Can I use bio products like hemp and mycelium for soundproofing?

If you’ve searched for information on sustainable home-building products, you’ve probably seen references to industrial hemp or mycelium. Certainly, hemp is touted as a carbon-neutral, non-toxic, sustainable alternative to familiar materials like fiberglass, concrete, or gypsum. But how does it rank in terms of acoustic performance?

Hemp insulation

Example of hemp insulation batts from Evolution in Sweden
This is an example of a hemp fiber insulation batt. Source: EKOLUTION in Sweden.

From available data, hemp wool’s sound-absorbing properties are superior to fiberglass, and it’s comparable to cellulose fiber. Like cellulose, hemp wool needs to be treated with a fire retardant to meet fire safety requirements. It might be more water resistant than fiberglass, but less resistant than rock wool. And while it offers thermal insulation, it’s neither the lowest nor the highest R-value of all the available options.

You can also make hemp fiber  into hempcrete by mixing it with lime. This creates a rigid, slightly porous block that can be used inside of walls or as a non load-bearing wall. It’s not as dense as concrete. And due to its porous nature, it absorbs sound, but it might not stop all frequencies from passing through it. Conversely, due to its reduced density, it won’t transfer as much impact noise as concrete does when it’s used in flooring. By mixing your own hempcrete, you can adjust the porousness or density of the finished material.

 

You can make sound-absorbing panels from hemp and mount them on a wall or ceiling. (Soundproofist)
This ceiling panel was made from a hemp mixture.

Hemp sound panels

I saw slabs of hempcrete mounted as sound panels on the ceiling of a shop, and it dampened the room noise pretty well.

Since it’s less readily available in your local home-improvement store, it’s going to be cost more than some other off-the-shelf materials. However, if you’re researching a DIY or PassivHaus project, hemp is a sustainable material worth considering.

 

 

 

This sample box from Havnens Haender in Denmark includes examples of bio building materials including hempcrete, hemp fiber, grass, and cork.
You can order a sampler box like this one from Havnens Haender in Denmark.

 

This sample box of sustainable building materials from Havnens Haender in Denmark includes hemp fiber, hempcrete, cork, grass, clay, cork, and bio cement.

Mycelium acoustics

Hemp isn’t the only sustainable, natural product with acoustical properties. Enter mycelium. At the Danish Design Museum in Copenhagen, an exhibit on sustainable architecture featured this exhibit, “MYX SAIL.” It’s a curved acoustic ceiling panel made by fusing mycelium with wool. You can hear the

This mycelium-based ceiling panel, designed by Jonas Edvard, was featured in an exhibit at the Danish Design Museum
Sound absorber made from mycelium

effectiveness of the sound dampening just by standing underneath it. This panel was a research project on “how living materials can be part of everyday life in architectural spaces” and it’s designed by Jonas Edvard with ARUP Engineers in Berlin.

Of course, mycelium sound-absorbing products aren’t readily available. And right now, only a few people are skilled in DIY processes for this material. We’ve included a few links that might inspire you to investigate it further or experiment with it on your own.

In conclusion: if you’re planning a home built from sustainable materials, or you want to experiment with these materials as a retrofit to existing construction, both hemp and mycelium are worth investigating. If you just need to address an immediate noise problem between shared walls in an urban environment, you might want to use more readily available, lower-cost commercial materials from your local building supply store.

 

Approximate STC and R-value of insulation materials, compared

Material STC  R-value, per inch
Fiberglass (batt) 36-38 3.1 – 3.4
Fiberglass (blown) 36-38 3.7 – 4.3
Closed cell spray foam 41 6.0 – 6.5
Cellulose fiber 41-44 3.8 – 3.9
Rockwool batts 45-50 3.1 – 3.4
Hemp 44 3.5 – 3.7
Mycelium 18.5 – 37.5 3 – 4

These specs can vary depending on the application, and hemp and mycelium vary depending on how the material was prepared as well as the density and thickness of the mixture.

 

Resources

  • Ekolution hemp wool (Sweden)
  • Insulation4U Example of R13 hemp wool, with pricing
  • Buy Insulation Online – UK Example of hemp insulation batts by IndiNature
  • Havnens Haender – products (Denmark)
  • Wikipedia Hempcrete
  • New Society “The benefits of using hempcrete in your construction projects”
  • Arch20 “5 Projects Using Hempcrete as an Environmental Building Material”
  • Science Direct “Environmental benefits of using hempcrete walls in residential construction: An LCA-based comparative case study in Morocco”
  • HempBuild Magazine “Hempcrete Approved for US Residential Building Codes”
  • Hempitecture – “HEMPCRETE – AN ECO-FRIENDLY BUILDING MATERIAL”
  • YouTube/SmuggleVision “How to Make a Hempcrete Wall”
  • Hemp Tiny House “How to mix and use hempcrete”
  • IndiNature: Natural fiber building materials and insulation in the UK
  • SilentFiber – Sells hemp acoustic panels (Austria)
  • Hempsulation – USA Sells hemp insulation and floor underlayment
  • Mogu – Italy Mycelium acoustic panels
  • NIH “A Study on the Sound Absorption Properties of Mycelium-Based Composites Cultivated on Waste Paper-Based Substrates”
  • ResearchGate “Room Acoustics of Mycelium Textiles – the Myx Sail at the Danish Design Museum”
  • Imagine5. “The designer turning rocks, seaweed and mushrooms into amazing objects” ISUU “Prototyping process for an acoustic panel in mycelium”
  • Olivia Birreteri – “Acoustical Mycelium Panel”
  • Soundproofist – “What’s inside your walls? A primer on the best insulation “
Hemp, mycelium and acoustics
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