Hi Max,
As long as the omissions comply with LCA standards’ cut-off rules then it should be fine. What are the cofferdams built from and what do the material estimates look like?
With regards to whether it’s ‘required’ or not, we always conduct our reviews and strongly encourage our users to model their LCA studies according to EN 15978 standards (i.e. as per cut-off rules) rather than to rating schemes.