Description
Specified at 160 g/m² with measured tensile strength of 1195 N/5cm warp and 1220 N/5cm weft per the Henkel TDS, the Ceresit CT325 Fibreglass Reinforcing Mesh (55 m² roll) is the heavier-duty mesh class engineered for impact-prone facade zones, plinth bands, and the high-stress EWI details where standard 150 g reinforcement reaches the limits of its mechanical envelope. Supplied through our fibreglass mesh collection, this Henkel-manufactured mesh is approved as a component in Ceresit Ceretherm EWI systems and tested to ETAG 004. Trade collection from our Southampton counter or next-working-day UK dispatch on full and pallet quantities.
What Ceresit CT325 160 g/m² Mesh Does in a UK EWI System
The Ceresit CT325 is a 160 g/m² woven fibreglass mesh with a 4.0 × 4.0 mm aperture, supplied in a 1.1 m × 50 m roll giving 55 m² nominal coverage and used to reinforce the basecoat layer of ETAG 004 ETICS systems. Its job is mechanical — distributing tensile stress across the basecoat so impact loads, thermal movement and substrate joints do not telegraph as cracks through the decorative finish. Specifiers reach for CT325 when the project documentation names it explicitly, or when the facade zone in question sits below the 2-metre impact line where heavier mesh earns its specification.
The visual identifier is the green colouring carried across Ceresit Ceretherm jobs UK-wide. After 28 days submerged in 5% sodium hydroxide per the Henkel test protocol, the mesh retains its specified strength — the alkali resistance demanded by long-service contact with cementitious reinforcing mortars. The 1.1 m roll width is the second reason CT325 appears on tall-elevation specifications: 100 mm of extra working width per sheet means fewer vertical overlaps across full-height facade runs, and that translates directly to faster install rhythm and less overlap waste.
Why Trade Specifiers Choose Ceresit CT325 for Impact Zones
- Higher tensile capacity: 1195 N/5cm warp and 1220 N/5cm weft per Henkel TDS, giving meaningful headroom over standard 150 g specifications for impact and high-stress zones.
- 1.1 m roll width: the extra 100 mm of working width compared to 1.0 m mesh reduces vertical jointing on full-height facades and cuts overlap waste on tall elevations.
- ETAG 004 tested: verified within the European Technical Approval Guideline for ETICS systems, supporting full Ceresit Ceretherm system warranties when installed inside the specified build-up.
- Verified alkali resistance: 28-day NaOH testing per manufacturer TDS confirms long-term stability in cementitious basecoat environments throughout service life.
- Named system component: the specified mesh for Ceresit Ceretherm EWI systems, removing the substitution question on warranty-supported installations.
- Slipproof, tearproof weave: the locked warp-and-weft construction stays dimensionally stable during top-down embedment, so the geometry the installer presses in is the geometry the system gets.
Technical Specifications — Ceresit CT325 Data Sheet Highlights
| Property | Value |
|---|---|
| Manufacturer | Henkel (Ceresit brand) |
| Material | Woven E-glass fibre with alkali-resistant coating |
| Mesh weight | ≥160 g/m² |
| Mesh aperture | 4.0 × 4.0 mm |
| Tensile strength — warp | 1195 N/5cm (standard conditions, per TDS) |
| Tensile strength — weft | 1220 N/5cm (standard conditions, per TDS) |
| Alkali resistance | 28 days in 5% NaOH — strength retained per TDS |
| Roll width | 1.1 m |
| Roll length | 50 m |
| Roll coverage | 55 m² nominal |
| Colour | Green (visual identifier) |
| Standard | ETAG 004 tested within ETICS systems |
How to Embed Ceresit CT325 — Notched-Trowel Method, Lap Offset, Stress Patches
Apply the prepared reinforcing mortar from the EPS adhesives and basecoats range using a notched trowel with 10–12 mm teeth, spreading evenly over the insulation board face. For mineral wool substrates, prime the board with a thin scratch coat of mortar before the main basecoat application; wool fibres absorb adhesive moisture, and the priming step prevents premature drying that would compromise mesh embedment in the next pass.
Press the mesh into the wet mortar top-down with a flat metal trowel, then immediately smooth a second mortar pass over the mesh until the weave is fully embedded and barely visible. Lap successive strips by 100 mm minimum at vertical joints, and offset the lap lines from the insulation board joints — lap lines coinciding with substrate joints concentrate stress in exactly the wrong place. The full reinforcement-layer process, including basecoat thickness windows and mesh sequencing on returns and reveals, is set out in our basecoat and mesh reinforcement layer guide. For overlap dimensions on awkward elevations and the geometry around corner beads and termination profiles, the fibreglass mesh overlap guide for UK projects is the working reference.
