Description
For UK solid-wall retrofit projects where a standard 215 mm brick wall needs to reach the 0.33 to 0.36 W/m²K U-value band without modifying window reveals or rainwater goods, EPS Grafit 80 mm delivers R 2.55 m²K/W at λD 0.031 W/mK — the volume domestic-retrofit thickness in the Genderka EPS 031 Fasada Extra Plus range, supplied at 7 boards per pack covering 3.5 m².
What EPS Grafit 80 mm Does in a UK EWI System
EPS Grafit 80 mm is a graphite-enhanced polystyrene primary-insulation board certified to EN 13163, delivering R 2.55 m²K/W at λD 0.031 W/mK in a 1000 × 500 mm panel that serves as the thermal core of a standard UK domestic EWI build-up. On a typical 215 mm solid brick wall (original U-value around 2.1 W/m²K), 80 mm of graphite EPS brings the assembly to roughly 0.33 to 0.36 W/m²K — a reduction of more than 80 percent in wall heat flow, sitting marginally above the 0.30 W/m²K Approved Document L retrofit target but at the depth most UK Building Control officers accept as compliant under the "technically feasible" provision. The board sits within the wider graphite EPS insulation range, which covers every façade zone from reveal strips through to Passive House main-wall thicknesses.
What makes 80 mm the volume specification is not the headline R-value but the practical detail. The total system build-up reaches roughly 95 to 100 mm from the original wall face — within the tolerance most existing window reveals, fascia boards, and downpipe standoffs can accommodate without replacement. The thicker 90 mm and 100 mm options deliver more thermal performance but pull more secondary trades into the programme, which is why 80 mm holds its place as the default depth across UK semi-detached and terraced retrofit programmes.
Why Specifiers Choose EPS Grafit 80 mm for UK Domestic Retrofit
- R 2.55 m²K/W in an 80 mm profile: over 80 percent reduction in heat flow through a typical 215 mm solid brick wall, bringing the assembly U-value into the 0.33 to 0.36 W/m²K band — the practical compliance target for the majority of UK retrofit programmes under current Approved Document L guidance.
- Preserves window-reveal proportions and rainwater goods: the total 95 to 100 mm system build-up keeps within the tolerance most existing reveals, fascia boards, and downpipe standoffs accept, reducing secondary-trade involvement and protecting project programme.
- Seven boards per pack, 3.5 m² coverage: a practical ordering unit that matches a storey-height strip approximately 1.75 m wide — the right granularity for surveyed-elevation procurement on semi-detached and terraced retrofit work.
- Annual heating energy saving of 4,500 to 6,000 kWh: on a three-bedroom semi-detached with roughly 80 m² of treated wall area, the heat-flow reduction translates to meaningful annual bill savings, subject to heating system efficiency and exposure zone.
- Identical mechanical spec across the range: CS70, BS100, and TR100 carry across every Grafit thickness, so the running-bond pattern and 6 to 8 fixings per m² used at parapets and reveals transfer directly to the main-wall layer.
- Light single-handed handling at scaffold height: at approximately 0.6 kg per board and 4.2 kg per pack, the 80 mm panel positions cleanly without hoisting equipment — practical for two-person retrofit crews on standard scaffold.
- UK warehouse stock for next-working-day dispatch: the volume thickness ships in the same consignment as detailing and parapet boards, so the main-wall material arrives with the rest of the EWI order rather than as a separate back-order.
Thermal Specifications — λ, R-Value, Reaction to Fire
| Property | Value |
|---|---|
| Declared Thermal Conductivity (λD) | 0.031 W/mK |
| Thermal Resistance (RD) at 80 mm | 2.55 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 | ≈ 100 mm at λ 0.038 W/mK |
| Solid Brick Wall U-Value (215 mm) | ≈ 0.33–0.36 W/m²K with 80 mm overlay |
R 2.55 m²K/W places the 80 mm board firmly in mainstream primary-insulation territory. The resulting wall U-value of 0.33 to 0.36 W/m²K on standard solid brick sits marginally above the 0.30 W/m²K Approved Document L retrofit elemental target — accepted as compliant under the "technically feasible" provision on most domestic retrofit programmes where stepping up to 90 mm or 100 mm would require disproportionate modification of existing reveals and rainwater goods. The U-value calculation guide for wall insulation thickness walks through the calculation method behind these figures.
