POLYSTYRENE EPS GRAFIT 50mm

For UK projects where wall U-value must drop without committing to full main-wall thickness, EPS Grafit 50 mm delivers R 1.60 m²K/W at λD 0.031 W/mK as the first standalone primary thickness in the Genderka EPS 031 Fasada Extra Plus range, supplied at 12 boards per pack covering 6 m² and meeting EN 13163 with full DoP traceability.

What EPS Grafit 50 mm Does in a UK EWI System

At R 1.60 m²K/W and λD 0.031 W/mK, EPS Grafit 50 mm is the graphite-enhanced polystyrene board certified to EN 13163 that marks the transition from junction-detailing to standalone wall insulation in a UK external wall insulation build-up. On a typical 215 mm solid brick wall, 50 mm of graphite EPS brings the assembly U-value down to roughly 0.48 to 0.52 W/m²K, a reduction of more than 75 percent, falling short of the 0.30 W/m²K Approved Document L retrofit target on its own but delivering most of the gain on parapets, secondary overlays, and depth-constrained zones. The board belongs to the wider graphite EPS insulation board range, which covers every façade zone from reveal strips through to Passive House main-wall thicknesses.

The role is specific. Specify 50 mm where boundary proximity, planning conditions, or existing architectural features restrict total build-up depth, or as a secondary overlay over partial cavity insulation that no longer performs. On those projects the board delivers a measurable EPC shift, typically band E into band D or band D towards band C, while keeping the elevation projection inside the constraints that ruled out a thicker primary specification.

Why Specifiers Choose EPS Grafit 50 mm for UK Depth-Constrained Walls

• R 1.60 m²K/W in a 50 mm profile: over one and a half units of thermal resistance, the first thickness in the range carrying genuine standalone main-wall duty rather than detailing or composite roles, and a clean step up from the 30 mm board's R 0.95 m²K/W.
• Twelve boards per pack, 6 m² coverage: one pack matches a typical parapet run, a gable triangle, or one storey of a narrow flank wall, practical procurement for the zones where 50 mm earns its place rather than for whole-elevation work.
• Identical mechanical spec across the range: CS70, BS100, and TR100 carry over from every Grafit thickness, so the adhesive bed pattern and 6 to 8 fixings per m² from the main wall transfer directly to the 50 mm zone with no schedule change.
• Heating-energy saving of 3,000 to 4,500 kWh per year: on a three-bedroom semi-detached with roughly 80 m² of exposed wall treated at 50 mm, the reduction in fabric heat loss translates to meaningful annual bills saved, subject to heating efficiency and exposure zone.
• Lightweight handling on framed structures: at around 0.375 kg per board, the 50 mm panel imposes minimal dead load on timber-frame and steel-frame cladding rails, making it a practical thermal core for direct-applied façade systems.
• UK warehouse stock for next-working-day dispatch: Renders World ships the 50 mm thickness in the same consignment as detailing and thicker primary boards, so parapet and secondary-layer material arrives with the rest of the EWI order.
• Full DoP traceability for compliance audits: each batch carries a factory-specific Declaration of Performance, supporting Building Control sign-off and PAS 2035 retrofit audits.

Thermal Specifications — λ, R-Value, Reaction to Fire

Property	Value
Declared Thermal Conductivity (λD)	0.031 W/mK
Thermal Resistance (RD) at 50 mm	1.60 m²K/W
Reaction to Fire (EN 13501-1)	Euroclass E
Classification String (EN 13163)	T1-L2-W2-Sb2-P5-BS100-DS(N)2-DS(70,-)2-TR100
Equivalent White EPS Thickness	≈ 62 mm at λ 0.038 W/mK
Solid Brick Wall U-Value (215 mm)	≈ 0.48–0.52 W/m²K with 50 mm overlay

 

R 1.60 m²K/W places the 50 mm board in genuine primary-insulation territory rather than junction-detailing territory, where the contribution flows through the assembly U-value rather than the psi-value at a single junction. On a 215 mm solid brick wall the resulting U-value sits in the 0.48 to 0.52 W/m²K band, a substantial gain but short of the 0.30 W/m²K Approved Document L retrofit elemental target, which is why 50 mm reads as a parapet, secondary-overlay, and depth-constrained thickness rather than a default main-wall specification. The U-value calculation guide for wall insulation thickness covers how each insulation layer feeds into the dwelling fabric calculation.

