ADLIan

Lots of references to Code for Sustainable Homes and Zero Carbon Homes in the Fen Drayton doc. As these are both dead in the water I doubt these conditions are now enforceable. I believe JSH had a similar issue and had the condition removed.

@JSHarrisJeremy - I would refer you to manufacturers test data on this one. Insulation in floors under the DPM can also experience the same hydrostatic pressure as basement walls (unless very well drained)

I didn't want to scare monger just giving information that is freely available from EPS manufacturers. Your house will not fall down or be ejected into oblivion but the thermal performance of the EPS will be slightly worse. I do not have shares in any DPM or insulation companies. I am aware of Peripor this is one of the enhanced moisture resistance products. If the manufacturers are OK with a free draining sub base then fine.

The comparison of EPS floor insulation to swimming floats is irrelevant - as a floor insulation it has a critical technical function to fulfill over the lifetime of the building. In constant contact with moisture, say under a DPM, EPS can absorb water something like 3-5% by volume (there are some newer products with enhanced water resistance where this figure may be 2% or better - these are often coloured pink, green, blue etc to make them look like extruded poly). This moisture absorption can add between 2-4 mW/mK to the thermal conductivity of EPS. Other physical properties generally not affected hence their use as inert fill/void formers.

I assume the eps here is only acting as a ‘cushion’ so probably not

DPM required in ground floors (GF) with just about all insulation types. DPM not required on upper floors but polythene VCL/slip layer/separating layer needed with insulation under screed

Same applies to pur/pir. Again check MIs and BBA certs for use in GF

Yes eps does need a dpm under it. Check MIs and BBA certs

South of the border I come across similar planning conditions quite often - not many 'zero carbon' but lots of 10% (inset other values to suit!) better than TER under the Building Regs. Normally applied to developments above a certain size - 5 houses, 10 houses or total floor area on site. As ever major house builders/developers appeal this as it will make the scheme 'uneconomic' or otherwise not feasible and as if by magic the condition disappears.

I doubt the planning officers who come up with these conditions are aware of SAP, it’s outputs and SAP ratings. From past experience they only look as far as Appr Doc L1A and the CO2 emission rate (DER) - get this to zero or less and box ticked. Would be interesting to see the exact wording of the condition.

No dpm required for upper floor but you will need membrane above the pur - acts as slip layer and vcl

EPS needs DPM under it too.

PUR/PIR has no acoustic properties so do not use this. Fully fill the studs with glass wool (check with manufacturer that its the right type). To improve things further add 2 or more layers of plasterboard each side to add mass to the wall or consider use of resilient bars to decouple the plasterboard from the studs.

Don't know the exact construction of your caravan wall but the decrement delay would typically be approx 0.5 hr! Decrement factor of about 1

The BBA logo should include a number, normally in this format 'Certificate No. ??/????' at the bottom. You can check on the BBA website that the certificate is real and is valid. The packaging on the product will also include the BBA logo and number. Once outside the packaging however very difficult to prove if BBA certified or not - if the boards are printed with manufacturer details, shift codes etc this can help traceability. The BBA will take action against abuse of the logo but I imagine with the growth of Ebay (and similar) it's almost impossible for them to follow every case.

With glass wool batts you can squeeze them together to make sure no gaps

A VCL always goes on the warm side of the insulation - in the UK this is internal to the insulation. Some studies of upgrading existing masonry walls suggest the use of a totally breathable insulation system (no VCL and careful choice of insulation) to allow the wall structure to dry to both the external and internal environment. See Society for the Protection of Ancient Buildings website for more info.

Seen it done but it not in most MIs or BBA cert instructions. Plus a foil tape on the external face creates a localised VCL on the COLD side of the insulation which can lead to condensation.

The condensation analysis normally ignores the effect of of the timber frame proportion - both thermal and vapour properties. I don't think the Glaser method is sophisticated enough to include these 2 items. I cannot find the reference section in the BS but the software I use certainly ignores it.

Try 'The Green Guide to Specification' available as a download from the BRE, though I think there is a cost involved. It's used as a reference document in BREEAM & Home Quality Mark (new alternative to the CfSH).

I was referring to misuse of the EPC and RHI system rather than TFEE/DFEE & air test. The cost of fabric upgrades to offset using 15 as the air leakage rate will be considerably more than cost of an air pressure test and this is the point I was making. As well as impacting DFEE the DER is also affected though not so much of an issue if using a heat pump - different if using gas, oil, electric etc.

The backstop air leakage of 15 is unlikely to comply with the fabric energy efficiency standard of the 2013 Regs. Normally looking at 7 or better so test must be done. Air pressure test cert and confirmation of make, model etc of heating system required for the as built SAP and EPC. Wouldn’t want to get involved in this type of fraud!

I assume Building Control are involved. Have they picked up on the fact that the extension is over glazed? This has an impact on overall BR compliance. I would guess it will be difficult to heat in winter and may also overheat in summer time (and the shoulder period?)

Celotex had also been overstating the thermal performance of this range of products!

Not a recognised method of insulating cavity walls and not BBA approved so would not comply with the Regs (north or south of the border). Injection of foam once the wall is complete is allowable but some of these systems are to cure wall tie failure and are not certified thermally - the completeinsulations.ie system referred to above falls into this category.