commercial landlord - allowances

I understand that eg industrial businesses can claim capital allowances for capital expenditure on industrial premises which they own. However small industrial units are usually occupied by short term tenants and the landlord has to provide any upgrade/ capital renewal. Can a commercial landlord who lets industrial property to an industrial business claim allowances against his rental income when he undertakes similar expenditure. EG builds an extension or access road? Does it make any difference whether the landlord is obliged to do this under the lease?