Recycled Textile Insulation: Cotton, Denim and Polyester Batts and Loose-Fill

Recycled textile insulation is a name for several constructions that share a raw material: fibre recovered from used clothing, garment off-cuts or, in one case, plastic bottles. This profile covers thermal and acoustic insulation made from recycled cotton and denim fibre (batts, panels, loose-fill and dense felts) and, in one product, recycled PET fibre, as building insulation for walls, roofs, floors and partitions. Sheep wool is a different feedstock and has its own profile: see sheep wool insulation. Needle-punched PET felts used as acoustic wall and ceiling panels (Texfel, Times Fibrefill) are covered in recycled plastic panels and are not repeated here.

We read manufacturer data sheets and application dossiers, certificate registries (ACERMI, INIES, EOTA), two European Technical Assessments, a US evaluation report, two environmental declarations and, at abstract level only, two peer-reviewed studies. Each section says which. We did not read any standard text (only BSI catalogue pages), and every thermal value, class and percentage below is what the named document prints. For other fibre insulations with their own profiles see cellulose, wood fibre and flax insulation.

What is recycled textile insulation made of?

Cotton and denim batts and panels

According to Le Relais' 2020 data sheet, Métisse RT is 85 % recycled textiles (at least 70 % cotton) and 15 % polyester binder, with a fire, anti-fungal and anti-bacterial treatment applied at the core of the fibre by a full-bath process.^[6] The INIES records list, per square metre at R = 2.55 m²·K/W (100 mm), 1.7 kg of "recycled and treated textile fibres" and 0.3 kg of polyester fibre, plus packaging; the polyester share is 0.3 / 2.0 = 15 % (our division), and 20 kg/m³ x 0.1 m = 2.0 kg/m² (our check) agrees with the total.^[16][6] The 2015 FDES says the product contains 12 % by mass of a fire treatment and 0.6 % of a biocide and calls the treatment free of boron salts.^[15] Soprema's Pavatextil P sheet lists cotton fibres, polyester binder fibres and anti-bacterial, anti-fungal and flame-retardant additives without percentages and without the word recycled; its R table is the same as Métisse RT's, and we did not find a document that states the relationship between the two products.^[13][6]

UltraTouch is described in ICC-ES report ESR-1134 as a nonwoven, unfaced batt of post-industrial recycled denim and cotton fibres treated with a borate solution, installed as concealed insulation in walls, floors, ceilings, attics and crawl spaces.^[1] Henry's web page says it is crafted from 80 % recycled denim and cotton fibres and treated with a borate solution that acts as a flame retardant and prevents fungal and bacterial growth; Henry's 2025 data sheet instead prints "a minimum of 80% cotton".^[5][3]

Loose-fill and dense felts

Métisse Flocon is described in the 2020 data sheet as 100 % recycled textiles with at least 73 % cotton, treated in the same way, while Le Relais' application dossier describes its fibres as 100 % cotton from recycled clothing, jeans in particular.^[7][9] The COTON-FRP assessment describes cotton fibres from frayed waste clothes, at least 65 % cotton and at most 35 % other textile fibres, with fire retardants and anti-fungal additives added in manufacture; it is blown by machine into closed cavities of roofs up to 10° and onto accessible ceilings not subject to foot traffic.^[17] The IsoFelt assessment describes thermobonded mats of 75 % cotton fibres and 25 % polypropylene binding fibres, 10 or 20 mm thick, for walls, ceilings, floors and under floating floors inside buildings, and not for external use.^[18]

Recycled PET fibre

The SupaSoft EPD describes insulation made from recycled PET microfibre bonded with a PET bi-component binder; its content table lists 0.90 kg per kg of recycled PET (100 % post-consumer) and 0.10 kg of PET, a total of 90 % post-consumer, and, in the EPD's own words, "no chemicals additives or binders" even though it names a PET bi-component binder.^[20] At 15 kg/m³ and λ 0.040 W/(m·K), R = 1 m²·K/W needs 40 mm, or 0.60 kg/m² (our calculation), which matches the EPD's 0.60 kg per declared unit.^[20] The documents we opened include no ETA, DoP or ACERMI certificate for SupaSoft, and its fire class is not stated in the EPD.

