1. Steel structure roof form
As the top bearing and outer protective structure of the building, the building roof's enclosure and facade modeling function are crucial to the whole building, and it is the important part of the light steel structure enclosure system that is most prone to water leakage. Its main function is to resist the invasion of wind, rain, snow and solar radiation, and to withstand the weight of the roof and the load of the wind, snow and people on the roof.
[1] According to the materials used, the light steel structure roof has a variety of types, such as colored molded steel plate, colored steel plate sandwich plate, colorful linoleum tile, various light roofing panels, GRC panels, metal arch corrugated roofing, composite molded steel plate and so on.
[2]The roof and wall materials of light steel structure are mainly colored molded panels or sandwich panels. The link of the color embossed plate has 3600 rolled edge plate, dark buckle plate lap connection, and also has nail plate. Purlins are thin-walled C-type or Z-type steel purlins with light weight, and the roof slope design is generally 1/10 ~ 1/15.
2. The roof plate connection
There are two kinds of long connection and side connection on the roof of the steel structure system building. The long connection is mainly lap, that is, the uphill plate presses the downhill plate, and the lap is provided with a special waterproof sealant and a special clamping strip, and the lateral connection is mainly divided into the following three types: lap connection, underbuckle connection, and bite underbuckle connection.
3. The causes of water leakage analysis and solutions
The water leakage of the roof maintenance system is mainly distributed as follows:
Ridge
★ Cause of water leakage: the crest of the ridge is too high, and the roof cover can not guarantee waterproof; Longitudinal lap does not put mud or silicone, forming a gap and water leakage; Ridge cover plate longitudinal lap with rivet connection, thermal expansion and contraction strength is not enough to pull the rivet, forming water leakage; No plug is laid between the ridge cover plate and the roof plate, or the plug is not placed in a standard and falls off to form water leakage.
★ Solution: the roof cover plate should be wider, and the slope should be larger; Cement or silicone shall be applied at the joint; Replace the stitching nails; The plug should be matched with the plate type plate, and the plug should be laid with mud or silicone.
Part of the roof gas building
★ Cause of water leakage: no foam plug is placed under the edge of the gas building and the roof at the junction, and the vertical lap of the edge is not laid with mud or silicone; The outer plate of the roof is not mounted at the junction of the gas building; The opening part of the pillar of the gas building structure has not been waterproof treatment; There are hidden water leakage hazards in the production and installation of the gas tower itself.
★ Solution: Foam plug should be laid before the edge installation, and the longitudinal lap must be set with mud or plug and fixed with stitching nails; The roof plate must be pulled up before the installation of the gas building; It is required that the construction party of the gas building must waterproof the opening part after the completion of the gas building structure; Check the installation quality and water resistance of the gas building.
Light plate part
★ Water leakage cause: the plate type and the roof plate type is not consistent, the wave peak on both sides of the plate is higher than the roof plate, after installation, the seal is too tight to form the pressure difference between the inside and outside the plate, and the capillary water enters the roof from the gap on both sides of the plate; The longitudinal bonding length of the light mining plate is not enough, and the adhesive mud loses viscosity after aging. Longitudinal slime off; There is a rigid lap between the light plate and the color steel plate, and the gap in the middle is not sealed.
★ Solution: waterproof screw is applied in the upper part of the wave crest; The edge plate at the light mining plate should be firmly sealed with the light mining plate, the longitudinal sides of the mud should be widened, and the upper part of the wave crest should be laid to prevent capillary water infiltration.
Opening part of the roof
★ Cause of water leakage: the opening hole is not waterproof according to the design node, and the steel plug is not laid with waterproof cement and silicone; The reserved range around the opening hole is small, the rainwater is not flowing smoothly, and it is easy to collect water; The wrap around the opening is not waterproof; No structural parts are added around the inside of the opening hole, forming a low concave water; There is water blocking phenomenon in waterproof construction, resulting in water accumulation.
★ Solution: according to the design drawings construction and strict construction process, laying cement, silicone; The reserved range around the opening must meet the drainage requirements; Wall and roof openings must be followed by waterproof treatment; After increasing the enclosure opening, purlin or Angle steel structure should be added as far as possible to reduce the enclosure deformation; Waterproof construction and installation must be strict and smooth, so that water flow is smooth.
