Bio-Based Building Materials: A Guide to 12 Documented Options

What "bio-based" means in this guide

In this guide, bio-based means materials whose main raw material is plant or animal biomass, as our profiles describe them: tree bark, grass, hemp and flax fibre, straw, wood fibre, sheep wool, recovered paper, linseed oil and the mycelium composites grown on agricultural residues. This is our editorial scope, not a standard, a certification or a performance claim.

Many of these products also contain other components, and the profiles name them: a PET binder in some sheep wool products, polyurethane resin in one wood fibre board, phenolic resins in bamboo, lime in hempcrete, and limestone in linoleum.^{[9][7][3][4][12]} Straw bale is in the first table and discussed again under structure.

Bio-based materials at a glance

The tables repeat what each profile states, with its units, standards and test conditions; each row links to the profile that lists the primary sources. Nothing is converted or averaged, and "not stated" means the profile has no value. The columns are not like-for-like, so a lower figure in one row is not a verdict on the product.

(a) Insulation materials

Fire classes are Euroclasses under EN 13501-1 unless the cell says otherwise, and thermal values may be declared, design or test values.

(b) Surfaces, finishes and other uses

Table (b) mixes products with different jobs, and several values are design values or research ranges. Carbon figures are left out of both tables because declared units differ: not comparable; they are listed with their units under declared carbon below.

How to choose between bio-based materials

This section sets out the conditions and trade-offs each profile states for an application, then the constraints that cut across them. It ranks nothing.

By application

Insulating a wall or roof. Between rafters, joists and studs, the profiles describe wood fibre batts, sheep wool mats and rolls, flax mats and hemp-fibre batts; the Flachshaus flax approval (valid until 2014, per the flax profile) lists timber-frame cavities without compression loads and protected from precipitation.^{[7][9][11][4]} For continuous insulation over rafters or behind rear-ventilated cladding, the wood fibre profile describes rigid boards (the 40 mm Pavatherm-Combi is not approved for roofs); the cork profile lists Amorim's expanded cork board for roofs, walls, floors, partitions and ceilings, with Euroclass E the point to check first for facades.^[7][1] For lofts and closed cavities the profiles cover loose fill: cellulose (30–50 kg/m³ in horizontal layers and 45–60 kg/m³ in wall cavities in the Climacell ETA, with settlement to allow for), wood fibre, sheep wool (NITA-WOOL's ETA covers closed cavities in horizontal or pitched roofs up to 10° and accessible top-storey ceilings without foot traffic) and flax (an ETA for floor fill and one attic study of flax shives), where the profile calls the evidence narrower and gives no λ or settlement value.^{[10][7][9][11]}

Flooring. Cork floors are sold as floating planks and glue-down tiles; the cork profile says, as general guidance rather than a cited test, that natural cork should not go in showers without proper sealing, so check the manufacturer's wet-area rating.^[1] Linoleum is a sheet or tile with EN ISO 24011 as its product standard, declared in reaction-to-fire classes from Cfl-s1 to Bfl-s1 depending on product; its profile names alkaline cleaners as a main limit.^[12] Bamboo flooring hardness is reported in different units (Brinell, N/mm², Janka) that cannot be compared across products.^[3] See also our articles on cork flooring and Forbo Marmoleum.^[13][15]

Wall and ceiling finishes. Cork wall tiles are glued-on interior wallcoverings: Granorte recommends a water-based contact adhesive on a dry, levelled wall, and its guarantee excludes wet or permanently damp areas.^[2] Mycelium panels suit a dry, indoor, non-structural brief; the profile advises assuming dry interior conditions unless a manufacturer documents otherwise.^[5] Bamboo boards and plywood are listed for walls, ceilings, furniture and joinery.^[3]

