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Material profile  ·  Bio-based  ·  Construction & Interior Design

Flax Insulation: Properties, Fire Class and Approvals

Flax insulation turns the short fibres left over from linen production into vapour-open mats, boards and loose fill. This guide sets out what approvals, datasheets and independent studies say, and where they stop.

ArchitectsInterior designers

By Pilar Flores· Published October 7, 2026· Updated October 8, 2026· 9 min read

Flax insulation properties at a glance

Family
Bio-based, plant-fibre thermal insulation (flax)
Origin
Short fibres, and in some products shives, from flax grown for linen. Isovlas states that its flax grows in clay soils along the coast from Zeeland to northern France and is a residual product of the linen industry.[4] Short fibre is 11 % of the mass leaving the scutching mill and shive 50 %.[5]
Production
Short fibre is cleaned (rescutched) and can be made into non-woven mats.[5] Mats and boards are bound with potato starch (Flachshaus) or a bicomponent fibre (JUTA, Isovlas) and treated with borate, soda or salts against fire and mould.[3][2][6]
Forms
Mats (Isovlas PL and PN, 40–140 mm;[1] NATURIZOL, 40–160 mm[2]) · boards (Flachshaus, 30–200 mm[3]) · loose fill (flax fill for floors, ETA 13/0481[7])
Thermal conductivity (λ)
Isovlas PL 0.038 and PN 0.035 W/(m·K), tested at 10 °C.[1] NATURIZOL λD 0.039.[2] Flachshaus ETA: 0.039 (category 1) or 0.038 (category 2).[3] An independent agency table gives 0.04–0.045 for flax in general.[8]
Density
30–50 kg/m³ in the Flachshaus ETA;[3] 32 kg/m³ for NATURIZOL (JUTA);[2] 20–80 kg/m³ as a general range.[8] We found no density on the Isovlas documents.
Reaction to fire
Euroclass E for the Flachshaus boards and NATURIZOL.[3][2] Isovlas lists Euroclass C, from an SBI test result of C-s2,d0.[1]
Embodied carbon (A1–A3)
We found no EN 15804 EPD for a flax insulation product. Fibre only, cradle to gate, EF 3.1 climate change, from the Alliance guide: rescutched short fibre 0.854 kg CO₂e per kg (section 4.7). For scutched long fibre the guide is inconsistent: its section 4.5 table shows 0.364, its section 4.6 text gives 0.85, and it does not explain the difference.[5]
Emissions
The Flachshaus ETA classes the product as type 2 for health protection under the EOTA criteria.[3] JUTA states that NATURIZOL has no formaldehyde or resins.[2] natureplus has a flax guideline, RL 0102,[9] but the natureplus product database lists no product in its two flax insulation categories (checked 8 October 2026).[26]
Moisture behaviour
Hygroscopic. Flachshaus ETA: 6.4 % moisture by mass at 23 °C/50 % RH and 13.8 % at 80 %; mould level 0.[3] In one independent test, a NATURIZOL sample held 17 % moisture at 95 % RH.[10] Vapour resistance: JUTA states μ below 2.2; the Isovlas brochure prints 5.7.[2][1]
Certifications seen
ETA 15/0153 (JUTA, version 4, 30.12.2020; EOTA entry opened 8 October 2026)[11] · ETA 13/0481 (loose fill; EOTA entry opened 8 October 2026)[7] · ETA-09/0023 (Flachshaus; DIBt register, opened 8 October 2026, shows validity ended 5 January 2014)[12] · KOMO attest 40047/09 as printed in the 2011 Isovlas brochure is superseded; the KOMO register (opened 8 October 2026) lists attest 40047/25 for Isovlas Oisterwijk B.V., issued 1 March 2025, status valid[25] · ETA-04/0047 as printed in the brochure, not found in the EOTA databases of valid or superseded ETAs, which list no ETA held by Isovlas[1][19]. See the supplier table.

Flax insulation turns the by-products of linen production into a vapour-open insulant. Designers use it in timber-frame walls, roofs and floors where a bio-based mat or fill is wanted.

This page covers flax as an insulation product. For the crop and the textile, see linen. The market is thin: few producers, few current approvals and no EPD that we could find.

