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. This completely immerses the beads, helping to hold them in place. They have also been designed 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 beads, depending on the situation and the type of render being used.
What is the reason for using corner beads?
Corner beads are used in render systems for 2 main reasons:
• Reinforce and protect external corners – this includes around windows and doors, as well as at the corner of the property.
• Provide a nice sharp finish when rendering.
They 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 reinforces 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 ensures 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 them, we would never advise it! 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 bead. For a visual demonstration of this process please watch our YouTube video “EWI-220 EPS Basecoat Application”.
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!
3 thoughts on “The Importance of Corner Beads in Rendering”
We had render put on our property two years ago and they didn’t put corner bead in the render, so the corners of the property weren’t really square. We bought it up with them at the time and they said no one used corner bead with Silicone render. My question is whether we can retrospectively install corner bead to smarten up the finish?
Hello all, I’m currently working on a project where I need to apply silicone render beads around windows and corners. I’m a bit unsure about the correct type of corner bead to use. should the beads have a ‘nose’. I can see wit hte mesh beads on this website you can get no nose, 3mm nose and 6mm nose.
Also, any installation tips to ensure a clean, durable finish would be really helpful. Thanks!
Hi Gary, corner beads are designed for 90 degree angles. Depending on what part of the window you’re looking to treat, you can use reveal beads or head drip beads; reveal beads provide protection at the top of window and door frames, whereas a head drip bead provides protection and prevents water ingress at the top of windows and doors. The nose acts as a protective barrier, helping to prevent chipping, cracking, or denting at the edges. When you apply joint compound or plaster over the corner bead, the nose helps to form a smooth, continuous surface that blends seamlessly into the wall. Its design also aids in guiding the trowel along the corner during application, helping to achieve a crisp, clean finish.
For the most durable and clean finish, use a silicone render and work it in small circles with a plastic float to distribute the aggregate and smooth out the surface.