What does "recycled" mean in these documents?

The word covers different things. Only ESR-1134 and the SupaSoft EPD use the terms post-industrial and post-consumer, and ESR-1134 describes UltraTouch as post-industrial, the SupaSoft EPD marks its PET as post-consumer, and the Le Relais documents describe clothing collected and sorted by Le Relais without using either term.^{[1][20][11][9]} Percentages also have different bases: a share of the whole product (Métisse RT 85 %), a figure for a product with no binder fibre that the same sheet says is treated (Flocon "100 % recycled textiles"), a minimum cotton content that is not a recycled-content figure (Henry's data sheet, the COTON-FRP assessment) or a post-consumer share given per component and in total (SupaSoft: 100 % of the recycled PET, 90 % of the product). The table shows the statements side by side without deciding between them. If a project claims recycled content, the claim needs the document that defines it.

How do the documented properties compare?

The tables show only values printed in the named documents, with the basis exactly as printed. They are not like-for-like. ACERMI certifies λD and R values under its own rules; the two ETAs base λ on EN 12667 measurements (COTON-FRP declares under EN ISO 10456, for which we read only the BSI catalogue page, while the IsoFelt ETA cites ISO 8301 and leaves the design value to national provisions); and ESR-1134 states a thermal resistance for a US evaluation.^{[12][17][18][1][26]} Densities are stated at different conditions, and the products are different forms (semi-rigid panel, loose-fill, dense felt), so a lower λ in one row is not a verdict on the product.

Thermal conductivity and density

Reaction to fire

Calculations (ours): the Métisse Flocon certificate lists R 3.50 at 220 mm laid and 165 mm after settlement, a 25 % compaction class (220 x 0.75 = 165), and 0.165 m / 0.047 W/(m·K) = 3.51 m²·K/W, so its R values are computed on the settled thickness.^[12] For COTON-FRP, the ETA tells designers to subtract 19.5 % from the installed thickness: 300 mm installed becomes 241.5 mm, and 0.2415 / 0.046 = 5.25 m²·K/W as an illustration.^[17] The documents differ with themselves and each other on the points below, shown here without deciding:

• Métisse fire class. E in the 2020 RT and Flocon sheets and for the product alone in the 2014 M+ panel sheet; "B/S1/d0" in final conditions of use in that 2014 sheet; D-s2,d0 in the ACERMI registry for the RT, PRT d25 and PRT d30 certificates, whose pages show a "date created" of 2025-05-16 and 2026-04-27 (checked 12 October 2026). We did not find a document that explains the difference or names the classification report behind each class; ask the manufacturer which report applies to the product and build-up specified.^[6][8][12]
• Métisse certificate numbers. The 2020 RT sheet prints certificate 14/179/916 and the 2020 Flocon sheet 14/D/179/918; the undated Flocon application dossier prints 14/179/916; the registry lists 14/179/918/9 for the RT range and 14/D/179/916/10 for Flocon, and the 2015 FDES gives 14-179-918 for RT. We use the registry's pairing.^{[6][7][9][12][15]}
• Métisse Flocon. The 2014 press release speaks of a density of 15 kg/m³, the application dossier of 15 kg/m³ in place and a settlement of 25 %, the 2020 sheet of 13.5 kg/m³ for its R table, and the registry of 13.5 to 16.5 kg/m³ and λD 0.047; the 2020 sheet and the dossier print different minimum thicknesses for the same R, as their tables assume different blowing densities (R 3: 190 mm at 13.5 kg/m³ in the 2020 sheet, 188 mm at 15 kg/m³ in the dossier).^{[10][9][7][12]}
• Métisse acoustics. Rw 42 dB for a 72/48 partition in the 2014 M+ panel sheet and, at 50 mm and 25 kg/m³, in the 2015 FDES; Rw 40 dB for 45 mm at 20 kg/m³ in the INIES record; and Rw + C of 39 dB, from a 2014 study plus simulations, on the Pavatextil P sheet. Rw and Rw + C are different quantities.^{[8][15][16][13]}
• UltraTouch. The 3.5 in batt has NRC 1.15 in the 2011 insert (ASTM C423 Type A mounting) and "NRC Value of 1.0" in the 2025 data sheet (ASTM C423-22); the insert's flame spread 5 and smoke developed 35 are not repeated in the later documents; the 2025 data sheet says its information may change without notice.^[2][3]
• ETA dates. The EOTA database lists ETA 10/0311 version 1 as issued 7 June 2018 and ETA 19/0224 version 1 as 12 August 2019; the PDFs print 8 June 2018 and 13 August 2019. We did not check for later versions beyond the EOTA entries.^[19][17][18]

