To be legally sold in the EU, thermal insulation products must comply with the EU Construction Products Regulation and the technical specifications outlined in the applicable harmonized standard, if one exists.1 These specifications cover a range of safety and performance characteristics, including thermal resistance, reaction to fire behavior, and dimensional stability, which are to be evaluated using standardized test methods.
In addition to meeting the applicable technical specifications, thermal insulation products must comply with EU chemicals legislation, including the Persistent Organic Pollutants (POP) Regulation and the REACH formaldehyde release restriction that applies from 6 August 2026.
Harmonized standards for thermal insulation products
All the most common types of factory-made thermal insulation products for use in buildings are covered by European harmonized standards, which means they must comply with the specifications outlined in the applicable standard:
EN 13162: Mineral wool (MW)
EN 13163: Expanded polystyrene (EPS)
EN 13164: Extruded polystyrene foam (XPS)
EN 13165: Rigid polyurethane foam (PU)
EN 13166: Phenolic foam (PF)
EN 13167: Cellular glass (CG)
EN 13168: Wood wool (WW)
EN 13169: Expanded perlite board (EPB)
EN 13170: Expanded cork (ICB)
EN 13171: Wood fiber (WF)
EN 16069: Polyethylene foam (PEF)
Harmonized standards also cover several types of insulation products for civil engineering applications (EN 14933, EN 14934), as well as building equipment and industrial installations (EN 14303, EN 14304, etc.).2 For products not covered by a standard, the applicable requirements are specified in European Assessment Documents (EADs).3
Properties covered by the standards
The European harmonized standards for thermal insulation materials cover a range of essential product characteristics to be determined and declared in the Declaration of Performance (DoP). These are summarized in Table 1. Further information about testing options for assessing the most commonly evaluated parameters is provided later in the article.
Table 1: Essential characteristics of factory-made thermal insulation products & test methods for determining them
Product characteristic | Testing standard(s) | Notes |
Thermal resistance and/or conductivity | EN 12667 EN 12939 (thick products) | Thermal resistance (R) and thermal conductivity (λ) are both declared if possible. R is always declared for products of uniform thickness and λ for products of non-uniform thickness. |
Reaction to fire performance | EN 13501-1 (classification standard)* | Declared as Euroclass (A1–F), plus designations for smoke (s) and flaming droplets (d) where applicable. |
Durability of reaction to fire performance and thermal resistance against aging and degradation | – | Testing is not needed if it is known based on material characteristics that these properties do not change over time. |
Dimensions | EN 822 (length and width) EN 823 (thickness) EN 824 (squareness) EN 825 (flatness) | A dimensional tolerance class is always declared for thickness, and also for other dimensions if the product is supplied in sheets with predefined measurements. |
Dimensional stability | EN 1603 (under constant normal laboratory conditions) EN 1604 (under specified temperature and humidity conditions) | Other dimensional stability tests are typically not required when the EN 1604 test is conducted at 70 °C and 90% RH. The resulting designation is DS(70,90)i, where i is the declared dimensional stability level. |
Compressive stress at 10% deformation | EN 826 | Declared as CS(10)i or CS(10/Y)i, where i is the measured value in kPa, rounded down to the nearest level specified in the product standard. |
Bending strength | EN 12089 | Declared as BSi, where i is the measured bending strength in kPa, rounded down to the nearest declarable level. |
Tensile strength perpendicular to faces | EN 1607 | Declared as TRi, where i is the measured tensile strength in kPa, again rounded down to the nearest level. |
Water absorption | EN 12087 (immersion method, long-term) EN 12088 (diffusion method, long-term) EN 1609 (immersion method, short-term) | Declared performance classes include WL(P)i, WL(T)i, WD(V)i, and WS, depending on the selected method, where i is the measured water absorption in % or kg/m2. |
Water vapor permeability/transmission | Declared as the water vapor diffusion resistance factor (µ) for homogenous products and water vapor resistance (Z) for non-homogeneous products. | |
Compressibility | EN 12431 | Applies to insulation used under floating floors. Declared as a compressibility level (CP) |
Dynamic stiffness | EN 29052-1 (equivalent to ISO 9052-1) | Applies to insulation used under floating floors. Declared as an SDi level, where i is the measured dynamic stiffness in MN/m3 |
Freeze-thaw resistance | EN 12091 | Relevant to products frequently exposed to low temperatures and moisture. Can also be measured after long-term water absorption. |
Sound absorption | EN ISO 354 EN ISO 11654 | Relevant to products used for both thermal and sound isolation, e.g., mineral wool. Results declared for practical and weighted sound absorption coefficients. |
Air flow resistivity | EN ISO 9053-1 | Relevant to products used for both thermal and sound isolation. Results declared as air flow resistivity (AFr) levels, rounded down to the nearest kPa⋅s/m2. |
* The actual tests are conducted in accordance with additional standards (EN 13823, EN ISO 11925-2, etc.), selected based on the target Euroclass classification.
It is not necessary to determine and declare all of the properties listed in Table 1. Rather, the Construction Products Regulation requires manufacturers to declare the performance of those essential characteristics that are related to the intended use of the product.4 In the case of thermal insulation, this means thermal resistance and/or conductivity, reaction to fire performance, the durability of these properties over time, and dimensional tolerances for the relevant dimensions.
The properties that have not been tested are declared as NPD (no performance determined) in the DoP, apart from reaction to fire performance, which is typically declared as Euroclass F if no testing has been conducted.
Thermal resistance and conductivity testing of insulation products
Thermal resistance (R) and conductivity (λ) are the most fundamental performance characteristics of any thermal insulation product, indicating its effectiveness in blocking heat flow. This means that at least one, and when possible both, need to be accurately determined and declared in the DoP.
