ADLIan

Both mineral wool rolls and slabs will do the same job acoustically. See AD E which recommends mineral wool, min density 10 kg/m3, min thickness of 100mm in intermediate floors and 25mm in stud walls. Rolls normally cheaper than slabs. Do not over fill studs and compress the insulation, especially with dense slabs, as this will acoustically couple the layers of plasterboard and degrade the overall performance.

Requirement was U=0.22 from memory. I'm sure older versions of Regs are archived on DCLG website.

Not sure about that Nick. See instructions/recommendations from both flooring and insulation manufacturers. Problem is lots of relatively narrow planks rather than large area of flooring grade chipboard.

Use correct underlay for laminate floor. Celotex, or similar, is not suitable for use directly under laminate flooring.

U-vals look to be correct for brick outer and probably only slightly higher with cladding of weather or render board.

Depends on fuel used, if mains gas expect approx SAP of 85, Band B. Figures above refer to existing housing stock.

+1 JSH. PUR manufacturers sell heavily on conductivity - try selling 0.023 product against 0.022 product and you’re dead in the water! 4.5% degradation does not sound much but on 8 years production it adds up. Temp variation effect on conductivity is not important here compared to USA which has massive changes in climate from north to south. Under BS conductivity is normally measured at mean 10K (0C - 20C).

With lamba value lower = better so ‘understating’ is not good. Since 2009 they’ve been claiming 0.022 W/mK when it should have been 0.023 W/mK. Makes all your U-values higher (worse). Not good for their certification and CE mark especially on the back of Grenfell and incorrect quoted fire performance - all on website.

See Celotex website , www.celotex.co.uk. Appears they have not been exactly truthful with their thermal performance!

Compliance with relevant British Standard, harmonised European Standard (CE mark), BBA (or similar) or European Technical Approval normally acceptable routes to show compliance/acceptability . Mainland European countries all have their own version of BBA but BCOs often reluctant to accept these. See Approved Document 7 of the Regs for mor info. Ian

Beware!!! Switching from gas space/water heating (especially heated floor) to mains electric will totally screw up the CO2 emissions. Failure here under the Regs is very difficult/expensive to remedy! Your assessor should be able to advise.

That version of BS 5250 is now out of date and BS 6229 is more specific for flat roofs. Calculation method for condensation analysis now in BS EN 13788. Remember these standards/methods are basically steady state rather than transient conditions you can however change internal/external conditions to asses greater/lesser risk.

In a house of that age I assume cavity to be only 50mm. With a medium/dense block the 'balance' of insulation with 100mm EPS externally should be OK to avoid condensation. As stated above even if condensation is predicted is it harmful? Bear in mind amount of condensate, net build-up (if any), location & nearby materials.

Agree with above - vent cavity negates effect of EWI. As regards condenaation it not just if it occurs - also how much, is there a net build-up over the year, are moisture sensitive materals adjacent. Suggest you get the insulation or the render system manufacturer to look at this for you in accordance with relevant BSs - the Vesma calc looks very rough and ready and is not using correct values in the bit I can see - not sure what's going on behind this!

Glass wool (unfaced) from all the major manufacturers is normally classed as non-conbustible. If there is a facing (or encapsulation) such as paper or polythene this will burn. Loft insulation is generally not faced or encapsulated (some are!)

For conversion to dwelling work EPC still required. No air permeability test required under Regs so default of 15 is used. You can still get test done and use that value in the as built.

Recticel traditionally been great quality. As for Celotex - after recent events make your own mind up. If the foil face is that bad then thermal properties must be open to question too.

Interesting to see latest Celotex issue with fire performance and testing - see announcement on home page of website. ian

Apologies - got my Guides mixed up. It was the Domestic Building Services Guide that was updated in 2013 not the Ventilation Guide (still at 2010 version)

Link above is to the old version of the Domestic Ventilation Compliance Guide - there is a 2013 version effective from April 2014.

This is one of the reasons why we don't render directly onto timber frame in this country. Render should be onto a carrier board with ventilated cavity behind to protect the structural frame (and any insulation external to the frame). ian

BS476, surface spread of flame, isn't referenced by any of the current standards covering insulation materials so I'm at a loss as to why some manufacturer even quote this. Correct BS is BSEN 13501. This measures reaction to fire, flammable or non-combustible (with points between) and importantly smoke generation and the presence of burning droplets.

Appr Doc B2 already covers the issues faced at Grenfell Tower. Not sure if it's lack of understanding or enforcement is the issue. Cannot copy from the AD but see Section 12 on External walls, in particular paras 12.5 and 12.7. Perhaps these particular statements need emphasising more - capitals, in bold & underlined!! Ian

I believe that test only covered one particular external cladding (12mm fibre cement sheet?) and is not valid in any other system.

All mainstream insulation products are covered by BS EN standards which are used for CE marking and use BS EN 13501 for the fire performance. This Standard not only looks at the flammability but also characterises smoke production and burning droplets. Surface spread of flame rating under BS 476 is NOT referenced by these Standards so is meaningless. For some reason all of the Celotex products discussed here, irrespective of chemical composition, type of facing or use of glass fibre reinforcement, all have the same reaction to fire rating of 'No Performance Dertermined' (NPD).. If for example their standard products were 'Euroclass E' but a special fire resistant version was better at 'Eurclass B why not do the test and publish the data I have looked at a few of the Declaration of Performance documents (I have no intention of checking the entire product range) and they are all 'NPD'. Bottom line is they all appear to have the same fire performance and I've not seen any published test data to indicate otherwise