Good terracotta product evaluation criteria turn a visual preference into a controlled specification. The decisive questions are not whether a sample looks attractive or whether a supplier uses broad quality language. They are whether the exact product, finish, tolerances, evidence, interfaces, production controls and delivery plan satisfy a defined application.
Reset the 2014 “important factors” advice
LOPO’s March 2014 article advised buyers to consider appearance, quality, durability, stability and installation when selecting panels, bricks or tiles. It also described LOPO as a leading manufacturer and presented its products as economical, environmentally friendly, resistant to water and moisture, visually stable in weather, easy to install and compliant beyond European standards.
Translate every adjective into a decision that can be checked. “Durable” needs an exposure, service condition and maintenance assumption. “Stable” needs a characteristic, tolerance and test or inspection method. “Easy to install” needs a sequence, crew, access plan and demonstrated rate. “Environmentally friendly” needs declared indicators, scope and current product data. If a bidder cannot identify the supporting document and its limitations, record the claim as unverified.
Define the product’s job before comparing offers
Start with location and function. A ventilated facade panel, bonded interior tile, brick slip, sunscreen element and landscape brick have different loads, exposure, interfaces and acceptance needs. Record whether the item sheds water, forms a finish, provides solar control or is simply decorative. Identify the responsible wall system and the parts supplied by others.
Issue drawings with elevations, sections, corners, openings, bases and transitions. State substrate, support zone, joint concept, module, orientation, access constraints, intended service environment and governing project requirements. A supplier cannot select meaningful evidence when the assembly and use remain undefined.
Freeze geometry and measurable acceptance criteria
List nominal length, height, depth, wall thickness, hole or channel geometry, edge condition, joint width, weight limits and fixing interfaces. Then distinguish product tolerance from installed tolerance. Include bow, twist, squareness and surface defects where relevant, with a measurement method, sampling plan and acceptance authority.
Do not approve a dimension because one handmade sample meets it. Ask whether the proposed shape has been produced with the intended clay body, die, drying and firing process. Review the extremes of the size range and adjacent pieces together. Changes to profile, finish or firing can require a new feasibility review.
Approve an appearance range, not one perfect piece
Colour
Define target family, permitted variation, glaze or body colour, and how batches may be blended.
Texture
Record relief, grooves, sheen, edge appearance and viewing distance under agreed light.
Range set
Keep labelled limit samples showing acceptable variation rather than only a central reference.
Mock-up
Combine units, joints, fixings, corners and interfaces at a scale large enough for a design decision.
Write who signs each sample, where it is stored, how long it remains valid and what happens if the recipe, source or process changes. Production inspection should compare material with the approved range under the same viewing protocol.
Match technical evidence to the proposed use
Build an evidence schedule from project risks rather than collecting unrelated certificates. It may address dimensions, strength, attachment, wind, impact, water, freeze-thaw exposure, reaction to fire, thermal movement, chemical resistance or slip, depending on the product and jurisdiction. The project professional must choose current methods, specimen configuration, conditioning, sample size, loads and acceptance limits.
ISO/IEC 17025:2017 sets competence, impartiality and consistent-operation requirements for testing and calibration laboratories. Confirm that accreditation includes the relevant method. Even competent laboratory work applies only to the tested specimen and stated scope; it does not automatically validate a different profile, fixing or complete assembly.
Coordinate wall interfaces and installation
A product can pass tests yet fail as a project choice if the wall is unresolved. Map structure, attachment, movement, air and water control layers, drainage, insulation, fire-stopping, openings and adjacent materials. The WBDG Building Envelope Design Guide explains broad envelope principles, but it does not approve a proprietary detail.
Request installation drawings, sequence, access, tolerances, adjustment range, inspection hold points and replacement method. Trial cleaning and repair on approved samples. Confirm who supplies brackets, anchors, membranes, sealants and special tools, and who accepts interfaces that cross contractual packages.
Verify production, programme and commercial scope
Before award, review a recent comparable production batch rather than relying only on catalogue samples. Ask for traceable inspection records, yield assumptions, current line allocation, packaging trials and logistics constraints. Confirm how an approved sample is transferred into production and how deviations are reported. A factory visit can support this review, but observations should be dated, tied to the correct plant and reconciled with records.
| Decision | Evidence to record |
|---|---|
| Manufacturability | Current trial, approved drawing, tooling revision and agreed tolerances |
| Repeatability | Control plan, batch traceability, inspection frequency and nonconformity route |
| Programme | Tooling, sample, production, inspection, packing and delivery milestones |
| Responsibility | Named legal entity, supplied scope, engineering duties, warranty and exclusions |
| Whole-value decision | Price basis, waste and spares, access, maintenance, replacement and documented risk |
Use the same schedule for every tenderer and mark each item accepted, conditional or missing. Review current terracotta product families and relevant work in the project gallery, then verify applicability rather than treating a reference as proof.