Physical Specifications — Density, Mechanical Strength, Dimensions
| Property | Value |
|---|---|
| Manufacturer | Genderka Sp. z o.o. |
| Product Range | EPS 031 Fasada Extra Plus |
| Thickness | 80 mm |
| Board Dimensions | 1000 × 500 mm |
| Coverage per Board | 0.50 m² |
| Boards per Pack | 7 |
| Pack Coverage | 3.50 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 80 mm Performs Best — Solid Wall, Cavity Over-Clad, Lightweight Façades
The 80 mm board earns its place in four specific scenarios across UK domestic and light-commercial work. Solid-wall retrofit on pre-1919 to 1970s housing stock sits at the top of the list: uninsulated 215 mm solid brick walls with original U-values in the 1.6 to 2.1 W/m²K band consistently reach the 0.33 to 0.36 W/m²K assembly band with 80 mm of graphite EPS — the result that most retrofit funding schemes and PAS 2035 specifications target as the practical compliance threshold.
Cavity-wall over-cladding follows as the second high-volume use case. Properties with partially filled or failed cavity insulation benefit from an external 80 mm graphite EPS layer that creates a continuous insulation envelope independent of cavity condition, sidestepping the diagnostic uncertainty that comes with cavity inspection on older stock.
- Solid-wall domestic retrofit (pre-1919 to 1970s): the primary use case — single-leaf solid brick brought from U-values of 1.6 to 2.1 down to 0.33 to 0.36 W/m²K.
- Cavity-wall over-cladding: external thermal upgrade independent of the cavity assembly condition, useful where cavity diagnosis is uncertain.
- Parapet, gable triangle, and exposed slab edges: 80 mm carries enough depth to wrap thermal-bridge zones where heat loss concentrates above the main wall plane.
- Lightweight timber-frame and steel-frame façades: low dead load at 0.6 kg per board makes 80 mm a practical thermal core for direct-applied and rendered rain-screen new-build systems.
How EPS Grafit 80 mm Fits Into a Full EWI System
Within the layered build-up, the 80 mm board forms the primary thermal layer between substrate and basecoat. Apply adhesive from the EPS adhesives and basecoats range using the circumferential-and-spot method — at this thickness, aim for at least 40 percent contact area between adhesive and substrate to satisfy wind-load design under BS EN 1991-1-4. Press onto the prepared substrate 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. The boards retain a brief repositioning window in the first few minutes of contact before the bond sets.
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 110 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 alkali-resistant fibreglass mesh in fresh basecoat. The full layer-by-layer sequence is covered in the complete EWI system build-up and layers explained guide; the wind-load fixing pattern is detailed in the insulation board fixing pattern and spacing guide.
How EPS Grafit 80 mm Compares to Sibling Thicknesses
| Property | 50 mm Grafit | 80 mm (this board) | 90 mm Grafit |
|---|---|---|---|
| Thickness | 50 mm | 80 mm | 90 mm |
| λD | 0.031 W/mK | 0.031 W/mK | 0.031 W/mK |
| RD | 1.60 m²K/W | 2.55 m²K/W | 2.90 m²K/W |
| Solid-Brick U-Value | ~ 0.48–0.52 W/m²K | ~ 0.33–0.36 W/m²K | ~ 0.31–0.33 W/m²K |
| Boards per Pack | 12 | 7 | 6 |
| Pack Coverage | 6.0 m² | 3.5 m² | 3.0 m² |
| Typical Use | Parapets, secondary overlay, depth-constrained | Volume domestic retrofit, main wall | Definitive Part L target on solid brick |
The three thicknesses bracket the transition from depth-constrained primary to definitive Part L compliance. The 50 mm board earns its place where depth rules out 80 mm; the 90 mm board crosses the 0.30 W/m²K target for projects where documented numerical pass matters more than reveal-detail preservation. The 80 mm board sits at the volume specification point — the balance between thermal gain and practical installation detail that most UK retrofit programmes accept as the compliance default.