Physical Specifications — Density, Mechanical Strength, Dimensions

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
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)
Colour	Steel grey (graphite)
Standard	EN 13163:2012+A1:2015

Where EPS Grafit 50 mm Performs Best — Parapets, Secondary Layers, Tight Geometry

The 50 mm board earns its place in four zones of a UK EWI build-up, all defined by the gap between detailing thicknesses and full main-wall primary insulation. Parapet and roof-edge upstands lead: where the main wall insulation terminates at the roofline, the parapet becomes a continuous thermal bridge running the full length of the dwelling. Wrapping it with 50 mm of graphite EPS brings that junction below the BR 443 default psi-values and protects the SAP improvement delivered by the main wall insulation below.

Secondary overlays come next. On properties with ageing or incomplete cavity-wall insulation that still underperforms, a continuous external 50 mm layer eliminates residual cold bridges between existing cavity batts and creates a uniform thermal envelope across the façade. The composite assembly of partial cavity plus external 50 mm can reach U-values in the 0.18 to 0.25 W/m²K band on the right substrate, bringing the wall within or close to current compliance thresholds without the depth of a full external retrofit.

• Parapet and upstand wrapping: closing the thermal bridge at the roof edge where main wall insulation terminates.
• Secondary overlay on partial cavity fill: eliminating residual bridges between existing cavity batts on a continuous external layer.
• Depth-constrained primary insulation: standalone main-wall duty where boundary proximity, planning conditions, or architectural features rule out thicker boards.
• Lightweight timber-frame and steel-frame cladding: thermal core for rendered rain-screen and direct-applied façade systems on new-build framed construction.

How EPS Grafit 50 mm Fits Into a Full EWI System

Within the layered build-up, the 50 mm board installs as a primary insulation layer either on bare substrate or laminated over existing wall finishes. Apply adhesive from the EPS adhesives and basecoats range using the circumferential-and-spot method; at 50 mm and above this pattern is the standard adhesive route, aiming for at least 40 percent contact area between adhesive and substrate to satisfy wind-load design under BS EN 1991-1-4. Press the board firmly onto the prepared wall in a running-bond pattern, offsetting vertical joints by at least 200 mm row to row with tight butt joints and no gaps exceeding 2 mm.

After a minimum 24 hours of adhesive cure, secure each board with 6 to 8 mechanical fixings per m² from the fixing accessories range. The matching plug at this thickness is the LTX 90 mm polystyrene fixing plug, which delivers 25 to 30 mm of embedment beyond the board and adhesive layer into standard masonry. Once fixed, rasp the outer face to create a basecoat key, then embed fibreglass mesh in fresh basecoat. The full layer-by-layer sequence is set out in the complete EWI system build-up and layers guide, and the wind-load fixing pattern is detailed in the insulation board fixing pattern and spacing guide.

How EPS Grafit 50 mm Compares to Sibling EPS Boards

Variant	Key Spec	When to Choose
EPS Grafit 30 mm	R 0.95 · U ~0.65 · 20/pack	Lintel, soffit, composite top-up
EPS Grafit 50 mm (this board)	R 1.60 · U ~0.50 · 12/pack	Parapet, secondary overlay, tight primary
EPS Grafit 80 mm	R 2.55 · U ~0.34 · 7/pack	Standard domestic retrofit main wall

 

The three thicknesses bracket the transition from cost-effective entry through to mainstream retrofit specification. The 30 mm board sits clearly in junction and composite-layer territory, and the 80 mm board is the volume domestic retrofit thickness for the main wall on most semi-detached UK stock. The 50 mm board is the bridge between them, a genuine primary thickness that earns its place specifically where the geometry rules out 80 mm and above.

How EPS Grafit 50 mm Performs in UK Weather — Moisture, Frost, Wind

The board's W2 water absorption classification and DS(70,-)2 dimensional stability hold declared performance through UK seasonal cycling. The closed-cell graphite matrix absorbs negligible bulk moisture, and the BS100 bending strength accommodates thermal movement between summer surface temperatures and winter lows without cracking at the joint with adjacent boards or at the base track. At 50 mm the board carries enough mass to remain stable on the wall during the 24-hour adhesive cure window, reducing the propping discipline needed on thinner detailing boards.

