ADLIan

Just a couple of comments; In Scotland all thermal insulation in cladding systems in high rise (18+m) must be 'non-combustible'. Celotex FR5000 - surface spread of flame 'Class O' which is not relevant or covered in the manufacturing standard for PUR/PIR insulation, BS EN 13165. In CE Mark, declaration of performance, for this product there is 'No Product Declaration' for reaction to fire to BS EN 13165/BS EN 13501-1 (fire test).

At least Actis are declaring realistic values for the certified product! Triso Super 10 was the product that created the problem several years ago and Actis still claim the exaggerated thermal performance based on their flawed comparison test for this. We do not know if the cladding system (rather than individual materials) is BBA approved here. Perhaps more info on the cladding and components will come to light in the coming days. Having seen tv coverage I've a good idea on type of insulation involved but will not speculate on this forum.

Re multi foil. The original multi foil from Actis was never accredited by the BBA. Actis made exaggerated claims based on their own, very flawed, test regime. Both BBA and BRE were very proactive in bringing multi foils in line using correct and recognised measurement techniques rather than the Actis comparison method. There are now several multi foils that are BBA approved with much more realistic thermals though I'm not aware of Actis being one of them!

Important to differentiate between systems. Low rise with insulation and render finish tends to be safe provided installed correctly (correct fixings, including metal, not all plastic, cavity barriers etc). Here the insulation (any fire performance) tends to be well encapsulated so protected from fire and even if breached the oxygen supply is limited. I believe in Scotland only non combustible insulation is allowed in any high rise cladding system, irrespective of cladding system, as a result of several fires many years ago. With rainscreen cladding and similar systems there is a ventilated void behind the cladding - add combustible insulation plus chimney stack effect and we can see the results. Simple solution - systems like this should only incorprate non-combustible, Euroclass 'A1', insulation products. Assuming the cladding itself is non combustible too!

Terrible fire and as mentioned we've seen them before! As regards insulation generally if it's plastic (EPS, XPS, PUR, PIR etc) it will burn. The term to look for is the 'Euroclass' under BS EN 13501 - this grades the product from A to F. The top of Euroclass A (A1) is 'non combustible' - everything below this is combustible to a degree. Mineral wool is generally A1, expect PUR at C and XPS/EPS at E or F (burns readily or no product performance declared). Adding flame retardants does not impact on these classes to any great degree. Do not take any notice of 'Class 1' or 'Class 0' as this relates to surface spread of flame as is not used in current manufacturing standards for insulation products.

Gentlemen As the (self) builder you are responsible for compliance with the Regs - in this repect if an OCDEA is involved it is your responsibilty to provide him/her with accurate information on the as built house and the kit installed in order to generate the as built numbers. There is no 'guestimating'. My use of the term '3rd party' was in relation to a non SAP accredited person undertaking the SAP calculation and providing the accredited assessor with the data. As an OCDEA I will not accept the data in this instance as this 3rd party may or may not have read, understood and input the data in accordance with SAP document & conventions and associated guidance. As stated before my accreditation scheme membership rules specifically warn against OCDEAs doing exactly what you expect, especially when generating the EPC. Perhaps some other accrediation bodies are not so strict in this respect. There are procedures & conventions in place for SAP calculations and I've never had an issue with a client objecting to having to use my services - in fact they've been most grateful for the help and guidance. Sorry but a few dissenting voices on this forum are not going to change SAP. Did you offer any feedbeck on the SAP consultation in Nov last year? - an ideal oportunity to voice your concerns. I have a living to make so will not be spending any more time posting on this particular thread. Ian