How EPS Grafit 80 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 EPS matrix absorbs negligible bulk moisture; BS100 bending strength accommodates thermal movement between summer surface temperatures and winter night-time lows without cracking at the joint between adjacent boards. At 80 mm the board carries enough mass to remain stable on the wall during the 24-hour adhesive cure window without propping, simplifying the installation sequence on whole-elevation work.
Wind-load design becomes a primary specification 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 baseline density steps up to 9 to 11 fixings per m² at corner and edge zones — the system designer's wind-load calculation sets the exact pattern for each elevation. The TR100 tensile strength of the board comfortably accommodates the resulting uplift loads in standard UK exposure.
Pro Tips From UK Installers Using EPS Grafit 80 mm
Five habits separate a fast, clean 80 mm install from one that drags on the programme. None of them appear on the technical data sheet, and all of them come from the way experienced UK applicators handle the volume retrofit thickness.
- Dry-stack the base course before adhesive: set the first row of 80 mm boards on the base track without bonding, check for level and continuous bearing across the full base course, then commit to adhesive working upward in running-bond. Catches base-track alignment issues before they propagate up the elevation.
- Rasp the bonding face lightly: the factory skin on graphite EPS is smoother than white EPS. A quick mechanical key with an EPS rasp lifts the adhesive contact area cleanly above 40 percent without chasing it with extra mortar.
- Use the brief repositioning window: at 80 mm the board retains a few minutes of repositioning capability after adhesive contact. Use it to true vertical alignment against a laser line, particularly on the first board of each course where small drifts compound across the elevation.
- 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 wind-load uplift more efficiently than even-spaced field patterns.
- Stagger horizontal joints across openings: avoid continuous horizontal joints aligned with window heads or sills. A full board running across the opening prevents cracking telegraphing through to the finished render at the most stressed locations on the elevation.
Handling and Storage on Site
The 80 mm board is the thickness most UK EWI installers handle every working day — firm, rigid, and comfortable to carry single-handed at scaffold height. Stack packs flat on a level surface and under opaque sheeting, both to prevent UV softening of the graphite finish and to keep 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 gives the cleanest edge at this thickness; a Stanley knife works for straight cuts but needs a firm second pass to clear the full 80 mm depth.
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 for use 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 DoP referencing the specific Genderka factory of origin (Bydgoszcz, Ostrów Mazowiecka, Oświęcim, Brzeziny, or Wschowa), 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 80 mm Right for Your Project?
- Specify EPS Grafit 80 mm for solid-wall domestic retrofit on pre-1919 to 1970s housing stock where the wall assembly target sits in the 0.33 to 0.36 W/m²K band and preserving window-reveal proportions matters as much as raw R-value.
- Use for cavity-wall over-cladding on properties with partially filled or failed cavity insulation, where an external continuous layer sidesteps the diagnostic uncertainty of inspecting the original cavity assembly.
- Drop to the 50 mm Grafit board at parapets, secondary overlays, and depth-constrained zones where 80 mm cannot fit without disproportionate modification of existing details.
- Step up to the 90 mm Grafit board for projects requiring a definitive numerical pass below the 0.30 W/m²K Approved Document L retrofit target — for example, on grant-funded schemes requiring documented compliance.
- 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 insulation requirements guide for new-build work and Approved Document L for retrofit programmes.
Declared thermal values (λD, RD) are stated per EN 13163 and the Genderka manufacturer technical data sheet. Actual installed U-values depend on wall construction, adhesive coverage, fixing thermal bridging, and the complete EWI system build-up. Verify system-level U-value calculations with a competent energy assessor or Building Control before specification.