Wind-load performance becomes a real design consideration at this thickness. On exposed elevations in BS EN 1991-1-4 wind zones 4 and 5, the 6 to 8 fixings per m² density may step up to 9 to 11 fixings per m² in corner and edge zones, with the system designer's wind-load calculation setting the exact pattern. The TR100 tensile strength of the board comfortably accommodates the resulting uplift loads.

Pro Tips From UK Installers Using EPS Grafit 50 mm

Five habits separate a tight, callback-free 50 mm install from one that develops adhesion issues at the second-year inspection. None appear on the technical data sheet, and all come from the way experienced UK applicators handle the first true primary-thickness board in the range.

• Dry-stack the base course before adhesive: set the first row of 50 mm boards on the base track without bonding, check for level and continuous bearing, then commit to adhesive working upward in a running-bond pattern. Saves repositioning freshly bonded boards.
• Rasp the bonding face lightly: the factory skin on graphite EPS is smoother than white EPS, so a quick mechanical key with a rasp lifts the adhesive contact area cleanly above the 40 percent minimum without chasing it with extra mortar.
• Fine-tooth handsaw for clean edges: at 50 mm a fine-tooth saw produces a cleaner edge in one pass than a knife, which needs a second scoring pass at this depth and tends to leave a ragged face that compromises butt-joint adhesion.
• Plug pattern follows board joints first: position the first fixing at the cross-joint between four boards, then the field-area fixings in the running-bond rhythm. Concentrating plugs at joints carries the wind-load uplift more efficiently than even-spaced field patterns.
• Stagger the parapet wrap from the wall course: when wrapping a parapet, offset the parapet board joints from the main-wall board joints by at least 250 mm. Continuous joints at the roof-edge corner are the single most common cracking initiation point on parapet installations.

Handling and Storage on Site

The 50 mm board feels noticeably more rigid than the thinner detailing variants, so packs stack neatly without distortion and lift cleanly from pallet to platform. Keep packs flat on a level surface and under opaque sheeting, both to prevent UV softening of the graphite finish and to hold boards at ambient temperature for predictable adhesive open-time. Lift packs by the strapping or by supporting the long edges rather than the short ends to avoid creasing the outer boards in transit. A fine-tooth handsaw remains the cleanest cutting tool at this thickness; a hot-wire cutter works for repetitive panel runs when fed at a steady rate.

Certifications and Compliance — EN 13163, Euroclass E, BS EN 1991-1-4

• EN 13163:2012+A1:2015: the harmonised European standard for factory-made expanded polystyrene in buildings, covering declared thermal conductivity, dimensional tolerances, mechanical strength, and water absorption.
• Reaction to Fire — Euroclass E: typically suitable within EWI systems on residential buildings below 18 metres, where the project fire strategy permits Euroclass E with approved fire-barrier detailing under current Approved Document B guidance.
• CE Marking and Declaration of Performance: each production batch carries a factory-specific DoP, supporting full traceability for Building Control inspections and PAS 2035 retrofit audits.
• Wind-load design under BS EN 1991-1-4: the 6 to 8 fixings per m² baseline density is set by the project wind-load calculation, with higher densities applied at corner and edge zones in exposed locations under current UK practice.

Is EPS Grafit 50 mm Right for Your Project?

• Specify EPS Grafit 50 mm for parapet wrapping and roof-edge upstands where the main wall insulation needs a continuous extension over the parapet to close the thermal bridge at the roofline.
• Use as a secondary overlay over partial cavity insulation where the existing assembly underperforms and a continuous 50 mm external layer eliminates residual cold bridges between cavity batts.
• Drop to the 30 mm Grafit board for lintel, soffit, and composite top-up duty where depth is constrained below 50 mm and standalone primary-layer performance is not required.
• Step up to the 80 mm Grafit board for standard domestic retrofit on the main wall area, the UK's most popular thickness for solid-wall and cavity over-cladding projects, with U-value performance in the 0.34 to 0.37 W/m²K band on standard brickwork.
• Switch to mineral wool slabs where the project fire strategy requires non-combustible A1-rated insulation across the whole build-up, typically on residential buildings above 18 metres.
• Confirm thickness against the dwelling target using the Future Homes Standard 2026 requirements guide for new-build work and Approved Document L for retrofit programmes.

