Description
Ceresit CT84 is the gun-applied polyurethane route in the Renders World EPS adhesives basecoats range, replacing a mixing station and a 25 kg bag with one canister — and the 850 ml pack size is what tells you which of Henkel's two CT 84 data sheets applies to it.
Where CT84 Foam Earns Its Place on a Facade
Ceresit CT84 adhesive foam 850ml canisters bond EPS and mineral wool in Ceretherm ETICS work at roughly 10 m² per can, letting anchors go in about two hours after placement. That single interval is what changes a programme, because the boards stop being the trade everyone waits on.
The sheet puts the weight difference plainly: bonding one square metre of EPS with CT 84 uses about 100 g of adhesive against 5 kg of cement mortar. Up three lifts of scaffold, that is the difference between a canister in one hand and a bagged pallet on a hoist.
- Cold-season and high-humidity work — the Express Plus sheet declares application from −10 °C and air humidity up to 100 %, with damp conditions accelerating the cure rather than stalling it.
- Insulation over insulation — the sheet names ETICS-on-ETICS renovation explicitly, where adding cement-bag weight to an existing system is the thing you are trying to avoid.
- Mixed EPS and slab elevations — boards from the EPS insulation boards range and slabs from the mineral wool insulation range are both named in scope, subject to the tensile grades below.
Why Installers Choose the Foam Route Over a Cement Bag
- Anchoring after approximately 2 hours: boards can be smoothed and doweled the same morning, and the sheet states that insulation works in Ceretherm systems can take up to five days less overall.
- Declared yield of 10 m² per canister in ETICS, rising to approximately 14 m² on foundation insulation, where the five-strip pattern uses less material per board.
- ≥ 0.08 MPa adhesion across every named substrate — concrete, EPS, mineral wool, ceramic brick, aerated concrete, OSB, coated and galvanised steel, XPS, bitumen coatings and timber all carry the same declared threshold under ETAG 004.
- Thermal conductivity of 0.040 W/mK: the sheet describes the cured adhesive as having insulating behaviour similar to foamed polystyrene or mineral wool, rather than the mineral bridge a cement dab forms.
- No water, no power, no mixing: the canister and gun are the whole kit, which is what makes the foam route workable on confined urban sites where a mixing station has nowhere to stand. The foam against cement adhesive comparison weighs the two workflows across a full elevation.
Which CT 84 Sheet Covers This Canister — Express Plus or Express STD
Henkel publishes two current CT 84 sheets under one product code, and they disagree on the figures a buyer plans around. Both were read this session. The pack size resolves it cleanly, so check the can in your hand against this table before committing to a cold-weather programme.
| What the sheet declares | CT 84 Express Plus | CT 84 Express STD |
|---|---|---|
| Packaging | 850 ml metal container | 750 ml metal bottle |
| Yield in ETICS | approx. 10 m² | 8 m² |
| Yield on foundations | approx. 14 m² | 12 m² |
| Application temperature | −10 °C to +40 °C | 0 °C to +40 °C |
| Boards named in scope | EPS and mineral wool | Expanded and extruded polystyrene |
| Dispensing | Applicator gun, valve upwards | Applicator straw, valve down |
This product is sold as an 850 ml canister, which is the Express Plus packaging line, so every figure published below is transcribed from that sheet. Where a delivered can reads Express STD on the label, plan on the stricter 8 m² yield and the 0 °C floor instead — and speak to the Renders World technical desk before scheduling sub-zero work.
Declared Data for the 850 ml Express Plus Canister
| Property | Declared value |
|---|---|
| Basis | One-component polyurethane adhesive |
| Packaging | 850 ml metal container |
| Application temperature | −10 °C to +40 °C |
| Air humidity | up to 100 % |
| Surface drying time | approx. 10 minutes |
| Hardening time | approx. 2 hours |
| Thermal conductivity | 0.040 W/mK |
| Adhesion, all named substrates | ≥ 0.08 MPa |
| Adhesion to EPS | ≥ 0.08 MPa, tear in the EPS layer |
| Consumption in ETICS systems | approx. 10 m² |
| Consumption on foundation insulation | approx. 14 m² |
| Shelf life | up to 15 months from the production date on the base |
| Storage | Cool, dry, above +5 °C, away from heat above +50 °C |
| Recommended EPS boards | White or graphite EPS meeting ETICS requirements to EN 13163 |
| Recommended wool boards | To EN 13162, TR ≥ 10, lamella TR ≥ 80 |
The tensile strength grades on that last row are the detail worth carrying to a specification: a slab has to reach TR 10, or TR 80 as a lamella, before the foam route is the manufacturer's intended one. The EPS adhesive selection guide sets that against the cement alternatives.
How to Apply CT84 — Bead Pattern, Placement Window and Anchoring
Shake the container hard for several seconds, remove the valve cap and screw it onto the gun with the valve kept upwards, then release a short bead to confirm an even dispense. Fix the starting profile before any board goes up, so the first course lands on a true datum.
Bead pattern on facades and foundations
- Facade boards: one bead around the periphery, approximately 2 cm in from the edges, plus a single strip running along the board parallel to its longer sides.
- Foundation boards: five strips parallel to the short side of the board, again about 2 cm from the edge.
- Cavities found later: where an elevation sounds hollow, pierce the board at that point and inject CT 84 through the puncture.
