RICS Knowledgebase

There is no specific RICS guidance on the valuation of air or roof space: it is more a case of applying established valuation principles.

The following article may be helpful (although quite old historic) 

https://www.peterbarry.co.uk/blog/valuing-roof-spaces-for-development/ 

If you have anything to contribute to this knowledge article or are a specialist in this area please do comment below.

#valuation