18(1)Subject to the following provisions of this paragraph, where the dwelling-house is a flat, a provision of the lease or of an agreement collateral to it is void in so far as it purports—
(a)to enable the landlord to recover from the tenant any part of costs incurred by the landlord in discharging or insuring against the obligations imposed by the covenants implied by virtue of paragraph 14(2)(a) or (b) (landlord’s obligations with respect to repair of dwelling-house, etc.), or
(b)to enable any person to recover from the tenant any part of costs incurred, whether by him or by another person, in discharging or insuring against any obligations to the like effect as the obligations which would be so imposed but for paragraph 15(3) (obligations not to be implied which landlord would not be entitled to discharge).
(2)A provision is not void by virtue of sub-paragraph (1) in so far as it requires the tenant to bear a reasonable part of the costs of carrying out repairs not amounting to the making good of structural defects.
(3)A provision is not void by virtue of sub-paragraph (1) in so far as it requires the tenant to bear a reasonable part of costs incurred in respect of a structural defect—
(a)of the existence of which the landlord informed the tenant in the notice under section 125 (landlord’s notice of purchase price, etc.), stating the landlord’s estimate of the amount (at current prices) which would be payable by the tenant towards the cost of making it good, or
(b)of the existence of which the landlord becomes aware ten years or more after the grant of the lease.
(4)Where the lease acknowledges the right of the tenant and his successors in title to production of the relevant policy, a provision is not void by virtue of sub-paragraph (1) in so far as it requires the tenant to bear a reasonable part of the costs of insuring against risks involving such repairs or the making good of such defects.
(5)Any estimated amount stated as mentioned in sub-paragraph (3)(a) (estimate of costs to be borne by tenant in respect of structural defect) shall be disregarded for the purposes of any statement under section 125(4) (estimate of service charges payable).