Insulation with XPS or EPS! What’s the difference?
The energy efficiency of a building often depends on the materials that make up its envelope. Choosing the right type of insulation is crucial to ensuring the required insulation performance for your project. The use of XPS and EPS insulation offers great flexibility, compatibility and thermal efficiency for all areas of the building envelope system. But what is the difference between XPS and EPS insulation?
XPS and EPS production method
XPS insulation is produced using an extrusion process. This continuous process results in a closed cell structure with a smooth surface on the top and bottom of the board. The closed cell structure prevents water from penetrating the insulation board structure and provides long-term strength and durability. Given its closed cell structure, XPS does not “breathe” and is an exceptionally suitable material for humid environments. When it comes to facade insulation, it is not a good solution.
EPS insulation is made from small polystyrene beads that, after the application of heat or steam, expand and fuse. The expansion process causes the expanded beads to fuse together in irregular shapes, leaving small spaces between them. The voids between the EPS cells allow air and moisture to penetrate the entire slab. This makes it unsuitable for humid environments, but for facade insulation it is an excellent solution.
Compressive strength
Compressive strength is required in the most challenging environments, such as under slabs, on flat roofs, concrete floors, foundations, platforms, podiums, etc. In general, when comparing the densities of EPS and XPS, the compressive strength of XPS is greater than that of EPS. At the same density, XPS achieves greater compressive strength. When it is not necessary to use a material with such high compressive strength, EPS is a more budget-friendly solution.
Insulation with XPS or EPS – thermal conductivity
Insulation is one of the most practical and cost-effective ways to improve the energy efficiency of a building. By improving the insulation in new and existing buildings, significant savings and reductions in energy consumption can be achieved. Both XPS and EPS provide good thermal conductivity. However, air trapped in the cavities in EPS will conduct heat. A much higher density EPS board would be required to match the thermal performance of XPS insulation, but as we have already noted EPS “breathes” while XPS does not.
Water vapor diffusion
The water vapor diffusion resistance (μ) of EPS ranges from approximately 30 – 70 compared to the water vapor diffusion resistance (μ) of XPS, which ranges from approximately 80 – 250. XPS is often chosen over EPS for wetter environments.
Fire resistance and service life
EPS and XPS have a flammability class of E or F, which does not protect the building from fire. Both materials age and change their insulation characteristics over time.
In conclusion, it can be said that XPS is the best solution for insulating the foundations and plinth of buildings, as it does not allow water to penetrate. When we talk about insulating the facade of a building, it is better to use EPS, but if we are looking for the best solution and a material that will not change its insulation characteristics over time, this is undoubtedly stone wool.