Protect the main structure, to extend the life of the building. Using exterior insulation scheme, since the outside of the building envelope, buffer stress caused by temperature changes cause structural deformation, to avoid the rain, snow, freeze, thaw, dry and wet cycles caused structural damage, reduce the air carbonation and corrosion of reinforced structures cause carbon dioxide and water on the concrete and reduce the harmful gases in the air and ultraviolet erosion of the maintenance structure. Facts have proved that as long as the walls and what maintenance is used for pvc composite boards roof insulation material selection of appropriate and reasonable thickness, external insulation can effectively eliminate common oblique top transverse wall cracks or character cracks.

Thus, external insulation can reduce both maintenance of the structure of temperature stress, but also on the main structure of the protective effect, thus effectively improving the durability of the main structure, it is more scientific and reasonable than the inner insulation. 2.3 Basic elimination of the "thermal bridge" phenomenon, played a better thermal insulation functional materials. Use of external insulation to avoid "thermal bridges" is more advantageous than the inner insulation, such as interior and exterior parts of the junction, exterior ring beam, structural column, in recent years, in the process of building insulation technology evolving, it became the main exterior insulation and holding two technologies form the framework of beams, columns, window and door openings and a top deck and parapet junction of interior and exterior perimeter generated by "thermal bridges" to increase.

According to statistics, the external walls of buildings along the "thermal bridge" to increase heat loss is about 25%, showing "thermal bridges" the increased heat load is quite large. He said "thermal bridges" internal covering concrete steps in trex decking insulation and sandwich, the almost inevitable, and the outer insulation can prevent "thermal bridges" part condensation, but also to eliminate the additional loss of heat "thermal bridge" caused. Calculations show that the thickness of the insulation condition within 370mm brick wall surrounding "thermal bridge" so that the average heat transfer coefficient increased by 10%; a thickness within 240mm brick wall insulation under the conditions of the surrounding "thermal bridge" so that the average heat transfer coefficient heat transfer coefficient than the main part of an increase of about 51% to 59% in thickness within 240mm brick wall insulation conditions, the impact is only 2% to 5%, showing that external insulation practices more effective in reducing indoor heat load.