When should I specify C30 instead of C24?

C30 is specified when engineering calculations show that C24 is insufficient for the required span, loading, or deflection limits, but the architect wants to maintain solid timber rather than switching to glulam. C30 is less readily available and more expensive than C24, so it is typically reserved for specific critical members rather than general framing.

C30 is specified when engineering calculations show that C24 is insufficient for the required span, loading, or deflection limits, but the architect wants to maintain solid timber rather than switching to glulam. C30 is less readily available and more expensive than C24, so it is typically reserved for specific critical members rather than general framing.

Why this matters

This question relates to C24 vs C16 vs C30 Timber Grading — What Architects Need to Know, 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:

→ C24 vs C16 vs C30 Timber Grading — What Architects Need to Know

Related questions

• What does C24 mean in timber?
• Is C24 better than C16?
• Can I use C16 for floor joists?

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.