What to Order Next — Pack Sizes, Lead Times, Compatible Components

One pack of 12 boards covers 6 m² of parapet, secondary-overlay, or targeted primary insulation, so one to two packs typically match a parapet run or single elevation zone on a semi-detached property. Pair the order with the matching adhesive from the EPS adhesives and basecoats range and the LTX 90 mm fixing plug for mechanical retention on standard masonry substrates. UK warehouse stock supports next-working-day dispatch on full-pack quantities ordered before midday, so the 50 mm material arrives with the rest of the EWI consignment rather than as a separate delivery.

FAQ — EPS Grafit 50 mm Coverage, Compatibility, Installation

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

A pack contains 12 boards, each 1000 × 500 mm, giving 6.0 m² of total coverage. For a typical parapet run of 8 to 12 linear metres at 300 to 600 mm height on a semi-detached property, one to two packs provide full coverage with a 5 to 10 percent allowance for cutting waste around corners, services, and non-standard geometries.

Which fixing plug length matches the 50 mm board?

The LTX 90 mm polystyrene fixing plug is the correct match for a 50 mm board on standard masonry, providing approximately 25 to 30 mm of embedment beyond the board and adhesive layer, within the minimum embedment band most UK wind-load calculations work to. Install 6 to 8 fixings per m² in the pattern set by the project wind-load zone, positioning fixings at board cross-joints first and then 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 to 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 meet the target on most solid-wall constructions. The board performs at its best as a parapet layer, secondary overlay, or depth-constrained primary specification; for full Part L compliance on the main wall area, thicknesses of 80 mm and above deliver the R-values needed on typical UK masonry substrates.

How does the 50 mm board work as a secondary overlay on existing cavity insulation?

On properties with ageing or incomplete cavity-wall insulation, an external 50 mm graphite EPS overlay eliminates residual cold bridges between existing cavity batts and creates a continuous insulated envelope. The composite U-value depends on the existing cavity assembly: a partially insulated cavity at around 0.55 W/m²K combined with external 50 mm can approach the 0.18 to 0.25 W/m²K band, bringing the wall within or close to current compliance thresholds without the depth of a full external retrofit.

How does the 50 mm compare to the 30 mm and 80 mm Grafit variants?

All three share λD 0.031 W/mK and identical mechanical properties (CS70, BS100, TR100). The difference is R-value and application band: the 30 mm gives R 0.95 m²K/W at 20 per pack as the cost-effective entry thickness for lintels and composite top-ups, the 50 mm gives R 1.60 m²K/W at 12 per pack as the first standalone primary thickness for parapets and depth-constrained zones, and the 80 mm reaches R 2.55 m²K/W at 7 per pack as the UK's volume domestic retrofit specification for main-wall work.

Is the 50 mm board suitable for timber-frame and steel-frame cladding systems?

At approximately 0.375 kg per board, the 50 mm panel imposes minimal 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. Detailing must allow for vapour-open performance of the wall assembly behind the insulation, so confirm the breather-membrane and airtightness layer specification with the system designer before bonding boards to a framed substrate.

What fire classification rules apply when specifying 50 mm graphite EPS in the UK?

The board carries a Euroclass E reaction-to-fire classification under EN 13501-1 and is typically suitable for residential buildings below 18 metres, where the project fire strategy permits Euroclass E with approved fire-barrier detailing under current Approved Document B guidance. For taller buildings or higher-risk façades requiring non-combustible A1-rated insulation, mineral wool replaces EPS across the build-up. Confirm classification with the designer and Building Control at design stage to avoid substitutions on site.

Technical Documentation — EPS Grafit 50 mm TDS, DoP, Certificates

• Genderka EPS 031 Fasada Extra Plus — Declaration of Performance (PDF)
• Genderka EPS 031 Fasada Extra Plus — Manufacturer Product Page and Technical Data