Acoustic and interior surfaces. Three profiles give declared acoustic data. Cork wall tiles declare αw 0.05 to 0.25 (EN ISO 354); the profile says to ask for the figure for the exact product and mounting.^[2] Mogu's mycelium panels, the most mature mycelium building product in its profile, are positioned for interior walls and ceilings, with a declared αw of 0.30–0.35 mounted directly and 0.45–0.50 with an insulation layer behind (ISO 354).^[5] The sheep wool profile reports a weighted sound absorption of 1.00 at 100 mm for Thermafleece.^[9] For linen upholstery, the profile says Martindale abrasion and ignition tests of the whole cover-and-filling combination decide a specification, and it found no linen-specific data for either.^[6]

Structure and walls from bio-based infill. Hempcrete is non-loadbearing infill, most often in a timber frame, and, per BRE, should not be used below ground level.^[4] Straw bale is used as site-built infill, as factory panels 26 to 43 cm deep (so the wall takes more floor area than a thin insulated wall) and, in the US model code, as plastered load-bearing walls in one-storey buildings.^[8] Bamboo's structural product in its profile is the N-finity laminated beam, covered by German approval Z-9.1-895 for service classes 1 and 2 only.^[3] Mass timber is outside this guide.

By constraint

• Fire class. Five of the seven insulation profiles we have published state Euroclass E for the basic product, and the profiles tie higher classes to particular products, finishes or conditions (see below).^{[1][7][4][8][10]}
• Moisture. Most stated vapour resistance factors for the insulations are low (μ 1 to 4), with two exceptions printed in single documents (cork board MU20, flax 5.7; see below), while the profiles flag wetting as a limit for straw bale, hempcrete, mycelium and the cork wall tile guarantee (see below).^{[7][10][4][9][8][5][2]}
• Embodied carbon declarations. EPDs exist, per the profiles, for cork insulation board, bamboo products, hempcrete blocks, wood fibre, straw bale, sheep wool, cellulose and linoleum; the hemp-fibre EPD has passed its printed validity date and the cork profile notes two different expiry dates, so confirm on the registry.^{[1][3][4][7][8][9][10][12]} The profiles found no EPD for mycelium, flax insulation or a cork wall tile (one moulded panel only), and linen has fibre-level figures only.^{[5][11][2][6]}
• Durability and maintenance. In our reading, durability evidence is uneven. Heat-treated, densified bamboo boards report durability class 1 (EN 350); cork can lighten under sustained UV and show impact marks (general guidance, not a cited test); linoleum is limited by alkaline cleaners; a 2025 review cited in the mycelium profile lists a lifespan of under 50 years among open challenges; and Straube, cited in the straw bale profile, says bale walls stay durable only if they can dry.^{[3][1][12][5][8]}
• Availability. The flax insulation profile calls the market thin. In the mycelium profile, acoustic panels and packaging are on sale while insulation, furniture and leather are mostly pilots or stalled ventures. The three bamboo EPDs reviewed cover production in China, and transport to a European site adds 0.98 kg CO₂e per kg in Dasso's EPD, against 2.40 for fossil A1–A3.^[11][5][3]

What cuts across the twelve profiles

Fire

Reaction to fire (a Euroclass) and fire resistance are different tests, as the hemp profile puts it.^[4] Euroclass E is stated for cork insulation board, wood fibre (loose fill carries added fire retardant), hemp-fibre batts, straw bales on their own and cellulose in the basic case.^{[1][7][4][8][10]} Higher classes come with conditions: cellulose B-s2, d0 where the ETA's end-use conditions are met; sheep wool B-s3,d0 for borate-treated loose fill; flax C on the Isovlas brochure; and mycelium B-s2-d0 only with the finish its datasheet labels "Fire-Proof". Separately, as fire resistance rather than reaction to fire, a German test certificate classifies a plastered straw bale timber-stud wall as F30-B (DIN 4102-2).^{[10][9][11][5][8]} Upholstery is tested as a cover-and-filling combination under EN 1021-1, and floor coverings carry the flooring classes of EN 13501-1 (Cfl-s1 to Bfl-s1 for linoleum).^[6][12]

