Polystyrene EPS Grafit 30 mm — Cost-Effective Graphite Insulation Board, λ 0.031 W/mK

Genderka EPS 031 Fasada Extra Plus 30 mm is a graphite-enhanced expanded polystyrene insulation board delivering a declared thermal conductivity of λD 0.031 W/mK and thermal resistance of R 0.95 m²K/W — the cost-effective entry thickness for primary insulation duties on lintels, soffits, and lightweight build-up layers within external wall insulation systems across the UK. Each board measures 1000 × 500 mm and is supplied in packs of 20 boards covering 10.0 m², balancing generous yield against manageable pack dimensions for on-site handling. Browse the full selection of graphite EPS insulation boards to match every zone of your façade build-up to the right thickness.

Certified to EN 13163:2012+A1:2015 with the classification string T1-L2-W2-Sb2-P5-BS100-DS(N)2-DS(70,-)2-TR100, this board shares the same graphite bead technology and mechanical properties as every variant in the Genderka EPS 031 Fasada Extra Plus family. At 30 mm it occupies a practical sweet spot — thick enough to provide meaningful standalone thermal resistance on lintels, ring beams, and secondary insulation layers, yet compact enough to avoid encroaching on window-reveal depths or soffit clearances. For context on how the evolving UK energy standards influence insulation thickness choices across the building envelope, see the Future Homes Standard 2026 and its insulation requirements.

Key Benefits and Performance Advantages

Nearly One Full Unit of R-Value in 30 mm

• R 0.95 m²K/W From a Compact Board: At just 30 mm thick, this board delivers close to a full unit of thermal resistance — enough to make a measurable difference on lintels, soffits, and secondary layers where thinner boards fall short but space constraints rule out the heavier primary-wall thicknesses.
• Graphite-Enhanced λ 0.031 W/mK: Integrated graphite particles reflect infrared radiation within each cell, delivering approximately 20 % better insulation than standard white EPS of the same thickness. A 30 mm graphite board matches the thermal performance of a 37–38 mm white EPS board, saving valuable build-up depth on every junction detail.

Versatile Across Multiple Application Zones

• Entry-Level Primary Insulation: The 30 mm board serves as the starting point for standalone insulation duties — thick enough to contribute genuine energy savings on lintels, ring beams, and ceilings where thinner detailing boards are insufficient, yet slim enough to keep total system depth manageable on projects with tight architectural tolerances.
• Composite Build-Up Layer: Bond a 30 mm board to a thicker primary slab to achieve non-standard total depths — for example, 80 mm plus 30 mm creates 110 mm where a single board of that thickness is unavailable, giving precise control over U-value calculations.

Handles and Cuts Cleanly on Site

• Bending Strength BS100 (≥ 100 kPa): Each board resists flexing during handling, cutting, and positioning, making it practical to work with around complex lintel geometry and at scaffold height without cracking or snapping.
• Tensile Strength TR100 (≥ 100 kPa): Adhesive bonds securely to the graphite-EPS surface, holding the board firmly in place even at exposed soffits and lintels subject to wind pressure throughout the UK heating season.

Efficient Pack Size for Junction and Secondary Work

• 20 Boards per Pack (10.0 m²): A single pack covers lintel and soffit detailing across a typical domestic façade with margin for cutting waste. At 15 kg/m³ density each board weighs approximately 0.225 kg, keeping single-handed positioning straightforward at height.

Drops Straight Into Standard EWI Build-Ups

• Compatible With All Standard EWI Adhesives and Finishes: Bond this board using cement-based or polyurethane foam adhesives from the EPS adhesives and basecoats range, then complete with basecoat, mesh, and render following the same build-up sequence as the main wall area. Where the specification requires mechanical retention, pair with the appropriate fixing plug from the insulation fixing accessories range.

Technical Specifications

Physical Properties

Property	Value
Manufacturer	Genderka Sp. z o.o.
Product Range	EPS 031 Fasada Extra Plus
Thickness	30 mm
Board Dimensions	1000 mm × 500 mm
Coverage per Board	0.50 m²
Boards per Pack	20
Pack Coverage	10.0 m²
Density	15 kg/m³
Colour	Steel grey (graphite)
Compressive Strength (CS)	≥ 70 kPa
Bending Strength (BS)	≥ 100 kPa (BS100)
Tensile Strength (TR)	≥ 100 kPa (TR100)
Dimensional Stability — Normal	± 0.2 % (DS(N)2)
Dimensional Stability — 70 °C	≤ 2 % (DS(70,-)2)
Reaction to Fire	Class E (EN 13501-1)
Standard	EN 13163:2012+A1:2015

Thermal Performance

Property	Value
Declared Thermal Conductivity (λD)	0.031 W/mK
Thermal Resistance (RD) at 30 mm	0.95 m²K/W
Classification String	EPS EN 13163 T1-L2-W2-Sb2-P5-BS100-DS(N)2-DS(70,-)2-TR100

