1.What influence do environmental factors have on the selection of galvanized sheet for building roofs?
Climate conditions: In humid and rainy areas, corrosion resistance should be considered; in high-temperature and strong ultraviolet areas, heat resistance and coating stability should be considered; in extremely cold areas, sheet toughness at low temperatures should be considered.
Corrosive environment: Industrial areas (containing sulfur dioxide and dust) and coastal areas (high salt fog) are highly corrosive environments, and high zinc layers or coatings with stronger weather resistance should be selected; conventional zinc layers can be selected in ordinary cities or rural areas.
2.What is the impact of construction demand on the selection of galvanized sheet for building roofs?
Roof function: whether it is a roof for people to walk on (need to consider load bearing, thicker plates can be selected), whether there is photovoltaic power generation (need to adapt to photovoltaic bracket installation, plate strength must meet the standard).
Design life: temporary buildings (5-10 years) can choose low zinc layer; permanent buildings (more than 20 years) require high zinc layer or alloy coating.
Aesthetic requirements: need to consider coating gloss, surface treatment (such as non-patterned galvanized sheet is more beautiful) or subsequent coating compatibility.
3.What is the impact of surface treatment and coating on roof panel selection?
Galvanized sheet without flower pattern: The surface is smoother without flower pattern, suitable for subsequent painting or direct exposure (good aesthetics). Galvanized sheet with flower pattern: The surface has zinc flower crystals, which is low in cost and suitable for scenes with low aesthetic requirements (such as warehouses). Anti-fingerprint treatment: The surface is coated with anti-fingerprint film to reduce fingerprint residue and facilitate cleaning (suitable for roofs with people or frequent maintenance areas).
4.How to choose models for special scenarios?
Coastal high salt fog areas
Preferably choose zinc-aluminum alloy coating (such as 55% aluminum-zinc alloy), which has 3-5 times the salt spray resistance of ordinary galvanized sheet; or adopt "galvanizing + fluorocarbon coating" composite solution (coating thickness ≥ 40μm).
The roof needs lightning protection. Choose hot-dip galvanized sheet with good conductivity (zinc is a good conductor) to avoid the influence of coating insulation on lightning protection effect (for example, some coated sheets need to reserve conductive connection points).
Low temperature and snowy areas
The substrate must contain nickel (≥0.3%) or use low-carbon steel with good low-temperature toughness (such as Q235B) to avoid low-temperature brittle fracture; at the same time, the plate thickness must be ≥0.6mm to enhance the load-bearing capacity against snow accumulation.
5.What are the considerations for selection?
Quality certification: give priority to manufacturers that have passed ISO 9001 quality system certification and provide zinc layer test reports, and avoid using recycled material substrates (impurities are prone to cause the coating to fall off).
Installation adaptability: consider the processing performance of the board (such as whether it is easy to crack when bending or shearing). The edge-locking roof must ensure that there are no burrs on the edge of the board to avoid scratching the sealant during installation.
Cost balance: The initial cost of high zinc layer or alloy coating is higher, but the long-term maintenance cost is low (reducing the frequency of replacement), which needs to be combined with the full life cycle cost calculation (for example, within a 20-year cycle, the comprehensive cost of high zinc layer may be lower).