Close up of Gramitherm Grass Insulation 100mm thick.

Close up of grass fibres used in Gramitherm Grass Insulation.

Gramitherm Sustainable Grass Insulation

Name: Gramitherm Sustainable Grass Insulation - 390mm x 1.2m x 40mm – pack of 6 batts
Brand: Gramitherm
Price: 17.90 GBP
Availability: InStock

Environmental Product Declaration (EPD) Certification

European Organisation for Technical Assessment (EOTA)

Stock code: GT40B MPN: 00026

Gramitherm Sustainable Grass Insulation

Natural insulation made from grass and recycled jute fibres

Product Overview
Technical Details
Downloads
Installation guide

Product Overview

Main Purpose

A sustainable, natural, breathable thermal, and acoustic insulation that protects buildings from cold in the winter and overheating in the summer.

Use it on

Use it on roofs between rafters, in stud walls, suspended floors, and as attic/loft insulation installed between ceiling joists in an attic or loft space.

Overview

Gramitherm Sustainable Grass Insulation is a environmentally friendly insulation, primarily manufactured from naturally abundant grass cuttings sourced from public spaces, such as parks and grass verges, and recycled jute fibres.

The insulation has a bio-based mass of 92%, the remainder being recycled binder fibres, sourced within 300km of the manufacturer, thereby cutting down on transportation carbon emissions.

Gramitherm is suitable for retrofit and new build and provides exceptional thermal insulation all year round. It is ETA and EPD certified to prove its environmental performance, and meets rigorous standards for health and environmental impact.

Where to use it

Gramitherm Sustainable Grass Insulation's versatility means it can be installed between rafters, joists, stud walls, ceilings, and suspended timber floors. It can be used to insulate new-build timber frame buildings, and its breathability makes it ideal for use in older properties too.

What it does

Gramitherm provides effective thermal and acoustic insulation. Its natural properties provide excellent thermal performance, while its high heat storage capacity helps prevent summer overheating.

Additionally, Gramitherm offers valuable soundproofing benefits, absorbing 99% of sounds at 1000 Hertz, which significantly reduces noise transmission within your building.

Why we love it

Gramitherm represents an ecological success story by using renewable grass fibres (70%) and recycled jute fibres (20%). These sustainable materials are combined to form a natural and high performing insulation batt, with a thermal conductivity of 0.041 W/mK

Grass fibres are entirely renewable and naturally abundant, while recycled jute fibres contribute to a carbon-negative resource, absorbing significant amounts of CO₂ during their growth. Gramitherm’s production process is energy-efficient and sustainable, making it an excellent choice for environmentally-conscious designers and homeowners.

The Gramitherm process allows “waste” grass to be fully used as a raw material, without creating any waste. This term is used because the process uses grass biomass which has until now been considered a waste product and not used as animal feed (hay). One hectare of grass can produce 200m³ of insulation material! Early in the manufacturing process, the grass is initially dried using the heat produced from the biogas generated by the grass as it ferments.

As a natural, non-hazardous material, Gramitherm is ideal for DIY and self-build projects, making it one of the most cost-effective natural, flexible insulation options available.

How it works

Gramitherm leverages the natural hygroscopic qualities of grass and jute fibres to help regulate humidity within the building envelope. This prevents moisture from becoming trapped, reducing the risk of mould formation. The combination of these fibres allows Gramitherm to absorb and release a high percentage of water vapour without compromising thermal performance.

Being resistant to fungal contamination, Gramitherm contributes to a healthy, safe, and comfortable living environment for occupants. Its density and flexibility ensure it is easy to work with, remains stable during installation, and resistant to slumping or compacting over time. This stability maintains its thermal performance, ensuring long-lasting insulation effectiveness.

https://www.youtube.com/embed/0qsQKynswIM

Features

Made from grass cuttings from public spaces such as parks and grass verges, and recycled jute fibres.
Exceptional environmental low carbon characteristics
High-performing thermal insulation (low thermal conductivity)
Hygroscopic: absorbs and releases moisture
Low vapour resistance for diffusion open construction
Excellent soundproofing qualities
A+ result from VOC emission testing
Has ETA, EPD, and DOP certification

Benefits

Supports the circular economy as it is manufactured from a renewable product that is naturally abundant
Efficiently maintains indoor temperatures to reduce heating and cooling costs.
Diffusion open and hygroscopic properties help offset mould and condensation risk within building elements in retrofit or new build
Excellent sound absorption properties, creating quieter indoor spaces.
Ensures excellent indoor air quality, achieving A+ results in volatile organic compound (VOC) tests
Verified for environmental performance, demonstrating sustainability throughout its lifecycle.
ISO 9001 quality control compliance

Questions

There are currently no questions and answers published for this product

Technical Details

Choose width and thickness (6 options)

Key Technical Data

1.2 m

40 mm

390 mm

0.041 W/mK

1560 J/kg K

70% (+/-5%) grass fibers, 20% (+/-5%) recycled jute fibers, 10% (+/- 2%) recycled binder fibers

40 Kg/m³

Yes

A+

Thermal bridge prevention, Thermal insulation

2 .

Ceilings, Loft / roof spaces, Roofs, Suspended timber floors, Walls (timber frame)

E (BS EN 13501-1 : 2007)

Installation Guide

How to Install

For a seamless, gap-free installation, cut the Gramitherm Sustainable Grass Insulation batt 10-20mm larger on each side. Use a sharp insulation saw such as Bahco Profcut Insulation Saw for best results. The natural flexibility of the Gramitherm allows it to be squeezed into place, ensuring a snug fit.

By installing Gramitherm slightly oversized, it becomes slightly compressed, which helps it push against the sides of the timber members. This ensures that the insulation stays securely in place without slumping or falling out over time.

Immediately after installation on external walls, ceilings or roofs, it is essential to cover the insulation with a suitable vapour control layer, such as Intello Plus, to maintain its effectiveness and longevity.

Installing Gramitherm grass insulation batts inbetween rafters

Hints and Tips

Packaged batts of Gramitherm Sustainable Grass Insulation

Always ensure that Gramitherm Sustainable Grass Insulation is protected from rain and moisture during transportation, storage, and installation to prevent any potential damage or degradation. Taking these precautions will ensure that the insulation performs optimally and provides long-lasting benefits.

Like all natural insulations, Gramitherm has a unique aroma, which dissipates after 3-4 weeks in a well-ventilated space.