Best Use Scenarios

Ideal Applications

• Lintel and Ring-Beam Insulation: Wrap exposed concrete lintels and ring beams with 30 mm graphite EPS to close thermal bridges at these dense structural elements. At R 0.95 m²K/W the board delivers enough standalone resistance to make a measurable SAP-calculation improvement without adding excessive bulk above window heads.
• Ceiling and Soffit Primary Layer: Apply to the underside of concrete or timber soffits as a single-layer primary insulation where depth is limited. The 30 mm profile fits beneath standard fascia-board heights while providing nearly three times the R-value of the thinnest 10 mm reveal board.
• Secondary and Equalising Layer: Bond over an uneven substrate or existing render carrier board to create a flat, thermally enhanced surface ready for basecoat and mesh. Adding 30 mm of graphite EPS to an existing wall assembly contributes almost a full unit of thermal resistance to the overall U-value calculation.
• Composite Thickness Build-Up: Layer with thicker primary boards to achieve precise non-standard insulation depths — 80 mm plus 30 mm gives 110 mm, or 100 mm plus 30 mm gives 130 mm, allowing fine-tuned U-value compliance without waste.

When an Alternative Fits Better

• Tight Reveals and Narrow Returns: Where less than 30 mm of clearance is available between the insulated wall plane and the window or door frame, the 20 mm Grafit board at R 0.60 m²K/W fits without encroaching on the glazing line or restricting opening operation.
• Primary Wall Insulation for Part L Compliance: For the main wall area on retrofit or new-build projects, the 50 mm Grafit board at R 1.60 m²K/W provides the step up into primary insulation territory, with thicknesses of 80 mm and above needed for full Part L compliance on most wall constructions.
• High-Rise or Non-Combustible Requirements: Where Euroclass A1 fire rating is mandated, the mineral wool insulation range provides non-combustible slabs compliant with Building Safety Act façade requirements for buildings above 18 metres.

System Integration

The 30 mm graphite EPS board integrates into a standard EWI build-up as either a standalone junction layer or a secondary insulation element. Apply adhesive from the adhesives and basecoats collection to the back face using the full-bed buttering method for boards up to 30 mm — full-face coverage maximises the adhesive bond area and prevents voids behind the relatively slim profile. Press firmly onto the prepared lintel, soffit, or substrate surface, ensuring tight butt joints between adjacent boards with no gaps exceeding 2 mm.

Where the project specification requires mechanical retention, select the appropriate fixing plug from the insulation fixing accessories range — at 30 mm board thickness, the shortest plug in the range provides suitable hold with adequate substrate embedment. Once bonded and (where specified) fixed, apply the reinforcing basecoat with embedded Atlas 150 g/m² fibreglass mesh, wrapping the mesh continuously from the main wall plane around any junction returns to create a monolithic crack-resistant surface. The full layer-by-layer build-up sequence — from substrate preparation through to the decorative render finish — is detailed in the EWI system build-up layers guide.

Comparison Table — Genderka EPS Grafit Variants

Property	20 mm Grafit	30 mm Grafit (This Board)	50 mm Grafit
Thickness	20 mm	30 mm	50 mm
λD	0.031 W/mK	0.031 W/mK	0.031 W/mK
RD	0.60 m²K/W	0.95 m²K/W	1.60 m²K/W
Pack Coverage	15.0 m²	10.0 m²	6.0 m²
Boards per Pack	30	20	12
Typical Use	Soffits, lintels, secondary layer	Cost-effective entry thickness	Primary insulation, domestic retrofit

UK Climate Performance Context

At R 0.95 m²K/W, the 30 mm board sits at the threshold between detailing-grade and primary insulation performance. Applied to a bare concrete lintel (localised U-value ≈ 3.5 W/m²K), it reduces that element's heat loss by approximately 55–60 % — noticeably more than the 40–45 % achieved by 20 mm. In SAP calculations, insulated lintels and soffits lower the linear thermal transmittance (psi-value) at wall-to-opening and wall-to-roof junctions, and the 30 mm board's near-unit R-value provides enough resistance to bring most standard concrete lintel junctions below the default psi-values published in BR 443. For a three-bedroom semi-detached home, fully insulating lintels and soffits at 30 mm can improve the energy performance certificate by 2–4 SAP points, providing meaningful progress towards EPC band C. Where 30 mm is used as a secondary layer over an already-insulated main wall, the total system U-value improves in proportion, keeping the overall assembly well within Part L targets for both new-build and retrofit scenarios.

