Galvanized steel roofing - comprehensive analysis of galvanized steel roofing

Galvanized steel roofing by forming a zinc-iron alloy layer on the surface of the steel plate (hot dip galvanized) or electric galvanized layer, using the principle of zinc sacrifice corrosion protection, priority oxidation to protect the internal steel.

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1. Material characteristics and classification

Protection mechanism of galvanizing layer

Galvanized steel roofing by forming a zinc-iron alloy layer on the surface of the steel plate (hot dip galvanized) or electric galvanized layer, using the principle of zinc sacrifice corrosion protection, priority oxidation to protect the internal steel. Zinc reacts with air to form a dense zinc hydroxide carbonate film, which can self-repair minor scratches and significantly extend service life (salt spray resistance test ≥500 hours). This protection mechanism ensures that galvanized steel roofing can maintain its performance and appearance in harsh environments for a long time.

Common categories:

Hot Dip Galvanizing (SGCC)

Coating thickness: ≥180g/m²

Corrosion resistance: strong

Application scenario: Suitable for outdoor buildings, such as industrial plants, public facilities, etc., because of its excellent corrosion resistance and long service life.

Electrogalvanizing (SECC)

Coating uniformity: thin and uniform

Application scenario: It is mainly used in precision machining scenarios, such as electronic equipment shells, furniture, etc., because of its smooth and beautiful surface.

Aluminized Zinc (SGLD)

Added elements: Aluminum, magnesium

Heat resistance: Better

Application scenario: Suitable for high temperature environments, such as tropical areas or building structures requiring high temperature resistance.

Core performance advantage

Weather resistance: can withstand 200km/h wind speed and extreme rainfall, especially suitable for typhoon-prone areas, to ensure the safety and stability of buildings.

Light and high strength: thickness range 0.12-0.8mm, light weight (about 2kg/m²), span up to 36 meters, easy to transport and install, while reducing the load of the building.

Environmental protection and energy saving: High surface reflectivity reduces the heat absorption inside the building and reduces the energy consumption of air conditioning, which helps to achieve the goal of green building.

Second, construction technology and node treatment

Key points of construction process

Pretreatment: After cutting, it is necessary to polish the cutting edge, spray anti-rust agent (such as neutral CA-Q01) or passivation treatment to avoid corrosion of bare steel and ensure the long-term performance of the material.

Fixed installation: self-tapping nails or bolts are used to connect, and the joints are sealed with sealant (such as silicone rubber) to ensure water resistance and prevent water penetration leading to corrosion.

Special structure:

Lighting design: Partial replacement of light mining panels, plasma cutting holes and strengthening the structure to meet the needs of indoor lighting.

Hood: To install type 500 ventilator, it is necessary to bury reinforcement parts to resist extreme weather and ensure the ventilation effect of the roof.

Quality acceptance standard

Surface zinc flowers: uniform (ordinary/small zinc flowers), no falling off, bubbles.

Thickness deviation: ≤±0.02mm to ensure the consistency and stability of the material.

Width deviation: ≤±2mm, to meet the requirements of construction accuracy.

Joint tightness: need to be verified by water test to ensure waterproof effect.

3. Application scenarios and cases

Architectural field

Industrial plant: Using corrugated galvanized sheet (such as YJ4519 type unit rolling), with polyurethane insulation layer, taking into account lightweight and heat insulation, improve energy efficiency.

Public facilities: For example, the Copenhagen "Silo" apartment, which uses the self-oxidizing properties of galvanized steel to form a gradient grey facade, elevates the industrial aesthetic and displays a modern architectural style.

Civil and innovative design

Rural residential: double-slope roof with color steel tile, the cost is as low as 53.7 yuan/sheet (1mm thick), but pay attention to the free drainage of the wall splash problem, to ensure living comfort.

Artistic transformation: For example, Beijing Mumu Art Community, through 0.3mm galvanized plate artificial folding treatment, to create a unique texture skin, combining art and practicality.

Iv. Maintenance and renovation program

Routine maintenance

Regularly clean the fallen leaves, check the aging of the sealant, avoid the blockage of the drainage hole, and keep the roof clean and functional.

Slight surface rust can be temporarily treated with WD-40 anti-rust oil to delay the corrosion process.

Renovation technique

Passivated galvanized sheet renovation: It is necessary to spray two-component connection paint (solvent-based) or water-based single-component primer, enhance the adhesion of the coating, and then cover the acrylic top paint, the life can be extended to more than 3 years, restore the aesthetic and protective function of the roof.

Coating upgrade: The use of aluminum coated zinc or zinc aluminum magnesium alloy plate, reduce the need for cutting edge protection, improve the overall corrosion resistance and durability.

V. Cost and market reference

Price range: hot-dip galvanized coil about 4240 yuan/ton (Hangzhou market), a sheet of 1.48 square meters (1mm thick) cost about 53.7 yuan, providing an economical material choice.

Custom processing: additional cost, about 10-15% increase in price, personalized customization according to customer needs, to meet the requirements of different projects.