Glossary of terms

A measure of how well a building prevents air leakage through the structure. High airtightness improves energy efficiency and comfort. Donaldson Timber Systems’ closed-panel systems achieve airtightness values below 3 m³/h·m².

The UK’s leading independent certification body for construction products. BBA certification confirms a product’s compliance with Building Regulations and its performance in areas like fire safety and durability.

A digital process for creating and managing data across a building’s lifecycle. Donaldson Timber Systems uses BIM to coordinate design, engineering, and manufacturing for precise, efficient offsite construction.

An accreditation that assures the durability, integrity, and mortgage ability of Modern Methods of Construction (MMC) systems over a minimum 60-year design life.

National standards governing safety, structural stability, fire performance, and energy efficiency in new builds. All Donaldson Timber Systems products are tested and certified for full compliance.

The use of software to produce detailed 2D and 3D drawings for design and manufacture. CAD enables precision engineering in timber frame and supports seamless transition to BIM environments.

A UK Government classification for panelised offsite systems such as timber frame where panels are manufactured in factories and assembled on site.

A factory-assembled wall panel that includes insulation, internal sheathing, vapour barriers, and sometimes pre-installed windows or service zones, offering faster build times and superior quality.

A design approach that simplifies fabrication and on-site assembly. At Donaldson Timber Systems, DfMA principles ensure components are efficient to produce, transport, and install — improving productivity and quality.

A document rating a building’s energy efficiency on a scale from A to G. Timber frame homes typically achieve higher EPC ratings thanks to excellent insulation and airtightness.

The total carbon emissions generated in producing, transporting, and assembling materials. Timber naturally stores carbon, making it one of the lowest-impact structural materials available.

A forthcoming UK standard (from 2025) requiring new homes to emit 75–80% less carbon. Donaldson Timber Systems products are engineered to meet or exceed FHS performance targets.

Growing, Recognising and Supporting Skills in Practice, the online training partner working with Donaldson Timber Systems to provide timber frame training.

International standards for Quality, Environmental, and Health & Safety management. They ensure consistent manufacturing quality, responsible environmental practices, and safe working environments.

An analysis of a product’s environmental impact throughout its life — from material extraction to end-of-life disposal. Timber frame systems perform strongly in LCA studies due to renewable sourcing and long-term carbon storage.

Building methods that reduce carbon emissions through efficient design, renewable materials, and offsite manufacture. Timber frame is a proven low-carbon solution.

A collective term for innovative approaches such as offsite manufacturing, modular building, and timber frame systems that improve quality, speed, and sustainability.

A state in which the total greenhouse gases emitted are balanced by those removed. Timber frame construction supports net-zero goals by locking carbon into the building fabric and reducing operational emissions.

The UK’s leading provider of structural warranties. NHBC Accepts certifies innovative products like Donaldson Timber Systems’ closed-panel solutions as fully warranty-approved.

Building components are produced in factory conditions and assembled on site. This method improves quality, speed, and safety while reducing waste and environmental impact.

A structural timber wall panel with sheathing boards fitted but insulation and membranes installed on site, offering flexibility and cost efficiency for larger housing projects.

A measure of how much construction work is completed offsite. Higher PMV means greater efficiency and quality control. Donaldson Timber Systems’ Sigma® II achieves PMV levels between 55%–58%.

The Government-approved method for calculating a dwelling’s energy performance and CO₂ emissions. Donaldson Timber Systems designs its timber frame systems to support high SAP ratings.

A high-performance closed-panel timber frame system from Donaldson Timber Systems, delivering low U-values, airtightness below 3 m³/h·m², and exceptional speed of build.

The UK’s trade body for timber construction. Donaldson Timber Systems holds STA Gold Assure status — the highest level of quality assurance.

A measure of heat loss through a building element. Lower U-values indicate better insulation and lower energy bills.

A method where structural timber forms the load-bearing framework of a building. It’s faster, cleaner, and more sustainable than masonry, supporting Future Homes Standard and net-zero targets.

Donaldson Timber Systems combines over 50 years of innovation with modern automation and sustainability leadership. Whether you’re learning industry terms or planning your first timber frame development, we’re here to make the process simple and transparent.