Description
Graphite-enhanced façade board at the deep end of the range: 180 mm carrying a declared thermal resistance of 5.60 m²K/W at λD 0.032 W/mK. Renders World stocks it for solid-wall build-ups where insulation depth is set by calculation rather than by habit, and where board flatness across a large elevation is worth paying attention to.
What the 180mm Graphite Board Does in a Wall Build-Up
Polystyrene EPS Grafit 180mm is a graphite-enhanced expanded polystyrene board declared to EN 13163:2012+A1:2015, fitted as the insulation layer of a bonded and mechanically fixed render system on solid masonry walls. It is the second-deepest board in the graphite EPS insulation boards range, and the depth is the whole point of specifying it.
Depth changes the detailing more than it changes the fitting. At 180 mm the reveal, sill and verge details all move outward, the plug schedule steps up, and the base of the wall needs a board declared for that zone — so the board arrives on site as part of a decided build-up rather than as a loose commodity.
The manufacturer's technical card declares the board for these uses:
- Walls in external render insulation systems — the primary declared application, and the one this board is stocked for.
- Walls with cladding and a ventilated air gap — the same board behind a rainscreen rather than a render finish.
- Lintels and reveals — declared, though thinner boards from the same grade usually serve the reveal itself.
- Ring beams as permanent shuttering under render, and soffits within render insulation systems — the two details where continuity of insulation is easiest to lose and easiest to design in.
Declared Thermal and Mechanical Performance
| Property | Declared value | Document and scope |
|---|---|---|
| Declared thermal conductivity (λD) | 0.032 W/mK | EPS 032 Fasada Extra graphite façade board — technical card and declaration of performance |
| Declared thermal resistance (RD) at 180 mm | 5.60 m²K/W | Declared resistance table, 180 mm thickness row, same board |
| Bending strength | ≥ 75 kPa (class BS75) | Same board, declared under EN 13163:2012+A1:2015 |
| Tensile strength perpendicular to faces | ≥ 80 kPa (class TR80) | Same board, declared under EN 13163:2012+A1:2015 |
| Reaction to fire | Class E | Declared for the board under EN 13163:2012+A1:2015 |
| Compressive stress at 10 % deformation | Not declared | Declaration of performance, Bydgoszcz plant |
| Water absorption and water vapour transmission | Not declared | Declaration of performance, Bydgoszcz plant |
Three properties a façade board is often assumed to have are left undeclared here, and that is useful rather than awkward: compressive strength, water absorption and vapour transmission carry no declared value, so this board belongs above the damp-proof course where those properties are not being asked of it, and the plinth and below-ground zone takes a board declared for immersion and load instead.
Reaction to fire class E is declared for the board, not for the wall that contains it. The class of a finished external wall is a property of the whole build-up and comes from the system holder's tested specification and the project fire strategy. Where a project calls for non-combustible insulation, the mineral wool insulation range is the route, and the trade-offs at comparable depths are set out in the graphite EPS and mineral wool facade comparison.
Checking Which Graphite Grade You Are Ordering
Two graphite façade grades from the same manufacturer circulate against boards of this description, and they are separate products with separate documents. The figures above are taken from the stricter of the two, so a calculation built on them holds either way.
The alternative grade, EPS 031 Fasada Extra Plus, declares λD 0.031 W/mK, 5.80 m²K/W at 180 mm, bending strength ≥ 100 kPa and tensile strength ≥ 100 kPa. Dimensional tolerances are identical across both grades, so the difference is confined to conductivity, resistance and the two strength classes.
Confirm the grade on the delivery note before a U-value calculation is signed off. Between 0.032 and 0.031 W/mK the declared resistance at 180 mm moves from 5.60 to 5.80 m²K/W — 0.20 m²K/W — and declared bending strength moves from 75 to 100 kPa.
Worth knowing how the paperwork works: the manufacturer's declaration of performance is issued on the manufacturer's own responsibility under System 3 assessment, with a notified laboratory named for the testing. No product certificate sits behind these figures, so the document to ask Renders World for is the declaration of performance for the plant that supplied the batch — not a certificate, which does not exist for this board.
Why Specifiers Choose Graphite EPS at This Depth
- 5.60 m²K/W in a single declared layer — one board depth, one declared value, no interlayer arithmetic to defend in a calculation.
- λD 0.032 W/mK from graphite bead chemistry — lower declared conductivity than standard white façade EPS, so the resistance target is met in less depth than a white board of the same grade family would need.
