Does insulation match its label? Lessons from building supervision tests

Material properties are a starting point for design and quotations. If a product fails to achieve its declared performance, careful installation does not remove the material problem itself. Public inspection results therefore also help companies that install insulation rather than manufacture or sell it.

What supervision found

In its summary of 2024 inspections, published in August 2025, GUNB reported that 30% of tested product samples failed to meet declared performance. Negative results accounted for 37% of thermal insulation materials and systems, and 30% of membranes insulating against water or water vapour. These are historical figures for that year, not a current measurement of the entire market. GUNB

This does not mean 37% of every insulation delivery is defective. Inspected samples are not automatically a random, representative sample of all products on sale. Documentation irregularities should not be confused with failure to achieve a parameter in laboratory testing either.

Exact identification matters

GUNB provides a public database of test results, filterable by factors including the year the test was commissioned and product group. GUNB Compare the exact product and sample details, not just the brand on the packaging.

For contractors, this suggests a simple purchasing practice: alongside price and delivery date, retain the product name and designation, photographs of labels and documentation supplied by the vendor. These records help establish what actually reached the site.

Cheaper substitutes need comparison

A proposed substitution should trigger comparison of the properties required for the intended use. Similar appearance, thickness or a general product description does not establish equivalence. Insulation systems also require compatibility between components specified in their documentation.

A short delivery checklist can help:

1. Is this the exact product ordered?
2. Can its markings be linked to the documentation?
3. Are packaging and storage conditions satisfactory?
4. Was any substitute genuinely agreed?

An inspection result is a reason to check facts, not to attribute shortcomings to all of a manufacturer's products. What matters most to the customer is a contractor who can show which material was used and why it met the requirements of the particular job.