To assess thermal resistance in accordance with the most commonly applied EN 12667 standard, the specimen is placed between plates held at controlled temperatures using either a guarded hot plate (GHP) or heat flow meter (HFM) apparatus, and the steady-state heat flow through the specimen is measured. Thermal resistance (in m2K/W) and thermal conductivity (in W/mK) are then calculated from the measured heat flux and temperature difference across the specimen thickness.
To ensure reliable results, harmonized standards for factory-made thermal insulation products require at least 10 tests to be performed to determine the declared R and λ values. The values must also be calculated using the so-called 90/90 rule (90% confidence that at least 90% of products meet the declared level under typical production conditions). As thickness affects thermal resistance, the R-value is declared separately for each thickness the product is supplied in.
Reaction to fire testing of thermal insulation products
Reaction to fire performance is another critical characteristic of any building material, including thermal insulation products, as it largely determines the types of environments the product can be safely installed in without unduly accelerating the spread of flames and smoke in the event of a fire. The following tests are used to assess and classify thermal insulation products under the EN 13501-1 Euroclass system:
Class A1 (non-combustible materials): EN ISO 1182 non-combustibility test and EN ISO 1716 gross heat of combustion test
Class A2 (materials with very limited combustibility): EN ISO 1182 or EN ISO 1716, plus EN 13823 single burning item (SBI) test
Classes B, C, and D (materials with very limited to medium contribution to fire): EN 13823 SBI test and EN ISO 11925-2 ignitability test with a small flame
Class E (materials with high contribution to fire): EN ISO 11925-2 ignitability test
If no testing is performed or the pass criteria for class E are not met, the insulation product is placed in class F and considered highly flammable. Additional ratings for smoke production (s1, s2, s3) and flaming droplets (d0, d1, d2) are also assigned to products in classes A2, B, C, and D.
The fire performance of thermal insulation materials is highly dependent on material type. Mineral wool and cellular glass insulation can typically be classified in Euroclass A1 without testing if it is demonstrated that the organic matter content does not exceed 1% by weight.5 On the other end of the spectrum, plastic foam insulation (particularly EPS and XPS) is typically rated as E or F.
Dimensional stability evaluation
Dimensional stability tests are performed to ensure that thermal insulation products retain their shape and size under the temperature and humidity conditions encountered throughout their service life. Typically, the worst-case EN 1604 test after 48 hours of exposure to 70 °C and 90% relative humidity is sufficient for declaration, and stability does not need to be assessed under other conditions (including constant laboratory conditions as specified in EN 1603).
The available dimensional stability designations depend on material type. For example, EPS insulation (EN 13163) can be declared as DS(70,90)1 if the length, width, and thickness do not change by more than 1%, and as DS(70,90)5 if the changes do not exceed 5%. For wood fiber insulation (EN 13171), the maximum permitted change is 3%, corresponding to a designation of DS(70,90)3.
Chemical testing of thermal insulation products
Hazardous substances that have historically been used in the manufacture of thermal insulation products include brominated fire retardants, such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD). These are now prohibited under Regulation (EU) 2019/1021 on Persistent Organic Pollutants, with the following maximum levels for unintentional trace contamination:6
350 mg/kg for the sum of tetra-, penta-, hexa-, hepta-, and decaBDE in products that contain recovered material (the limit will be lowered to 200 mg/kg from 30 December 2027)
10 mg/kg for the sum of PBDEs in other products
100 mg/kg for HBCDD in EPS and XPS insulation containing recycled polystyrene
75 mg/kg for HBCDD in other products
Compliance with these limits can be assessed using high-performance GC-MS and LC-MS methods, such as GC-MS QQQ and LC-MS QQQ.
The new REACH restriction on formaldehyde release also applies to thermal insulation products, which are subject to the 0.080 mg/m3 limit for materials other than furniture or wood-based articles. According to European Chemicals Agency (ECHA) guidance on compliance testing, emissions from insulation materials should be measured using the EN 16516 test method.7
Our testing solutions
Measurlabs offers a range of testing services for evaluating the performance and regulatory compliance of thermal insulation products. Examples include:
Dimensional stability determination under specified temperature and humidity conditions in accordance with EN 1604
Formaldehyde and VOC release testing in accordance with EN 16516
POP testing to ensure HBCDD and PBDE concentrations do not exceed the regulatory limits
Use the form below to describe your testing needs, and one of our experts will get back to you in one business day.
References:
1 The Construction Products Regulation can refer to the new Regulation (EU) 2024/3110, or Regulation (EU) No 305/2011, which remains partly in force in parallel with the new regulation until up-to-date technical specifications have been adopted for all product groups.
2 Summary list of harmonized standards under Regulation (EU) No 305/2011 (updated February 9, 2026)
3 According to the European Organisation for Technical Assessment (EOTA) EAD database, there are currently around 50 published EADs for different types of insulation materials.
4 Article 6(3) of Regulation (EU) No 305/2011
5 Commission decision establishing the list of products belonging to Classes A ‘No contribution to fire’ without testing lists mineral wool and cellular glass as eligible materials.
6 The limits are specified in Annex I to Regulation (EU) 2019/1021.
7 Table 5 of ECHA Guidelines for the measurement of formaldehyde releases from articles and formaldehyde concentrations in the interior of vehicles (November 2025). Results from the EN 16516 test are accepted directly if the measured emissions are ≤ 0.080 mg/m3. If the result is higher, a scientifically valid correlation to the reference conditions in method EN 717-1 is required.