- Declared resistance rather than derived resistance — the manufacturer publishes a value per thickness, which is the figure a calculation should use; dividing thickness by lambda gives a slightly different answer and is not the declared route.
- Tight thickness tolerance at ± 1 mm — class T1, which keeps the basecoat thickness even across a large elevation instead of chasing steps between boards.
- ≥ 75 kPa bending strength — enough stiffness for the board to be handled and offered up at depth without flexing out of plane during bonding.
- Same system components as the thinner boards — adhesives, basecoats and mesh are unchanged across the range, so only the plug schedule and the perimeter details move with depth.
- Stocked as part of a full build-up — Renders World holds the adhesive, mesh and fixing components alongside the boards, which keeps a deep build-up on one delivery rather than three.
Board Format and Tolerances, and What They Mean on Site
| Dimension or class | Value | What it means when fitting |
|---|---|---|
| Board format | 1000 × 500 mm | 0.50 m² per board, and a size one person can offer up at height |
| Pack | 3 boards, 1.5 m² | Small take-off unit, so quantities land close to the measured area |
| Thickness tolerance | T1, ± 1 mm | Even basecoat thickness across the elevation |
| Length and width tolerance | L2 and W2, ± 2 mm | Tight closed joints without packing |
| Squareness | Sb2, ± 2 mm/m | Courses stay square off a level base track |
| Flatness | P5, ± 5 mm | The tolerance to check against a straightedge before rasping |
| Dimensional stability, normal conditions | DS(N)2, ± 0.2 % | Boards hold their size in store |
| Dimensional stability, elevated temperature and humidity | DS(70,-)2, ≤ 2 % | The figure behind the sun-protection instruction below |
Flatness at ± 5 mm is the tolerance that decides how much rasping a wall needs, so it is worth a straightedge across the first course before any adhesive is mixed. Board format and pack quantity here are the ones published on this product page; the manufacturer's card lists other formats as standard, so the format is confirmed on the order rather than assumed from the card.
How to Fit the Boards Into an EWI Build-Up
The manufacturer's card is specific about sequence and about what may touch the board, and those instructions are the backbone of a build-up that performs as calculated. The full layer-by-layer sequence, base track upwards, is mapped in the EWI system build-up guide.
- Bond with an adhesive dedicated to graphite boards. The card permits cement-based adhesives, polyurethane foam adhesives, or water-dispersion bituminous compounds intended for grey graphite boards, each used to its own manufacturer's instructions. Graphite-compatible products sit in the EPS adhesives basecoats range.
- Rasp the face immediately before bonding. The card recommends abrading the board surface directly before it goes on the wall, which is what lifts adhesion of the bedding mortar.
- Leave mechanical fixing until at least 24 hours after bonding. Plugging earlier than that is outside the card's instruction; the pattern, count and plug length come from the system holder's schedule, and the components sit in the insulation fixing accessories range.
- Build the reinforced layer once fixing is complete. Basecoat with fibreglass reinforcing mesh embedded, then the specified finish — the card treats the reinforced layer as a required step over the boards rather than an option.
One prohibition carries real weight on a mixed site: nothing containing organic solvents goes near these boards, which rules out certain sealants, primers and cleaning products stored on the same scaffold. Keeping solvent-based products on a separate lift is the simplest way to protect the boards, and it costs nothing to organise.
Where 180mm Boards Belong on UK Walls
Solid masonry walls are where this depth earns its place, because the wall itself contributes little resistance and the insulation layer does the work. The board is declared for render systems and for ventilated cladding, which covers most of what a deep retrofit or a new masonry build asks of it.
Depth is chosen by calculation, not by rule of thumb. A declared 5.60 m²K/W is one input to a wall build-up figure that also depends on the existing construction, the finishes and the thermal bridges around openings — the method is set out in the U-value and insulation thickness guide, and the direction of travel for new-build fabric standards in the Future Homes Standard 2026 guide. No board thickness satisfies a regulation on its own; the build-up does.
Two zones need a different board rather than this one:
- Plinth and below the damp-proof course — water absorption and compressive strength are undeclared for this board, so that zone takes a board declared for immersion and loading.
- Projects requiring non-combustible insulation — a declared class E board is not the answer there, and mineral wool slabs are.
