Polystyrene EPS Grafit 50 mm — Graphite Insulation Board for Domestic Retrofit, λ 0.031 W/mK

Genderka EPS 031 Fasada Extra Plus 50 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 1.60 m²K/W — the first thickness in the range designed for standalone primary insulation duties on domestic retrofit and light-commercial projects across the UK. Each board measures 1000 × 500 mm and is supplied in packs of 12 boards covering 6.0 m², making it a practical starting point for small façade areas, parapet wrapping, and secondary-layer upgrades within external wall insulation systems. 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 50 mm it marks the transition from junction-detailing thicknesses into genuine primary-wall insulation territory — thick enough to deliver measurable heating energy savings on its own, and commonly specified for parapet returns, secondary insulation over partially filled cavities, and lightweight façade assemblies on timber-frame structures. For context on how current and emerging 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

Meaningful Warmth in a Mid-Range Thickness

• R 1.60 m²K/W From 50 mm: This board delivers over one and a half units of thermal resistance — enough to make a genuine standalone contribution to wall U-value on retrofit projects, and a significant step up from the 30 mm detailing board's R 0.95 m²K/W.
• 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 50 mm graphite board matches the thermal performance of roughly 62–63 mm of white EPS, saving over 10 mm of build-up depth on every square metre of wall.

Versatile Across Primary and Secondary Applications

• First Primary Insulation Thickness in the Range: The 50 mm board is the entry point for standalone wall insulation on projects where depth constraints prevent thicker boards — including parapet wrapping, ground-floor façade zones below first-floor projections, and flank walls where the building line is tight to the boundary.
• Secondary Layer Over Partial Cavities: Properties with partially filled cavity walls that still underperform can benefit from an external 50 mm graphite EPS overlay that creates a continuous insulated envelope, eliminating residual thermal bridges between cavity batts.

Handles and Cuts Cleanly on Site

• Bending Strength BS100 (≥ 100 kPa): Each board resists flexing during handling, cutting, and positioning — at 50 mm the board feels firm and manageable, sitting neatly on a workbench for precise saw or knife cuts without cracking.
• Tensile Strength TR100 (≥ 100 kPa): Adhesive bonds securely to the graphite-EPS surface, providing a reliable hold that withstands wind-load deflection across exposed façade elevations throughout the UK heating season.

Practical Pack Size for Targeted Areas

• 12 Boards per Pack (6.0 m²): Each pack covers a targeted façade zone — a typical parapet run, a gable triangle, or one storey of a narrow flank wall — without excess material. At 15 kg/m³ density each board weighs approximately 0.375 kg, keeping single-handed positioning straightforward at scaffold 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 thicker primary insulation layers. Where the specification requires mechanical retention, pair with the appropriate fixing plug from the insulation fixing accessories range — the LTX 90 mm fixing plug provides the correct embedment depth for a 50 mm board on standard masonry substrates.

Technical Specifications

Physical Properties

Property	Value
Manufacturer	Genderka Sp. z o.o.
Product Range	EPS 031 Fasada Extra Plus
Thickness	50 mm
Board Dimensions	1000 mm × 500 mm
Coverage per Board	0.50 m²
Boards per Pack	12
Pack Coverage	6.0 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 50 mm	1.60 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

• Parapet and Upstand Wrapping: Wrap parapet walls and roof-edge upstands with 50 mm graphite EPS to close the thermal bridge where the main wall insulation terminates at the roofline. At R 1.60 m²K/W the board provides enough resistance to bring parapet psi-values below BR 443 default thresholds, improving the dwelling's SAP calculation.
• Secondary Layer Over Partial Cavity Fill: Properties with ageing or incomplete cavity insulation benefit from a continuous external 50 mm graphite EPS layer that eliminates residual cold bridges between existing cavity batts, creating a uniform thermal envelope across the entire façade.
• Depth-Constrained Primary Insulation: On projects where boundary proximity, planning conditions, or existing architectural features restrict total build-up depth, the 50 mm board delivers meaningful standalone insulation without the projection of thicker primary boards.
• Lightweight Timber-Frame and Steel-Frame Cladding: The low density of 15 kg/m³ (approximately 0.375 kg per board) minimises dead load on lightweight structural frames, making it a practical thermal core for rendered rain-screen and direct-applied façade systems on new-build framed construction.

When an Alternative Fits Better

• Tight Junctions and Reveal Detailing: Where depth is limited to 30 mm or less at lintels and soffits, the 30 mm Grafit board at R 0.95 m²K/W fits within tighter clearances while still contributing meaningful thermal resistance at junction details.
• Full Part L Compliance on Main Walls: For the primary wall area on most retrofit and new-build projects, the 80 mm Grafit board at R 2.55 m²K/W provides the step up needed to approach or meet Approved Document L elemental U-value targets on standard masonry 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 50 mm graphite EPS board integrates into a standard EWI build-up as either a primary insulation layer or a secondary overlay. Apply adhesive from the adhesives and basecoats collection to the back face using the circumferential-and-spot method — at 50 mm, aim for a minimum 40 % contact area between the adhesive and the substrate to satisfy wind-load design requirements under BS EN 1991-1-4. Press firmly onto the prepared wall surface in a running-bond pattern, offsetting vertical joints by at least 200 mm from row to row and ensuring tight butt joints with no gaps exceeding 2 mm.

