5.—(1) The cost floor is an amount equal to the aggregate of the costs which under sub-paragraph (2) may be treated as relevant costs.
(2) The costs which may be treated as relevant costs are the costs incurred by the landlord in respect of–
(a)the acquisition of the dwelling-house, and
(b)the construction of the dwelling-house (including development works and the acquisition of land), or
(c)relevant works to the dwelling-house.
(3) Where the landlord has previously disposed of the dwelling-house and has subsequently re-acquired it in circumstances in which discount was recovered in whole or part, only the costs of re-acquisition net of any discount recovered shall be taken into account for the purposes of sub-paragraph (2)(a).