Tag Archives: external wall insulation

External Wall Insulation and Verge Trim

What is Verge Trim?

A Verge Trim is a thin strip of plastic or metal that sits at the top of the wall where the insulation meets the either the roofline or the window sill. Our Verge Trim are made from 1mm powder coated aluminium, and each come in various widths to house different thicknesses of insulation. Verge Trim is suitable for most situations where the external wall insulation requires capping, whether around window sills or at the top of the system to extend the roof line. Its main purpose is to redirect water away from the EWI system and prevent any moisture penetrating behind the insulation boards.

As we know, water ingress can be extremely detrimental to an EWI system. Water has a direct effect on the insulating properties of the external wall insulation, because water reduces the ability of the insulation to slow heat transfer. Water ingress can also be really dangerous for the structural integrity of the EWI system; continuous water ingress will eventually wear away the adhesive which holds the insulation boards to the wall. This will eventually cause the insulation boards to become insecure and even fall off the wall, potentially causing injury. This is why technical design is so important – at EWI Store, we always stress that installations need to be done properly by fully trained installers such as those that we have trained ourselves.

UK properties tend to vary depending upon the type of roofs they have. Some roofs have a wide enough soffit to allow the insulation to sit underneath, and so in this case good quality beading will be sufficient to create a seal with the soffit board – water ingress should never be a problem here because the water will simply run off the side of the roof. However, not all roofs have a wide enough soffit to accommodate the insulation, so in these cases a Verge Trim will be required.

Verge Trim – Creating a Waterproof Seal for EWI

Where there is a fascia board, it is possible to tuck the Verge Trim behind it or up under the roof line. Here at EWI Store, we offer different types of Verge Trim for a range of areas, so no matter the project we’ve got everything you need! 

Over-Sill Verge Trim:

The Over-Sill is intended to extend the length of an existing window sill. The idea is to ensure that the extended window sill overhangs the insulation so that water runs straight off.

over-sill verge trim

Dropdown Verge Trim:

For use when fixing from below, the Dropdown fits under sills and soffit boards and effectively ensures that water falls away from the system while also minimising the need for expanding foam tape and other sealants.

dropdown verge trim

Upstand Verge Trim:

When fixing from above, the Upstand is ideal. Used in areas such as the connection to a flat roof or where the Upstand can slide up behind the fascia board, the Upstand creates a waterproof seal which again minimises the need for foam tape.

upstand verge trim

Additional Items…

Verge Trim Connectors and End Caps:

Verge Trim Connectors are used to secure the joint where continuous lengths of Verge Trim are installed, while End Caps come in pairs and are designed to create an aesthetically pleasing finish. Both the connectors and the end caps ensure effective waterproofing around all joints.

verge trim connectorsverge trim end caps


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external wall insulation EWIPRO

How can I insulate my external walls?

Why should I consider external wall insulation?

Perhaps you have installed cavity wall insulation but are looking for a bigger impact, or maybe you live in a solid walled property. We recommend external wall insulation for a number of reasons;

  • Save energy and therefore save money on bills
  • Improves the external appearance of home
  • Improves the acoustics within your home – sound proofing
  • Takes up no internal floor space
  • Keeps home warmer in the winter and cooler in the summer (many people report that their houses stay so warm that they hardly need to turn the heating on)
  • Prevents damp and condensation
  • Prolongs the life of your building – protects against extremes of weather
  • Can increase the value of your property in terms of external appearance and Energy Performance Certificate Rating
  • Low maintenance and long lasting

A quick run through of the main stages of installation:

First, the wall is prepared to make sure the insulation system will stick. It should be possible to install our insulation system on top of existing render or pebbledash, but at this point a substrate check will need to be done. Next, the surface is primed and this needs to set for 24 hours. A starter track is attached to the wall above the damp proof course to support the insulation boards. They are then attached with adhesive and double-fixed with mechanical fixings. Fibreglass mesh is used to reinforce the system and then the wall is rendered and a topcoat applied. Each part of the system is designed to minimise cold bridging and maximise efficiency.

Can I choose the materials?

All the steps work together to create an effective, attractive and long-lasting system. It’s a customisable system – the householder can choose between three insulation materials: mineral wool, expanded polystyrene (EPS) or extruded polystyrene (XPS) boards. Mineral wool is durable, breathable and highly fire retardant. Polystyrene insulation is cheap and a fantastic insulator, so a thinner layer can be added to achieve the same results as a larger amount of mineral wool.

There is also a choice of render, tailored to different environments, as well as options for the final colour and texture of the walls.

How much does external wall insulation cost?

Fill in our calculator to find out approximate costs of materials or give us a call and we can put you in touch with one of our approved installers who will be able to carry out the work for you to the highest standard. All our installers are given full training and we offer a free aftercare service for customers.

Check out our video with TheGreenAge all about installing external wall insulation!