1. Design reasons
Technical specification for steel structure of portal frame light house stipulates that the roof slope of portal frame light house should be 1 / 8 ~ 1 / 20, and in areas with more rain
The larger value should be taken in the region. In the actual
design project, in order to save money or other requirements, the construction unit shall minimize the roof slope
The slope of the project roof is too small, so that the water in the house area cannot be discharged to the gutter in time.
to the lack of node design, the construction unit randomly selects the node method, the parapet height at the ridge is not enough, and the position of the pipeline and exhaust duct extending out of the roof is inappropriate or
The height is not enough to affect the waterproof construction.
Improper plate type selection. For the plate types of concealed buckle and bite, as long as they are properly installed on site, there will generally be no big problem. If they
are directly installed
For the plate type connected with self tapping screws, even if the site treatment is good and the waterproof glue can be made, the performance of thermal expansion and cold contraction will leak due to the damage of the panel
The color plate of the enclosure is too thin and the stiffness does not meet the requirements. After a period of use, the outer plate corrodes or deforms under the influence of temperature, and the gap between the plates increases
of strong wind, the color plate will be lifted off.
2. Construction reasons
Trampling on the roof at will in the construction project destroys the flatness of the roof and even cracks. The gutter anticorrosion of some construction units is
only painted with antirust paint or
After using asphalt paint for a period of time, the gutter is seriously corroded.
Due to the large span of the house panels in the steel structure plant, there is a lapping process of the roof panels in
many cases, although polyurethane sealant is used at the lapping points
However, after a period of time, the plate surface port is cracked due to cold and hot deformation, resulting in rain leakage.
The construction of key nodes is rough.
There are few flashing anchor points at the internal corners of the parapet and other roots, the sealing is not tight, the profiled parts are deformed, and the root of the pipe extending out of the roof
The hole is not blocked tightly, and the flashing
height of the waterproof layer around the pipeline is not enough.
3. Use reason
During use, the external facilities of the main body are arbitrarily set on the roof, resulting in the increase of load and the deformation of roof slab. In particular,
the load is arbitrarily increased on the roof purlin
Strip deformation, resulting in water in the house area. Or the board is damaged by people on the non accessible roof, the waterproof glue and sealant are aging, and there is no regular inspection
in the use project
Repair and maintenance: the roof plate is eroded by sunlight, rain and snow for a long time, and the internal thermal insulation material is weathered, loses its stiffness and deforms.