Independent measurements. Two peer-reviewed studies by authors at Politecnico di Milano (affiliations as listed in the OpenAlex records; one ENEA co-author), read at abstract level only, measured loose fibres and semi-finished panels rather than the commercial products above. Angelotti and colleagues (2024) measured loose post-consumer cotton fibre at 30, 50 and 70 kg/m³ and report an effective thermal conductivity between 0.0381 W/(m·K) (30 kg/m³, 10 °C, 17 % RH) and 0.0546 (50 kg/m³, 30 °C, 80 % RH), mainly sensitive to temperature and relative humidity and less to density and fibre orientation.^[24] Dama and colleagues (2025) measured panels from post-consumer textile waste (mostly polyester, mostly cotton and mixed) at 50 to 150 kg/m³ with the transient hot-disk method and report 0.042 to 0.062 (printed "W/K/m"), rising linearly with density and with relative humidity, sound absorption classes C and D, and on average the lowest conductivity for the polyester-based panels, then the mixed fabric.^[23] The abstracts support the point that λ depends on conditions, which is why the declared values above are tied to a stated basis.

What do the environmental declarations say?

We found one current third-party verified EPD for a recycled textile insulation (SupaSoft, recycled PET), one verified French declaration for Métisse RT from 2015 that is no longer current, and registry records for three newer Métisse declarations whose PDFs we could not open.^[20][15][16] The table shows each as declared; nothing was converted between units.

Source notes. In the 2015 FDES the A1–A3 figure excludes the burden of the recovered cotton, while the end-of-life scenario sends all 2 kg to landfill and counts the cotton there; this is the FDES's own method, and we read the C4 column from the printed table.^[15] The SupaSoft EPD also declares module D at −1.01 kg CO₂e per declared unit, from assumed incineration with energy recovery; we draw no conclusion from module D.^[20] The EPD's own text says EPDs from different programmes, or not conforming to EN 15804, may not be comparable.^[20] We found no EPD for UltraTouch, COTON-FRP, IsoFelt or Pavatextil P.

EPDs built on different standard versions, methods or declared units are not directly comparable. Dividing the Métisse FDES by its R value (about 2.56 at 100 mm and λ 0.039, our division) to put it per R = 1 would still mix EN 15804+A1 and A2, different impact methods and different data years, so we do not do it. We rank no product.