What is flax insulation and how is it made?

Fibre and shives

Flax straw is pulled, dew-retted and scutched. The Alliance for European Flax-Linen and Hemp lists the outputs by mass: 22 % long fibre, 11 % short fibre, 50 % shive, 5 % seed and 12 % dust and stone.[5] Long fibre goes mainly to clothing; rescutched short fibre goes to yarn and non-woven mats, including insulation.[5] The shive, the woody core, can be used loose. A French study monitored flax shives in a house attic for ten months, and an Austrian ETA issued in December 2022 covers loose flax fill for floors.[13][7]

Binders and treatments

Mats need a binder and a fire treatment. The 2010 Flachshaus approval names potato starch as binder and a borate-based fire protection that also guards against mould.[3] JUTA describes a PES bicomponent binder fibre and soda as the retardant.[2] Isovlas states that it uses natural salts and a bicomponent binder fibre, and a contractor card gives 80–85 % flax, 10–15 % bicomponent fibre and 5 % salt for an Isovlas roof product.[6][14] An Austrian public energy agency notes that flax mats are bound with starch or with plastic or bio-plastic fibres.[8]

How does flax insulation perform?

Thermal conductivity and density

Declared values sit close to 0.04 W/(m·K). Isovlas lists 0.038 for its PL mat and 0.035 for PN, and a declared R of 2.63 m²K/W at 100 mm for PL.[1] JUTA states 0.039 for NATURIZOL at 32 kg/m³.[2] The Flachshaus approval declares 0.039 or 0.038 at 23 °C and 50 % RH for 30–50 kg/m³.[3] An Upper Austrian agency table gives 0.04–0.045.[8] Compare products at the declared λ and the thickness you need.

Moisture and vapour

Flax takes up and releases water vapour. The Flachshaus approval gives a mass-related moisture content of 6.4 % at 23 °C/50 % RH and 13.8 % at 80 %, with conversion factors of 1.015 and 1.03 for λ, and mould resistance level 0 under EN ISO 846.[3] Isovlas lists the same mould level.[1] Sources disagree on vapour resistance: JUTA states μ below 2.2 for NATURIZOL, while the Isovlas brochure and current website print 5.7,[27] and a Slovak retailer table cited in a paper also gives 5.7 for NATURIZOL.[2][1][10] Check the current declaration of performance.

An independent 2020 Slovak study tested one 100 mm NATURIZOL sample in a climate chamber. At 95 % RH the sample held 17.05 % moisture by mass, and λ rose from the declared 0.039 to 0.0755 W/(m·K). The authors also reported mould formation after exposure up to 95 % RH.[10] The study used a single specimen and a portable probe, so treat it as a warning about moisture and not as design data. Read it as a warning to keep flax dry, not as design data.

Heat storage

The 2011 Isovlas brochure, the 2022 product sheet and JUTA list a specific heat capacity of about 1,550 J/(kg·K); Isovlas's current website lists about 1,600 for both PL and PN.[1][6][2][27] JUTA argues that this limits attic overheating.[2] We found no independent measurement of time lag or overheating for flax mats.

How does flax insulation behave in fire?

Fire class depends on the product and its treatment. The Flachshaus approval and the JUTA article state Euroclass E under EN 13501-1.[3][2] The Isovlas brochure lists Euroclass C and cites an SBI test (EN 13823) with the result C-s2,d0 under the 2002 edition of EN 13501-1. The 2022 product sheet and a 2026 contractor card repeat class C.[1][6][14] The brochure dates from 2011. Isovlas's current product pages still list Euroclass C, but we found no current declaration of performance or test report, so ask for them for your build-up.[27]

All three treat the fibre with a retardant: borate, soda or salts.[3][2][6] We found no peer-reviewed fire study of flax insulation mats.

How much carbon does flax insulation hold?

What data exist

We found no EN 15804 EPD for a flax insulation mat, board or fill, so there are no A1–A3 or biogenic carbon figures to quote for a finished product. A product-name search of the IBU EPD list found none either; its only “flax” entry is a wood-flax particleboard.[29] Three kinds of data come close.

