Marley is supporting NHBC standards by clarifying ventilation for integrated solar panels
In early 2024, the National House Building Council (NHBC) introduced significant updates to its Technical Standards, with a focus on ventilation for roof-integrated solar PV panels. As solar PV gains further traction in the construction industry, these changes address the critical relationship between ventilation, energy efficiency and moisture control in roofing systems, providing much-needed clarity for architects, builders and contractors.
The rising demand for integrated solar panels
With consumer demand for sustainable energy solutions escalating, integrated solar panels, such as the Marley SolarTile®, are becoming a popular choice for new builds and retrofit projects. These panels seamlessly integrate into the roofline, offering both aesthetic appeal and reliable energy output.
Additionally, Government regulations, like updates to Part L of the Building Regulations and the upcoming Future Homes Standard in 2025, place increasing emphasis on energy efficiency, further driving the adoption of solar PV systems.
However, there are some industry misconceptions around integrated solar PV panels, with some believing that they reduce ventilation, leading to heat build-up and reduced energy output. The NHBC’s updated standards directly address this; reinforcing the performance and compliance of integrated solar PV systems.
The NHBC’s key ventilation updates
The revised NHBC standards clause 7.2.15, “Ventilation, vapour control and insulation”, underscores that roofs with integrated solar panels must now be treated as air impermeable unless proven otherwise by the manufacturer. This classification necessitates careful planning to prevent condensation and ensure proper airflow, in line with British Standard (BS) 5250:2021, which governs moisture management in buildings.
For integrated solar PV panels, the NHBC advises that traditional roof ventilation strategies, such as ridges, eaves and tile ventilation, are generally sufficient to maintain airflow and manage moisture, without requiring additional counter battens. This is true for Marley SolarTile® system, which meets these requirements without compromising the panel’s performance or increasing the roof’s complexity.
Practical guidance for compliance
Meeting the new NHBC standards and BS 5250 for ventilation depends on the specific roof build-up – whether it’s a cold, warm or hybrid roof, for example. Key considerations include:
- Cold roofs with non-permeable underlay: require 10,000mm²/m eaves ventilation and 5,000mm²/m ridge ventilation.
- Cold roofs with vapour-permeable underlay: eaves ventilation may be reduced to 7,000mm²/m for normal ceilings, and ridge ventilation can be used as an alternative for well-sealed ceilings.
- Warm roofs: typically require 25,000mm²/m eaves ventilation and a vapour control layer (AVCL) on the warm side of insulation.
Achieving standards with Marley SolarTile®
Marley’s SolarTile® system simplifies compliance with NHBC standards. As an integrated roofing solution, it combines solar power generation with a weatherproof roof covering, eliminating the need for additional counter battens to ensure good ventilation and prevent overheating. Additionally, Marley’s comprehensive product range includes:
- High-performance underlays: vapour-permeable and non-permeable options.
- Ventilated dry ridge and eaves systems: designed for seamless installation and optimal airflow.
- Tile vents: aesthetic solutions for supplementary ventilation.
Marley’s full roof system, backed by a 15-year warranty, ensures builders and architects have everything needed for compliant and efficient roof installations.
By adopting these systems, the industry can continue delivering energy-efficient, moisture-managed and aesthetically superior homes, driving confidence in integrated solar panel systems.
To download a Marley Roof Systems Specification Guide visit: Download of Spec Guide | Marley.
For further information on Marley SolarTile go to Roof Integrated SolarTile® | Marley | Solar Roof Tiles.