Moisture

Stated vapour resistance is low: μ 1–3 for wood fibre, 1–3 for cellulose, 1–2 for hemp fibre, 1 to 4 for NITA-WOOL sheep wool loose fill, μ = 2 in the German straw bale approval and μ 2.8 for an IsoHemp hempcrete block.^{[7][10][4][9][8]} Two profiles flag documents that disagree: cork board MU20 in the datasheet but MU1 on the ACERMI certificate, and flax μ below 2.2 for JUTA but 5.7 in the Isovlas brochure.^[1][11] Several materials take up moisture: Thermafleece lists 7.21 % moisture content by mass at 50 % RH and 14.84 % at 95 % RH, and the mycelium profile reports water absorption from 6% to 436% in research composites, depending on fungus and substrate.^[9][5] For straw bale, the German approval limits moisture uptake to 18 % by mass at 23 °C and 80 % RH, and the codes read cap bale moisture at 18 to 20 % at installation or first plaster coat.^[8]

Declared carbon

Where a profile reports a negative A1–A3 total, it attributes the figure to stored biogenic carbon; for hempcrete blocks the A1–A3 total also takes credit for lime carbonation during curing and for the biogenic carbon in the wooden pallets. The figures below show the fossil and biogenic parts alongside wherever the profile states them, never netted. The wood fibre, straw bale, cellulose, sheep wool and linoleum profiles report that the EPDs model the carbon returning at end of life; the cork profile says its negative figure covers A1–A3 only.^{[7][8][10][9][12][1]} Declared units differ: not comparable. They are grouped by unit only to show what each states.

Per m³

• Cork expanded insulation board (115 kg): GWP-total −2,040 kg CO₂e; GWP-fossil 82.8 kg CO₂e.^[1]
• Wood fibre: STEICOtop board (140 kg/m³) GWP-total −138 kg CO₂e/m³, fossil +105, biogenic −244.^[7]
• Straw bale: loose Baustroh bales at 100 kg/m³, fossil GWP 18.5 kg CO₂e, biogenic GWP −148, total −129.^[8]
• Sheep wool: Isolena at 23.26 kg/m³, 16.9 kg CO₂e fossil, −36.4 biogenic, −19.3 total.^[9]
• Bamboo: Smith & Fong plywood 250 kg CO₂e/m³ in its 2023 EPD.^[3]

Per m² (different things per square metre)

• Hempcrete blocks: −17.38 kg CO₂e per m² of 36 cm wall in A1–A3, including credits of 13.91 kg CO₂ for lime carbonation and 11.54 for pallet biogenic carbon; cradle-to-grave +64.42. Hemp-fibre batts: −3.70 per m² at 100 mm (GWP-fossil +4.15), EPD validity passed.^[4]
• Bamboo: MOSO X-treme cladding GWP-total −5.50 kg CO₂e/m² (19.9 kg) in A1–A3, of which fossil +23.8 and biogenic −29.4, but +17.9 across all declared modules.^[3]
• Straw bale: EcoCocon average wall panel, fossil 17.4, biogenic −119, total −101.^[8]
• Sheep wool: Thermafleece CosyWool roll at R = 1 m²K/W, 0.90 kg CO₂e fossil, −0.86 biogenic, 0.05 total.^[9]
• Linoleum: Forbo Marmoleum sheet 2.5 mm per m² of installed floor, A1–A3 only: fossil GWP 2.83 kg CO₂e, biogenic −4.40, total −1.57 (Forbo's 2025 passport lists −0.67 for the same thickness under a different EPD reference).^[12]

Per kg

• Cellulose: Isocell EPD −1.42 kg CO₂e total (fossil +0.13, biogenic −1.55); ECIA EPD −1.28 total (fossil +0.16, biogenic −1.43), both the cellulose profile's arithmetic from the EPD module values; biogenic carbon returns in C3.^[10]
• Bamboo: Dasso boards +0.77 kg CO₂e/kg in A1–A3 (fossil +2.40, biogenic −1.64); Smith & Fong plywood 0.368 kg CO₂e/kg in its 2024 EPD.^[3]

