12.—(1) Where an application, or a deemed application other than an outline application, relates to development which is partly within category 1 and partly within category 2, the following sub-paragraphs shall apply for the purpose of calculating the fee.
(2) The amount of gross floor space which is to be created by that part of the development which is within category 2 (“the non-residential floor space”), shall be calculated and the sum payable in respect of that non-residential floor space shall be added to the sum payable in respect of that part of the development which is within category 1 and, subject to sub-paragraph (4), the result of the addition shall be the fee payable.
(3) For the purpose of sub-paragraph (2) where any of the buildings is to contain floor space for the purposes of providing common access or common services or facilities for persons occupying or using that building for residential purposes and for persons occupying or using it for non-residential purposes (“common floor space”), the amount of non-residential floor space shall be assessed in relation to that building, as including such proportion of the common floor space as the amount of non-residential floor space in the building bears to the total amount of gross floor space in the building.
(4) Where an application or deemed application to which this paragraph applies relates to development which is also within one or more than one of categories 3 to 11 an amount shall be calculated in accordance with each such category and if any of the amounts so calculated exceeds the amount calculated in accordance with sub-paragraph (2) that higher amount shall be the fee payable in respect of all of the development to which the application or deemed application relates.