The Benefits of Jablite Insulation: A Comprehensive Guide for UK Specifiers

The range of grades caters to diverse structural demands :  

• EPS 70: This grade is conventionally used for standard domestic loads, such as residential ground floors.

• EPS 100: This heavier grade is appropriate for non-domestic applications, including offices and schools, where slightly increased traffic and point loads are expected.

• EPS 150 to EPS 250: These medium to heavy commercial grades are suitable for industrial settings and heavy commercial applications. Higher grades, such as EPS 200, EPS 300, and even up to EPS 500, are specifically produced for substructure and basement applications where high resilience against ground pressure and heavy static loads is mandatory.  

The compressive figures at 1% nominal strain are particularly relevant for predicting long-term creep, confirming that the material will maintain its structural depth and insulating value over decades.

The table below summarises the mechanical performance characteristics of the primary Jablite EPS grades, reflecting their application suitability based on required strength.

Jablite EPS Grades and Mechanical Performance Summary

Note: Compressive strength values are equivalent to kPa.  

Jablite Product Line Overview

Jablite provides specialised product lines tailored to specific construction elements, ensuring optimal performance:

1. Jabfloor: This is the core range used primarily for insulating floors, suitable for installation below a ground supported slab, above a slab beneath a screed, or in suspended concrete floor systems.  

2. High Performance (HP/HP+): These variants incorporate carbon additives to improve thermal efficiency, enabling the achievement of lower U-values with reduced thickness. The boards are grey to distinguish them from the standard white Jabfloor product.  

3. Basement Board/Substructure Insulation: These products are typically produced in higher grades (e.g., EPS 200 and EPS 300) to meet the demands of below-ground applications, offering superior compressive strength and resistance to ground moisture penetration. These substructure boards also feature low thermal conductivity, potentially as low as 0.031 W/mK.  

All Jabfloor products are suitable for use with underfloor heating systems, as the material retains stability at temperatures up to 80°C.  

UK Building Regulations and Certification Requirements 

Compliance with Approved Document L: Thermal Efficiency

In the UK, the performance of insulation is primarily governed by Approved Document L (Part L) of the Building Regulations, which focuses on the conservation of fuel and power. This regulation mandates the use of materials that achieve specific levels of thermal performance to reduce energy demand and carbon emissions.  

Jablite's low thermal conductivity characteristics make it a viable material for assisting builders in meeting, and potentially exceeding, the standards required by Part L. This focus on highly efficient building fabric is becoming more stringent, driven by initiatives such as the Future Homes Standard, which dictates significantly reduced energy demand targets for new dwellings. To meet these progressively strict requirements, meticulous attention must be paid to the overall system U-value, including detailed mitigation of thermal bridges.  

Quality and Verification: BBA and NHBC

Due to the critical nature of insulation materials, independent third-party verification is essential. The British Board of Agrément (BBA) provides Agrément Certificates (e.g., Certificate 87/1796), which verify that Jablite products are fit for their intended use. This certification covers key performance factors including declared thermal conductivity, condensation risk, floor loading capability, and durability.  

For construction projects covered by a warranty, the certification is a crucial assurance factor. The BBA has assessed Jablite products, such as Jabfloor 70 and 100 (including the HP and HP+ variants), as satisfying or contributing to satisfying the relevant requirements of NHBC Standards, specifically Chapters 5.1 (Substructure and ground bearing floors) and 5.2 (Suspended ground floors). The existence of this BBA certification, backed by regular surveillance and formal reviews, provides specifiers with confidence that the design intent for long-term compliance with durability and thermal performance requirements will be met, assuming correct installation.  

Fire Safety Considerations: Approved Document B

Fire safety compliance is regulated by Approved Document B (Part B) of the Building Regulations. Jablite insulation is manufactured to meet specifications defined in BS EN 13163 and its reaction to fire is classified under the Euroclass system (BS EN 13501-1).  

Standard EPS materials typically receive a Euroclass F rating, while those incorporating a flame-retardant additive are generally classified as Euroclass E. Euroclass E is the lowest classification level that requires any testing, involving exposure to a small flame for a limited duration. When fire-retarded EPS is exposed to ignition energy, it has the characteristic of shrinking away from the heat source and self-extinguishing once the heat source is removed.  

Regulatory Restrictions on Combustible Materials

The fire classification of EPS imposes critical limitations, particularly in external wall applications. Current UK regulations restrict the use of combustible materials in and on the external walls of residential buildings with a storey 11 metres or more in height. For these structures, materials must achieve the highest reaction to fire classifications: Class A2-s1,d0 or A1. Since Jablite EPS typically achieves Euroclass E, its general use in the external walls of taller buildings is prohibited.  

However, specific system applications, such as Jablite Full Fill Cavity Wall Insulation (Jabfill HP), have been certified by the BBA for use in external masonry cavity walls up to 25 metres in height. This certification explicitly states that  

additional requirements apply for buildings above 12 metres in height. This highlights a complex regulatory environment: while Jablite is widely compliant and safe for internal, protected, and low-rise applications, its use in the external fabric of medium to high-rise construction demands rigorous adherence to bespoke fire engineering solutions, fire stopping, and cavity barrier protocols to satisfy Approved Document B requirements. Specifiers must differentiate carefully between internal and external envelope applications when considering the material’s fire performance.  

Best Practice Installation and Detailing for Longevity

The durability and thermal effectiveness of Jablite insulation are intrinsically linked to the quality of the installation and the meticulous attention paid to detailing.

Preparation and Cutting Techniques

Jablite EPS is notable for its ease of handling; it is lightweight and clean, and no specialised personal protective equipment (PPE) is required for cutting. The boards can be easily cut to size on site using a sharp knife or a fine-toothed saw, allowing for a precise fit within the construction element. It is essential that all boards are tightly butted together during placement to ensure continuity of the thermal envelope.  