Installation Notes — Conditions, Substrates, Detail Reinforcement
Working window matters more with the heavier 160 g weave than with standard mesh. The denser construction takes a fraction longer to push into the wet bed, so each lift wants slightly more open time in the basecoat. Plan around an ambient working window of 5–25 °C and avoid embedment when the substrate is below 5 °C or in direct, drying sun, since premature skinning of the first basecoat pass is the most common cause of poor embedment on impact-zone facades.
At openings, embed 200 × 300 mm diagonal stress patches at roughly 45 degrees before the main mesh layer goes on. This sequence prevents the diagonal corner cracking that otherwise initiates at window and door corners within the first two heating cycles — the failure pattern explained in detail in our guide to render cracking causes and prevention. On plinth bands and the lower impact zone, Henkel's own technical guidance permits two layers of CT325 where mechanical loading is heaviest, with the second layer offset from the first to maintain continuous reinforcement coverage.
Pro Tips From UK Installers Using Ceresit CT325
The CT325 rewards a slightly different rhythm to standard mesh work. The list below is what UK applicators consistently get right on impact-zone and Ceretherm-system installs.
- Offset the lap from the board joint: mark out lap positions before cutting, so vertical laps fall a minimum of 100 mm clear of any insulation board joint behind.
- Trowel teeth, not flat spread: the notched 10–12 mm spread guarantees consistent mortar thickness for embedment; flat-troweled beds run thin in patches and leave the weave sitting proud.
- Two operatives, two passes: one bedding the mesh top-down, the second following with the closing pass while the first lift is still open — the heavier weave demands this tempo to avoid dragging.
- Pre-cut diagonal patches in 50s: batch 200 × 300 mm corner patches at the start of the day; opening corners are where rhythm breaks on a busy facade and pre-cut stock keeps the run moving.
- Trim the green to the bead line: the visible green tells you instantly whether a corner patch or lap has been missed — a final walk-round before basecoat skins over catches what the embedment lift may have left.
Is Ceresit CT325 Right for Your Project?
- Impact-zone reinforcement: the right specification for plinths, ground-floor commercial facades, and any rendered zone where mechanical contact is foreseeable.
- Standard EWI above the impact line: for full-facade reinforcement above 2 metres on standard residential EWI, the Atlas 150 g/m² mesh (50 m² roll) is the specified weight and reduces material cost without compromising system performance.
- Ceresit Ceretherm system work: the named mesh component for warranty-supported Ceretherm installations, removing the substitution question from the build-up.
- Tall elevations: the 1.1 m roll width reduces vertical jointing on full-height facade runs, cutting overlap waste compared to 1.0 m formats and easing the install rhythm.
FAQ — Ceresit CT325 Coverage, Compatibility, Ordering
What does the higher 160 g weight actually deliver in practice?
Higher tensile capacity (1195/1220 N/5cm warp/weft per TDS) and improved impact resistance once embedded. In typical service this translates to stronger performance at building corners, around openings, and on facade zones below 2 metres where mechanical contact is foreseeable. On standard mid-facade reinforcement above the impact line, the practical difference compared to a 150 g mesh is marginal — specification is driven by zone, not by a blanket preference for heavier.
How many rolls do I need per square metre of facade?
One 55 m² roll typically reinforces around 50 m² of finished facade once 100 mm vertical overlaps and corner stress patches are deducted. As a planning rule, divide measured facade area by 0.91 to estimate roll demand, then round up for offcuts.
Is CT325 compatible with non-Ceresit basecoats?
Yes. While CT325 is the named mesh for Ceresit Ceretherm system warranties, the alkali-resistant coating is formulated for embedment in any standard cementitious or polymer-modified EWI basecoat. For non-Ceretherm system installs, confirm the basecoat manufacturer's stated mesh weight and width requirement matches the CT325 specification.
How does CT325 compare to the Atlas 150 g/m² mesh?
Atlas 150 g/m² is the specified weight for general full-facade reinforcement and ships in a 1.0 m × 50 m roll (50 m² nominal). The CT325 is heavier at 160 g/m², supplied in the wider 1.1 m × 50 m roll (55 m² nominal), suited to impact-prone zones, plinth bands and projects where the Ceretherm system DoP calls for it specifically.
Can two layers of CT325 replace a heavier-weight mesh?
Yes, where the system documentation permits. Henkel's own technical guidance allows two layers of CT325 on facades and plinths exposed to higher mechanical loads as an alternative to specifying a 330 g/m² mesh class. Offset the second layer from the first to maintain continuous reinforcement and ensure the basecoat thickness accommodates the double weave.
What is the storage requirement before installation?
Store rolls flat, dry and out of prolonged sun before installation. The alkali-resistant coating is stable through normal site exposure, but extended UV on uncovered rolls is best avoided to preserve coating integrity through the storage period.
Technical Documentation — Ceresit CT325 TDS and Manufacturer Data