Hemp Soundproofing Material Lasts More Than 16 Years

As sustainable construction continues to evolve, one question remains difficult to answer: how well do eco-friendly building materials actually hold up over time? While many natural materials have demonstrated impressive environmental benefits, evidence of their long-term durability has often been limited.

Emerging research¹ is beginning to finally fill that gap. Scientists recently revisited acoustic materials first tested more than 16 years ago to determine whether years of indoor ageing had significantly affected their performance. Among the materials examined was a hemp-based sound-absorbing panel, and the findings suggest industrial hemp may have the durability needed for long-term use in sustainable building products, offering rare long-term evidence that hemp-based soundproofing materials can retain much of their structure and sound-absorbing ability after more than a decade and a half of indoor ageing. Let’s dive into the study and examine exactly how well the hemp-based materials performed.

Why Hemp Is Used for Soundproofing

Industrial hemp has attracted growing attention within the construction industry because it offers a renewable source of strong natural fibers that can be incorporated into a variety of building materials, such as hempcrete and fiber board, and now hemp is also showing promise in acoustic insulation.

Acoustic insulation uses sound-absorbing materials that work by trapping and dissipating sound waves as they pass through a network of interconnected fibers and air pockets. Hemp’s fibrous structure makes it well suited for this purpose while also providing a lower-impact alternative to some conventional construction materials.

However, performance on the day a product is manufactured only tells part of the story. Building materials are expected to remain functional for many years, making long-term durability an important consideration for architects, engineers, builders, and property owners.

What the Study Examined

To better understand long-term performance, researchers evaluated 32 thermobonded fibrous acoustic materials that had originally been developed approximately 16 years and six months earlier. The materials represented several categories, including recycled polymers, recycled textiles, natural fibers, and mixed-fiber formulations. Rather than producing new samples, the researchers re-examined the original materials using the same experimental methods that had been used during the initial testing.

Throughout the ageing period, the materials were stored under uncontrolled indoor conditions and experienced natural fluctuations in temperature, humidity, and exposure to ambient air. Although they were not installed inside functioning buildings, these indoor environmental conditions resemble many of the factors building materials encounter during normal indoor use.

The team measured normal-incidence sound absorption and airflow resistivity using standardized impedance tube testing. They also examined the materials under optical microscopy to evaluate fiber condition, fiber diameter, and porosity after years of ageing.

Hemp Materials Showed Minimal Physical Changes

One of the formulations examined consisted of 50% industrial hemp fiber and 50% polypropylene bonded into an acoustic panel, and after approximately 16.5 years of indoor ageing, the material showed only modest physical changes.

Its thickness decreased slightly from 11.8 millimeters to 11.4 millimeters, while bulk density remained remarkably consistent, changing from 150.6 kilograms per cubic meter to 152.2 kilograms per cubic meter. These relatively small differences suggest the panel retained much of its original physical structure despite more than a decade and a half of natural indoor ageing.

Sound Absorption Remained Largely Intact

The study also evaluated whether the hemp-based material continued to perform its primary job of absorbing sound, and it delivered. Its Noise Reduction Coefficient (NRC), a commonly used measure of sound absorption, decreased slightly from 0.26 to 0.23 over the 16.5-year period. Airflow resistivity, another important property that influences how sound waves travel through fibrous materials, also declined modestly from 53.8 kPa·s/m² to 47.6 kPa·s/m².

While these measurements indicate some reduction in acoustic performance, the changes were relatively limited. Importantly, researchers found no evidence of severe structural degradation that would suggest the material had broken down or lost its overall functionality. Instead, the hemp formulation continued to retain much of its original sound-absorbing capability after years of natural indoor ageing.

Rare Long-Term Evidence for Hemp Fiber

Long-term durability studies of natural building materials are relatively rare because they require researchers to revisit the same materials many years after they were first developed. That makes this investigation particularly valuable. Rather than relying on accelerated ageing tests conducted over weeks or months, the researchers evaluated a hemp-based acoustic material that had naturally aged indoors for more than 16 years using the same testing methods employed during its original assessment.

The results demonstrated that the hemp formulation retained broadly similar physical and acoustic characteristics despite the extended ageing period. While some measurements declined modestly, there was no indication of severe structural degradation, supporting the material’s potential for use in sustainable acoustic panels and other interior building applications.

Hemp’s Role in Construction

The findings do not necessarily demonstrate that hemp outperformed every other fiber evaluated in the study, nor do they prove exactly how the material will perform under every real-world building condition. However, the results still provide meaningful evidence that hemp-based acoustic materials may offer durability alongside sustainability. For architects, manufacturers, and builders seeking lower-impact construction materials, long-term performance is just as important as renewable sourcing. Materials that lose their functionality quickly may require earlier replacement, reducing some of the environmental advantages they initially provide.

This research suggests hemp may be capable of maintaining useful acoustic performance for well over a decade under indoor conditions, contributing to the growing evidence that hemp has a role in construction.

Final Thoughts

Interest in industrial hemp continues to expand beyond traditional applications. Researchers are investigating hemp fibers for lightweight composites, insulation products, construction panels, and other building materials designed to reduce environmental impacts while maintaining performance.

The latest findings add another piece to that growing body of evidence. Rather than positioning hemp as a replacement for every conventional material, the study supports its potential role as a durable component in acoustic panels, interior wall linings, suspended ceilings, and other sound-absorbing building products where long-term indoor performance matters.

As demand for sustainable construction continues to increase, long-term studies like this provide valuable information for manufacturers and designers evaluating natural materials, as it offers encouraging evidence that renewable fibers can remain functional long after installation.

References:

^{1. Jesús Alba, Romina del Rey, Jordi Garcia-Peris, Durability of recycled and natural fibrous acoustic materials undergoing long‑term indoor ageing, Case Studies in Construction Materials, Volume 25, 2026, e06339, ISSN 2214-5095, https://doi.org/10.1016/j.cscm.2026.e06339}