The UK’s housing stock is among the oldest and least energy efficient in Europe. With buildings responsible for around 20% of national emissions, the route to net zero is not primarily a new-build challenge but a fabric-first retrofit challenge.
The UK replaces its housing stock very slowly. At current replacement rates, a home built today would need to last around 1,000 years, meaning it is the existing housing stock that will continue to dominate operational emissions for decades to come. Improving what already stands is therefore essential to meeting national energy efficiency and carbon reduction targets.
For landlords, specifiers and contractors, the roof and the wider building envelope is a natural place to start. It’s where heat loss, moisture control and overall energy performance converge and where smart system choices can deliver meaningful, measurable improvement.
What’s driving the shift to retrofit?
Under the Minimum Energy Efficiency Standards (MEES), landlords and block management companies are not permitted to let properties rated F or G on their EPCs. Government proposals, if enacted, would raise this minimum to EPC C for new tenancies from 2028 and all tenancies by 2030, driving a wave of energy upgrades across the rental sector. At the same time, local authorities and social landlords are under increasing pressure to evidence energy performance, embodied carbon and responsible sourcing through frameworks such as the Publicly Available Specification PAS 2035 and the Social Housing Decarbonisation Fund (SHDF).
For many landlords, this shift is both a regulatory and commercial imperative. Estimates suggest that achieving EPC C could require average investment of £6,000–£7,000 per property but failure to act risks fines, lower asset value and reduced tenant demand.
Government funding is helping to offset these costs. The Warm Homes Local and Social Housing Funds, announced in March 2025, aim to upgrade more than 170,000 homes, while the Energy Company Obligation (ECO) and Great British Insulation Scheme (GBIS) have already improved 2.8 million properties across the UK. Together, these programmes are reshaping refurbishment, rewarding solutions that cut carbon, lower bills and extend building life.
The benefits reach beyond compliance. Retrofitting a home reduces energy consumption, improves comfort and creates healthier living spaces. Studies link better insulation and ventilation with improved thermal comfort and reduced respiratory illness.
Understanding PAS 2035: the foundation of safe and effective retrofit
PAS 2035 is the UK’s recognised standard for domestic retrofit. It sets out a structured, whole-building approach to improving existing homes, focusing on energy efficiency, occupant health and long-term performance. The standard ensures that every measure, whether ventilation, insulation or waterproofing, is installed safely, in the right order and as part of an integrated design strategy.
For roofing and insulation, PAS 2035 promotes a fabric-first philosophy. Before any heating systems or renewable technologies are added, the building’s envelope, including its roof, walls and floors, must be optimised to retain heat, control moisture and maintain airtightness. This ensures improvements work together, rather than against each other, avoiding issues such as condensation or thermal bridging.
At IKO, we offer complete roofing and insulation system solutions designed to support the full spectrum of retrofit requirements. Improving thermal performance at roof level helps reduce energy demand at source and supports wider retrofit measures. IKO enertherm insulation boards are designed to deliver low Lambda values in a thinner profile, allowing required U-values to be achieved without increasing roof build-up. This supports both energy efficiency and space efficiency, particularly on retrofit projects where structural constraints or detailing tolerances are limited.
Once fabric performance has been addressed, the roof build-up must be protected by a compatible waterproofing system. Single ply solutions such as IKO Armourplan and IKO Spectraplan provide a flame-free waterproofing option with system-specific performance credentials.
As assessed in BBA Agrément Certificate 05/4287, IKO Armourplan systems have a service life of at least 35 years when designed, installed and maintained in accordance with the certificate and IKO instructions. Periodic additional maintenance can extend this to more than 40 years.
The white IKO Spectraplan TPE membrane has a BBA life expectancy of 30 years and achieves a Solar Reflectance Index of 91, supporting high solar reflectivity. By reflecting a greater proportion of solar radiation, the membrane can help limit heat gain through the roof, reducing the energy required to cool the internal environment, depending on the building design, climate and operational conditions. This can support improved overall building energy performance.
Both membrane ranges are manufactured in the UK by IKO. Where available and subject to the scheme’s acceptance criteria, IKO’s membrane recycling service can also support the recovery of eligible installation offcuts, thereby reducing on-site waste and repurposing material that would have been sent to landfill.
