4. (1) Where the Competent Authority upon information received or otherwise in its possession is satisfied that any building in a slum area is in any respect unfit for human habitation or any land in that area requires any work of improvement, it may, unless in its opinion the building is not capable of being rendered so fit at a reasonable expense, or the required improvements to the load are not capable of being affected at reasonable expense serve upon the owner of the building or the land, as the case may be, a notice requiring him within such reasonable time, not being less than forty-five days, as may be specified in the notice or as may be extended by the Competent Authority from time to time, to render the building fit for human habitation or execute on the land the works of improvement, specified therein. The notice shall also state the things which in the opinion of the Competent Authority will render the building fit for human habitation and the required works of improvement on the land together with the estimated cost of such things and works.
Explanation I-In determining whether a building can be rendered fit for human habitation at a reasonable expense, or the required improvement can be effected on the land at a reasonable expense, regard shall be had to the estimated cost of the works necessary to render the building so fit, or of the required improvement on the land to be effected, and the estimated value of the building or the land after the works have been completed or improvement effected.
Explanation II-For the purpose of this sub-section "reasonable expense" in relation to rendering a building fit for human habitation means expenses not exceeding fifty per centum of the value of the building.
(2) In addition to serving a notice under this section on the owner, the Competent Authority may also serve a copy thereof on any other person having interest in the building or the land whether as lessee, mortgagee or otherwise.