Description
Ceresit CT 174 pairs a silicate binder with a silicone one in a single 25 kg tub, and the fetched data sheet puts that pairing at Sd 0.14 m — vapour permeability class V1 under EN 15824 — with class W3 low water absorption beside it. Renders World lists the tub at £56.60, fetched August 2026.
Where CT174 1.5mm Performs Best on UK Walls, Soffits and Interiors
Ceresit CT174 silicate-silicone render 1.5mm is a ready-mixed thin-layer facade render declared to EN 15824, applied over a primed reinforced basecoat at roughly 2.5 kg/m², which puts about 10 m² on one 25 kg tub. It sits in the Renders World silicone render range as the hybrid-binder option, and the sheet's permitted field of use runs wider than most listings show.
- Ceretherm ETICS facades: the sheet recommends it as the facade render within Ceresit Ceretherm systems built on EPS boards and mineral wool.
- Mineral substrates: concrete over three months old and cement or lime-cement renders over 28 days old, both at 4% moisture or below.
- Reinforced layers: CT 80, CT 85, ZU and CT 190 mortars once three days old, or CT 87 after two days, each primed with CT 16.
- Interior substrates only: gypsum below 1% moisture, chipboard, gypsum-fibre board, plasterboard and sound existing paint coats.
One limit is worth planning for rather than meeting on site: for intensive dark colours the sheet restricts application to small areas such as architectural details. A deep shade therefore works best as a feature panel with a lighter body colour carrying the main elevation, which keeps the specification inside its documented field of use and still gives the facade its contrast.
Why Specifiers Choose the Hybrid Binder
- V1 permeability at Sd 0.14 m: the declared diffusion resistance is low enough that a retrofitted solid wall keeps an outward path for moisture through the finish coat.
- W3 water absorption: w ≤ 0.1 kg/m²h⁰·⁵ under the same standard, so high breathability arrives without the uptake that usually comes with it.
- Adhesion of 0.6 MPa: declared to EN 15824, well clear of the 0.08 MPa the sheet quotes for inter-layer adhesion after ageing in a system test.
- BioProtect formula: resistance to fungi, mould and algae is listed in this sheet's characteristics; the machine-applied 1.0 mm sheet lists no such formula, so the two grades are not interchangeable on a shaded north elevation.
- Hand or machine: the sheet confirms machine application is possible and names Wagner PC 15, PC 830 and SPG Baumaschinen PG 20, so one tub covers both routes.
Declared Performance and the Scope Behind Every Figure
Every value below was read from the Ceresit CT 174 data sheet fetched for this page. The scope column decides how each one may be used, because the EN 15824 and ETAG 004 lines describe different things.
| Property | Declared value | Scope |
|---|---|---|
| Base | Water dispersion of synthetic resins, mineral and pigment fillers | Product |
| Density | Approx. 1.8 kg/dm³ | Product |
| Consumption, 1.5 mm grain | Approx. 2.5 kg/m² | Product |
| Water vapour permeability | Cat. V1, Sd 0.14 m — EN 15824 | Product |
| Water absorption | Cat. W3, w ≤ 0.1 kg/m²h⁰·⁵ — EN 15824 | Product |
| Adhesion | 0.6 MPa — EN 15824 | Product |
| Thermal conductivity | ≤ 0.61 W/(m·K) — EN 15824 | Product |
| Open time | Approx. 15 min | Product |
| Resistance to rain | After approx. 24 hours | Product |
| Impact resistance | Cat. I or II — ETAG 004, depends on system | System |
| Vapour permeability | Sd ≤ 1.0 m — ETAG 004 | System |
| Declaration of Performance | No. 00269, EN 15824 | Product |
Two permeability figures sit on one sheet and they are not alternatives. The EN 15824 line, Sd 0.14 m in class V1, is the product's own declared value and is the one to compare renders on; the Sd ≤ 1.0 m under ETAG 004 belongs to the render inside a certified build-up and is the one an assessor uses on the whole wall.
Reaction to Fire Is a System Class, Never the Tub's
Reaction to fire is declared on this sheet against named Ceresit Ceretherm assemblies, so the class travels with the complete build-up and is confirmed from the assembly on the drawing. The strictest of the three is listed first.
- B-s2,d0 in Ceresit Ceretherm Universal XPS and Ceresit Ceretherm Impactum.
- B-s1,d0 in Universal EPS, Ceretherm Popular, Classic, Premium, Wool Classic and Wool Premium.
- A2-s1,d0 in Ceresit Ceretherm Universal MW.
The sheet also lists BBA Certificate No. 14/5142 among its documents of reference. That is a pointer to a system document rather than certification of the tub, and it is stated here exactly as the sheet states it.
How to Apply CT174 — Priming Gates, Mixing and the 15-Minute Window
Application runs cleanly once the substrate has cleared its age and moisture gates, and the sheet sets those gates by condition rather than by a fixed calendar. Get the primer right and the rest of the method is ordinary thin-coat work.
