Fibre glass mesh on rendering systems

Why is fibre glass mesh so important on rendering systems

If you have had the solid wall insu­la­tion installed or a new ren­der­ing sys­tem put onto your wall, then you may have seen the fit­ters empha­sise how impor­tant it is for them to install the fibre glass mesh.  When the piece is being installed it is skil­fully sunk into a thick layer of adhe­sive mor­tar. A notched trowel leav­es a nice smooth sur­face for the top coat to be applied.

For insu­la­tion sys­tems, it is an essen­tial piece of kit that is installed on top of the insu­la­tion and just under the final ren­der. It binds the whole thing together and gives the new insu­lated wall much needed flex­i­bil­ity.

In the rest of the blog we spend a bit of time going over some of the ben­e­fits of this piece of kit. Hope­fully if you are a builder or an archi­tect, you will take this away, and poten­tially look to inte­grate some of these ideas onto your future projects.

Gives the finish strength and flexibility

An obvi­ous ben­e­fit of the fibre glass mesh on rendering systems is its abil­ity to bind the insu­la­tion layer or the exist­ing wall into a nice and strong fin­ish. When the mesh is sunk into the adhe­sive basecoat, it pro­vides a solid hard­ened layer. Should any­thing hap­pen to the top coat, the fibre glass mesh inter­wo­ven into the adhe­sive will hope­fully not fail. This allows you to repair any parts of the damaged surface render.

If you ever feel a piece of EWI fibre­glass mesh in your hands, then try to pull it, you will notice how flex­i­ble the sys­tem is. Now imag­ine if some­thing hap­pened to the prop­erty itself. For exam­ple, you have some move­ment around the win­dow lin­tels, or the prop­erty moves. The mesh is designed to absorb most of that impact. By stretch­ing out, it will allow you to keep the sur­face look­ing visu­ally intact.

Accord­ing to the EWI Pro (sys­tem designer) instal­la­tion guide, fibre glass mesh sheets should be installed with an over­lap rather than butting up against one another. Refer to their train­ing guide for more details.

Enforces weak points around openings

Most sys­tem providers stip­u­late how the mesh should be installed prop­erly. Why is this impor­tant?

The weak­est point of a build­ing is around the open­ings, especially around win­dows and doors. This is log­i­cal because on win­dows and doors you have lin­tels and frames hold­ing down a lot of weight from the other build­ing mate­ri­als. The key thing then is to ensure those areas are prop­erly enforced. How does the fibre glass mesh help?

EWI sys­tem design­ers like EWI Pro will stip­u­late a set of instal­la­tion pro­ce­dures and treat­ments around open­ings to link back to the first fea­tures, which are strength and flex­i­bil­ity.  For exam­ple, the EWI Pro sys­tem advises fit­ters to cut out small pieces of mesh and over­lap the edges of open­ings at 45’ angles.

If the fit­ters strictly fol­low these instruc­tions then there is no rea­son to sug­gest that the prod­uct will not do as it says on the tin.

Impact resistance

If you have ever held a piece of insu­lat­ing poly­styrene or a slab of min­eral wool, you may have won­dered how on earth will that stuff stay robust on my walls.

A stan­dard 125g piece of mesh sunk into the basecoat will give the sys­tem some impact resis­tance. However, on its own, it may not with­stand con­stant pres­sure or high impact. So what can actu­ally be done to give the sys­tem addi­tional impact resis­tance?

You can go two ways about it; one, you can dou­ble up the mesh (install another layer on top the exist­ing one). Or secondly, use “Panzer” mesh, which is 335g which is designed for more robust­ness.

Obvi­ously if you take a sledge ham­mer and smash into the wall or you drive your car into your newly insu­lated bay, there may not be a lot out there to mit­i­gate from the effects of that. You will not just dent the insu­la­tion but a heck of a lot more.

On rendering new builds

If you are embark­ing upon a new build project, whether it is from scratch or extend­ing an exist­ing prop­erty ensure you give the exter­nal ele­ments as much atten­tion as you do with the inter­nal ones. In this instance we want to draw your atten­tion to the type of ren­der­ing that you use.

Due to a lack of indus­try cohe­sion on the topic, most devel­op­ment projects out there still use the tried and trusted sand and mor­tal ren­der approach. While all this is all well and good in the short run, it can be dis­as­trous in the long-run.

A lot has been made about the fibre glass pro­vid­ing a wall much needed flex­i­bil­ity. If we sim­ply put mor­tar on the wall, would that have pro­vided us with the desir­able out­come fur­ther down the line? The answer is sim­ply no. With­out the flex­i­bil­ity, your new shiny wall will prob­a­bly show signs of hair­line cracks within 18 months. Fur­ther down the line those cracks may open up and it could be much worse.

Although using fibre glass in the sys­tem will add a bit more work and be slightly more expen­sive to the tra­di­tional route, you are actu­ally invest­ing for the long-term and sav­ing your­self a lot of headaches.