First, the fibre. The Alliance guide gives cradle-to-gate EF 3.1 climate-change results per kg of certified European flax fibre. For rescutched short fibre, the grade it lists for non-woven mats including insulation, the section 4.7 table shows 0.854 kg CO₂e per kg (EF 3.1 background data; the guide reports an external review completed on 19 December 2025). For scutched long fibre the guide is inconsistent: the section 4.5 results table shows 0.364 kg CO₂e per kg and says it is the same as the dataset featured in the European Commission's EF 3.1 database, while the text of section 4.6 gives 0.85 kg CO₂e for the EF 3.1 long-fibre dataset (and 1.05 in ecoinvent 3.10). The guide does not explain the difference, so we give no single long-fibre figure.[5] The guide says the PEF method does not count temporary carbon storage in intermediate natural products (a 0:0 approach), so we read these fibre results as carrying no credit for stored carbon.[5] They are fibre figures only, not an insulation product, and the Alliance is an industry body.

Second, Isovlas. The Dutch national environmental database shows a category 1 declaration for Isovlas PL with an environmental cost indicator of € 0.1357 per m², with no thickness given.[4] A contractor card for a 180 mm Isovlas roof panel with finishing board states 8.47 kg CO₂ per m² and 12.11 kg CO₂ of storage per m².[14] We could not read the declaration behind either figure.

Third, independent LCAs. A 2021 comparative LCA covered wood fibre, hemp, flax and miscanthus against EPS and stone wool from cradle to grave. Wood fibre and miscanthus were the most environmentally friendly bio-based options, cultivation had the largest impact for agriculturally sourced insulants, and end-of-life incineration impacts were strongly influenced by the fossil components of the materials.[16] A 2016 cradle-to-gate study of fibre-flax panels made in the Czech Republic found impacts comparable with other insulation materials, with transport significant.[17] Both are abstracts only.

Which standards and approvals apply?

EN 13171 covers factory-made wood fibre products, not flax;[28] see wood fibre insulation. Factory-made flax mats and boards, such as JUTA's ETA 15/0153, go through a European Technical Assessment under EAD 040005-00-1201, "Factory-made thermal and/or acoustic insulation products made of vegetable or animal fibres". The EAD is listed as harmonised and was first published in the Official Journal on 12 February 2016.[18] Loose fill is assessed under other EADs: ETA 13/0481 cites EAD 041125-00-1201.[7] The Flachshaus approval of 2010 predates the EAD system and cites EOTA assessment criteria instead.[3]

The EOTA register lists JUTA's ETA 15/0153, version 4 issued 30 December 2020, for NATURIZOL, NATURFLAX, DÄMM FLACHS and other trade names.[11] Few other flax-named assessments appear in the register list: Flachsfloc (12/0037) and two Flachsschütt entries (13/0481, 13/0482), all held by NFF Naturbaustoffe, FLAXISOL (16/0715, IGRA Tekhnika, Moscow, version 1 of 18 December 2016, under EAD 040005-00-1201) and the JUTA entry.[19] The Flachshaus ETA-09/0023 is shown in the DIBt database as valid until 5 January 2014, with no later version (checked 8 October 2026).[12] The Isovlas brochure cites ETA-04/0047, which we did not find in the EOTA database of valid ETAs or in its superseded-ETAs database (both searched by number on 8 October 2026); searches by trade name and by holder found no Isovlas entry in either.[1][19]

The current edition of the fire classification standard is EN 13501-1:2018, which replaced the 2007 edition; the approvals above cite the 2007 and 2002 editions.[15][3][1] natureplus publishes award guideline RL 0102 for flax insulation, status January 2022.[9] The natureplus product database shows “no products found” in both its flax categories, loose fill and boards (checked 8 October 2026), so we found no flax product that carries the label.[26] The Isovlas brochure also prints KOMO attest 40047/09. The KOMO register (checked 8 October 2026) now lists attest 40047/25 for Isovlas Oisterwijk B.V. under BRL 1001, non-load-bearing inner cavity leaves and facade-filling elements, issued 1 March 2025, valid for an indefinite period, issued by SKH. We did not read the 2025 attest, because the register's link to the file returned HTTP 404 on 8 October 2026, so we state no performance values from it.[25][1]

Where is flax insulation used, and what are the limits?