How 160mm, 180mm and 200mm Compare
| Board | Declared RD | Choose it when |
|---|---|---|
| 160mm graphite board | 5.00 m²K/W | The calculation is met with 0.60 m²K/W less resistance and reveal depth is tight |
| 180mm graphite board (this page) | 5.60 m²K/W | The target sits between what 160 mm and 200 mm deliver |
| 200mm graphite board | 6.25 m²K/W | A further 0.65 m²K/W is needed and the detailing can absorb the extra depth |
The steps are modest and worth quantifying before ordering: 5.60 − 5.00 = 0.60 m²K/W going down to 160 mm, and 6.25 − 5.60 = 0.65 m²K/W going up to 200 mm. Both sit within the same declared resistance table, so the three boards can be compared directly without mixing documents.
Storing and Handling Grey Boards on Site
Graphite boards ask for one discipline that white boards do not, and the manufacturer's card is unambiguous about it. Getting it right takes a tarpaulin and five minutes at the end of each lift.
- Shield the boards from direct sunlight, in store and on the wall. The card requires this without qualification because of the steel-grey colour, and the ≤ 2 % dimensional stability class at elevated temperature is the figure behind it — a board that has sat in the sun is a board whose joints have moved.
- Keep them away from ignition sources and from solvent vapours during transport and storage, as the card instructs.
- Protect against mechanical damage — corners and edges are what a deep board loses first, and they are exactly what closes the joints.
- Bond boards on the day they are rasped — the freshly abraded face is what the card's adhesion recommendation depends on.
Ordering, Delivery and What to Pair With the Boards
Take the surveyed wall area in m², divide by the pack area and add a cutting allowance agreed on the take-off for reveals, soffits and service penetrations. At 1.5 m² per pack, 100 m² of wall works out at 100 ÷ 1.5 = 66.7, so 67 packs before that allowance.
Delivery terms are set at store level rather than per product. Renders World processes orders the same day where stock is available, ships pallets on a next working day service or a two business day economy service, and delivers from its Southampton base by company van locally on qualifying orders. All deliveries are kerbside, so a pallet of polystyrene EPS Grafit 180mm boards needs someone on site to move it and somewhere dry to put it — pallets are wrapped but not weatherproof.
- Adhesive and basecoat — a graphite-compatible product from the adhesives and basecoats range, quantity to the adhesive manufacturer's own consumption figure.
- Mesh — reinforcing mesh for the layer over the boards, with the overlap taken from the mesh manufacturer's sheet.
- Fixings — plug type and length from the system holder's schedule, ordered against the confirmed board thickness.
- Next step — compare the full range of thicknesses and confirm the grade before ordering, on the graphite EPS board range page.
FAQ — Quantities, Compatibility, Fixings and Fire
How many packs cover a 100 m² elevation?
Sixty-seven, from 100 ÷ 1.5 m² per pack, before the cutting allowance agreed on your take-off. Packs of three boards keep the over-order small on irregular elevations, which is one advantage of the 1000 × 500 mm format over full-size boards.
Which adhesives may be used with graphite boards?
The technical card names cement-based adhesives, polyurethane foam adhesives and water-dispersion bituminous compounds, in each case a product dedicated to grey graphite boards and used to its own instructions. Anything carrying organic solvents is excluded, and that exclusion covers ancillary products stored beside the boards as well as what goes on the wall.
What plug length suits a 180 mm board?
Plug length is a manufacturer table value read against board thickness, the adhesive bed and the embedment the substrate needs, so it comes from the system holder's fixing schedule rather than from a rule of thumb. Pattern and spacing work the same way, and both are covered in the fixing pattern and spacing guide.
Can these boards go below the damp-proof course?
Water absorption and compressive strength are undeclared for this board, so the plinth and below-DPC zone is served by a board declared for immersion and loading. Running the graphite board down to a plinth board at DPC level is the normal detail, and it keeps each board inside the performance its own document declares.
Is 180 mm worth it over 160 mm?
The step adds 0.60 m²K/W of declared resistance for 20 mm of depth, which is decided by the wall build-up calculation rather than by preference. Where the calculation is already satisfied at 160 mm, the shallower board keeps reveal and sill details simpler.
How long can the boards stay on the scaffold before rendering?
Covered and out of direct sunlight, they hold their declared dimensions in store; the constraint is exposure rather than time, because the grey face is what the card requires protecting. Bonding, fixing and the reinforced layer following on promptly is the sequence the card describes, and it is the one that keeps joints tight.
What does class E mean for a rendered wall?
Class E is declared for the board on its own. A rendered external wall is assessed as a complete build-up, so the figure that matters for compliance comes from the system holder's tested specification and the project fire strategy, and mineral wool is specified where non-combustible insulation is required.
Technical Documentation