The correct choice of insulation material and thickness is becoming increasingly important already in the design phase of the building. It can also affect the useful floor area and facade height of the house that can be built on a given plot. In an extreme situation, when the entire buildable area is used, the building will have to be redesigned, or even worse, during the construction phase, it may be possible to meet the energy requirements of the legislation only by demolishing and rebuilding.
Performance-based design and RAVATHERM XPS
If the aspects taken into account in performance-based design exist, the thickness of the thermal insulation material is determined according to the rules of thermal engineering and energy design. This is no different in the case of RAVATHERM XPS thermal insulation.
It should be noted that the thermal conductivity of XPS varies somewhat depending on the manufactured thickness. From 80 mm, it decreases by 0.02 W/mK, i.e. the thermal conductivity of the product, i.e. the λ (W/mK) value, increases. The λ value for RAVATHERM XPS 300 SL (smooth surface) and RAVATHERM XPS 300 WB (patterned surface) is 0.033 W/mK up to 60 mm, and 0.035 W/mK between 80 and 280 mm. In the case of a larger material thickness requirement (over 100 mm), the thermal insulation is made of a multi-layer, so-called We manufacture using welded technology, meaning that the panels are produced in the factory, using our own material, by welding. The thermal insulation performance of RAVATHERM XPS thermal insulation panels – thanks to the cutting-edge welding technology of the 21st century – is excellent across the entire thickness range, outstanding compared to other similar materials.
Place of RAVATHERM XPS
There is hardly any energetic difference between the different thermal insulation materials (XPS – EPS – MW – GW – PUR-PIR…), while in addition to the thermal conductivity (λ value), it is necessary to evaluate several technical parameters in order to use not only the sufficient material that meets the requirements of e.g. the “U” (thermal transmittance coefficient), but also the most suitable material. It can be stated that RAVATHERM XPS closed-cell, extruded polystyrene thermal insulation boards, taking into account fire protection requirements, can generally be used anywhere. However, they have typically spread as thermal insulation in flat roofs, building plinths, floors above ground and basement levels.
Recommended thermal insulation thicknesses
The recommendations and suggested trends given in the table show the achievable heat transfer performance (in general), but since there may be countless special and local conditions, without a specific assessment of the deteriorating conditions, at least + 10% thickness increase is necessary to offset the safety risk resulting from the omission of detailed calculations. Of course, it is recommended to accurately determine the additional heat loss caused by thermal bridges and other effects due to other conditions for the given building, taking into account its geometry and structure, and to increase the thickness of the planned thermal insulation accordingly.
In the case of the aspects taken into account in performance-based design, the thickness of the thermal insulation material is determined according to the rules of thermal engineering and energy sizing.
Although during the process, when taking into account -all- necessary and sufficient technical performance, the sufficient aspect usually comes to the fore (due to price sensitivity on the part of the customer), reasonable safety should never be forgotten and abandoned.
Selection criteria for thermal insulation
The comfortingly, reasonably and economically safe condition is decisively influenced by the sensitivity of the thermal insulation material to stress. During installation, complex stresses usually have to be taken into account. For inverted roofs, therefore, only closed-cell thermal insulation can be used, and of course it has a load capacity that is also suitable for green roofs and parking roofs. For plinths, if it is not protected by facing walls, but is made with glued cladding or thin plaster, in addition to the closed-cell structure, the so-called plaster holding capacity is also required.
In floors lying on the ground, depending on the performance of the waterproofing, it may be necessary to ensure a minimum water absorption of 5, but especially the load capacity that most thermal insulation materials, with the exception of closed-cell polystyrene foams, cannot meet.
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