What to Order Next — Pack Sizes, Lead Times, Compatible Components
Two boards per square metre at 0.50 m² coverage each — a three-bedroom semi-detached property with around 80 m² of exposed wall area typically requires 23 to 25 packs of 7 boards, including 5 to 10 percent cutting margin around reveals, soffits, and service penetrations. Pair the order with the matching adhesive from the EPS adhesives and basecoats range and the LTX 110 mm fixing plug for mechanical retention on standard masonry. UK warehouse stock supports next-working-day dispatch on full-pack quantities ordered before midday, so the main-wall material arrives with the rest of the EWI consignment rather than as a separate delivery.
FAQ — EPS Grafit 80 mm Coverage, Compatibility, Installation
How many 80 mm boards do I need per square metre, and how many packs for a semi-detached house?
Each board covers 0.50 m², so 2 boards per m² of wall area are required. A three-bedroom semi-detached property with approximately 80 m² of exposed wall area (after deducting windows and doors) typically needs 23 to 25 packs of 7 boards, allowing 5 to 10 percent for cutting waste around reveals, soffits, and service penetrations. The technical desk can sense-check pack quantities against a surveyed elevation drawing before dispatch.
Which fixing plug length matches the 80 mm board on standard masonry?
The LTX 110 mm polystyrene fixing plug is the correct match for an 80 mm board on standard masonry substrates, providing approximately 25 to 30 mm of embedment beyond the board thickness 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, with higher densities at corner and edge zones on exposed elevations.
Does the 80 mm board meet Part L on a 215 mm solid brick wall?
The 80 mm board brings a typical 215 mm solid brick wall to approximately 0.33 to 0.36 W/m²K — marginally above the 0.30 W/m²K Approved Document L retrofit target. Many Building Control officers accept the 80 mm specification as compliant under the "technically feasible" provision when stepping up to 90 mm or 100 mm would require disproportionate modification of existing reveals and rainwater goods. For grant-funded schemes requiring a documented numerical pass below 0.30 W/m²K, the 90 mm Grafit board closes the remaining gap.
Can the 80 mm board be used to over-clad properties with existing cavity insulation?
Cavity-wall over-cladding is a common application for 80 mm graphite EPS, particularly on properties where original cavity insulation has failed, settled, or was never fully installed. The external 80 mm layer creates a continuous insulated envelope independent of cavity condition, sidestepping the diagnostic uncertainty of inspecting the cavity itself. The resulting composite U-value depends on the existing cavity assembly, but typically reaches the 0.20 to 0.28 W/m²K band on a partially insulated cavity wall.
How does the 80 mm compare to the 50 mm and 90 mm Grafit variants?
All three share λD 0.031 W/mK and identical mechanical properties (CS70, BS100, TR100). The difference is R-value and the application band: the 50 mm variant gives R 1.60 m²K/W at 12 boards per pack for parapets and depth-constrained zones, 80 mm gives R 2.55 m²K/W at 7 boards per pack as the volume domestic retrofit specification, and the 90 mm variant reaches R 2.90 m²K/W at 6 boards per pack for projects requiring a definitive Part L pass below 0.30 W/m²K.
Does an 80 mm build-up require modifying window reveals and rainwater goods?
The total system build-up at 80 mm (insulation plus basecoat and render) reaches approximately 95 to 100 mm from the original wall face. On most standard UK window installations this depth allows the existing reveal to accommodate the insulation return without new oversills or frame extensions, and typically fits within the tolerance of existing fascia boards, gutter brackets, and downpipe standoffs. The practical effect is fewer secondary trades on the programme — one of the reasons 80 mm holds its place as the volume retrofit specification.
What fire classification rules apply when specifying 80 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 in accordance with current Approved Document B guidance. For taller buildings or higher-risk façades where the fire strategy requires 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 80 mm TDS, DoP, Certificates