Timber-frame walls, roofs and floors

Best for: architects · self-builders

Isovlas mats are cut oversize so that they clamp between the ribs of the frame.[20] The Flachshaus approval lists cavity insulation in timber-frame walls, insulation between rafters and between floor joists, and top-storey ceilings, all without compression loads and protected from precipitation.[3] Isovlas instructs installers to cut 3–4 cm oversize so the mat clamps, and to store, install and keep it dry.[20] The Van Wijnen card flags the use of Isovlas in wet rooms as a point of attention.[14]

Masonry cavity walls

Best for: retrofit designers

Isovlas PN suits partial cavity fill. The manufacturer requires a ventilated gap of at least 30 mm, and recommends 40 mm; full fill is not possible.[20] Behind a ventilated facade, the Flachshaus approval allows flax boards only when a covering protects them from the ventilation plane.[3]

Loose fill for attics and floors

Best for: retrofit designers · installers

Loose flax has a narrower evidence base. One attic study replaced glass wool with flax shives and tracked temperature and humidity for ten months.[13] NFF Naturbaustoffe holds an ETA for flax fill in floor constructions.[7] We read only the abstract and the register entry, so we give no λ or settlement values.

Product and industrial designers

Best for: product designers

We found no sourced data on flax insulation in product design.

Where has flax insulation been used in real projects?

We found one credited, completed project that names flax insulation. None of the sources gives performance monitoring.

Hemma House, Egchel, Netherlands

Architect: stek architecten · completed 2020

A single-storey, 112 m² timber-frame house. The Galleo project listing, marked as delivered, says it is "insulated with flax" and tags "Flax fibre insulation"; ArchDaily gives the credits, the year and the area.[21][22] A Czech trade article of May 2021 describes flax insulation, including pressed flax cladding boards, in the perimeter walls.[23] The article and ArchDaily both list Isovlas among the material suppliers; neither says which product it supplied.[23][22]

One further plan is announced but not built: in February 2024 the developer AM described a plan for 112 homes in Utrecht with a wooden load-bearing structure, "insulated with as many biobased materials as possible such as straw and flax". The release names no product, and we found no source showing the homes completed.[24]

Where to buy flax insulation in Europe

Suppliers selected by our editors and checked against company documents and approval records where available. We could verify four.

SupplierProductsCountryCertifications
Isovlas (Isovlas Oisterwijk bv) Isovlas PL and PN mats, 40–140 mm Netherlands KOMO attest 40047/09 and ETA-04/0047, as printed in the 2011 brochure. The KOMO register (checked 8 October 2026) lists attest 40047/25, issued 1 March 2025; we did not find ETA-04/0047 in the EOTA valid or superseded ETA databases. Category 1 declaration in the Dutch national environmental database.[1][25][19][4]
JUTA a.s. NATURIZOL (also NATURFLAX, DÄMM FLACHS under the same ETA) Czech Republic ETA 15/0153, version 4 issued 30.12.2020, as listed in the EOTA register (checked 8 October 2026); the document was not read.[11]
NFF Naturbaustoffe (Martin Mahringer) Flachsschütt lastabtragend, loose fill for floors Austria ETA 13/0481, version 1 issued 22.12.2022, as listed in the EOTA register (checked 8 October 2026); the document was not read.[7]
Flachshaus GmbH Flachshaus Wärmedämmplatte DP, Naturaflax, HAGA-Flachsdämmplatte, Dämmplatte DP Germany (plant in Falkenhagen; Austrian plant named in the ETA) ETA-09/0023, version of 8 July 2010; validity until 5 January 2014 (DIBt register, checked 8 October 2026). We found no current approval.[3][12]

Certificate numbers are taken from the registers and company documents named in the sources. Confirm them with the issuing body before specifying. Listing policy: editorial selection, not paid.

Frequently asked questions about flax insulation

What is flax insulation made of?

Short flax fibres, and in some products shives, from the linen industry. Mats add a binder such as potato starch or a bicomponent fibre, plus a fire and mould treatment such as borate, soda or salts.

What is the thermal conductivity of flax insulation?

