Fibreglass Mesh

Fibreglass mesh is the reinforcing layer that holds a render or external wall insulation system together and stops it cracking. At Penguin BM we supply trade-quality fibreglass render mesh for EWI and rendering projects, in stock for fast UK delivery or collection from our Wembley store. Choose the right weight for your build-up below, or speak to our team about bulk trade pricing.

What Is Fibreglass Mesh?

Fibreglass mesh, also called render mesh, reinforcement mesh or scrim, is an open woven grid of glass fibre coated to survive inside a cement basecoat. It is embedded into the reinforcing coat of a render or EWI system, where it spreads stress across the surface and creates a strong, crack-resistant bed for the decorative topcoat. Without it, thermal movement, impact and shrinkage would quickly telegraph cracks through the finish.

Why the Alkali-Resistant Coating Matters

The basecoats and adhesives used in rendering are cement based and highly alkaline. Bare glass fibre loses strength in that environment over time, so a purpose-made render mesh carries an alkali-resistant coating that protects the fibres and keeps the mesh at full tensile strength for the life of the facade. This is why you should always use a proper render mesh rather than a general fibreglass cloth or jointing tape.

What Fibreglass Mesh Is Used For

• EWI reinforcement: embedded into the basecoat over insulation boards to lock the system together and resist cracking. See our external wall insulation systems.
• Render reinforcement: worked into the reinforcing coat on direct-to-wall rendering to give the topcoat a stable, crack-free base.
• Fibreglass mesh for plastering: reinforcing plaster and render across joints, over dissimilar materials and on areas prone to cracking.
• Corner and detail work: diagonal reinforcing patches at window and door corners, where movement cracks usually start.

Fibreglass Mesh Weights and Grades

The weight of the mesh, measured in grams per square metre, tells you how much reinforcement it provides. Heavier mesh gives more impact and crack resistance.

Weight (g/m²)	Type	Best for
145-160 g	Standard render mesh	General render and EWI reinforcement on walls above ground-floor impact zones
165 g	Standard system mesh	The common all-round choice for EWI on EPS and mineral wool. Our Tytan IS165 and Penguins 165g rolls sit here
300 g+	Armour / heavy mesh	Ground floor, entrances and high-traffic areas that need extra impact resistance

On vulnerable zones such as ground-floor elevations you can either specify a heavy armour mesh or double-layer a standard mesh for the same effect. Always follow the system manufacturer's specification.

How to Install Fibreglass Mesh

1. Apply the first pass of basecoat over the insulation board or substrate.
2. Press the mesh into the wet basecoat from the centre outwards, keeping it flat and free of wrinkles.
3. Overlap adjacent lengths by around 100mm so there are no weak joints.
4. Add diagonal reinforcing patches at the corners of all openings.
5. Apply a second basecoat pass so the mesh sits in the outer third of the coat and is fully covered.

Always work to the data sheet for your chosen render or EWI system, as coverage and overlap can vary.

Why Buy Fibreglass Mesh from Penguin BM

We stock trusted system mesh including Tytan IS165 alongside our own Penguins fibreglass reinforcement mesh, all at trade prices with discounts on bulk orders. Order online for fast UK delivery or collect from our Wembley store. Because mesh works as part of a system, match it with the right insulation board adhesive and basecoat, insulation fixings and render finish. New to EWI build-ups? Our guide to choosing the right render and EWI fixings guide walk through the full system.

What weight of fibreglass mesh do I need for render?

For most render and EWI work a 165g system mesh is the standard all-round choice. On ground-floor and high-impact areas, step up to a heavier armour mesh or double up a standard mesh.

Is fibreglass mesh alkali resistant?

A proper render mesh is coated to resist the alkaline cement basecoat it sits in, which keeps it strong for the life of the facade. Uncoated or general-purpose fibreglass is not suitable.

What is the difference between fibreglass mesh and fibreglass mesh tape?

Render mesh comes in wide rolls and is embedded into the basecoat across whole elevations. Fibreglass mesh tape is a narrow self-adhesive tape for jointing plasterboard. They do different jobs and are not interchangeable.

How much should I overlap fibreglass mesh?

Overlap adjacent lengths by roughly 100mm to avoid weak joints, unless your system data sheet says otherwise.

Can I use fibreglass mesh for plastering?

Yes. It is widely used to reinforce plaster and render over joints, over dissimilar materials and on crack-prone areas.