4 Different External Wall Insulation Systems

By Jamie Orr
Date 19/04/2022
4 different external wall insulation systems

If you want to keep more heat inside a building, there are a few different external wall insulation systems to choose from. In this post, we’ll introduce the different options along with their advantages, drawbacks and limitations to help determine which is best for you.

1. Cavity wall insulation

Starting with probably the most well-known option, cavity wall insulation is a way of insulating walls that have been built with a cavity. Insulation is injected into the cavity through holes which are drilled from the outside of the walls, before being refilled. The insulation expands to fill the cavity and create a barrier between the inside and outside of a building.

It’s an effective way of minimising heat loss from a building. However, there are a few instances where it’s not suitable:

  • Solid walls – quite simply because they have no cavity
  • Walls exposed to wind-driven rain – rain can soak and penetrate brickwork, wetting the insulative material and diminishing its insulative properties
  • Walls with existing damp problems – similar to the point above, the insulative material will be less effective if it’s exposed to moisture

2. Foam panels

There are a range of different foam panels, including phenolic, polyurethane, polyisocyanurate and expanded polystyrene. They come in a variety of sizes but are usually around 50mm thick.

Size is the main drawback of these external wall insulation systems, as it often interferes with windows, doors, eaves and downpipes. Adjustments may be required as a result, which adds to the cost and timescale of the job at hand.

On top of that, most foam panels are impermeable. This makes them unsuitable for older properties with permeable walls, as they can trap moisture inside walls, leading to problems with damp.

3. Fibre-based systems

Fibres are a vapour-permeable alternative to foam and come in two main categories – fibreglass or wood fibre. Each has their own disadvantages, according to an independent report on behalf of the government:

  • Wood fibre – Offers “somewhat lower insulation value than other materials” and requires three coats of lime plaster, which takes longer to dry than modern plaster and could increase installation costs.
  • Fibreglass – Prone to slumping, which creates cold bridges on the wall where heat can pass through.

4. Cork coatings

Cork-based render is different to other external wall insulation systems as it’s a standalone coating for exterior walls. Straight away, that means there’s no need to adjust fixtures as the coating is much thinner than panels or fibre systems.

Unlike panels, cork coatings are completely breathable, so they don’t pose any damp-related issues. They’re also suitable in any conditions, given that the coating is highly water-resistant. Most importantly, none of this comes at a cost to thermal performance – cork is naturally insulative, making the coating 7-8 times more insulating than traditional renders.

The choice is clear for external wall insulation

If you want to insulate your external walls with a system that’s sound resistant, weather resistant, eco-friendly and stylish in appearance, the choice is clear. Installed exclusively by our National Network of Approved Applicators, SprayCork comes with a 25-year guarantee, so you can enjoy impressive thermal performance long into the future.

Get the ball rolling today by calling 01484 442420 or emailing [email protected].

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