Cornice
★ Cause of water leakage: cornice part is the main source of water leakage problem, the roof outer plate is installed without foam plug, the roof outer plate is not pulled down; The length of the outer panel of the wall is insufficient, and the cornice is not waterproof.
★ Solution: Foam plug should be placed at the same time when the roof outer plate is installed, and the roof outer plate should be pulled down 30 degrees; Eaves should be added in accordance with the design requirements.
Gutter site
★ Cause of water leakage: there is a gap in the welded joint of the inner gutter, resulting in water seepage; Gutter and rain pipe diameter design is too small, and does not match the slope length of the workshop; No head plate is made at the end of the gutter; The length of the roof outer plate extending into the gutter is insufficient, and the water will pour into the inside of the plant.
★ Solution: appropriately increase the depth of the gutter, so that the gutter rain does not exceed the lap joint.
Part of connection between brick wall and light steel roof
★ Water leakage reason: this part is easy to form a hidden water leakage, roof board and cement wall joint water leakage, the main reason is the stress is not synchronized caused by silicone adhesive and bonding surface cracking and water leakage.
★ Solution: prevent temperature deformation, use two edge connection treatment; When connected with the brick wall, the edge should be at a certain Angle and completely sealed; Sealant should be pre-applied between the folding edges.
4. Analysis of other water leakage causes in the maintenance system
Design reason
[1] The roof rainwater system does not set overflow measures according to the specifications, and when the rainstorm intensity exceeds the drainage capacity of the rainwater system, it will exceed the lap joint and even spread on the roof, resulting in accidents;
[2] The number of downspouts is insufficient, and the rain water flows far along the gutter for a long time, resulting in backwater; The upper part of the outer panel of the wall does not add L-shaped edge pieces, resulting in hidden water leakage in the gutter;
[3] Color steel flooding accessories design is unreasonable, can not achieve waterproof effect.
[4] The specification specifies the deformation control value of the component, purlin deflection L/180, roof beam deflection L/180(type L is the span of the bending component), the roof purlin section design is too small, the distance is too large, under the wind load purlin and pressure plate deformation will be too large;
[5] does not fully consider the impact of structural deformation, temperature difference deformation, dry shrinkage deformation, vibration, etc., fortification does not meet the needs of base deformation.
[6] The roof slope of the portal rigid frame light house is suitable for 1/8~1/20, and the larger value is suitable for the areas with more rain, and the roof slope in the southern region should not be less than 5%. In the actual design project, many project roof slope is too small, roof rainwater can not be discharged to the gutter in time.
Improper selection of materials
[1] Plastic pipe for rainwater pipe, poor strength, steel structure plant from installation to operation, easy to damage.
[2] The steel plate used for gutter is relatively thin, and the weld is prone to problems.
[3] Not according to the slope of the roof to choose the appropriate plate type and roof color plate plate type, wave crest is small, side lap too little, is not conducive to drainage.
[4] The enclosure part of the color plate is too thin, after a period of use, the outer plate corrosion or deformation under the influence of temperature, the gap between the plates increases.
[5] The quality of the galvanized layer of the substrate is not good, the coating is too thin, resulting in short service life of the plate, easy to rust and damage;
[6] The quality of self-tapping screw gasket is poor and easy to crack, and the glass sealant is easy to aging.
[7] The gusset plate is obviously deformed, and the height and spacing of the adjacent two plates are different; The fastener nails shall be waterproof.
Structural measure
[1] The plug has a role in the water leakage caused by the seam, and should not be ignored, such as ensuring that the color steel plate and ridge cover plug are installed in place, the lower part of the plug between the light mining plate and ridge cover plate is applied silicone sealant, and the steel plug is set at the peak end of the color steel plate at the opening of the roof;
[2] The gap is easy to be affected by temperature when bonding, and the length of the bonding should be fully left;
[3] The water should be sparse and not blocked, and the sealant on the inside of the steel plate is generally installed, the more the better;
[4] We must pay enough attention to the adverse effects of thermal expansion and cold contraction of the steel structure roof enclosure system, and take reasonable structural measures.
In use
[1] The load on the roof purlin is increased at will, resulting in the deformation of the roof panel.
[2] Rainwater riceps more, there is water obstruction.
[3] Waterproof glue and sealant aging, lack of necessary maintenance during use.
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