I. Gutter survey of roof maintenance system
Gutter is an essential component of roof drainage system. Gutter is mainly used to collect rainwater temporarily and drain it in time through downpipe. Try to use external gutter, small size, and can also be used as cornice trimming. The color is suitable, the installation of exquisite gutters and finishes will undoubtedly add a lot of color to the decoration effect of the whole project.
II. Common problems in fabrication and installation of steel structure gutter
（1） Advantages and material selection of color steel gutter
In large-scale steel structure workshop, the amount of steel used in the color steel plate gutter is also a large part, but the color steel plate gutter also has its own advantages, and the wind load in the coastal area is generally large. If the color plate gutter is used, under the strong wind load, the color plate gutter is fragile and weak, and easy to be lifted off by the wind suction. The design of color plate gutter also has a great impact on its durability, so the design and material selection of color plate gutter cannot be ignored.
The most commonly used gutter materials are 1.2mm, 2mm or 2.5mm thick stainless steel; 3mm or 5mm thick galvanized color steel plate; it should be considered comprehensively according to the importance, cost and grade of other materials used. Generally, the gutter depth of civil buildings shall not be less than 250mm, which shall be reasonably determined according to the clearance between the roof slab bottom and roof truss top, and the space required for gutter slope adjustment shall be considered. When determining the width, two factors should be considered: first, whether the drainage can pass through should be calculated; second, the commonly used gutter board width is 1.0m, 1.2m and 1.5m, and the board should be used reasonably as far as possible, and the gutter must be designed as scalable for buildings with high requirements.
（2） Treatment of water leakage at the joint of color steel gutter
The gutter plate can be lapped for 100 mm, and the laps are connected by rivets. If you want to ensure that the gutter is watertight, you should use waterproof glue. The specific method is to lap the gutter of the color steel plate, apply two layers of neutral silica gel (acid glue and alkaline glue are not allowed, and the compatibility and durability of the color steel plate are problematic). The sealing position is respectively 10 mm from the edge of the two overlapping plates, and fix the overlapping position with two waterproof rivets. The center distance of each waterproof rivet is 80mm, two of which are staggered, and the rivet shall be punched on the sealing line. Pay attention to that the rivet should be waterproof, and it should not be a through rivet in the middle. After such careful construction, water leakage may be caused by incomplete silica gel, rust penetration of rivets, rust penetration of color steel plate at rivets, and silica gel failure. The main reason for the failure of silica gel is the fracture of polymer chain caused by ultraviolet irradiation. The life of good silica gel between color steel plates should be very long.
（3） Sagging treatment of steel gutter in steel structure workshop
In the construction of steel gutter, it is sometimes found that the gutter will deflect because of the large column spacing and the small gutter thickness. The solutions are:
1. Set a long tie beam under the gutter to support the gutter, so as to ensure that it will not sag, or make a support below. It is better to weld the gutter with a larger slope in the middle. When installing, try to avoid walking in the gutter to avoid downward deflection.
2. With the combination of welding gutter, the problem can be solved completely if the middle part of the gutter is arched to both ends with a certain slope, but the processing cost of the gutter will increase if it is not curved.
（4） Gutters and downpipes
The size of the steel gutter does not have much to do with the area of the roof. The height of the steel gutter is consistent with the height of the purlin. The main one is the number of rainwater pipes. Generally, the ponding area of rainwater pipe shall be no more than 180m2 according to the ponding area of rainwater pipe with diameter of 110mm. The rest are calculated on this basis. In this way, the water in the ditch will not overflow. If the exact value is needed, it must be calculated according to the formula.