1—Subject to paragraph 3, the total amount of approved expense for the provision of standard amenities in respect of any one application shall not exceed the sum of the amounts allowable under the following provisions of this Part of this Schedule.
2—Subject to paragraph 4, for each of the standard amenities provided there shall be allowed an amount of approved expense not exceeding the maximum eligible amount specified for an amenity of that description in the second column of Part I of this Schedule or the amount substituted therefor under the following provisions of this Part of this Schedule.
3—Subject to the provisions of section 242, the maximum eligible amounts specified in the second column of Part I of this Schedule may be exceeded by such amount as the local authority approve if the local authority are satisfied in any particular case that an increased estimate for the works is justifiable.
4—An amount shall not be allowed for more than one amenity of the same description; and no amount shall be allowed for an amenity of any description if at the time the works were begun the house was provided with an amenity of that description, except where the works involved interference with or replacement of that amenity and the local authority are satisfied that it would not have been reasonably practicable to avoid the interference or replacement.