What EWI Thickness Do I Need in Ireland? U-Values, BER Targets & Fabric Strategy
Choosing the right EWI thickness is a balance between performance, detailing, and aesthetics. The goal is to reduce the wall U-value enough to hit your BER target (often B2 or better) while keeping reveals, eaves, and drainage well detailed.
Key factors
- Existing wall type: Solid brick/stone vs cavity masonry perform very differently.
- Insulation material: Thermal conductivity (λ-value) changes required thickness.
- Details: Window/door reveals, eaves projection, sill extensions, and services.
- Location: The property’s location may influence the best insulation and finish option due to weather exposure.
Typical approach
Your designer will calculate the target U-value and back-solve the required thickness based on the insulation material. On site, installers coordinate insulation type, detailing, sills, ventilation, and finish choice to keep water out and maintain long-term comfort.
Don’t forget thermal bridges
Even with a low U-value, poorly treated junctions can cause heat loss and surface condensation. Specify insulated reveals, ensure continuous insulation at corners, and design smart threshold details to avoid cold bridging.