Description
Measured at 1195 N/5cm warp and 1220 N/5cm weft per the Henkel data sheet, Ceresit CT325 160 g/m² Fibreglass Reinforcing Mesh is the heavier-duty reinforcement class for impact-prone facade zones, plinth bands and the high-stress EWI details where standard 150 g mesh reaches the limit of its mechanical envelope. Supplied on a 1.1 m × 50 m roll for 55 m² nominal coverage, it is the named mesh component for Ceresit Ceretherm systems on plinths, ground-floor zones and tall elevations.
What Ceresit CT325 160 g/m² Mesh Does in a UK EWI System
Ceresit CT325 is a 160 g/m² woven fibreglass mesh with a 4.0 × 4.0 mm aperture, supplied on a 1.1 m × 50 m roll for 55 m² nominal coverage, 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 finish. Stocked through the Renders World fibreglass mesh range, it is the roll specifiers reach for below the 2-metre impact line.
The green colouring is the visual identifier carried across Ceretherm jobs UK-wide, and it earns its keep on site: a final walk-round shows instantly whether a corner patch or lap has been missed before the basecoat skins over. After 28 days submerged in 5% sodium hydroxide per the Henkel protocol, the mesh retains its specified strength, the alkali resistance that long-service contact with cementitious mortars demands. The 1.1 m width is the second reason it appears on tall-elevation specs, since the extra 100 mm per sheet means fewer vertical overlaps up a full-height run.
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 mesh for impact and high-stress zones.
- 1.1 m roll width: the extra 100 mm of working width over 1.0 m mesh reduces vertical jointing on full-height facades and cuts overlap waste, so tall elevations install with fewer strips per storey.
- Verified alkali resistance: 28-day NaOH testing per manufacturer TDS confirms long-term stability in cementitious basecoat environments through the system 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, alkali-resistant coating |
| Mesh weight | ≥ 160 g/m² |
| Mesh aperture | 4.0 × 4.0 mm |
| Tensile strength — warp | 1195 N/5cm (per TDS) |
| Tensile strength — weft | 1220 N/5cm (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 with a notched trowel of 10–12 mm teeth, spread evenly over the board face. On mineral wool substrates, prime with a thin scratch coat first; wool fibres draw moisture from the adhesive, and priming prevents the premature drying that would compromise embedment in the next pass.
Press the mesh into the wet mortar top-down with a flat metal trowel, then close immediately with a second pass until the weave is barely visible. Lap successive strips by 100 mm minimum at vertical joints and offset the lap lines from the insulation board joints, because laps coinciding with substrate joints concentrate stress in exactly the wrong place. The full reinforcement-layer method, basecoat thickness windows and detailing around reveals sit in the basecoat and mesh reinforcement layer guide and the fibreglass mesh overlap guide, which own the step-by-step depth this page summarises.
Installation Notes — Conditions, Substrates, Detail Reinforcement
Working window matters more with the 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 window of 5–25 °C, and hold off when the substrate is below 5 °C or in direct drying sun, since premature skinning of the first pass is the most common cause of poor embedment on impact-zone facades.
At openings, bed 200 × 300 mm diagonal stress patches at roughly 45° before the main mesh layer. This sequence heads off the diagonal corner cracking that otherwise initiates at window and door corners within the first two heating cycles, the pattern set out in the guide to render cracking causes and prevention. On plinth bands, Henkel's own guidance permits two layers of CT325 where mechanical loading is heaviest, the second offset from the first to keep reinforcement continuous.
Pro Tips From UK Installers Using Ceresit CT325
The CT325 rewards a slightly different rhythm to standard mesh. 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 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, whereas a flat-troweled bed runs thin in patches and leaves the weave proud.
- Two operatives, two passes: one bedding the mesh top-down, the second following with the closing pass while the lift is still open, because the heavier weave demands that tempo to avoid dragging.
- Pre-cut diagonal patches in fifties: batch 200 × 300 mm corner patches at the start of the day, since opening corners are where rhythm breaks on a busy facade.
- Read the green before it skins: the visible green tells you at a glance whether a corner patch or lap has been missed, so a final walk-round catches what the embedment lift left behind.
How Ceresit CT325 Compares to the Atlas 150 g/m² Mesh
Renders World's technical desk specifies these two rolls by facade zone rather than by a blanket preference for heavier mesh. The table below places this roll against its nearest sibling so you can match the weight to the exposure.
| Variant | Key Spec | When to Choose |
|---|---|---|
| Ceresit CT325 160 g/m² (55 m²) | 160 g/m² · 1.1 m × 50 m | Plinths, impact zones, Ceretherm-specified systems |
| Atlas Mesh 150 g/m² (50 m²) | 150 g/m² · 1.0 m × 50 m | Standard full-facade reinforcement above impact line |
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 m on standard residential EWI, the Atlas 150 g/m² mesh is the specified weight and trims material cost without compromising system performance.
- Board continuity: works over EPS insulation boards and standard basecoats to form the continuous reinforcement plane across the build-up.
- Tall elevations: the 1.1 m roll width reduces vertical jointing on full-height runs, cutting overlap waste against 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 service this shows at building corners, around openings and on zones below 2 m where mechanical contact is foreseeable. On standard mid-facade reinforcement above the impact line, the practical difference against 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 overlaps and corner 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 Ceretherm system warranties, the alkali-resistant coating is formulated for embedment in any standard cementitious or polymer-modified EWI basecoat. For non-Ceretherm 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 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 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