Extruded polystyrene foam (XPS) is an insulating material made of styrene, free of CFCs, HCFCs and HFCs as well as other climate-damaging propellants, which is characterized by a particularly homogeneous closed cell structure. This makes it very pressure-resistant and absorbs hardly any water. It is ideal as perimeter insulation and can be used almost without restrictions in areas in contact with the ground, provided that building authority approvals have been obtained.
Source: bauwion
Image: Insulation XPS - Die Umweltberatung
properties:
XPS has very good thermal insulation properties (λ = 0.031 to 0.042 W/mK). The water vapour diffusion resistance (μ) is 50 to 200. Due to the closed-cell foam structure and the foam skin of the panels on both sides, water absorption is extremely low. The compressive strength is high. Due to the flame retardants used, fire behaviour class E is achieved. In the event of a fire, heavy smoke can develop. For this reason, depending on building regulations, XPS may not be used on facades in multi-storey residential buildings or may only be used in compliance with certain fire protection requirements.
Delivery forms:
Boards
Production:
Polystyrene rigid foam boards are offered as extruded polystyrene (XPS) for special applications. As in the production of EPS, raw styrene is produced from crude oil in several stages. Liquid polystyrene is foamed (extruded) with propellant gases and pressed into sheet form via wide-slot nozzles. In the past, CFCs were used as propellants (banned since 1990), which damage the ozone layer. Furthermore, strong greenhouse gases such as HFCs were also used. Nowadays, CO2 and blends with 2–3 % ethanol are mainly used. In Austria, HFC compounds have been banned by the ordinance since 2008 (HFC-HFC SF6 Ordinance, Federal Law Gazette 447/2002). However, there are still exceptions in Austria. However, the first choice should be CO2-foamed XPS plates. For XPS sheets, the chemical HBCD is also used as a flame retardant (see also EPS sheets). Here, too, you should switch to HBCD-free disks.
:
XPS is used for applications in wet areas and under high pressures, such as insulation boards for insulating inverted roofs (roofs where the insulation layer is above the moisture seal), green roofs, terraces, basement exterior walls and floors. Since XPS is not UV resistant and there is also a risk of floating, it should always be covered with gravel, terrace slabs on stud construction or with a green roof system. The use of stepped seam plates avoids gaps that could act as thermal bridges. XPS boards are glued to the vertical moisture seal on the outside of external insulation boards in the area in contact with the ground (perimeter insulation). For their protection and better water drainage, a bubble wrap can be applied on the outside. Caution in case of direct contact with PVC waterproofing membranes. The plasticizers in the PVC can cause damage to XPS.
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red= Areas of application, grey= not possible
