWilts to confirm if we are under English Regs.

In many walls, if constructed to relevant section of Appr Doc B, the cavity closer around openings does not need to meet any particular fire rating. Hence the use of plastic, PUR, EPS and similar cavity closers. Pretty sure the Scot Regs are similar.

Its been a while since I used THERM but those GF U-values do not look correct - the U-value is more dependent upon the size, shape and edge conditions of the slab (plus any insulation). I would expect the ground floor of a 'typical' dwelling to have a U-value of approx 0.12 W/m2K with 200mm of EPS in it, adding vertical edge insulation would be of little benefit to the U-value in this instance. With no insulation the U-value would be approx 0.65 W/m2K, adding vertical edge insulation perhaps reducing this to 0.45 W/m2K. The external wing insulation would probably have little effect on the U-value - it is more for frost protection in colder climates.

I don’t think AD B references Class 0 any more, Euroclass reaction to fire should be used. If so your BCO needs bringing up to date post Grenfell.