Since the recent addition of Wood Fibre Insulation to our systems, we’ve been talking to customers a lot about the benefits of different insulation materials and how they compare against each other.

Here at EWI Store, we have a broad range of insulation materials for use as part of our external wall insulation systems, so we wanted to give a more comprehensive comparison between the different types of insulation so that our customers can get the full picture! So without further ado, here is how Wood Fibre, Mineral Wool and EPS compare against one another…

Wood Fibre Insulation

Wood Fibre Insulation is our most environmentally friendly type of insulation. It is extremely appealing to the environmentally conscious customer, nonetheless its high performance is also a main attraction for customers.

Wood Fibre is also an extremely sustainable and renewable material. We source our Wood Fibre Insulation boards from a company called Pavatex, who are certified by the renowned natureplus standard – the European quality standard for building materials set up by the WWF, FSC and Greenpeace.

All of the timber used for their Diffutherm Wood Fibre Insulation boards comes from waste timber cuttings and their entire manufacture process aims to be as eco friendly as possible.

The Fire Resistance of Wood Fibre Insulation is rated at Class E, which is very similar to other insulating materials. However, Pavatex state that their Diffutherm Wood Fibre Insulation goes above other insulating materials because of the fact that it slows down the spread of fire. This is because the Wood Fibre is timber, which chars instead of burning. The charred exterior of the board creates a barrier which stops oxygen passing through and feeding the flames, thereby slowing the spread of fire.

Wood Fibre also offers something called a decrement delay, which is how long it takes for the energy of the sun to pass through. Many people think that all insulation keeps you cool in the summer, which is a myth. However, Wood Fibre does and this decrement delay depends on the thickness of the board.

Wood Fibre Overview:

  • Wood Fibre has a thermal conductivity of: 0.043 [W/(mK)]
  • 100mm of Wood Fibre can bring the U value of a wall down to 0.36 [W/(mK)].
  • Vapour diffusion resistance factor (μ): 5.
  • Price per square metre of 100mm Diffutherm Wood Fibre Insulation is £30.93 excluding VAT.
  • Reaction to Fire: Class E (see above for more info).
  • Recyclable and compostable.

Mineral Wool Insulation

We source our Mineral Wool Insulation boards from Rockwool, who offer the most non combustible insulation material on the market.

Rockwool insulation offers high levels of breathability due to the fact that it is a vapour open material. The presence of fibres and water-repelling compounds wick moisture and water vapour through the material away from the substrate, allowing it to escape. Mineral Wool is non-hygroscopic, which basically means that it pushes water away. It is a fantastic acoustic and thermal insulator because of the fact that the material is so hard wearing and the fibres allow for pockets where air becomes trapped and thus acts as an insulator.

Much like Wood Fibre Insulation, Rockwool is also made from a renewable, naturally occuring resource – volcanic rock. The insulation boards themselves are also 97% recyclable, which is slightly less than Wood Fibre’s status as 100% recyclable and compostable, yet is nevertheless still impressive!

Because of the fact that Mineral Wool is made from rock there are a number of associated benefits (resistance to rot and mould, long life span, hard wearing and water repellency) which makes it an attractive choice for customers. 

Rockwool Overview:

  • Rockwool has a Thermal Conductivity of: 0.036 [W/(m2K)].
  • 100mm of Rockwool insulation can bring the U value of a wall down to 0.34 [W/(m2K)].
  • Vapour Resistivity = 5.9 MNs/gm.
  • Price per square metre of 100mm of Rockwool Mineral Wool is £22.37 excluding VAT.
  • Highest Euroclass Fire Rating of A1.
  • 97% Recyclable.

EPS Insulation

Our final insulation material is Expanded Polystyrene (EPS). It’s the most affordable insulation material that you can get for external wall insulation, not only because the actual material is affordable but also because it is so lightweight it only requires lower strength adhesives and plastic fixings – which in turn cost less. The downside to EPS when you compare it to Wood Fibre and Rockwool is that it’s not an especially environmentally friendly material due to the fact that it is a type of plastic.

EPS is made from a polymer permeated with a foaming agent which, when exposed to steam, creates a uniform closed cell structure, highly resistant to heat flow and moisture penetration. EPS is 98% air and only 2% EPS, which means it acts as a fantastic thermal insulator because of its high air content.

EPS insulation products won’t burn but will likely melt away under high levels of heat. Fire retardancy is achieved by adding a small quantity of a fire-retardant agent to the material, which has the effect of ensuring that the EPS insulation boards shrink away from the energy expelled by heat. They also self-extinguish when the heat source is taken away.

EPS Overview:

  • EPS has a Thermal Conductivity of: 0.032 [W/(m2K)].
  • Vapour Resistivity = 200 MNs/gm.
  • Water vapour diffusion resistance factor (μ): 30-70.
  • Reaction to Fire: Class E.
  • Price per square metre of 100mm of EPS is £9.90 excluding VAT.
  • Generally Non-Recyclable.

Choose the insulation that is right for you…

So there you have it! If you are considering having external wall insulation installed on your property, it’s always best to be well informed about the options available to you so that you can make the best choice – so we hope this was helpful! For further information give us a call or leave a comment down below.

Stay tuned to our blog, we upload a new post every Tuesday and Thursday all about technical advice and materials FAQ’s!