Are you struggling to navigate the complexities of PAS 2035? Do you find that your retrofit projects are hitting unexpected roadblocks during the Trustmark lodgement process? You are not alone. As the industry transitions further into the requirements of the PAS 2035:2023 update, the margin for error has become razor-thin.

At CPH Retrofit, we understand that compliance is more than just a regulatory hurdle; it is the foundation of energy efficiency and resident safety. With over 15 years of experience in the sector, we have seen firsthand how minor oversights can lead to costly remedial works and funding clawbacks. Look no further! We have compiled this comprehensive guide to the seven most common mistakes currently being made with PAS 2035 Compliance and, more importantly, how you can fix them.

1. Treating Documentation as a Mere "Tick-Box" Exercise

One of the most frequent misconceptions we encounter is the belief that simply uploading a set of documents to a data warehouse constitutes compliance. In reality, PAS 2035:2023 demands a narrative of quality. If your documentation doesn’t tell a clear, evidence-based story of the building’s journey from assessment to handover, it will likely fail an audit.

The Mistake: Providing blurry photos, incomplete building condition reports, or generic floor plans that lack specific measurements. Many organizations assume that once the Retrofit Coordinator hits "submit," the job is done.

The Fix: You must prioritize documentation at every stage. This means capturing high-resolution photographic evidence of the thermal envelope, clear shots of existing ventilation (or lack thereof), and detailed records of homeowner briefings. At CPH Retrofit, we provide streamlined retrofit experiences that ensure every piece of evidence is robust and audit-ready from day one.

2. The Communication Gap Between the Assessor and the Coordinator

A successful retrofit relies on a seamless handoff between the Retrofit Assessor and the Retrofit Coordinator. Far too often, these two roles operate in silos, leading to designs that are technically sound on paper but impossible to implement on-site.

The Mistake: The Assessor fails to identify specific site constraints (like restricted access or complex masonry), and the Coordinator produces a design based on incomplete data. This disconnect leads to "change requests" mid-installation, which can compromise the entire compliance chain.

The Fix: Foster a collaborative environment. We advocate for a "one-stop-shop" approach where the Assessor and Coordinator work within a unified framework. By choosing CPH Retrofit’s coordination services, you ensure that our experts are talking to each other daily, preventing data gaps before they become expensive problems.

3. Ignoring the Critical Role of Air Pressure Testing

In the rush to install insulation and heat pumps, many projects overlook the fundamental physics of the building. Air tightness is often the "hidden" factor that determines whether a retrofit succeeds or fails.

The Mistake: Failing to conduct pre- and post-installation air pressure tests. Without knowing how "leaky" a building is, it is impossible to accurately calculate the required ventilation strategy. Ignoring this often leads to the dreaded "sealed box" effect, where moisture is trapped, leading to mould and structural damage.

The Fix: Make Air Pressure Testing a non-negotiable part of your workflow. It provides the empirical data needed to validate the fabric-first approach. We recommend testing early in the process to identify unexpected air paths that could undermine your new insulation.

4. Missing Mandatory In-Person Inspections (PAS 2035:2023 Update)

The 2023 update to PAS 2035 introduced stricter rules regarding the physical presence of the Retrofit Coordinator. While remote monitoring has its place, the standards now mandate more "boots on the ground" for specific high-risk interventions.

The Mistake: Relying solely on digital photos sent by installers to sign off on complex junctions. Where a new measure connects to or penetrates an existing fabric measure, an in-person inspection by the Coordinator is often mandatory.

The Fix: Review your project timelines to include scheduled site visits at critical milestones. Do not wait until the end of the project to check the quality of the work. Our team at CPH Retrofit prides itself on thoroughness; we don't just sit behind desks: we ensure the work meets the Trustmark standards through physical verification.

5. Poor Identification of the Thermal Envelope

If you don't correctly define where the heat stays in and the cold stays out, your entire retrofit design will be flawed. We see this mistake most often in complex properties with extensions, converted lofts, or unheated basements.

The Mistake: Misidentifying which walls are internal and which are external, or failing to account for thermal bridging at floor and ceiling junctions. This results in inaccurate EPC ratings and, worse, cold spots that invite condensation.

The Fix: Ensure your Retrofit Assessor is highly trained in identifying thermal boundaries. Use our Domestic EPC services as a starting point to get an accurate baseline of the property. A detailed building survey is the only way to guarantee that the proposed measures will actually improve the building’s performance.

6. Neglecting Occupant Behaviour and Ventilation Risk

A building doesn't exist in a vacuum; it is occupied by people whose habits significantly impact energy use and moisture levels. PAS 2035:2023 places a much heavier emphasis on how the residents interact with the new technology.

The Mistake: Installing high-performance measures without assessing the occupants' ability to use them. For example, installing an Air Source Heat Pump but failing to explain that it operates differently than a gas boiler, or sealing a home without ensuring the residents understand how to use trickle vents.

The Fix: Conduct thorough occupant assessments and provide clear, accessible "Handover Packs." We focus on the human element of retrofit, ensuring that ventilation strategies are not just compliant with BS 5250 but are also practical for the people living in the home. This reduces the risk of post-installation complaints and "performance gaps."

7. Operating Without Independent Oversight

There is a growing trend of "self-certification" in the industry, where the same entity designs, installs, and signs off on the work. While this might seem efficient, it often leads to a lack of critical friction that catches errors.

The Mistake: Lack of independent technical monitoring or third-party audits. Without an outside eye, small errors in calculation or installation techniques can become systemic across a large-scale social housing project.

The Fix: Partner with an independent consultancy like CPH Retrofit. We act as your quality assurance partner, providing a "gold standard" of oversight. Whether you need Non-Domestic EPCs or full-scale coordination, our independence is your greatest asset in maintaining PAS 2035 Compliance.

Why Choose CPH Retrofit for Your Compliance Needs?

Navigating the transition to a low-carbon future is a monumental task, but you don't have to do it alone. At CPH Retrofit, we offer a comprehensive suite of services designed to take the stress out of energy efficiency consulting.

Our Expert Advantage:

1. 15+ Years of Experience: We have navigated every iteration of the PAS standards, giving us deep institutional knowledge.
2. End-to-End Support: From initial assessment to final lodgement, we handle the technical heavy lifting.
3. Dedicated Professionals: Our team consists of accredited Retrofit Coordinators and Assessors who are committed to quality.
4. Peace of Mind: We ensure your projects meet all Trustmark and funding requirements, protecting your investment.

Take the Next Step Toward Compliance

Don't let avoidable mistakes derail your retrofit projects. Whether you are a local authority, a housing association, or a private developer, we have the tools and the expertise to ensure your properties are warm, dry, and fully compliant.

Ready to streamline your retrofit process?
Contact our expert team today to discuss your upcoming projects. Let us show you why we are the trusted partner for domestic retrofit services across the UK.

Check out our latest blog posts for more industry insights and technical guides on achieving net-zero goals. Together, we can build a more energy-efficient future, one home at a time.