Slab edge can be responsible for approximately 80% of the slab’s total heat loss1, with further research showing that thermal resistance does not significantly improve by fully extending the insulation under the slab or by increasing the thickness of the insulation under the slab. The reason being that, with no insulation on the perimeter foundations, most of the heat is conducted along the slab2 and out through the exterior face of the footing.
This suggests that insulating slab edges is far more effective for preventing heat loss than insulating the underside of the slab.
Styroboard XPS from Foamex is an ideal material for Slab Edge Insulation. Extruded polystyrene (XPS) is a rigid insulation that is formed with polystyrene polymer, but manufactured using an extrusion process. This rigid foam provides a strong, yet lightweight and flexible insulation solution which is resistant to water absorption, making it a long term, sustainable solution to reducing slab edge heat loss.
Recently launching into the Australian market, MAXRaft used Styroboard XPS and Styroboard EPS to achieve their first Australian PassivHaus project. The thermal efficient design of the MaxRaft home utilised the inherent insulation qualities of Foamex’s Styroboard XPS and Styroboard XPS products.
MAXRaft is focused on energy efficiency, fully insulated foundations to help deliver warm and healthy homes, both in terms of comfort and energy usage. Their patented MAXRaft is the only fully insulated and thermally broken floor system on the market today.
Foamex Styroboard EPS and XPS both provide highly efficient and effective insulation. In addition to their insulation qualities, Styroboard EPS is fully recyclable, won’t support mould or mildew growth thanks to its moisture resistance, and has a long-term, stable R-value. Styroboard XPS has all the same qualities but delivers a higher compressive strength, R-value and moisture resistance.
PassiveHaus is a building standard that is truly energy efficient, comfortable and affordable at the same time. PassiveHaus is not a brand name, but a tried and true construction concept that can be applied to any design, anywhere. PassiveHaus design allows for energy savings of up to 90% compared with a conventional build.
View MAXRaft installation of a standard MAXRaft floor with a thermal break between the interior of the home and the garage.
Image with thanks to MAXRaft
References
[1] http://www.buildmagazine.org.nz/assets/PDF/Build-134-24-Build-Right-Concrete-Edge-Slab-Insulation.pdf
[2] http://www.buildmagazine.org.nz/articles/show/insulation-of-slab-on-ground-floors
