ADLIan

And it is the compressed insulation thickness that is used in the U-value calculation.

Knauf glass wool going up by 35% on 1 July!!!

The difference in density between all those mineral wool products will have no affect on the overall acoustic performance. Price of all insulation products has increased massively in the last 12 months - perhaps by 50-60%!!

Whole window is assessed - glazing and frame

Yup. You’ve already designed it.

I think that’s water use rather than drainage

Nothing has really changed with conservatories. If thermally separated they can ignored - if not they are treated as part of the dwelling so included in the heat loss, CO2 emissions, DER/TER calculations etc and the solar gain (overheating) assessment. What has changed is that this part of overheating is now in the new Appr Doc O which has both a simplified method and complex dynamic thermal modelling method

'Seconds' will be downgraded for a reason. This means they will not comply with relevant British/European Standards, not be covered by CE marking or BBA certification and as such not fit for use under the Bldg Regs/Approved Docs. Not that any BCO I've come across would police this! Perhaps more of an issue if fire performance questioned.

SAP assessor may not have taken account of low emissivity foil on the PUR. As above, manufacturer figures can be used provided you have proof of the numbers

standard block outer, aircrete block inner, plasterboard on dab and 75mm PUR partial fill should give about 0.20 W/m2K (25mm or 50mm cavity makes no difference to U-value)

'Wind wash' is not normally an issue with loft insulation as the wind speed over the insulation is insignificant. From memory BBA and/or BRE have done work on this

Mass air movement into the loft also needs to be considered. Seal any gaps in the ceilings - around pipe and cable penetrations, light fittings etc. Not sure that emulsion paint will create much of a vcl as its moisture vapour resistivity is only about 0.5 MNs/g (polythene is 250 MNs/g or more)

Both systems work and problems are more down to workmanship or wall not being suitable for injection. More problems reported with mineral wool simply because this has the biggest part of the market, especially refurb. injected cavity insulation will also reduce air movement in the cavity so getting the best from the EWI. The EWI will mitigate potential penetrating damp across the wall.

But the sap assessor must have this info to sign off this part of the works. Rock and a hard place come to mind!! I give my clients a full design stage report with recommendations/requirements for building reg compliance (or more), not really my issue if Building Control do not take this into consideration. SAP assessor is not responsible for policing this part of the Regs

Totally agree. But checking BR compliance is a job for Building Control not a SAP assessor who will never visit the site.

I regularly see those U-values under current Regs, walls perhaps slightly higher at 0.20-0.22. They are only slightly better than the current Notional Building.

All On 15 Dec Govt issued the new Approved Doc L for England. https://www.gov.uk/government/publications/conservation-of-fuel-and-power-approved-document-l Also new version of SAP, Part F (Ventilation) & Part O (Overheating). All becoming effective in June 2022. Does not look to be a big change in U-values apart from tightening of worst case values. Air tightness tightened and use of solar PV used in Notional Dwelling. I am waiting for the new software from Elmhurst to assess the impact in more detail. One good point is plenty of practical guidance - not read it all so not sure how relevant. One big change is information gathering - documentary and photographic evidence required of almost all construction stages (insulation being fitted, junctions, windows, boilers, controls etc, etc....... ). These will be required by Building Control and the SAP energy assessor to assess the 'as built' dwelling. I can see this increase in red tape increasing the cost of assessments considerably. Personally I do want to spend the majority of my time chasing this data knowing its probably not available (I tend to deal with self builders and small developers) so will cease to be a SAP assessor for the new version of the Regs. I'll switch to 2D thermal modelling of junctions for bespoke psi-values. Plenty to read in the new ADs and SAP - perhaps 500 pages! Get your Building Reg application in before next June!

They are the limiting, backstop, values - in practice your u-vals will need to be much better. Your sap report contains the current values, the lower numbers are in the new AD L effective from June 2022

Incorrect install of plasterboard on dabs is another matter. Mineral wool cavity batt normally quite forgiving to quality of workmanship. Blown in open to problems if all cavity/voids not fully filled which is very difficulty to verify.

Mineral wool cavity batt /blown in at a density of at least 18 kg/m3 is normally enough to prevent air movement in a fully filled cavity.

Appr Doc Q only applies to new dwellings (including change of use).

To be expected. House drying out, ceiling not finished, no plasterboard, no AVCL…….It’ll be ok once ceiling etc finished correctly.

+1

May be……may be not???!!!

Read BS 5250. I’m not wasting any more of my time on this subject