Placement, correction and anchoring
Place the board on the wall 2 to 4 minutes after laying the bead and press it gently with a long float. Surface flatness stays correctable with that float for up to 20 minutes from fixing, which is the forgiveness a cement bed does not offer. Anchor at around two hours, then build the reinforced layer — the basecoat and mesh reinforcement guide covers that stage, and anchors are in the insulation fixing accessories range.
Substrate checks and site conditions
Prove the wall before the first board: bond 10 × 10 cm EPS blocks in several places and pull them off by hand after two to four hours. The substrate carries the system only where the polystyrene itself tears. Keep surfaces free of frost, ice and snow in cold weather, remove hollow-sounding render, treat moss and algae and let washed walls dry fully. In strong wind or rain, scaffold sheeting is mandatory and building corners need particular attention — the weather window planning guide maps the workable months.
Certification and Fire Class — Read the System, Not the Canister
The reaction-to-fire class on this sheet belongs to complete Ceresit Ceretherm systems, not to the adhesive in the can. Quoted correctly it is genuinely useful; quoted as a product property it is wrong.
- B–s1,d0 to EN 13501-1, declared for the Ceresit Ceretherm Popular, Classic and Premium systems. A build-up assembled from other components does not inherit it.
- European Technical Assessments covering those systems: ETA 08/0309 for Popular, ETA 09/0014 for Classic and ETA 08/0308 for Premium, each with its own certificate and DoP number printed on the sheet.
- ITB-KOT-2018/0472 edition 1, a Polish national technical assessment, covers the Ceretherm Reno system used for insulation over existing insulation.
- BBA Certificate 14/5142 and Irish Agrément Certificate 09/0340 are listed on the sheet as documents of reference. Neither certificate was fetched this session, so both are named as references here rather than as this canister's own certification.
Where a project's fire strategy is the deciding factor, the facade fire requirements guide works through how a system class is assessed against building height and use under current UK guidance.
CT84 Foam Against the XPS Variant and the Cement Route
| Option | What separates it | Choose it when |
|---|---|---|
| CT84 adhesive foam, 850 ml | EPS and wool named in scope, 10 m² in ETICS | Field elevations, fast programmes, cold months |
| CT84 foam for XPS boards | Named for extruded board work | Plinth and below-DPC zones on the same job |
| Atlas Hoter U Grey, 25 kg | Cement adhesive and basecoat in one bag | Uneven walls, and where one product must do both stages |
Foam bonds; it does not level. On a wall with real undulation a notched cement bed absorbs deviation that a bead cannot, so the cement products in this collection remain the right call there. Both Hoter U grades sit alongside this product in the range, with their own scopes on their own sheets.
Ordering CT84 Foam for Your Elevation
Renders World lists Ceresit CT84 adhesive foam 850ml at £14.00 per 850 ml canister, August 2026, showing as available at that fetch. At the declared 10 m² in ETICS that is £14.00 ÷ 10 m² = £1.40/m² for the bonding stage, and on foundation work at 14 m² per can, £14.00 ÷ 14 m² = £1.00/m².
- Quantity for 100 m²: 100 m² ÷ 10 m² per canister = 10 canisters, plus a planning margin of about one can in ten for cut-arounds and part-used cans = 11.
- Pair it across the elevation: add the XPS-board CT84 variant for the plinth so one workflow runs from ground level to eaves.
- Complete the build-up: the EWI build-up guide shows where bonding sits against the layers that follow it.
FAQ — CT84 Coverage, Compatibility and Conditions
How many canisters cover 100 m²?
Ten, at the declared ETICS yield of 10 m² per canister, and eleven with a margin for cut-arounds. Foundation work goes further at approximately 14 m² per can, because the five-strip pattern lays less adhesive per board than the perimeter-plus-centre-strip facade pattern.
Can this foam bond mineral wool slabs?
Yes — the Express Plus sheet names EPS and mineral wool boards in ETICS as its scope and declares ≥ 0.08 MPa adhesion to wool. The condition is the slab grade: EN 13162 boards at TR ≥ 10, or lamella at TR ≥ 80. The Express STD sheet, which covers the 750 ml pack, names polystyrene instead, so the label matters here.
How cold can it be applied?
The Express Plus sheet declares application from −10 °C to +40 °C with humidity up to 100 %, provided the substrate carries no frost, ice or snow. All its published data was measured at +23 °C and 50 % relative humidity, so cure times stretch as the temperature drops — worth building into a winter programme rather than working to the two-hour figure.
When does a cement adhesive still win?
On walls flat enough for a bead to reach full contact, the foam saves days. Where deviation is significant, or where one product needs to serve as both adhesive and basecoat, a cement mortar does work the foam cannot. Checking the wall with a batten before ordering settles it quickly.
Does the B–s1,d0 class apply to a wall built with this adhesive?
Only where the wall is one of the Ceretherm systems the sheet names — Popular, Classic or Premium — as assessed under the relevant ETA. Substituting a board, basecoat or render from outside those systems puts the build-up outside that classification, and the project fire strategy governs from there.
How should canisters be stored?
Upright, cool and dry, above +5 °C and away from any heat source above +50 °C, with a shelf life of up to 15 months from the production date printed on the base. Bring cans indoors overnight before winter work so the first dispense of the morning is as even as the last of the afternoon.
Technical Documentation — Both Current CT 84 Sheets