by Alana / on 10th July 2020 / 1 Comment

Corner bead is used on all external corners on render-only systems. It is a pretty important component of the render/external wall insulation system and in this blog we look at what it is, where it is used and why!

What are corner beads?

Corner beads tend to be made from rigid PVC, moulded into a 90-degree angle. The PVC has lots of holes within it so when it is embedded with the adhesive, the adhesive can travel through it and completely immerse the corner beads, helping to hold them in place. Sometimes corner beads come with mesh wings attached to the rigid PVC; these can be covered with adhesive, again helping to keep the corner beads in place.

At EWI Store we offer several different types of corner beads, depending on the situation and the type of render being used. Our main corner beads are either:

• For use in thin coat render systems (the corner beads are completely buried within the thin cost render system). These come with or without mesh wings attached to the PVC.

• For use in monocouche scratch render systems (beads protrudes out of the render on the corner).

The above example is the EWI-65520, it is mesh,  it has no nose and is 2.5m in length.

What is the reason for using corner beads?

Corner beads are used in render systems for 2 main reasons:

• Corner beads reinforce and protect external corners – this includes around windows and doors, as well as at the corner of the property.

• Corner beads provide a nice sharp finish when rendering.

Corner beads add an extra layer of protection for external corners, which often take a lot of knocks. The layer of impact-resistant plastic provided by corner beads reinforce stress points and allows render to be flexible without cracking. It is amazing the number of knocks that the corners of buildings take. Using corner beads ensure that even if knocks do occur, then the system will be able to withstand the impact.

Corner beads are also used to provide sharp 90-degree angles on the corners of buildings. Trying to free form a 90-degree angle is difficult and although some renders decide not to use corner beads, we would never advise it! Corner beads are relatively cheap in the scheme of things and so it makes sense to use them to ensure you can get that perfect angle on the property!

Above is a Flexible Arch Bead, it is the EWI-66500, it has no mesh and is 2.5m in length. This bead easily bends to reinforce curves and arch forms. The Arch Bead fixes to the profile of the curve, giving you a smooth strong finish.

How do you embed corner bead?

If using a thin coat render system, then corner beads are embedded using either the EWI-220 Adhesive or the EWI-225 Premium Adhesive. It is completely embedded within the adhesive/basecoat layer, but be sure not to wrap the basecoat mesh around the corner – instead run the mesh up to the rigid PVC moulded plastic. This ensures you don’t ‘round’ the corner when installing the corner bead. For a visual demonstration of this process please watch our YouTube video “EWI-220 EPS Basecoat Application”.

Above is an example of a corner bead that you would use for monocouche scratch render systems. The above example is the EWI-63300, it has a 6mm nose (that part that will protrude out of render), no mesh and is 2.5m in length.

With monocouche scratch render, the scratch render is taken up to the corner of the bead, but the bead still shows through the render. You can therefore get different colours of monocouche scratch render corner bead – get in touch for options!

Above is the EWI-65620, this type of bead is shown in the linked demonstration video above. It is also known as a Panzer corner bead. This bead is used for internal corners, it has extra strength for additional movement and is used for both external wall insulation and render only.

Corner beads make your life easier during installation, increases the lifespan of the system and gives a better looking final result – so make sure to use them when rendering or installing EWI systems!