ADLIan

I greatly doubt that you would get a UK based insulation manufacturer or waterproofing system manufacturer to promote a hybrid flat roof, not without many caveats! They are specifically warned against in BS 5250 and BS 6229. The Scot Regs push true warm roof detail (and avoid cold deck).

Window supplier need to provide test data to confirm window performance. Calculated U-values can be used but these must be done by a BFRC certified window thermal modeller.

Because it’s an input into the SAP assessment.

Sorry no - been a few years since I worked in that sector. From memory BS EN 13165 on PUR manufacture gives info on gas tight and non-gas tight facings and their effect on thermal performance. Gas transfer into/out of the foam matrix at the edges has little impact on aged lambda.

Most of the blowing agent loss, hence loss in thermal performance, is through the top and bottom faces and is accounted for in the declared lambda value. The foil facings slow this process hence foil faced PUR has a lower lambda than product with glass tissue or bituminous facings. Edge losses are minimal. The foil-facing is a complex laminate of al foil, kraft paper and polyethylene and is adhered to the uncured, liquid foam in the manufacturing process. Adding a self adhesive foil tape to the edges would not be gas tight and would make no difference.

No. Waste of time and tape

50mm mineral wool slab in brick/brick cavity wall is woefully inadequate. Would expect at least 100mm, probably 150mm under 2021 version of Appr Doc L. As above, timber frame can be insulated in cavity but 50mm clear cavity must be left assuming masonry outer.

0.16 W/m2K is the worst acceptable for roofs under the 2021 Appr Doc L1 so 0.16/0.15 are both 'OK'. Probably will not help get compliance though if they are that high as the 'notional' house uses 0.11 W/m2K. Would need offsetting by more insulation in other elements.

Lower thermal conductivity = better thermal performance. Thermal conductivity of PUR is lower, better, than that of EPS. To get the same overall thermal performance 300mm of EPS would equate to about 175mm (not 100mm) of PUR.

Problem is that magply is not a ‘cement’ board it is based on magnesium oxide. Problems were identified with these ‘MgO’ boards several years ago including not being compatible with some render systems. Several warranty providers, including LABC and NHBC, banned their use.

+1 to that. It is now down to the SAP assessor to police this, not something they signed up for as this is a Building Control function. In the absence of this photographic evidence assessors must revert to default SAP numbers at which point the house will probably fail under Appr Doc L and the assessor is the messenger (who probably will be shot!). Because of this, and a whole raft of other admin procedures, I will let my SAP assessor status lapse in the next few months.

Photographic evidence of build quality (insulation levels, dealing at junctions, preventing thermal bridging etc) is now part of the Building Regs. Requirement of the 'new' 2021 Approved Doc L, effective mid 2022, for all new dwellings.

Only for new build. Not sure how you’d retrofit a dpm under an existing b&b floor?? Under existing Appr Docs and British Standards adding the insulation layer under b&b floor makes it a ‘solid’ floor which requires a dpm.

'SFUF' has a core thermal resistance of 0.8 m2K/W. This is equivalent to approx 18mm of polyurethane foam board - I'm sure we'll all agree totally inadequate for a heated floor.

No real rocket science there! Report needs a different title too - sends the totally wrong message.

Fire is a totally different issue and not part of the ‘normal’ use of insulation, or most other construction products. Most houses are full of materials that are perfectly safe to use on a day to day basis but set fire to them and is very different scenario. Combustible insulation products are still acceptable in many instances under the Building Regs provided they are encapsulated within the construction - within masonry cavity walls, concrete floors etc. the risk is deemed to be low and they will not contribute to the development stage of a fire. Smoke inhalation from burning furniture and fittings in a house will kill a person a long time before the insulation in a cavity wall is involved. Grenfell was very different with certain manufacturers conspiring to promote the use of combustible insulation in an application where the risks were already well understood, documented and covered by the Approved Document B. Rock and glass wool products, both ‘mineral’ wool, are safe to use; modern glass wool formulations being much more pleasant to handle and install.

I don’t think any insulation manufacturer would market a product that was inherently dangerous to health either in its install or use. Mineral wool products are well understood and newer formulations are much more pleasant to handle. In France look at ‘pure one’ from Ursa, better thermals than rock wool and claimed much better handling, softer & less irritant.

Work has been done on this about 12 years ago. Search internet for ‘co heating test’. NHBC Foundation has a summary document which outlines the method and its complexities. Leeds Met University (now Leeds Becket) done testing to better understand the mechanism of heat loss from cavity party walls - as high as 0.7 W/m2K. This lead to party wall thermal bypass being included in Appr Doc L a couple of revisions ago and also the solution of fully filling the cavity with mineral wool to give zero U-value.

Kingspan - see grenfell tower inquiry evidence. Both product variations are combustible. Depending upon formulation pir may achieve slightly better Euroclass rating, D rather than E?

PUR and PIR are very similar chemically, slight tweak in the formulation. They do not melt and flow in a fire (as polystyrene does), they are both combustible but pir will perform slightly better than pur. I’m not aware of any safety/toxicity issues from either product as supplied as boards - the manufacturers would have to make you aware in their health and safety data. Products of combustion are a different matter!!

One or both layers have not recovered to the full 200mm thickness - a common problem with type of material. Make a formal complaint to manufacturer and get it replaced FOC. Contractor’s excuse is laughable.

I was merely pointing out why DIY systems are not available. Not my gift to be pragmatic as that's a decision for the OP - its his house!. The approval scheme (BBA normally) for injected cavity wall insulation has been around for many years and is well documented covering manufacturer, system designer through to the installer. Approved Document C specifically covers this requirement. The installer does not have to understand how a building goes together just how to install the product correctly. Joe Public cannot purchase the 'approved materials' as they are only available as part of the 'approved' package.

I’ve done numerous energy assessments over the last few years using ASHP - they became popular as the COP made building reg compliance, based on CO2 emissions, easier. Downside was the running cost which is reflected in the SAP energy rating. I would imagine that a badly designed and/or commissioned system, perhaps with COP of 2 or less, would be a lot more expensive to run than gas.

Only materials of Euroclass A1 & A2 are non combustible; B to F are all combustible with increasing combustibility/risk. If a product can only achieve class D or E the manufacturer may decide to use class F and avoid all the testing costs. Table 10.3 only refers to the external surface of external walls. This information should not be read in isolation as other sections of the AD will also apply. Combustible insulation can be used in applications such as concrete floors and certain masonry walls as they are protected by non combustible materials and will not be involved in the development stage of a fire (and perhaps not even in a well developed fire).

Compliance with the requirements of the British Standard for sheep’s wool insulation will be a starting point including the initial type testing (fire performance, thermals, density, moisture vapour resistance etc, etc) and ongoing quality assurance procedures. Perhaps also independent certification. See Approved Doc 7 of the Building Regs for ways of showing fitness for use. Then use all of this to convince specifiers, users, building control officers etc. Not easy!!