Answer From Our Loft Conversion Expert by: Jeremy Wedge
Tables are published for single timber joist as this is the most common application and can be found in part A of the Building Regulations.
All other cases are subject to design as there are a number of external influences that require to be checked, this is usually undertaken by a structural engineer.
We can provide a design for you to cover multiple joists on your behalf, please feel free to contact us should you wish the design undertaken.
