The National Insulation Association (NIA) published its comments on the BS 40104 code of practice for retrofit assessment of domestic dwellings on 25 September 20241. The trade body said the new code should raise standards but raised concerns about cost, timing and the readiness of the existing assessor workforce1.
The NIA said the code should improve assessment quality and consistency, describing this as welcome given what it called the variable quality of assessments currently being carried out1. It also said a more detailed and accurate assessment should raise the standard of retrofit work and reduce the risk of harm to properties1. Against that, the association said the code is likely to increase the cost of delivering retrofit assessments significantly and will significantly increase the time they take, meaning a larger assessor workforce would be needed just to maintain current delivery levels1.
"This new code of practice should improve the quality and consistency of retrofit assessments across the industry."
The NIA said the code does not mention a transition period anywhere, and that clarity is needed on its length, when the code comes into effect and how it fits with PAS 2035:20231. It noted the code is designed to supersede clauses 7.3 and 7.4 of PAS 2035, and that throughout the document "should" is used rather than "shall", which it said makes it unclear what is mandated and what is best practice1. The association also said the code references a "project manager" in several cases but never mentions a retrofit coordinator, the role named in PAS 20351.
On the workforce, the NIA said the existing retrofit assessor workforce does not currently possess all of the competencies outlined in Annex C, and that the level of detail in the code is beyond the current content of many retrofit assessor training courses1. It said a background ventilation assessment is beyond the competency of many retrofit assessors and should be carried out by a qualified specialist, and that the condition assessment content seems closer to a Level 3 RICS Home Survey than current retrofit assessment requirements1. On occupancy assessments, which the code requires as part of every assessment, the NIA said the imminent introduction of RdSAP10 means there will be no formal methodology for conducting them, or software approval mechanism1.
The NIA suggested one option to mitigate cost and complexity concerns would be to permit different levels of retrofit assessment depending on the funding scheme or scope of the project1. It said a full assessment to this level of detail may not be necessary or cost-effective for GBIS, primarily a single-measure scheme, while it is useful for a deep, whole-house retrofit like those carried out under SHDF1. It also asked whether an impact assessment has been conducted on the additional cost to businesses of complying with the code1.
Why it matters for households
Retrofit assessments are the survey stage that decides what insulation, glazing or heating work a home needs, so the standard behind them shapes what householders are told and what gets installed. The NIA's response indicates the code is expected to produce more thorough assessments, which it links to a lower risk of harm to properties1. It also indicates assessments are likely to cost more and take longer, and that the assessor workforce needs substantial upskilling before the requirements can be met in full1. For a household, those points bear on the price and waiting time attached to an assessment, and on whether the person carrying it out has the competencies the code sets out. The NIA's own position is that the code should balance improved quality against practicality and cost for businesses, and that if more stringent requirements are introduced, businesses should be properly supported with the costs of compliance1.
What happens next
The NIA has asked for a lengthy transition period, more clarity on when the code comes into effect and how it fits with PAS 2035:2023, and confirmation of whether an impact assessment on compliance costs has been carried out1. No date for the code coming into force, and no transition period length, has been reported1.