Thermal insulation of Industrial Lightweight Flat Roofs
Insulating flat roofs with RAVATHERM SW (Stonewool) on trapezoidal metal deck is particularly advantageous due to its excellent properties such as superior sound and thermal insulation capabilities, as well as fire resistance. In addition to being non-combustible, stonewool is durable, dimensionally stable, and has good vapour permeability.
Advantages of RAVATHERM SW
RAVATHERM SW products designed for flat roofs have an exceptionally high point load capacity, up to PL(5)750N (Roof 80), allowing safe traffic during construction. It is recommended to use lighter materials in the lower layer of thermal insulation. The high compressive strength prevents the edge of the waterproofing from becoming wavy along the fastening points and allows for easy joining and welding. Stonewool thermal insulation provides a suitable base for any type of waterproofing without the need for additional separation layers. However, it is necessary to use a high-quality vapour barrier layer underneath the thermal insulation.
During the installation of multiple layers of thermal insulation boards, it is important to ensure offset laying to ensure a structure without any thermal bridges.
Pay attention! Use suitable materials!
The choice of layer build-up should correspond to the level of the loads the roof has to bear. Higher quality materials should be used where the regular maintenance of mechanical equipment on the roof pose a greater mechanical load on the waterproofing. The thickness of thermal insulation should be determined through building physics calculations, taking into account the winter and summer energy aspects of the interior space, as well as the protection against condensation in the building structure.
During the construction of the roof, it is also necessary to install the air and vapor barrier layer under the thermal insulation layer, the vapor diffusion resistance of which must exceed this value of the waterproofing of the roof!
In industrial flatroofs, it is necessary to install an air and water vapour barrier membrane beneath the thermal insulation, which should have a vapour diffusion resistance higher, than that of the waterproofing membrane. The quality of the vapour barrier membrane should be selected based on the temperature and humidity conditions of the interior space, while also considering the construction technology requirements of the layer structure. The vapour barrier membrane should be folded up along the edges and sealed with vapour barrier tape. Penetrations through the layer should be sealed in a vapour-proof manner.
Installation
During installation, the vapour barrier membrane should be laid with 10 cm overlaps, then secured by adhesive tape at the edges then fastened mechanically.
The RAVATHERM SW thermal insulation boards are then laid tightly on the membrane, without any gaps. The mechanical fixing elements are used to simultaneously fix the boards (a minimum of 2 anchors per board) and the vapour barrier membrane to the trapezoidal sheet. The PVC/EPDM waterproofing material is welded together in the overlap width. The mechanical fixing elements are placed at the overlaps. In the case of a two-layered bituminous membrane insulation system, the underlayment is also welded in the overlap width, and the final layer is laid with an offset and fully welded to the underlayment.
Slope formation on lightweight flat roof
Flat roofs must have a minimal slope, which can be point or linear slope depending on the structural design and function. Adequate slope formation is essential for proper functioning and long lifespan. In the case of industrial buildings, when designing roof structures, it is important to ensure a 2% slope, even at the maximum deflection under full load. The intersecting roof planes must also have a slope and ensure the free flow of rainwater towards the drains.
The base surface of the trapezoidal metal deck should have a slope of at least 2.5%, on which we create a point slope towards the drains as a counterslope. A 1% slope is also allowed in bends and valleys, but because of a small degree, stagnant water must be expected.
Therefore, special attention must be paid during the preparation of the slope elements, because due to construction errors, the surface of the waterproofing may have pits, in which the water can stop permanently after a rain or thaw.
No-flow areas cannot form anywhere (not even on a temporary!) RAVATHERM SW high-density, pre-cut slope-forming stone wool boards are easy to install and are an excellent solution for preparing the slope of a lightweight, metal-deck roof.
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