Question 1

What size C24 ceiling joist do I need in the UK?

Accepted Answer

C24 ceiling joists are typically supplied in 90×45, 120×45, 140×45, 190×45 and 240×45 mm sections. The correct size depends on span, spacing and load — verify against TRADA published Eurocode 5 (BS EN 1995-1-1) span tables and your structural engineer's calculations for Building Control approval under Part A.

Question 2

What spacing should C24 ceiling joists be installed at in the UK?

Accepted Answer

UK ceiling joists are typically installed at 450 or 600 mm centres. 400 mm centres are the most common in residential construction and align with standard 1200 mm wide plasterboard sheets.

Question 3

Does C24 timber comply with UK Building Regulations?

Accepted Answer

Yes — C24 Softwood is a recognised strength class under BS EN 338 and is widely used to demonstrate compliance with Part A of the Building Regulations (Structure) in England & Wales when sized to TRADA Eurocode 5 span tables or by an engineer's calculation. Equivalent provisions apply under Section 1 of the Scottish Technical Handbook and Part D in Northern Ireland. NHBC Standards Chapter 6.4 sets the practical specification baseline for warranty providers.

C24 ceiling joists span tables (UK)