Trade Insight: Handling and Storage

The 30 mm board is the thinnest variant that sits firmly in a stack without noticeable flex, so storage is straightforward — keep packs flat on a level surface and under opaque sheeting to protect the steel-grey graphite surface from UV exposure. Cumulative sunlight softens the outer bead layer over time, even on overcast UK days, so covering packs immediately on delivery gives the best adhesive bond later. When cutting to lintel or soffit dimensions, a sharp long-blade Stanley knife gives a clean through-cut in a single confident pass; at 30 mm the blade reaches comfortably through the full depth without needing a second scoring pass. For best edge quality on composite build-ups, cut the 30 mm board first, then dry-fit against the primary board before applying adhesive — this ensures the combined thickness matches the target depth precisely at every opening. One practical time-saver on domestic projects: measure all lintel and soffit zones during the survey, pre-cut the entire 30 mm allocation at ground level, and label each piece by elevation and opening number before lifting to scaffold height.

Certifications and Compliance

• EN 13163:2012+A1:2015: Harmonised European standard for factory-made expanded polystyrene products used in buildings, covering declared thermal conductivity, dimensional tolerances, and mechanical strength properties.
• Reaction to Fire — Euroclass E: Suitable for use within EWI systems on buildings up to 18 m in height when combined with approved fire-barrier detailing at each floor level, in accordance with Approved Document B and Building Safety Act guidance.
• CE Marking and DoP: Each production batch carries a Declaration of Performance referencing the specific Genderka factory of origin (Bydgoszcz, Ostrów Mazowiecka, Oświęcim, Brzeziny, or Wschowa), supporting full traceability for Building Control inspections.
• Junction Detailing Compliance: Insulating lintels and soffits with graphite EPS is recommended under Approved Document L and the conventions in BR 443 to reduce linear thermal transmittance at critical junctions, supporting improved overall dwelling fabric energy efficiency.

Technical Disclaimer

All thermal values stated are declared (λD, RD) per EN 13163 and manufacturer technical data sheet (Genderka karta techniczna nr W31FEP, July 2024). Actual installed performance depends on substrate condition, adhesive application method, and the complete EWI system build-up. Confirm current specifications with the manufacturer or your project energy assessor before specifying. Data is subject to manufacturer update; verify at point of order.

Summary

The Genderka EPS Grafit 30 mm board delivers λ 0.031 W/mK and R 0.95 m²K/W — nearly a full unit of thermal resistance in a compact profile that serves as the cost-effective entry thickness for standalone insulation duties on lintels, soffits, and secondary layers within EWI systems. Each pack of 20 boards covers 10.0 m², providing efficient material for junction detailing and build-up layering across a typical domestic project. Need a slimmer profile for tight soffits and lintels? The 20 mm Grafit board delivers R 0.60 m²K/W in a narrower format. For primary wall insulation duties, the 50 mm Grafit board steps up to R 1.60 m²K/W — the first thickness in the range designed for standalone domestic retrofit performance.

Frequently Asked Questions

How many 30 mm boards are in a pack, and what area does one pack cover?

Each pack contains 20 boards covering 10.0 m². For lintel and soffit detailing on a three-bedroom semi-detached property, a single pack typically covers all junction zones with a comfortable margin for cutting waste. Adding 5–10 % to the measured area accounts for trimming around complex profiles, services, and non-standard opening sizes.

Is graphite EPS recyclable, and what environmental benefit does 30 mm insulation at junctions provide?

Graphite EPS is fully recyclable through specialist polystyrene recovery programmes — off-cuts from lintel and soffit trimming can be collected on site and returned for granulation and re-expansion into new products. At 30 mm, the board closes thermal bridges with nearly a full unit of R-value, meaning less energy is needed to maintain comfortable indoor temperatures. Over a 25-year lifecycle, insulating junctions at this thickness can save several tonnes of CO₂ per dwelling by reducing cumulative heating demand.

Does a 30 mm board require mechanical fixings, or is adhesive alone sufficient?

For most lintel and soffit applications, a full-bed adhesive bond is sufficient when the board is propped or temporarily supported until the adhesive cures — typically 24 hours. At approximately 0.225 kg per board, the gravity load on a horizontal adhesive joint is minimal. Where the project specification or Building Control explicitly requires mechanical retention, a short fixing plug provides supplementary hold, provided the substrate behind the board offers at least 25 mm of embedment depth into sound masonry or concrete.

Can I use the 30 mm board as the primary wall insulation to meet Part L?

The 30 mm board provides R 0.95 m²K/W, which is best suited to junction detailing and secondary insulation duties rather than standalone main-wall insulation. Approved Document L wall U-value targets — 0.26 W/m²K for new build and 0.30 W/m²K for retrofit where feasible — require substantially thicker insulation on the main wall area. The 30 mm board performs at its best as a lintel, soffit, and composite build-up layer that complements thicker primary boards of 80 mm and above, which deliver the R-values needed for full Part L compliance.