Critical Moisture Management: Vapour Control Layers (VCLs)

Although EPS itself is moisture-resistant, managing water vapour within the structure is critical to prevent interstitial condensation, which occurs when warm, moist internal air meets colder elements within the structure. Condensation compromises thermal performance and can cause damage to other building components.  

The requirement for vapour management is governed by BS 5250 (British Standard for Moisture Control in Buildings), which dictates that materials with the highest vapour resistance must be placed on the warm side of the insulation.  

• Floor Applications: When Jablite is installed over a concrete slab and beneath a liquid screed, a suitable membrane, such as a 125μ (500 gauge) polythene sheet, must be laid over the EPS. This VCL serves the dual purpose of managing vapour diffusion and preventing the wet screed from seeping into the insulation joints.  

• Airtightness: The VCL functions effectively only when it is continuous and airtight. All joints must be thoroughly lapped and sealed using specialised airtightness tapes. Punctures caused by follow-on trades, or failure to seal joints, can allow paths for water vapour to bypass the barrier, leading to critical failure of the condensation control strategy.  

Mitigating Thermal Bridging (Cold Bridging)

Thermal bridges occur where there is a discontinuity in the insulation layer, resulting in localised heat loss that is significantly higher than through the main body of the wall or floor. These bridges severely compromise the overall thermal performance of the building, making it difficult to achieve compliant Part L U-values.  

Two key detailing methods are mandated when installing Jablite to mitigate thermal bridging:

1. Floor Perimeters: In ground-bearing or suspended floor applications, a vertical upstand of EPS insulation must be installed continuously around the entire perimeter where the floor slab meets the external walls. This technique prevents a significant heat loss path at this junction.  

2. Fixings: When securing the boards, metal fixings must be avoided, as metal is highly conductive and creates a thermal bridge across the insulation layer. Best practice requires the use of non-metallic, non-conductive fixing rods or anchors to maintain the integrity of the thermal envelope.  

Chemical Protection and Service Integration

Jablite EPS is chemically inert under normal conditions, but it is susceptible to degradation from specific substances. EPS is soluble in aromatic, halogenated solvents, and ketones, and must therefore be shielded from contact with hydrocarbons and strong solvents using an appropriate protective membrane.  

A particularly important consideration on site is the interaction with electrical cables. EPS should never be permitted to come into direct contact with PVC-sheathed electrical cables. The plasticiser within the PVC can migrate into the EPS, leading to the chemical degradation of the insulation and subsequent embrittlement of the cable sheath. To prevent this, cables must be physically protected, typically by enclosing them in a conduit or ensuring an adequate air gap is maintained.  

The table below provides a checklist of essential detailing requirements for Jablite installation:

Best Practice Checklist for Installation and Detailing

Environmental Profile and Sustainability Credentials

Jablite EPS demonstrates a robust environmental profile, which is increasingly important for sustainable construction in the UK. The product achieves an A+ rating in the Building Research Establishment (BRE) Green Guide to Specification, placing it among the materials with the highest environmental performance in certain application classes.  

The material’s composition contributes positively to sustainability objectives. Jablite is non-toxic, biologically inert, and will not promote mould growth or attract vermin. From a material life-cycle perspective, Jablite EPS is 100% recyclable, assisting builders in meeting construction waste reduction goals.  

Furthermore, Jablite HP insulation is manufactured with zero Ozone Depletion Potential (ODP) and a low Global Warming Potential (GWP) of less than 5. These characteristics confirm that the material selection supports responsible environmental practices without contributing to ozone depletion.  

Conclusions and Summary Recommendations

Jablite insulation offers a versatile, durable, and cost-effective Expanded Polystyrene solution that is highly suited to the thermal demands of contemporary UK construction. Its core technical strengths lie in its consistently low thermal conductivity, high compressive strength across a range of applications (EPS 70 up to EPS 500), and proven longevity equivalent to the structure’s intended life.

For successful specification and long-term compliance with UK Building Regulations, specifiers must exercise careful diligence beyond simply selecting the required U-value. The effectiveness of the insulation system is conditional upon three critical factors:

1. Correct Grade Selection: Matching the specific EPS grade (e.g., EPS 70 for domestic, EPS 100+ for commercial) to the projected structural load is essential to prevent material creep and maintain system stability over decades.

2. Thermal Continuity: Meticulous detailing to mitigate cold bridging, especially through the implementation of perimeter upstands and the mandatory use of non-conductive fixings, is required to prevent the installed U-value from being significantly worse than the designed U-value.

3. Moisture Management: Strict adherence to Vapour Control Layer protocols, including placing the barrier on the warm side of the insulation and ensuring all joints and penetrations are sealed and protected, is necessary to prevent interstitial condensation and preserve the material’s long-term effectiveness, as verified by BBA certification.

While Jablite is a foundational material for energy efficiency (Part L), its standard fire classification (Euroclass E) necessitates rigorous review of Approved Document B, especially regarding external wall applications above 11 metres in height.

UK Legal Disclaimer

This report has been prepared for informational and educational purposes only. The technical details provided are derived from general industry information and relevant UK standards (such as BS EN 13163, Approved Document L, and Approved Document B). This content does not constitute professional advice, design specification, or a guarantee of suitability for any particular project. Building Regulations, fire safety legislation, and associated guidance (including BBA certification and NHBC Standards) are subject to frequent change. All users, especially professional specifiers, contractors, and architects, must consult the most current version of the Building Regulations applicable to their jurisdiction and project type, and obtain independent advice from a qualified construction professional, structural engineer, or fire engineer before selecting, installing, or specifying any construction material, including Jablite insulation products. The user assumes all responsibility for verifying the compliance and safety of materials and systems as installed.