For residential projects with more complex detailing, cold applied liquid waterproofing from IKO’s Cold Applied Liquids range provides a fully bonded option for varied roof configurations, including balconies, terraces and podium decks. Because these liquid systems are applied cold, with no hot works involved, they can also help reduce site risk and disruption for occupants during installation.
Refurbishment options for every roof type
IKO Carrara and IKO Roofgarden, meanwhile, offer alternative refurbishment options where reinforced bituminous systems or green roof build-ups are more appropriate. IKO Carrara features a high Solar Reflectance Index (SRI) of 82, a titanium dioxide (TiO₂) mineral finish, helping to reduce solar heat absorption at roof level along with a lower surface temperature by up to 30%. IKO Roofgarden, with its anti-root coating, enables the integration of green roofs to support rainfall attenuation, biodiversity and surface temperature moderation. Each system combines compatible underlays, insulation, capsheets and air and vapour control layers. This coordinated roof build-up supports energy efficiency gains and protection against water ingress.
IKO Permascreed LI, on the other hand, provides a low-carbon, fast-setting screed solution, achieving up to 38% lower upfront embodied carbon compared to our previous IKO Permascreed range. Its zero-water formulation reduces curing time from an average of 28 days to as little as one day, while removing the requirement for water in this otherwise water-intensive sector. With zero water content, this removes the risk of freeze/thaw cracking, reducing the likelihood of repair works and associated energy-intensive interventions. Using IKO’s Screed Calculator, specifiers can model weight, thickness, curing time and potential carbon savings, making it easier to evidence performance and embodied-carbon reductions in line with PAS 2035.
For projects looking to extend environmental value even further, IKO Elements sustainable roof systems can be incorporated to boost solar energy capabilities, enhance insulation, manage rainfall and support biodiversity.
IKO INFO: Counting the benefits of lower embodied carbon
Embodied carbon is the total amount of greenhouse gases released during a product’s life cycle, from raw-material extraction and manufacturing to transport, installation and end-of-life. Unlike operational carbon, which comes from how a building is powered or heated, embodied carbon is “built in” at the point of construction or refurbishment.
Reducing embodied carbon is an increasingly important consideration within PAS 2035-aligned retrofit and associated funding schemes such as the Social Housing Decarbonisation Fund (SHDF). Procurement frameworks, including LHC RS5M, also assess suppliers on sustainability performance, responsible sourcing and social-value delivery. Meeting these expectations helps housing providers demonstrate compliance, value and measurable carbon reduction.
As the top-ranked traditional flat roofing supplier on the LHC RS5M Roofing Systems Framework, IKO provides a framework-aligned route to responsibly sourced, UK-manufactured systems. Our third-party verified EPDs, BES 6001 certification and ISO 14001 environmental management align with the sustainability criteria used within PAS 2035 and public-sector frameworks.
A key part of this approach is IKO’s LI technology, developed to reduce upfront embodied carbon across selected waterproofing and screed solutions. By reformulating products to lower carbon intensity at the manufacturing stage, this proprietary technology enables meaningful embodied-carbon reductions without compromising performance, supporting retrofit projects where carbon reporting and lifecycle impact are under increasing scrutiny.
IKO also provides lifecycle carbon data compatible with One Click LCA, along with specification guidance, Continuing Professional Development (CPDs) and carbon-reporting support to help project teams interpret data and achieve sustainability targets. By combining verified data with practical technical expertise, IKO helps architects, contractors and housing providers make informed, confident choices that support retrofit compliance and long-term efficiency.
Future-ready homes, built on collaboration
The retrofit challenge is complex but entirely achievable with the right expertise and materials. These IKO systems are responsibly manufactured in the UK, helping to reduce transport impact, strengthen supply chain resilience and support traceability from raw materials to roof.
Ongoing investment in low impact production, reduced-waste packaging and more efficient delivery shows IKO’s continued commitment to sustainability in practice, not just in principle. By working closely with architects, contractors and housing providers, IKO supports retrofit projects with products and guidance designed to improve energy efficiency, enhance service life, and enable measurable carbon reductions.
Ready to start your residential retrofit journey?
Speak to our Technical Team for tailored guidance on roofing and insulation upgrades that deliver long-term energy savings and compliance assurance.
To learn how these commitments fit into IKO’s wider environmental goals, explore our sustainability and ESG strategy.