Priming and the Substrate Gates
- CT 16 priming paint is the specified coat, in a colour close to the render; take it from the exterior render primers range.
- Absorbent substrates get CT 17 first, then CT 16 after a minimum of two hours.
- Render when CT 16 is completely dry — the sheet sets dryness as the trigger, not a stated number of hours.
- Reinforce the basecoat with 150 g/m² Atlas mesh before priming; full preparation sequence is in the substrate preparation guide.
Mixing and Working the Wall Without a Visible Join
Stir the whole container, adding no more than 1% clean water if consistency needs it, and keep rusty tools and containers away from the material. Apply at grain thickness with a steel float held at an angle, then texture with a plastic float in circular movements — and never sprinkle the surface with water.
- Plan the stop, don't discover it: where a break is unavoidable, tape a line, render up to it, form the texture, then pull the tape with the render on it and restart from that edge.
- Staff the scaffold: enough operatives across the lifts to keep the wall wet on wet, with one batch number per elevation to hold colour.
- Conditions: +5 °C to +25 °C air and substrate, humidity below 80%, off walls in direct sun, protected until dry — rain resistance arrives after about 24 hours. Seasonal planning sits in the guide to render application timing, and the trowel method in the step-by-step thin-coat method.
What CT174 Costs on a 100 m² Elevation
A 100 m² elevation in CT174 silicate-silicone render 1.5mm carries a material figure that can be derived in full, because both operands are on file. The arithmetic is shown so it can be checked against a live quantity.
- Tub price: £56.60 per 25 kg tub, fetched August 2026.
- Coverage: 25 kg ÷ 2.5 kg/m² = 10 m² per tub, so £56.60 ÷ 10 m² = £5.66/m² at the sheet's assumed consumption.
- Quantity: 100 m² ÷ 10 m² per tub = 10 tubs, +10% for reveals, corners and waste = 11 tubs.
That figure is the render coat only — no labour, primer, basecoat, mesh or beads, and no installed rate, since labour is not something this store publishes. Build the full materials list with the render coverage calculator. Renders World ships parcels up to 25 kg next day and pallets next day or on a two-business-day economy service, kerbside.
CT174 1.5mm Against the Machine-Applied 1.0mm Variant
The two CT 174 renders share a name and a binder family but not a data sheet, and the differences are larger than the grain size suggests. Method-level trade-offs are covered in the comparison of machine and hand application.
| Variant | Grain and consumption | Declared limits |
|---|---|---|
| CT174 1.5 mm (this tub) | 1.5 mm, approx. 2.5 kg/m² | V1, Sd 0.14 m; +5 to +25 °C; max 1% water |
| CT174 Machine 1.0 mm | 1.0 mm, approx. 1.5 kg/m² | V2, 0.14 ≤ Sd ≤ 1.4 m; +5 to +30 °C; max 2% water |
The lower consumption on the machine grade is not the same finish bought cheaper. It is a thinner grain in a different vapour class, without the BioProtect formula on its characteristics list, so the two are specified for different walls rather than different budgets.
Choosing Between the Two CT174 Renders
- Take the 1.5 mm tub where V1 permeability at Sd 0.14 m and the BioProtect formula matter — solid-wall retrofit, shaded elevations and any wall where the reveals and detail are trowelled by hand.
- Take the 1.0 mm grade where a spray rig runs a large uninterrupted elevation and the finer texture suits: the machine-applied 1.0 mm variant is declared for +5 to +30 °C, a wider working window.
- Confirm the shade physically before ordering; the sheet declares the full Ceresit Colours of Nature palette without stating a count, so the render colour charts and sample books are the reliable reference.
- Reading breathability as a specification rather than a marketing word is worth the ten minutes — the background sits in the guide to vapour-permeable renders on older buildings. Renders World holds this 1.5 mm grain silicate silicone render in 25 kg tubs for next-day dispatch.
FAQ — Quantities, Priming, Dark Shades and Renovation
How many tubs cover 100 m²?
Eleven, allowing waste: at 2.5 kg/m² a 25 kg tub does 10 m², so ten tubs meet the bare area and a 10% allowance covers reveals, corners and off-cuts.
Which primer does the sheet specify?
Ceresit CT 16, in a colour close to the render. Absorbent substrates take CT 17 first and CT 16 at least two hours later, and rendering starts once CT 16 is completely dry.
Can it be used in a very dark shade?
In small areas, yes — the sheet limits intensive dark colours to details such as bands and panels, which is a documented restriction rather than a preference. Orientation and shade behaviour are covered in the guide to dark colours and solar exposure on render.
Is the 1.5 mm grain suitable for spraying?
The sheet confirms machine application and names Wagner PC 15, PC 830 and SPG Baumaschinen PG 20, so a rig set up for thin-coat work will run it at the same 2.5 kg/m² consumption.
How is an aged CT 174 facade refreshed?
By overpainting: the sheet names Ceresit CT 54, CT 48 and CT 49 as the renovation route, which keeps the existing render in service instead of stripping it.
Technical Documentation — CT 174 Data Sheets