After a minimum of 24 hours' adhesive curing, secure each board with 6–8 mechanical fixings per m² from the insulation fixing accessories range. The matching plug for this thickness is the LTX 90 mm polystyrene fixing plug, which provides the correct embedment into standard masonry substrates. Once fixed, rasp or sand the outer face to create an adhesion key, then apply the reinforcing basecoat with embedded Atlas 150 g/m² fibreglass mesh for long-term crack resistance. The complete 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	30 mm Grafit	50 mm Grafit (This Board)	80 mm Grafit
Thickness	30 mm	50 mm	80 mm
λD	0.031 W/mK	0.031 W/mK	0.031 W/mK
RD	0.95 m²K/W	1.60 m²K/W	2.55 m²K/W
Pack Coverage	10.0 m²	6.0 m²	3.50 m²
Boards per Pack	20	12	7
Typical Use	Cost-effective entry, lintels	Parapets, secondary layer, light primary	Domestic retrofit, most popular UK thickness

UK Climate Performance Context

On a typical UK solid-wall property (original wall U-value around 2.1 W/m²K), adding 50 mm of graphite EPS with λ 0.031 W/mK reduces the wall U-value to approximately 0.48–0.52 W/m²K — a reduction of over 75 % in heat flow through the wall. While this falls short of the Approved Document L elemental target of 0.30 W/m²K for retrofit, it represents a substantial energy saving: for a three-bedroom semi-detached home with roughly 80 m² of exposed wall area, this improvement translates to an estimated annual heating energy saving of 3,000–4,500 kWh, depending on heating system efficiency and exposure zone. In SAP calculations, the improvement can shift a property from EPC band E into band D or from band D towards band C, supporting both comfort and resale value. For projects where 50 mm is combined as a secondary layer over existing partial cavity insulation, the composite assembly can approach U-values of 0.18–0.25 W/m²K, bringing the wall within or close to current compliance thresholds.

Trade Insight: Handling and Storage

At 50 mm the boards feel noticeably more rigid than the thinner detailing variants, making them practical to carry and position single-handed without flex or droop. Store packs flat on a level surface and under opaque sheeting — the steel-grey graphite surface absorbs solar radiation quickly, and cumulative UV exposure softens the outer bead layer over time, weakening the adhesion key for basecoat application. When cutting boards to size, a fine-tooth handsaw gives the cleanest edge at this thickness; a Stanley knife works for straight cuts but requires a second pass to get through the full 50 mm depth cleanly. For best adhesive coverage, rasp the bonding face lightly before application — the factory skin on graphite EPS is smoother than white EPS and benefits from mechanical keying. One practical approach that saves time on secondary-layer projects: dry-stack the first course along the base track to confirm alignment and level before committing adhesive, then fix the boards in sequence working upward. This avoids repositioning freshly bonded boards and keeps adhesive waste to a minimum.

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.
• Part L Contribution: At R 1.60 m²K/W, the 50 mm board makes a measurable contribution to wall assembly U-value. On secondary-layer and composite build-up projects, it helps assemblies approach or meet the elemental U-value targets set out in Approved Document L (2021 edition, England) when combined with existing insulation and appropriate finish layers.

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 U-values depend on wall construction, adhesive coverage, fixing thermal bridging, and the complete EWI system build-up. Always verify system-level U-value calculations with a competent energy assessor or building control body before specifying. Specifications are subject to manufacturer update; confirm current data at point of order.

Summary

The Genderka EPS Grafit 50 mm board delivers λ 0.031 W/mK and R 1.60 m²K/W — the first thickness in the range that serves as a standalone primary insulation layer for parapets, secondary overlays, and depth-constrained façade zones within EWI systems. Each pack of 12 boards covers 6.0 m², providing efficient material for targeted insulation areas on domestic and light-commercial projects. Need a slimmer profile for lintel and soffit detailing? The 30 mm Grafit board delivers R 0.95 m²K/W in a compact format. For full domestic retrofit performance on the main wall area, the 80 mm Grafit board steps up to R 2.55 m²K/W — the UK's most popular thickness for solid-wall and cavity over-cladding projects.

Frequently Asked Questions

How many 50 mm boards are in a pack, and what area does one pack cover?

Each pack contains 12 boards covering 6.0 m². For a typical parapet run on a semi-detached property (approximately 8–12 linear metres at 300–600 mm height), one to two packs provide full coverage with a comfortable margin for cutting waste. Adding 5–10 % to the measured area accounts for trimming around corners, services, and non-standard geometries.

Is graphite EPS recyclable, and what environmental benefit does 50 mm insulation provide?

Graphite EPS is fully recyclable through specialist polystyrene recovery programmes — off-cuts generated on site can be collected and returned for granulation and re-expansion into new products. The graphite additive does not affect recyclability. Over its installed lifespan, the energy saved by reducing heat flow through the wall with 50 mm of graphite EPS far outweighs the embodied energy of manufacture, with a carbon payback typically achieved within the first two to three heating seasons on a typical UK dwelling.

What fixing plug length pairs with the 50 mm board?

The LTX 90 mm polystyrene fixing plug is the correct match for a 50 mm board on standard masonry substrates, providing approximately 25–30 mm of embedment beyond the board thickness and adhesive layer. Install 6–8 fixings per m² in the pattern recommended for the project's wind-load zone, positioning fixings at board junctions and in the field area for even load distribution.

Can the 50 mm board meet Part L wall U-value targets on its own?

On a standard 215 mm solid brick wall, 50 mm of graphite EPS brings the assembly U-value to approximately 0.48–0.52 W/m²K. The current Approved Document L elemental target for retrofit walls is 0.30 W/m²K where technically feasible, so 50 mm alone does not achieve full compliance on most solid-wall constructions. The 50 mm board performs at its best as a secondary overlay, a parapet layer, or a depth-constrained primary layer — for full Part L compliance on the main wall area, thicknesses of 80 mm and above deliver the R-values needed to meet the target on typical UK masonry substrates.