the construction, alteration, or removal of an internal wall (including the construction, alteration, or removal of an internal doorway) in any existing building if—
(i) compliance with the provisions of the building code relating to structural stability is not reduced; and --不影響結構
(ii) the means of escape from fire provided within the building are not detrimentally affected; and--不影響防火
(iii) the wall is not made of units of material (such as brick, burnt clay, concrete, or stone) laid to a bond in and joined together with mortar:--不是磚牆
2. 廚房改位置，如果符合 (AC) 就不必報批
the alteration to drains for a dwelling, if the alteration—
(i) is of a minor nature (for example, shifting a gully trap); and -- 工程規模不大(很難介定)
(ii) does not include making any new connection to a service provided by a network utility operator; and -- 沒有增加接頭
(iii) is carried out in accordance with the Plumbers, Gasfitters, and Drainlayers Act 2006: --由註冊水工根據法規建造。
3. 楼下的1室+卫浴是非法改建，沒錯，因為不符合SCHEDULE 1 AC (ii) 的規定，需要報批。