What are the most common mistakes in Section J Reports and how can I avoid them?

Short answer

Mistakes often include incorrect glazing ratios, underperforming insulation, overlooked lighting / controls, poor sealing, and incomplete documentation. Avoid them by using experienced consultants and following NCC DtS or JV3 paths carefully.

Full answer

Some of the most common errors in Section J compliance reports include miscalculations in glazing ratios, such as incorrect wall-to-window area proportions or using glazing products with unsuitable thermal performance without considering shading and orientation. Insulation mistakes are also frequent, including specifying products that do not meet required R‑values, omitting thermal breaks or failing to properly insulate walls, roofs and floors. In lighting, errors often involve omitting required controls like motion sensors or timers, selecting inefficient fixtures or not accounting for natural daylight and lighting power density. Building sealing issues such as unsealed gaps, poorly installed vents or doors and windows that do not meet airtightness standards are also problematic. Additionally, reports may lack critical documentation such as accurate climate zone data, material specifications or design assumptions, which can prevent certifiers or councils from approving them. These mistakes can result in costly redesigns, project delays or even outright non‑compliance.

Why this matters

Errors in your Section J compliance report can pose serious risks to your project. They may lead to report rejection or approval delays, causing setbacks in your construction timeline. Redesigns or retrofits required after the detailed design or permitting stage can be significantly more expensive and disruptive. Poor compliance can also result in sub‑optimal building performance, leading to higher energy bills and reduced occupant comfort. For architects, builders and developers, repeated compliance failures can damage professional reputation and affect relationships with certifiers, councils and future clients.

How Certified Energy can help

At Certified Energy, our experienced team regularly prepares Section J Reports and understands the common pitfalls that can lead to compliance issues. We follow a rigorous review process that checks every component of your design, including glazing, insulation, sealing and lighting, to ensure full compliance with NCC requirements. Our reports are clearly documented and professionally communicated, providing certifiers and councils with exactly what they need the first time to avoid delays. We also conduct early-stage checks to identify and resolve potential issues before they escalate into costly or time-consuming problems later in the project.

Related regulations

• NCC’s Part J provisions on glazing (Part J2), building fabric (Part J1/J4), lighting (Part J7) etc. 

• State adoption dates and amendments to NCC which may change some requirements.

Helpful resources 

• What is a Section J Report and why is it required?

• When is a Section J Report Required?

• How to Choose between DtS and JV3

• Cost and Timeline for Section J Reports