The documents we read declare 0.035 to 0.039 W/(m·K). An independent agency table gives 0.04 to 0.045 for flax in general, so compare products at the declared value.

Is flax insulation fireproof?

No. The Flachshaus approval and JUTA state Euroclass E. Isovlas lists Euroclass C. We found no independent fire study of flax mats, so ask for the test report for your build-up.

Is flax insulation breathable, and does it cope with moisture?

It is vapour-open and hygroscopic, but sources disagree on the vapour resistance factor. It must stay dry in storage, installation and use. One independent test measured λ nearly doubling at 95 % humidity.

Is flax insulation carbon negative?

We found no EPD, so we cannot give a figure for a finished product. Fibre-level data exist, but the Alliance guide is inconsistent on long fibre. One independent LCA found end-of-life impacts strongly influenced by fossil components.

Is flax insulation the same as linen?

No. Both come from the flax plant. Linen textile uses the long fibre. Insulation uses short fibre or shives with a binder and treatment.

Which standards and approvals cover flax insulation?

There is no product standard like EN 13171 for wood fibre. Factory-made flax mats and boards use a European Technical Assessment under EAD 040005-00-1201, loose fill uses other EADs, and fire is classified under EN 13501-1.

The bottom line on flax insulation

Flax insulation is a documented but thinly supplied option, with declared λ values of 0.035 to 0.039 W/(m·K) and fire classes from E to C depending on the product. Its gaps are the lack of an EPD, vapour-resistance figures that disagree between sources and little independent testing. Ask each supplier for the current ETA, the fire test for your build-up and a declaration of performance.

Related materials

Hemp & hempcreteBio-based Wood fibre insulationBio-based Sheep wool insulationBio-based LinenBio-based