Hi Jeremy Procedure should be as follows; Design Stage - assessor takes data from BR drawings and written spec (much as you did). If house complies then issue design stage documents, if not offer recommendations to ensure compliance. At this stage boiler type, heat pump, MVHR, air leakage, amount of PV etc may not be known so SAP and other defaults may have to be used. I issue a comprehensive report at this stage outling the spec and any recommendations. As Built Stage - calculation is updated with information from the builder to reflect the actual house. This will include the air leakage test cert, confirmation of make/model of boiler, heat pump, MVHR, PV output etc. Will also incude any changes to insulation type/thickness and glazing spec, etc. Builder provides witten confirmation that this information is an accurate description of the as built (in my case compared to the design stage report). As built documents and EPC can be issued. Important to remember that all this is done with reference to the SAP document, SAP conventions, U-value conventions & applicable sections of the Bldg Regs (not only part L). I don't know how knowledgable any 3rd party is of above documents so would not accept such data. The accreditation schemes recommend against this and warn of the dangers, any errors carried over in this scenario are deemed to be the assessors problem. With reference to issuing the EPC my accreditation body is very specific in that I must have done all the data collection and assessment work myself. ian

Thanks for the feedback a few more issues to comment on; On Site Audits & client/site visits - no problem with this but there will be additional costs. Back to where this thread started! 3rd party data. @JSHarris. Sorry Jeremy perhaps you misunderstood. You may have read and understood the SAP and supporting documents but I don't know that. In the abence of this understanding I don't know the accuracy & quality of any data supplied to me. To put this in context I remember a post on the previous incarnation of this site from a potential self builder and he didn't know how to calculate foor and wall areas for estimating purposes! OCDEAs. There will always be those who jump ship from one scheme to another - perhaps this should ring an alarm bell. The OCDEA scheme has thankfully not been a real target for this activity and I find many assessors (the good ones?) who have been around for many years. As mentioned before the big housing slump sorted the good from the bad. @Triassic Most of my self build clients only want Bldg Reg compliance and at the lowest cost. I work closely with them in this repect to come up with the most cost effective solution. I've added value but the client doesn't perhaps recognise the fact or put a value against it BR Compliance - the person responsibe for the building work is responsible for Bldg Reg compliance. This means that it is probably you, as the (self) builder, who is responsible for providing accurate information on the as-built house for the assessor. Ian

All Just to clarify a few points following the above posts @JSHarris New build SAP and accreditaion was introduced in the Regs in the mid 1990s and thankfully has avoided any Govt boom or bust schemes. Similalry it has avoided the marketing/sales hype & get rich quick promises such as rdSAP assessments, cavity wall surveys, solar panels & MCS. The size of the new build housing market dictates the numbers of OCDEAs. 10 years ago we were building approx 250,000 house pa, this more than halved after the financial crisis and no doubt sorted the wheat from the chaff. My accreditation body rules warn against using data (either raw data or a suitabe file format) from a 3rd party - for all I know they may not be able to spell SAP never mind have read & understood the associated documents! Specifically when producing an EPC I must obtain all relevant data myself. I am sure other accrediation bodies will have similar rules @Onoff Please check the role of an OCDEA. If my client wants more input than this then no problem - but there will be additional costs. An OCDEA has no power of enforcement, we can only advise. Enforcement is down to the BCO (a well trodden path on this site and in the industry) more importantly compliance with the Regs is down to the person/people responsibe for the building work (or the building owner). As mentioned before most of my clients are self builders so should supply all of the correct information to produce the as-built assessment and EPC. As regards the volume house builders they are often self -policing which is wrong. Also because of their land banks many are still building to the 2010 Regs - I am currently working with one large housebuilder (not with their energy assessments) and was staggered to realise they are only now looking at how to comply with the 2013 Regs!. Ian

Thanks Sigaldry for the excellent overview of SAP and how it relates to the Regs and compliance. Unfortunatley the view of quite a few on this forum re OCDEAs is summed up here, posted after one of my posts; Yes offence was taken. Onoff knows nothing of my experience, qualifications and how I operate. It may interest him to know however that the majority of my clients are self builders with 'repeat' work from recommendations. Some want to just pass Regs others are interested in going beyond Regs - in this respect I get heavily involved in the detailed design. @JSHarris The assessor used to complete your as built and lodge the EPC is probably in breach of the rules of his accreditation body those rules relating to lodging of EPCs. A risk he takes! Not something I would ever do - I would walk away from any request to do this. @Alphonsox Unfortunately the EPC is a legal requirment. The cost to lodge on completion is minimal within the costs indicated above for whole SAP assessment, consultancy works & as built version and fades to nothing of the overall build cost.

