it is not illegal to install smoke exhaust pipes on the external wall of the house, so there is no problem in installing the flue. The consideration is whether the material for installing the flue is suitable for installation on the external wall. Before installation, it is necessary to comply with safety measures and refer to the design code for smoke exhaust in building installation. Usually, when installing the external wall flue, it is necessary to build a wooden frame and support it with a ring beam, mainly to ensure the safety of construction. Illegal buildings refer to buildings that are built in urban planning areas without obtaining the construction project planning permit or in violation of the provisions of the construction project planning permit, which seriously affects urban planning. The main criteria are as follows:

(1) occupying buildings that have been planned as public places, public facilities or public green land;

(2) buildings that are not constructed according to the approved design drawings;

(3) buildings rebuilt or added without authorization;

(4) buildings illegally transferred from non-agricultural construction land of rural economic organizations or villagers' own homesteads; Buildings built by illegal transfer of non-agricultural land of urbanized residents' committees or joint-stock cooperative companies in special zones;

(5) The non-agricultural land of rural economic organizations or the homestead occupied by villagers violate the urban planning or exceed the standards set by the municipal government;

(6) buildings that change the use function of industrial plants, houses and other buildings without authorization;

(7) Temporary buildings that have not been demolished within the time limit;

(8) other buildings that violate the relevant provisions of laws and regulations.

Legal basis

Law of the People's Republic of China on Urban and Rural Planning Article 3 Cities and towns shall formulate urban plans and town plans in accordance with this Law. Construction activities within the planned areas of cities and towns shall meet the planning requirements. The local people's governments at or above the county level shall, according to the local rural economic and social development level and the principle of adapting measures to local conditions and being practical, determine the areas where township planning and village planning should be formulated. Townships and villages in the designated areas shall make plans in accordance with this Law, and the construction of townships and villages in the planned areas shall meet the planning requirements. Local people's governments at or above the county level shall encourage and guide townships and villages in areas other than those specified in the preceding paragraph to formulate and implement township plans and village plans.