12.—(1) Where an application (other than for outline planning permission) or a deemed application relates to development which is in part within category 1 and in part within category 2, 3 or 4, the following sub-paragraphs apply for the purpose of calculating the fee payable in respect of the application or deemed application.
(2) An assessment must be made of the total amount of gross floor space which is to be created by that part of the development which is within category 2, 3 or 4 (“the non-residential floor space”), and the sum payable in respect of the non-residential floor space to be created by the development must 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 sum so calculated is the fee payable.
(3) For the purpose of calculating the fee payable under sub-paragraph (2)—
(a)where any of the buildings is to contain floor space which it is proposed to use for the purposes of providing common access or common services or facilities for persons occupying or using part of that building for residential purposes and for persons occupying or using part of it for non-residential purposes (“common floor space”), the amount of non-residential floor space must 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 to be created by the development;
(b)where the development falls within more than one of categories 2, 3 and 4 an amount must be calculated in accordance with each such category and the highest amount so calculated is the sum payable in respect of all of the non-residential floor space.
(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 5 to 12—
(a)an amount is calculated in accordance with each such category; and
(b)if any of the amounts so calculated exceeds the amount calculated in accordance with sub-paragraph (2) that higher amount is the fee payable in respect of all of the development to which the application or deemed application relates.
(5) In sub-paragraph (3), the reference to using the building for residential purposes is a reference to using it as a dwellinghouse.