Read the scope before the price
The lowest number is not automatically the best offer. Start with the list of components: main frames, purlins and girts, bracing, roof and wall cladding, fasteners, anchor bolts, gutters and downpipes, doors, windows, ventilation and insulation. Then check what services are included: drawings, foundation design, marking and packing, inspection, export declaration, freight and erection support.
最低数字不等于最优报价。先看构件清单：主框架、檩条与墙梁、支撑、屋面与墙面板、紧固件、地脚螺栓、天沟与落水管、门、窗、通风与保温。再看包含的服务：图纸、基础设计、编号与包装、检验、出口报关、运输与安装支持。
Check the specification behind each line
- Steel grade and the standard the material is supplied to.
- Member sizes or the design basis used to determine them.
- Surface preparation grade and coating system, with dry film thickness or galvanizing thickness.
- Cladding type and thickness, and the insulation material if included.
- Which code the design is checked against, and who confirms the wind, snow and seismic parameters.
钢材等级与供货标准；构件截面或确定截面所依据的设计条件；表面处理等级与防腐体系及干膜或镀锌厚度；围护板型与厚度，以及保温材质（如包含）；设计所依据的规范，以及风、雪、抗震参数由谁确认。
Compare the commercial terms on the same footing
Put the delivery term and the named place next to each offer, for example FOB Tianjin or CIF Matadi. Note the validity period, the payment milestones and the documents required for each payment, the schedule for design confirmation, manufacturing, inspection and shipment, and how deviations found at inspection are handled.
把交付条款与指定地点并列比较，例如 FOB 天津或 CIF 马塔迪。同时记录报价有效期、付款节点与各节点所需单据、设计确认与生产检验发运的进度安排，以及检验发现偏差时的处理方式。
Ask for the exclusions in writing
Every offer leaves something out. Ask the supplier to list the exclusions explicitly: foundation and civil works, site erection labour and equipment, inland transport at destination, customs clearance and duties, permits, and any spare parts. An offer that states its exclusions is easier to compare than one that does not.
任何报价都有不含项。请供应方明确列出：基础与土建、现场安装人工与设备、目的地内陆运输、清关与税费、许可手续以及备品备件。写明不含项的报价比未写明的更容易比较。