The profiles found no product declaration for mycelium (a peer-reviewed lab-scale LCA gives 0.3668 kg CO₂e per kg of hemp-based composite, cradle to gate, not a product declaration), flax insulation (fibre only: 0.854 kg CO₂e per kg of rescutched short fibre) or linen fabric (fibre-level figures only).^[5][11][6]

Emissions and binders

Binders and treatments are where bio-based products meet other chemistry: phenol formaldehyde or phenolic resins (about 10–13%) in bamboo; a PET bi-component binder in Thermafleece sheep wool, while Isolena mats are needled with no adhesive, per its EPD; polyurethane resin in STEICO's dry-process sheathing board; boric acid above 0.1 % of mass in cellulose, listed as a substance of very high concern; borate, soda or salts in flax; and naturally occurring volatile compounds in cork, so "VOC-free" is not accurate.^{[3][9][7][10][11][1]} In the profiles, emission evidence is uneven: Forbo declares TVOC below 0.05 mg/m³ after 28 days (EN 16516) for linoleum; Mogu's mycelium result is manufacturer-reported and its Indoor Air Comfort Gold label was not found on Eurofins' public list; and the profiles found no sourced emission test for hemp products, straw bale walls or linen fabrics.^{[12][5][4][8][6]}

The 12 profiles

• Cork: The bark of the cork oak, harvested about every nine years without felling the tree, used for flooring, wall tiles, insulation board and objects.^[1]
• Cork wall tiles: Glued-on interior wallcoverings of veneered or solid agglomerated cork, from 3 mm tiles to 30 mm 3D tiles.^[2]
• Bamboo: A fast-growing grass that building products turn into beams, boards, plywood and decking by gluing and pressing strips.^[3]
• Hemp and hempcrete: Two product families: hempcrete, hemp shiv bound with lime, as non-load-bearing infill, and hemp-fibre batts for insulation.^[4]
• Mycelium: Fungal networks grown through agricultural residues and dried into lightweight composites; acoustic panels and packaging are on sale, other uses mostly pilots.^[5]
• Linen: A textile spun and woven from flax, grown mainly in France, Belgium and the Netherlands, with environmental figures that cover the fibre rather than the fabric.^[6]
• Wood fibre insulation: Insulation made from softwood chips and sold as flexible batts, rigid boards or loose fill.^[7]
• Straw bale: Pressed cereal straw used as wall insulation or, in some codes, as a plastered load-bearing wall.^[8]
• Sheep wool insulation: A mat, roll or loose-fill insulation made from washed, carded wool.^[9]
• Cellulose insulation: Recycled paper, shredded and treated with mineral fire retardants, then blown into cavities and lofts.^[10]
• Flax insulation: Insulation made from the short fibres left over when flax is processed for linen, sold as mats, boards and loose fill.^[11]
• Linoleum flooring: A sheet or tile of oxidised linseed oil, rosin, wood flour and limestone on a jute backing; EN ISO 24011 is its product standard.^[12]

Related: timber and wood. Cross-laminated timber, glulam, thermally modified wood and reclaimed wood have their own profiles and are not compared here.

Further reading. Our article Hemp Insulation vs Wood Fibre Insulation: Declared Data Compared sets those two products side by side from their declared data.^[14]

Frequently asked questions about bio-based building materials

About these data

Every figure on this page comes from the linked profiles, each of which lists the primary sources behind its numbers (datasheets, approvals, ETAs, EPDs and registry entries). This guide adds no measurements and no sources of its own. Some profiles predate our comparison-table standard, so a cell may carry what a profile's fact sheet states rather than a row from a product table, and a cell reads "not stated" where the profile found no value. Registry statuses and validity dates are as each profile reports them on its own checking date: confirm them on the registry before specifying.