The Importance of Breathable Insulation for Stone Walls

By Chris Heaton
Date 13/06/2022
the importance of breathable insulation for stone walls

Breathable insulation is a must-have if you want to stop heat passing through walls while still allowing moisture to escape. It helps you to avoid problems with damp, and it’s especially important for stone walls. Why? It comes down to their permeability…

Permeable vs impermeable walls

Walls can vary in a number of ways, but one of the most important is permeability. Put simply, they can be permeable or impermeable:

  • Permeable walls are designed to let moisture through, which can then be evaporated away.
  • Impermeable walls stop moisture getting through on both sides.

Impermeable walls can be great, as long as the building has alternative means of ventilation to stop moisture getting trapped inside. This is generally the case on modern buildings. Permeable walls were often used on older buildings, which weren’t designed with that alternative ventilation in mind.

Unsuitable insulation on permeable stone walls

Here’s where it can get complicated. If you use the wrong insulation on a permeable wall, you’ll affect its permeability. In turn, that will alter the natural ventilation of a building.

Stone walls are a case in point. They are permeable but may also be poor in terms of thermal efficiency. With that in mind, it’s no surprise that they’re a prime candidate for wall insulation.

If you ignore breathability and opt for foam panels, which are typically impermeable, moisture will be able to pass through one side of the wall, but not the other. The result is moisture becoming trapped in the walls - and inside your building.

As you might expect, that can lead to damp and mould developing. With the allergic reactions, respiratory problems and immune issues that come with mould, that’s definitely something you want to avoid.

Choosing breathable insulation

It’s clear that breathable insulation is vital for stone walls. So, how do you find it? Products will generally be quite clear about their breathability – as it’s not something you can simply claim. Remember that permeable is often used interchangeably with breathable, so you can also check for permeability when searching for breathable insulation.

While most insulation panels are impermeable, there are some you can find made from natural materials which offer good breathability. That said, they still have the other disadvantages of external wall insulation boards – namely, size and cost. The bulk of insulation panels makes them harder to install, which increases the installation cost too.

If you’re looking for breathable insulation that doesn’t require complex and costly installation, SprayCork can provide the ultimate solution. Used as an exterior wall coating, it can provide 7-8 times the insulative performance of traditional renders. Because it’s made from cork, it’s naturally permeable and breathable to stop moisture being trapped inside your stone walls.

Get a quote from an approved applicator

If you’d like to find out more about SprayCork for your stone walls, contact the CorkSol team on 01484 442420 or email [email protected]. We can answer any questions you might have about breathable insulation for external walls and put you in touch with your local approved applicator for a no-obligation quote.

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