Sources

  1. Isovlas Oisterwijk bv (2011, from the file name). Brochure "Hét ideale woonklimaat: Isovlas bouwisolatie" (Dutch) with product information for Isovlas PL and PN, assortment table with declared R values, list of tests and certificates. Source of λ (PL 0.038, PN 0.035 W/(m·K), EN 12667 at 10 °C), Euroclass C and the SBI result C-s2,d0 (EN 13501-1:2002), heat capacity ca. 1,550 J/(kg·K), μ 5.7 as printed, mould level 0, ETA-04/0047 and KOMO attest 40047/09 as printed. Manufacturer brochure (company claims); full text read; copy hosted by the distributor eurabo.be. KOMO attest 40047/09 is superseded (see [25]); ETA-04/0047 was not found in the EOTA databases (see [19]). PDF (eurabo.be)
  2. Rypl, J. (JUTA a.s., application manager), "Přírodní lněná tepelně izolační vata NATURIZOL" (Czech), article PDF on TZB-info, undated; cites ETA No. 15/0153. Source of λD 0.039 W/(m·K), 32 kg/m³, c 1,550 J/(kg·K), μ below 2.2, Euroclass E, soda as fire retardant, PES BiCo fibre binder, thicknesses 40–160 mm. Manufacturer-authored article (company claims); full text read. The PDF is linked as the “Detail” document of the NATURIZOL entry in a TZB-info article dated 1.12.2019 (Infotherm 2020 competition entries; read through a page summary), so it dates from 2019 or earlier. PDF (tzb-info.cz)
  3. Deutsches Institut für Bautechnik (DIBt) (2010). European Technical Approval ETA-09/0023, thermal insulation product made of flax fibres ("Flachshaus Wärmedämmplatte DP", "Naturaflax", "HAGA-Flachsdämmplatte", "Dämmplatte DP"), holder Flachshaus GmbH, Falkenhagen; version issued 8 July 2010, validity to 5 January 2014 (expired). Source of composition (flax, potato starch, borate), density, λ categories, moisture content and conversion factors, Euroclass E, mould level 0, intended uses and limits, EOTA assessment criteria. Independent approval document; full text read. PDF (dibt.de)
  4. Stichting Nationale Milieudatabase (Dutch national environmental database), featured category 1 declaration "Isovlas PL Bouwisolatie": functional unit per square metre, environmental cost indicator € 0.1357, lifespan 75 years, flax grown "along the coast from Zeeland to Northern France", residual product of the linen industry. Database showcase page; it gives no thickness, GWP, verifier or validity date. Independent database, company-supplied data. milieudatabase.nl
  5. Alliance for European Flax-Linen & Hemp (2026). European Flax-Linen Environmental Footprint Guide: progress report on LCA, PEF, life cycle data for certified fibres, processes and products, May 2026 update. Source of scutching output fractions (section 3.10), end markets of short fibre (section 4.7), the PEF 0:0 biogenic carbon explanation (section 3.9) and cradle-to-gate EF 3.1 climate-change results: rescutched short fibre 0.854 kg CO₂e/kg (section 4.7 table); scutched long fibre 0.364 kg CO₂e/kg in the section 4.5 table, but 0.85 in EF 3.1 and 1.05 in ecoinvent 3.10 in the section 4.6 text, which the guide does not reconcile. Industry association document (data are sector-collected, not independent of the sector); the chapters on biogenic carbon, allocation and the fibre datasets were read. PDF (allianceflaxlinenhemp.eu)
  6. Greenworks (product sheet dated 01-06-22). "Isovlas bouwisolatie, vlaswol isolatieplaat" (Dutch): fibres released in linen production, natural salts and a bicomponent binder fibre, Euroclass C, heat capacity 1,550 J/(kg·K), thicknesses and R values. Product sheet issued under the Greenworks brand; treated as a manufacturer-side document. Full text read. PDF (cloudinary host)
  7. EOTA, ETA database entry for ETAssessment 13/0481, "Flachsschütt lastabtragend" (in-situ loose-fill thermal and/or acoustic insulation made of vegetable fibres for floor constructions); holder Martin Mahringer NFF Naturbaustoffe, Vorderweißenbach (Austria); assessment body OIB; EAD 041125-00-1201; version 1 issued 22 December 2022. Entry opened 8 October 2026; the same holder also holds 12/0037 (Flachsfloc, EAD 040138-00-1201, version 1 of 1 March 2018) and 13/0482 (Flachsschütt raumfüllend, EAD 040138-01-1201, version 1 of 4 May 2020), per their EOTA entries. Independent register entry; the assessment document was not read. eota.eu
  8. OÖ Energiesparverband (agency of the Province of Upper Austria), brochure "Umweltfreundlich gedämmt: Ökologische Dämmstoffe", status 01/2026 (German). Source of the general ranges for flax insulation (λ 0.04–0.045 W/(m·K), μ 1–2, 20–80 kg/m³, c about 1,600–2,300 J/(kg·K)) and of the binder description. Public, product-independent advisory brochure; full text read. PDF (land-oberoesterreich.gv.at)