Registry notes. The SupaSoft EPD is within weeks of its printed expiry (31 October 2026 in the PDF and the registry, 21 October 2026 on the ASBP listing); check the registry before relying on it. The registry prints PCR version 1.3.4 while the PDF prints 1.11.^[20][21][22]

When to specify it, and when not

Where the documents support it

• Cavity insulation in walls, roofs and partitions. Le Relais lists Métisse RT for walls, under roofs and floors, with technical opinions (Avis Techniques) for walls and roofs; Henry lists UltraTouch for interior and exterior walls, ceilings, basements and crawl spaces; Soprema lists Pavatextil P for timber-frame and masonry walls (100 mm and more), roofs and partitions.^{[6][3][4][13]} The stated water vapour resistance factors are µ 1 to 4 for COTON-FRP, µ 1 to 2 for Flocon and µ 2.2 for the 2014 Métisse M+ panel, and µ 7.81 and 4.55 for the dense IsoFelt felts; whether an assembly is vapour-open depends on all of its layers, and the documents give assembly rules only as follows.^{[17][7][8][18]} Soprema asks for a vapour-open (HPV) roof underlay and a vapour barrier of Sd ≥ 18 m in rafter use (Sd ≥ 57 m in very cold zones) and says none is needed on lost-attic floors over a plasterboard ceiling at 100 mm or more; Le Relais' Flocon dossier lists cases that may need a vapour barrier (a floor that is not airtight, a boarded floor over the insulation, very cold zones or mountain climate); Henry's guide specification asks for a vapour barrier in vented crawlspace and floor cavities. These rules cover only the assemblies each document describes.^[13][9][4]
• Sound insulation in partitions. The Métisse and Pavatextil P documents print partition values (see the list above), and the 2011 UltraTouch insert prints absorption coefficients and STC values from ASTM tests for 3.5 and 5.5 in batts.^[8][13][2] These are manufacturer figures for specific test set-ups and are not interchangeable.
• Attic floors with loose-fill. COTON-FRP is assessed for closed cavities of roofs up to 10° and for accessible horizontal areas without foot traffic; Métisse Flocon is described for non-habitable attic floors over low or medium humidity spaces, on airtight substrates, in new and renovation work.^[17][9]
• Impact sound under floating floors. The IsoFelt assessment gives ΔLw of 25 dB (10 mm) and 32 dB (20 mm) for a resilient mat under a 7 cm concrete screed on a 14 cm slab, and an apparent dynamic stiffness of 17 and 9 MN/m³; its fire performance was not determined.^[18]
• A one-hour wall in the US. ESR-1134 describes a one-hour non-load-bearing wall assembly (2x4 southern yellow pine studs at 16 in, 5/8 in Type X gypsum board each side, 3½ in UltraTouch, maximum 9 ft high).^[1]

