Expanded polystyrene EPS insulation board is a high-performing thermal insulation at the centre of our external wall insulation systems. It significantly upgrades the thermal properties of a building, improving U-values, and reducing the risk of water penetration and condensation. EPS boards are compatible with timber, masonry and system-built properties, as well as tile hanging and a wide range of rendering systems. EPS has been designed specifically to be applied onto masonry or timber-backed walls using adhesive and mechanical fixings. They can also be installed in the cavity void if the property is being insulated using cavity wall insulation.
EPS insulation is the most popular material used in external wall insulation systems. One of the stand-out benefits of using EPS for your project is that it’s great value for money. In this way, choosing a cost-effective insulation board means that you can cut down on cost without sacrificing quality or thermal performance.
When installing EPS as part of an EWI system, applicators will also find that the materials required for the installation are available at a much lower cost. This is because EPS is extremely lightweight, so the required adhesive is of a much lower strength and the fixings are plastic rather than metal. EPS is also a non-breathable material and so lower-cost thin coat renders can be used in combination. For example, with the EWI-075 Silicone Render or EWI-040 Acrylic Render.
- Composition: expanded polystyrene, graphite
- Thermal Conductivity: 0.032W/(m2K)
- Reaction to Fire: Class E
- Compressive strength: 70kPa
- R-value: 1.97W/(m2K)
- Weight: 13.02kg
- Weight/m2: 1.13kg
- Size of boards: 1200 x 600mm
- Coverage per board: 0.72m²
- Bending strength: >= 75kPa
Use netting on scaffolding to reduce the amount of polystyrene blowing about in the wind. We highly recommend that you try to use a hot knife or hot wire cutters to minimise the number of polystyrene offcuts. However, you can still use a standard knife should you choose. Ideally, you should cut the EPS insulation boards within a covered area as this reduces offcuts blowing around.
EPS Insulation Application
EPS insulation boards should always be installed in accordance with the manufacturer’s installation guidelines. This should cover design and all aspects of the application of the insulation. Initially, you can fix the EPS boards to the substrate (masonry or timber) by a mortar/adhesive or simply by mechanical fixings.
After fixing the board to an external wall, we recommend that you cover the boards with an outer layer. This can be either be the mortar basecoat or simply a netting covering to protect from excessive heat, moisture and UV exposure.
Before you apply the basecoat or mortar for the fibreglass mesh, you should rasp or sand down the top surface of the board to produce an abrasive surface. Once you’ve done this, the substrate is ready for the application of the fibreglass mesh. For further information, please download the full installation guide.
EPS Insulation Storage
Shelf life: please see the manufacturer’s date of expiry. Keep in a dry place, in the original packaging. Avoid excess heat or UV light exposure.