  9. Umweltbundesamt (Germany), "Dämmstoffe" (last updated 06.07.2022): lists the natureplus award guideline "RL 0102 Dämmstoffe aus Flachs" (status 01/2022). Institutional page; it gives no technical values, and the guideline itself was not read. umweltbundesamt.de
  10. Hellová, K.E., Unčík, S. & Cabanová, T. (2020). "Sorption properties of thermal insulation composed of flax or hemp fibers." Slovak Journal of Civil Engineering 28(3):47–52. Independent peer-reviewed laboratory study (Slovak University of Technology) of one 100 mm NATURIZOL sample and one hemp sample: equilibrium moisture and λ at 20–95 % RH. Full text read. doi:10.2478/sjce-2020-0023
  11. EOTA, ETA database entry for ETAssessment 15/0153: trade names NATURIZOL, NATURFLAX, DÄMM FLACHS, Sonnenklee Flachs, Bioflachs, EcoFlax and variants; holder JUTA a.s., Dvůr Králové nad Labem (Czech Republic); category "Factory-made thermal and/or acoustic insulation products made of vegetable or animal fibres"; assessment body TZUS; EAD 040005-00-1201; version 4 issued 30 December 2020. Entry opened 8 October 2026. Independent register entry; the assessment document itself was not read, so no ETA values are quoted. eota.eu
  12. DIBt, approval database entry for ETA-09/0023 (Flachshaus GmbH): lists two versions, valid from 06.01.2009 and from 08.07.2010, both until 05.01.2014, and no later version. Registry page, read in full on 8 October 2026. dibt.de
  13. Brachelet, F., Asli, M., Antczak, E., Brue, F., Defer, D. & Lucas, J.-P. (2020). "Hygrothermal behaviour of flax shives used as insulation material in an attic of a traditional house." MATEC Web of Conferences 307:01017. Independent peer-reviewed conference paper: laboratory tests and ten-month monitoring of flax shives in an attic in French Flanders. Abstract read via Crossref; full text not accessed. doi:10.1051/matecconf/202030701017
  14. Van Wijnen (contractor), "Informatiekaart Isovlas Reno TG Elegant 180 mm", version 1.0, dated 17-06-2026 (Dutch): composition 80–85 % flax, 10–15 % bicomponent fibre, 5 % salt; 8.47 kg CO₂ per m² and 12.11 kg CO₂ storage per m²; MKI €1.58 per m²; BCRG declaration 20210297GK as printed; fire class insulation C. A roof panel with a finishing board, not a plain mat; the underlying declaration was not seen. Contractor information card, company-side data; full text read. PDF (van Wijnen)
  15. Standard Norge, catalogue page for NS-EN 13501-1:2018, "Fire classification of construction products and building elements - Part 1: Classification using data from reaction to fire tests": published March 2019, replaces the 2007 edition. Independent catalogue page, read 8 October 2026; the standard text was not read. online.standard.no
  16. Schulte, M., Lewandowski, I., Pude, R. & Wagner, M. (2021). "Comparative life cycle assessment of bio-based insulation materials: Environmental and economic performances." GCB Bioenergy 13(6):979–998. Independent peer-reviewed cradle-to-grave LCA and LCC of wood fibre, hemp, flax and miscanthus against EPS and stone wool, Germany. Abstract read via Crossref; full text not accessed. doi:10.1111/gcbb.12825
  17. Struhala, K., Stránská, Z. & Sedlák, J. (2016). "LCA of Fibre Flax Thermal Insulation." Applied Mechanics and Materials 824:761–769. Independent peer-reviewed cradle-to-gate LCA of insulation panels made from fibre flax stems, production in the Czech Republic. Abstract read via Crossref; full text not accessed. doi:10.4028/www.scientific.net/AMM.824.761
  18. Nlfnorm (Czech standards information service), catalogue page for EAD 040005-00-1201, "Factory-made thermal and/or acoustic insulation products made of vegetable or animal fibres": status harmonised, first publication in the Official Journal of the EU on 12 February 2016 (2016/C 054/03; the EOTA EAD list shows the same EAD adopted 05/10/2014 and cited as 2016/C 054/14, so the item number differs between the two sites). Independent catalogue page, read 8 October 2026; the EAD text itself was not read. nlfnorm.cz
  19. EOTA, ETA database list (retrieved 8 October 2026; the database states it contains currently valid ETAs). Flax-named entries we noticed: 12/0037 Flachsfloc, 13/0481 and 13/0482 Flachsschütt (holder NFF Naturbaustoffe, Austria), 15/0153 NATURIZOL and related names (JUTA), 16/0715 FLAXISOL (IGRA Tekhnika LLC, Moscow; OIB; EAD 040005-00-1201; version 1 of 18 December 2016). We found no entry numbered 04/0047 in this list, nor in the separate EOTA superseded-ETAs database (etassessments-history; searched by ETA number on 8 October 2026, the same search finds 15/0153). Searches by trade name (“isovlas”, “vlas”) and by holder (“isovlas”, “oisterwijk”, “flachshaus”) returned no ETA in either database. Trade-name searches for “flax” and “flachs” in the valid database return 12/0037, 13/0481, 13/0482, 15/0153, 16/0715 and ETA 10/0019, a stressed-skin panel assessment (Unilin) whose trade names include SW-FLAX-ML and OPEN FLAX and which we did not read. Independent register listing. eota.eu
