What FRI actually means
"Full repairing and insuring" means the tenant is responsible for all repairs (internal, external and structural where the demise includes structure) and for the insurance of the building (often by way of reimbursing the landlord's insurance premium). It is the most onerous lease structure on the tenant.
The asymmetry FRI creates
An FRI lease places the tenant in the position of repairing a building they may have inherited in poor condition, without any prior obligation to inspect, document or evidence what they took on. The Schedule of Condition corrects that asymmetry by fixing the inherited condition in writing.
Qualifying the repairing covenant
The standard mechanism is a clause in the lease that states the tenant is not required to put or keep the property in any better state of repair than evidenced by the appended Schedule of Condition. Your solicitor will draft and negotiate the precise wording.
IRI and other structures, does the schedule still matter?
On internal repairing and insuring (IRI) leases the tenant's obligation is narrower, but a Schedule of Condition is still valuable. On effective FRI structures (IRI plus service charge for external repairs) the practical exposure is similar to FRI, and the schedule remains highly recommended.