Design and Construction of Enclosure System of Light Steel Structure(2)

3.Thermal insulation

Thermal insulation has rock-wool, glass-wool and other materials, thermal insulation has excellent thermal insulation performance, convenient construction, and installation, significant energy-saving effect, low thermal conductivity characteristics. At present, the domestic steel structure workshop roof system mostly adopts :

(1) steel mesh + aluminum foil insulation cotton + single color steel sheet;

(2) double layer color plate + insulation cotton

The following mainly introduces the construction method of steel wire mesh + aluminum foil insulation cotton + roof single-color plate:

Cross pull the stainless steel or galvanized wire into a diamond or rectangular shape and fix it on the purlin with 215 cm self-tapping nails. Lay glass cotton blanket with aluminum foil facing the interior side and perpendicular to the purlin. Keep about 20 cm of blanket on both eaves and fix it on the outermost purlin with double-sided tape. Use reserved 20 cm veneer for glass wool edge. Attention should be paid to the tensioning, alignment, tight seams between coils of glass cotton blanket, and lapping joints should be arranged in purlins when lapping is needed longitudinally. According to the project needs, to avoid the generation of cold bridge, it can be considered to pad the hard insulation material on the purlin.

4.Gutter and Cornice

The structure of eaves can be divided into external drainage gutter eaves, internal drainage gutter eaves and free fall gutter three forms. Free-falling water and outer drainage gutter cornice form can be preferred. According to the material, there are stainless steel gutter, steel gutter, color plate gutter. As the main drainage system of the roof, the gutter determines the rain and snow discharge and the normal use of the building roof.

In cold areas, there is a big temperature difference between indoor and outdoor in winter, so condensation water will appear under the gutter. Therefore, insulation cotton is required to be laid under the gutter. The method shown in Figure 1 can be adopted in construction. The insulation cotton is fixed by hanging the purlin of the gutter. At the same time, add an edge collection at the bottom of the gutter (generally using color steel plate), as shown in the figure of edge collection A, both beautiful and can be fixed insulation cotton.

In the north of the less rain area and the project is not high requirements for the eaves can be used free fall eaves, eaves from the wall to pick out, actually pick out the wall should not be less than 300 mm. If the wall roof color board is steel sheet, the sawtooth interspace between the wallboard and the roof board is blocked by the special plate type water retaining parts. When the slope of the roof is less than 1/10, the edge of the trough of the roof plate should be bent down 5-10 mm with clamps as a drop of water.

External drainage gutter cornice is also widely used in engineering because of its good leakproof and low cost. External drainage cornice gutter more mining plate gutter. Construction of the color plate gutter does not need to support its structural components, the trench wall can be directly close to the outer wall plate, support on the wall, in the roof plate out of the connecting piece picked in the outer wall of the gutter, each section of the gutter lap each other, using pull rivet connection and sealant seal.

5.Covered edge

The edge and flood water not only outline the lines of the building, affect the aesthetic degree of the building, but also connect the building into a whole structure, windproof, rainproof, make the building more durable.

6.Summary and Conclusion

The light steel structure has been widely used in workshops, small exhibition halls, and office buildings because of its characteristics of less steel, short installation and design time and high degree of industrial production. Its envelope system often adopts color steel plate, study and summarize the design and construction experience of color steel plate maintenance system, put forward economic and reasonable node structure and construction scheme has important practical significance.

For the exterior layer plate, the hidden button type color steel plate should be preferred to be processed, can avoid the temperature difference deformation caused by the tapping screw is cut off, and can avoid in rainy areas, typhoon areas exposed tapping screw in temperature deformation, wind load vibration, rubber pad aging caused by plate corrosion and water leakage phenomenon.

The design and construction of the light plate should pay attention to its thermal expansion and cold contraction, and the connection between the light plate and the tapping nail must have a cover plate. At the same time, note the difference between it and the color steel plate. The light plate should be pre-punched (8mm hole is appropriate).

To avoid the formation of cold bridges, it can be considered to pad rigid insulation composite plates on purlins.

It is recommended to adopt free fall cornice in the north of China where there is little rain and the project does not require high cornice. It has good leakproof, low cost and is widely used in engineering.