UK Building Regs Part L Holzbau 2026 (GB)

Building Regulations Approved Document Part L governs the energy efficiency of buildings in England and is directly relevant to the timber construction and engineered timber sector. The 2021 uplift — which came into force for new dwellings in June 2022 — represents a 31% improvement in energy efficiency over the previous 2013 standard and forms an interim step towards the Future Homes Standard, expected to be fully enacted by 2025/26. For timber-frame house builders and commercial timber construction companies, Part L compliance shapes insulation specifications, airtightness targets, and whole-building energy performance.

All developers, main contractors, and timber frame system manufacturers working on new dwellings or major renovations in England must comply with Part L. This applies to traditional timber frame, structural insulated panels (SIPs), cross-laminated timber (CLT), and hybrid timber systems alike. Building Control Bodies (BCBs) — either local authority or approved inspectors such as NHBC Building Control — are responsible for verifying compliance at design stage (plans approval) and on completion (as-built SAP). Failure to achieve compliance can result in enforcement notices and delay of occupation certificates.

Under the 2021 Part L uplift, new dwellings must achieve a maximum of 60 kgCO₂/m²/year and demonstrate compliance via a Standard Assessment Procedure (SAP 10.2) energy calculation, submitted to Building Control. Key requirements affecting timber construction include: enhanced fabric U-values (walls typically ≤0.18 W/m²K), airtightness testing to ≤8 m³/h/m² at 50 Pa, thermal bridging calculations (Psi values), and MVHR or equivalent ventilation. The NHBC provides specific guidance for timber frame systems under its Standards Chapter 6.2 and issues structural and energy warranties for compliant builds.

To achieve compliance, timber construction businesses should engage an accredited SAP assessor at the design stage and work with suppliers to confirm insulation and system U-values. As-built SAP must be submitted upon completion, supported by an airtightness pressure test. For projects within NHBC warranty schemes, the NHBC Accepts process allows pre-approval of innovative timber systems. Businesses should also monitor DLUHC consultations on the Future Homes Standard — anticipated to require near-zero carbon new homes from 2025/26 — to ensure product development and system specifications are future-proof.

Hinweis: Dieser Beitrag ist kein Ersatz für rechtliche oder steuerliche Beratung. Bitte konsultieren Sie für individuelle Fragen einen Fachexperten.

Umsetzungs-Checkliste

1. Engage an accredited SAP 10.2 assessor at the earliest design stage for all new timber-frame projects
2. Confirm wall, roof, and floor U-values meet Part L 2021 targets (e.g. walls ≤0.18 W/m²K)
3. Calculate and submit thermal bridging (Psi values) for all key timber junctions
4. Specify and document compliant ventilation strategy (e.g. MVHR for airtight timber systems)
5. Submit design-stage SAP to Building Control (local authority or NHBC Building Control) for plans approval
6. Carry out airtightness pressure test on completion (target ≤5 m³/h/m² recommended for timber frame)
7. Submit as-built SAP calculation to Building Control to obtain compliance certificate
8. Monitor DLUHC updates on the Future Homes Standard and adapt system specifications accordingly