Offence taken. Bear in mind that SAP is not a detailed design tool. It is simply the Govt's preferred method of showing compliance with the Building Regs by assessing energy use under standardised conditions.

As another energy assessor (among other things) +1 to Clive Chitty. SAPs are now considerably more complex/time consuming if a correct assessment of the linear thermal bridges is done.

See also individual manufacturers BBA certs - these will give more details of type of construction and max exposure limits. @JSHarris - I am aware of the procedures for injected CWI having developed blown in cavity products, taken them through the approval process and approved contractor status.

Problem with blown insualtion is that any defects (voids, density variations, clumping) are hidden - the method for 'guestimating' the adequacy of fill is woefully innacurate and would not identify any of the above. With retrofit in old walls I take the view that anything is better than nothing so the odd void may not be an issue. In new build this is not the case - at least with built in cavity batts you can see any issues/problems and correct them.

Ask for the manufacturers declaration of performance (DoP) - this should state the product meets all necessary requirments/standards, identify the products even down to serial number and give the manufacturer details, name and address. I suppose even these can be faked but if you have a problems getting the DoP then alarm bells should ring. I believe Trading Standards are the policemen for CE Marking - best of luck taking action against any naughty importers/manufacturers via this route.

Re Andi & Fergie house. I worked for the manufacturer of the cavity wall insulation (pink colour) at the time this was built. Nothing special as I remember just basic Buildng Regs for the time. Ian

Perhaps the solid timber here is fire fire reasons - internal fire breaks thru window and could then travel within hidden cavity?? ian

I've not seen JSH detail but noting his attention to detail I'm sure it'll work! My concern is with the diag you show at the top which fails to show the vent required to this airspace - I find this a little misleading from the manuf. ian

Both knauf render panel requires drained/vent airspace behind. See manuf instructions and BBA certificate. They omit to say how to deal with this detail above window however and diag is misleading. As JSH says TRADA will have more details (I don't have these to hand however). ian

+1 on mech fixings & fire issue when using D&D/foam. See plasterboard manufacturers instructions.

While since I worked in pur foam industry but I'm sure the gases generated by HW cutting are pretty nasty. Perhaps ok if well vented room and on a small scale.

Pur/pir foams are NOT classed as non combustible.

Good point! Phone call or email to your insulation manufacturer of choice tomorrow outlining your proposed wall and you'll get the number crunching done in accordance with the BS and BRE 443 which is all you need to keep your BCO (and SAP assessor) happy. All of the mainstream insulation manufacturers will provide accurate calculations along with detailed breakdown of the numbers used. Ian

I've been out for a couple of beers and come back to a bit of spat!!! Back to the top of the page. BS EN (DIN) 6946 gives method for calculating U-values for walls, roofs etc and thermal resistance of air spaces/cavities. For U-values it includes the effect of repeating thermal bridges (timber studs in TF construction, mortar beds in aircrete blocks etc), mech fixings penetrating the insulation layer (wall ties in masonry, fixings through insulation in rendered insulated systems, flat roofs etc) and air gaps in the insulation layer. BR 443 from the BRE gives guidance and how the Standard applies to our Building Regs/Standards. The thermal (not cold) bridge is accounted for but can be mitigated if there is an insulation layer internal or external to the bridged layer. As for ProDave's calculation linked to above - it's wrong. Mainstream UK insulation manufacturers would give accurate numbers (multi foils excepted!) Ian

I was being critical of the company doing the calculation. They mention EN ISO (DIN) 6946 which includes accounting for repeating thermal bridges but then totally ignore the effect. A layer of insulation internal or external to the studs mitigates the effect but the UValue will be higher than that shown - not at my PC at the moment so can't check but would still guess nearer 0.15 than 0.13W/m2K.