Why Loose Specifications Cost Money
A vague gabion specification invites every bidder to quote a different, often weaker, product, making bids impossible to compare and leaving the door open to substitution. Phrases like supply gabions, 1 x 1 x 1 m tell a supplier almost nothing about wire diameter, mesh type, coating or standard, the very things that determine whether the structure lasts five years or fifty. The lowest price will usually come from the thinnest wire and lightest zinc, which is the worst long-term value. A precise specification levels the field: every bidder prices the same engineered product, the evaluation is genuinely like-for-like, and the delivered goods can be verified against the words on the page. The effort of writing it well is repaid many times over. As a manufacturer that quotes against tenders daily, Zhongman sees the difference clearly, and this checklist reflects what a strong gabion specification contains.
Dimensions, Mesh and Wire
Start with the geometry: basket length, width and height, the number and spacing of internal diaphragms (typically every one metre to control bulging), and whether you need box gabions, sack gabions or thinner revet mattresses for erosion protection. Then define the mesh: double-twisted hexagonal weave with the mesh type stated, such as 8 x 10 or 6 x 8, since this controls aperture and stone retention. Specify three wire diameters separately, the mesh wire, the heavier selvedge wire reinforcing the edges, and the lacing wire for assembly, because conflating them is a common loophole. Insist on double-twist construction explicitly, as it is the non-ravelling property that distinguishes a structural gabion from a fence basket. Zhongman manufactures all standard and custom basket sizes, mesh types and wire diameters, so a fully detailed specification can be met exactly rather than approximated.
Coating, Standards and Certification
Coating is the heart of durability and the most frequently undercut clause, so it must be explicit. Name the coating type, hot-dip zinc, Galfan zinc-aluminium for aggressive or coastal sites, or PVC over metal for severe abrasion, and state the minimum coating mass in grams per square metre for the specified wire diameter. Tie the whole specification to a standard, ASTM A975 or EN 10223-3, which fix the tolerances, tensile strength and coating tables, and require mill and coating test certificates against that standard with delivery. Adding a clause that allows the engineer to test samples on receipt deters corner-cutting. Without these requirements, compliance is unverifiable. Zhongman supplies gabions to ASTM A975 and EN 10223-3 with certified zinc, Galfan and PVC coatings and full documentation, so an inspecting engineer can confirm every clause rather than trust a label.
Fill, Assembly and Workmanship
A good specification reaches beyond the basket to how it is built. State the stone fill requirement: hard, durable, angular rock, sized larger than the mesh aperture, commonly 100 to 200 mm, and well packed to minimise voids and bulging, with facing stones placed by hand for appearance where the gabion is visible. Define the assembly method, lacing wire stitched continuously or approved spiral binders and stiffeners at the required spacing, since poor stitching is where field-built gabions fail. If a geotextile filter is needed behind the baskets to stop fines migration, specify it here as part of the system. Calling out workmanship and tolerances on alignment and packing turns a pile of baskets into an engineered wall. Zhongman provides assembly and lacing instructions with every consignment and can supply matched accessories and geotextile filters as part of the package.
Packing, Delivery and Evaluating Bids
For imported gabions, packing belongs in the specification because damaged goods erase any saving. Require flat-packed, folded baskets bundled and strapped for dense container loading, clearly labelled to match the bill of quantities, with lacing wire and instructions included and certificates travelling with the shipment. When evaluating bids, score on compliance first and price second: confirm each offer states the wire diameters, coating mass and standard you asked for, and treat any silence as non-compliance rather than a discount. Request a sample basket and certificates from the shortlisted bidder before award. Zhongman exports certified gabions worldwide, palletised and documented for safe transit, and is happy to provide samples, coating test reports and a fully itemised, standard-referenced quotation that your evaluation team can compare line by line. Send us your tender drawings and we will respond with a compliant, costed bid.