How to Read a Chinese Factory’s SGS Test Report for Aluminum Roof Panels

Most buyers receive the SGS certificate, glance at the logo, and file it away. Three numbers on that document determine whether the panels you’re receiving match what was agreed. If you don’t know which three numbers to look at, the certificate is just paper with a logo on it.

Number 1: PIR foam density

Find the line that reads “apparent density” or “bulk density” — test standard GB/T 6343 or ISO 845. The value should be ≥38 kg/m³. The spec we quote is 40–42 kg/m³. Below 38 means corners were cut on foam formulation. Below 35 is structurally marginal for a roofing application and should trigger a rejection conversation.

This number is the most commonly misrepresented spec in the panel business. A factory can write 42 kg/m³ on a product datasheet and deliver panels at 34–36. The SGS test report from the actual production batch is the only document that verifies it. Make sure the report date corresponds to your production run — a report from 18 months ago means nothing for today’s shipment.

Number 2: Thermal conductivity

Test standard GB/T 10294 or ISO 8301. For PIR at correct density, thermal conductivity should be ≤0.024 W/m·K at 10°C mean temperature. If the report shows 0.028–0.030, the foam is either off-spec density or not PIR — it may be lower-grade PUR or a PIR/EPS blend. If the report doesn’t include this value at all, ask for it specifically before accepting the shipment.

Why it matters: the U-value calculation for your entire roof depends on this number. If you specified 75mm PIR at 0.022 W/m·K to meet a building code U-value requirement, substituting foam at 0.030 means your panels don’t meet the specification you agreed to — and your client’s building may not pass energy compliance inspection.

Number 3: Coating dry film thickness

Test standard ASTM D7091 or equivalent. For PVDF per AAMA 2605: total dry film thickness ≥25μm. For SMP: ≥20μm. The report should show both the primer layer and the top coat layer measurements, typically as “primer: 5–8μm / top coat: 18–22μm / total: 25μm minimum”.

A coating report that only gives one aggregate number without layer breakdown is a yellow flag. PVDF test protocols under AAMA 2605 require the individual layer measurements. If the supplier’s SGS report doesn’t break it down, the testing may have been done to a looser standard than AAMA 2605.

What to do if the numbers don’t match

If any of the three numbers is below spec, you have three options before the container is loaded: request re-testing of a second sample from the same production batch (occasionally an outlier), reject the batch and request remanufacture (if time allows), or negotiate a price adjustment that reflects the actual spec delivered.

Once the container is on a ship, your leverage drops significantly. SGS pre-shipment inspection happens at the factory before loading. If your order terms don’t include a pre-shipment inspection clause, add one before the next order. The cost is 0.3–0.5% of order value. The cost of disputing a non-conforming shipment from 8,000km away is considerably higher.

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Related reading: the foam-density corner-cutting an SGS report exposes.