Can timber roof trusses be modified on site?

No. Timber roof trusses must never be cut, notched, or modified on site without written approval from the truss designer.

No. Timber roof trusses must never be cut, notched, or modified on site without written approval from the truss designer. Removing or cutting any member — including web bracing — can cause immediate collapse or progressive failure under load. If modifications are needed (for tank platforms, loft hatches, chimney openings), these must be designed into the truss layout at the manufacturing stage. Site modifications void the structural warranty and may breach Building Regulations.

Why this matters

This question relates to Timber Roof Structures: Trusses, Rafters & Engineered Solutions, which covers the broader topic in detail. Understanding this specific aspect helps architects, builders, and timber dealers make informed specification decisions.

For full context and additional technical detail, see our comprehensive guide:

→ Timber Roof Structures: Trusses, Rafters & Engineered Solutions

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About this answer

This answer is part of the PuurModulair Knowledge Base — comprehensive timber specification guidance for architects, builders, and dealers across the UK, EU, and Scandinavia. All technical content is reviewed by qualified timber technologists before publication.