Putting IndiTherm To The Test

An improved standard of fire classification for IndiTherm as part of a build-up, a hemp insulation from IndiNature.

What’s new – IndiTherm’s improved fire rating as part of a build-up?

IndiNature is always seeking to improve its products, whether through increased production efficiency, enhanced safety, or robust testing. They are always on the lookout for ways to improve the UK natural insulation market and will consider their own products first.

Through independent testing, IndiNature now has certification for IndiTherm when installed as part of a build-up. A ‘build-up’ is when a combination of materials is used to represent a real-world installation of insulation within a building.                                                                                                                                                                                                                                                                                                                              
What is the fire testing procedure?

IndiNature sought independent testing to ensure its products meet the highest standards. Here is what IndiNature had to say:

“Following recent independent fire testing, IndiTherm has achieved a Euroclass B-s1, d0 reaction to fire classification when used within a tested timber frame build-up with a plasterboard lining in accordance with EN 13823 (Single Burning Item).

What does that mean?

• Limited contribution to fire (B)
• Lowest smoke production (s1)
• No flaming droplets (d0)

Testing was carried out using the Single Burning Item (SBI) method by Warringtonfire, one of Europe’s leading independent fire testing organisations. 

This result reflects how IndiTherm performs in practice as part of a build-up - this is important because fire performance depends on how materials work together.”

What gets tested as part of the build-up?

The classification relies on a robust build-up that mirrors typical construction. It features a plasterboard lining with sealed joints, a vapour control layer, IndiTherm insulation placed between timber studs, and an OSB substrate. This is crucial because fire performance depends on the interaction of materials. The results show how IndiTherm performs in real-world applications within a complete wall assembly.

For Safety in real buildings

In real-world applications, IndiTherm is always integrated into a broader construction system, and the fire classification accounts for this. To achieve the specified performance, the insulation must be fully enclosed by a fire-resistant lining board made in accordance with BS EN 520, have completely sealed joints, and be supported by appropriate timber studs or battens.

These are standard timber frame construction details and are part of the tested assembly. When installed correctly, the system ensures predictable fire response, low smoke emission, and performance that aligns with modern building standards.

In-house testing

In addition to independent third-party testing, IndiNature regularly conduct in-house fire tests as part of their ongoing product development and quality assurance, following EN ISO 11925-2.

These tests help understand flame spread and fire-retardant properties and ensure consistency across different production batches. They enable continuous product improvement while maintaining confidence in its performance. However, independent accredited testing remains the foundation for official fire classification.

A milestone for natural fibre insulation

Achieving Euroclass B-s1, d0 in a tested wall system marks a major milestone, not only for IndiTherm but also for the broader use of bio-based materials in construction. It shows that natural fibre insulation can be part of high-performing building systems, providing excellent fire safety while offering the environmental benefits that designers increasingly seek.

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Who are IndiNature?

As you may have seen on our website, we are big supporters of IndiNature. Who are they, and where did they come from?

IndiNature, based in Jedburgh, on the Scottish Borders, was co-founded in 2016 by Scott Simpson whilst studying sustainable architecture. Scott conducted lab-based research on natural insulations and their performance compared with conventional insulations. As part of his case study, Scott renovated his own home, installing the best natural materials he could find.

Upon completing the renovations, Scott found that his bills were a quarter of the average UK heating bill, whilst making his home more comfortable with even temperatures and humidity, allowing the building to breathe and regulate itself.

Scott found it difficult and expensive to source the natural materials for his study, so he founded IndiNature to offer natural, high-quality materials for insulating your home, and it grew to an industrial scale whilst keeping their goal of helping our planet, through their products being carbon negative – a monumental achievement in natural fibre insulations.

Why do we love IndiTherm?

Using raw materials sourced from UK-grown hemp, IndiTherm’s carbon-neutral insulation offers excellent sound and thermal insulation properties, whilst maintaining a positive impact on our environment.

That’s exactly the type of products we, and the planet, need.

Another great aspect of IndiNature products is being Circular by Design. IndiTherm can be reused at the end of its life or safely disassembled for use in other applications, thereby reducing the product's impact.

Growth

We love to see the growth that IndiNature is experiencing, delivering excellent-quality products whilst being at the forefront of innovation in the natural fibre insulation market through continuous testing and evaluation. Keeping standards high, with healthy, safe insulation at the top of the list, the effort and drive of the IndiNature team is clear to see, truly putting hemp insulation on the map.