  20. Isovlas (undated). "Verwerkingsvoorschrift PL & PN Bouwisolatie" (Dutch installation instructions): dry storage, 3–4 cm oversize, partial cavity fill with a ventilated gap of at least 30 mm for PN. Manufacturer document; full text read; the same text is on the maker's own documentation page (uploaded September 2022). PDF (isovlas.nl) · copy (isolatiemateriaal.nl)
  21. Galleo, project listing "Hemma" by stek architecten, Egchel (Netherlands), 2020; description: "The single-storey house is fully executed in timber frame construction and insulated with flax." Project database entry marked "Opgeleverd" (delivered); the page does not say who wrote the description. It also describes the Hemma concept as built either as flax-insulated timber frame or as solid timber with wood fibre insulation. galleo.co
  22. ArchDaily, "Hemma House / stek architecten": lead architects Frank van Winden and Annette Marx, Egchel, 2020, 112 m². Used for credit, year, area and the manufacturer list (VELUX Group, Isovlas, Xinnix); the page text does not name flax. archdaily.com
  23. ESTAV.cz (Czech building portal), article by R. Dohnal on Hemma House, 29 May 2021: describes flax insulation, including pressed flax cladding boards, in the perimeter walls; project data list stek architecten, project leads Frank van Winden and Annette Marx, material suppliers Isovlas, Xinnix and Velux, completion 2020, 112 m². Trade-press article; no performance data. estav.cz
  24. AM (area developer, part of Koninklijke BAM Groep), news release "Area developer AM will develop circular and bio-based homes in Leeuwesteyn Utrecht", 15 February 2024: 112 owner-occupied homes with a wooden load-bearing structure "insulated with as many biobased materials as possible such as straw and flax"; plan team includes Studio Ard Hoksbergen among others. Developer press release; it describes a plan, and we did not find a source showing the homes built. am.nl
  25. KOMO (Stichting KOMO) certificate register, entry for attest 40047/25, holder Isovlas Oisterwijk B.V.: issued 01-03-2025, valid for an indefinite period, status valid, BRL 1001 (non-load-bearing inner cavity leaves and facade-filling elements), type attest, certification body SKH; opened 8 October 2026. The SKH attest 40047/13 (valid 01-10-2013 to 01-10-2018, copy hosted by eurabo.be) states that it replaces 40047/09. The register's link to the 2025 attest file returned HTTP 404 on 8 October 2026, so we did not read it. Independent register. komo.nl · attest 40047/13 (eurabo.be)
  26. natureplus product database (baubook.at/natureplus, linked from natureplus-label.org as “Produktdatenbank”), category tree “Dämmstoffe aus nachwachsenden Rohstoffen”: the categories “Flachsdämmstoffe (lose)” and “Flachsdämmstoffplatten” each show “Keine Produkte gefunden!” (no products found) on 8 October 2026, whereas the wood fibre board category renders a product table. Independent register; the category pages load product rows dynamically, so confirm with natureplus before relying on this. baubook.at/natureplus
  27. Isovlas, current product pages “Isovlas PL Bouwisolatie” and “Isovlas PN Bouwisolatie” (isovlas.nl, read 8 October 2026): λ 0.038 (PL) and 0.035 W/(m·K) (PN), Euroklasse C, specific heat capacity ca. 1,600 J/(kg·K), vapour resistance factor μ 5.7, sound absorption alpha-w 1.0, energy input ca. 1.6 MJ/kg; no density, certificate or declaration of performance is shown. Manufacturer web pages (company claims). PL · PN
  28. Estonian Centre for Standardisation and Accreditation (EVS), catalogue page for EVS-EN 13171:2012+A1:2015, “Thermal insulation products for buildings - Factory made wood fibre (WF) products - Specification” (valid from 02.04.2015); the scope text of the earlier EN 13171:2012 page covers wood fibre products in rolls, batts, felts, boards or slabs and excludes in situ insulation. Independent catalogue page, read 8 October 2026; the standard text was not read. evs.ee · EN 13171:2012 scope
  29. Institut Bauen und Umwelt e.V. (IBU), published-EPD list on epd-online.com (queried 8 October 2026 by product name): a search for “flax” returns one entry, “Wood/flax particleboard” (Linex Panneaux SAS, EPD-LNX-20250362-CBA1-EN); searches for “Flachs” and for the manufacturers Flachshaus, JUTA and Isovlas return nothing. A name search only, not a full-text search of the registry. epd-online.com
Flax insulation Bio-based Insulation Timber frame ETA Retrofit