Where it needs care or may not suit

• Fire class and treatment. The classes in the documents differ (E, D-s2,d0, B-s2,d0, none determined, ASTM E84 indices), and they depend on product, form and test set-up. Treatments are described (borate for UltraTouch, a full-bath treatment without boron salts and 12 % by mass for Métisse RT in the FDES, added fire retardants for COTON-FRP) but none of the documents we read reports a test of treatment durability, leaching after wetting or loss over time. Specify against the classification report or certificate for the exact product, thickness and build-up; EN 13501-1 is the European classification standard (we read the BSI catalogue page, not the standard).^{[1][15][17][25]} Clearances: ESR-1134 bars installation over recessed light fixtures or against heat-producing appliances, and within 3 in of a fixture's enclosure, wiring compartment or driver unless the fixture is rated Type IC; the Métisse dossier asks 20 cm from chimney flues and no contact with recessed spots; Henry's guide specification asks 3 in from recessed lights not rated IC, metal chimneys, gas water heater flues and other heat sources.^[1][9][4]
• Moisture. The COTON-FRP assessment excludes compression loads, precipitation, wetting and weathering and puts the critical moisture content at 75 %; the IsoFelt assessment applies only if the product is protected from precipitation and wetting and not in contact with water or soil; Henry's guide specification asks installers to verify that basement walls are sealed and not to work on wet surfaces.^[17][18][4] Le Relais calls Flocon hydrophilic and requires a floor free of damp, an airtight floor and a ventilated roof space.^[9] λ rises with moisture: the COTON-FRP assessment prints moisture conversion factors (Fm1 and Fm2 of 1.07), and the abstracts of the two Milan studies report conductivity rising with relative humidity.^[17][23][24] We found no assessment of these products after real wetting.
• Settlement of loose-fill. COTON-FRP: settlement up to 11.8 % (impact excitation, 13.8 kg/m³, 303 mm) and up to 19.5 % (temperature and humidity cycles, 13.5 kg/m³, 308 mm), with 19.5 % deducted in design.^[17] Métisse Flocon: compaction class 25 % for 220 to 500 mm and 30 % for 570 to 750 mm in the registry, and "Tassement : 25 %" in the application dossier.^[12][9] For batts, Le Relais prints 100 % thickness recovery after compression and says its thermobonded fibres avoid settlement; we found no long-term settlement test, and Bonded Logic's 2011 UltraTouch insert says full recovery may take up to 72 hours after the batts leave their package.^[6][11][2]
• Dense felts are a different product. IsoFelt, 10 or 20 mm thick at about 95 to 100 kg/m³, is assessed for thermal and acoustic insulation of walls, ceilings, floors and roofs and for impact sound under floating floors, and its assessment prints 34.6 to 44.5 % thickness change under 20 kPa at 80 °C (EN 1605 condition 1) and compressive creep of 1.24 % and 1.96 %. In our reading, its thickness and density make it a different product from the cavity batts and loose-fills above.^[18]
• Pests and mould. The documents describe fungal resistance: Métisse class 0 (inert) under EN ISO 846, COTON-FRP growth class 0, IsoFelt intensity of growth 1, UltraTouch no growth under ASTM C739.^{[6][17][18][2]} The documents we read say nothing on insects or rodents.
• US and Europe are separate markets in the documents. UltraTouch is evaluated under US codes by ICC-ES with Henry as listee; Métisse, Pavatextil P, COTON-FRP and IsoFelt are described under ACERMI certificates and European Technical Assessments; we found no US approval for the second group and no European approval for the first.^{[1][12][17][18]} The ESR's California supplement says the California Energy Code requires verification of certification by the state's Bureau of Household Goods and Services.^[1]
• Handling and dust. Henry's 2025 brochure says no gloves or special gear are needed to install UltraTouch; the COTON-FRP assessment recommends a mask and safety glasses during blowing; Le Relais' 2015 FDES reports a 2009 dust test at installation below INRS thresholds and says nothing was measured in service.^[3][17][15] These are manufacturer or assessor statements with different scopes.
• Recycled content and end of life. The recycled-content statements differ in basis (see the table above). The 2015 FDES models disposal of the product to landfill; Le Relais' 2020 press release says production waste, site off-cuts and product removed at deconstruction can be recycled as raw material, and the SupaSoft EPD models incineration with energy recovery for module D; we found no take-back scheme document.^[15][11][20]

Compared with other fibre insulations

We read no document that compares these products head to head with sheep wool, cellulose, wood fibre or flax insulation, and the thermal values above are on different bases, so a comparison has to be made product by product on the same standard and conditions. The profiles for sheep wool, cellulose, wood fibre and flax insulation cover those materials with their own documents.

Suppliers whose documents we read

Frequently asked questions about recycled textile insulation

The bottom line on recycled textile insulation

In the documents we read, the useful questions about a recycled textile insulation are which form it is (batt, loose-fill, dense felt), which standard its numbers come from, and which fire classification report applies to the exact product. Most of the documents print low water vapour resistance factors (µ 1 to 4 for the loose-fills and batts, 4.55 and 7.81 for the dense IsoFelt mats) and describe a fire and fungal treatment (none is described for IsoFelt, and SupaSoft's EPD says it has no chemical additives); the two European assessments put wetting outside the assessed conditions; and the documents differ on recycled-content basis, fire class and settlement allowance. We did not read any standard text, we could not open the three INIES declarations for Métisse or the ETA for COTTON-3D, we found no independent test of fire-treatment durability, and the only third-party verified EPD we opened is for a recycled PET product; the figures above are what the named documents state.

Related materials