Thermal insulation of industrial flat roof

General information

The thermal insulation layer of general flat roofs is located on the load-bearing structure itself, above which the waterproofing is placed.  RAVATHERM SW Roof stone wool thermal insulation has many advantages. Due to the mineral fibre material, thermal insulation has a durable, high heat tolerance and is classified as A1. The high-density, step-resistant boards are easy to install, do not crumble, provide an excellent base for waterproofing.

It is recommended to use lighter materials of lower density into the lower layer of insulation. During the construction of multi-layered thermal insulation structure, care must always be taken when laying the boards, ensuring that the structure is thermal bridge free. Thus attention must be also payed during the selection and installation of fastening anchors.

There are two solutions for the fixation of the waterproofing: if the load-bearing structure is suitable, then it should be fixed with ballast, if not, then the mechanical fixation should be chosen. The latter is more common in steel trapezoidal plate structures, as thin upper belt plates of roof panels made of high-strength concrete are not suitable for mechanical fixation. In the case of mechanical fixation, the forced punctuation of the vapour barrier layer shall also be taken into account.

However, in industrial buildings, mechanically fixed soft PVC insulation is the most common. Less frequently is bitumen plate insulation fixed with adhesives, in this case steam pressure equalization layer is required. In both cases, care must be taken to ensure that the wind load along the edges cannot rip off the plate, which must be protected by proper ballast or anchorages.

Gravel ballast is only permitted at lower building heights or on the inner sections of higher roofs. With more costly concrete board ballast, there is less chance of weeds settling down. If the concrete slabs are placed on washers, it is also easier to check and clean the draining layer and waterproofing. A protective, separating layer, felt or geotextile shall be placed under the ballast.

Installation advice

Under the thermal insulation layer, a vapour barrier must always be built-in, for which elastomer-bitumenous vapour barrier membranes with aluminium reinforcement are best suited. The vapour barrier membrane is loosely spread out on the steel trapezoidal plate with a minimum of 10 cm interlaying, then glued together with adhesive tape, folded up at the edges of the roof and mechanically fastened (without gluing, the overlap must be at least 50 cm)! On the vapor barrier membrane, the step-resistant, high-density RAVATHERM SW Roof plates are laid in two layers. When installing thermal insulation, boards can be laid tightly, heat expansion of the boards are not expected due to the material structure. Work with at least 1/3 overlap when placing the second layer. The boards must be mechanically fixed one at a time, regardless of the waterproofing!

Roof 40-50-60 products can also be used in the bottom layer.

With the help of mechanical fastening elements, we simultaneously attach the boards (minimum 2 anchors per board) and the vapour barrier membrane below to the trapezoidal plate.

After the thermal insulation layer has been completed, the RAVATHERM SW Roof SC slope elements are also placed according to the roof plan. When designing the slope of the flat roof, the roof drains shall be located at the low points of the roof surface and their size and placement shall be carried out in accordance with the requirements of current EN regulations. Roof drains shall be located at least 50 cm from roof penetrations and other structures on the flat roof. The area around the roof drains shall be carried out with an excess drop of 5% in relation to the roof plane, or the drain mut be built with 1-2 cm lowering.

With the help of mechanical fastening elements, we simultaneously attach the RAVATHERM SW SC slope elements, the thermal insulation boards and the water vapour barrier membrane below to the structure. The mechanical fastening elements are placed on the overlaps, placed according to the roof design.

There are no restrictions on the material of waterproofing, as there is no harmful interaction between the waterproofing material used and the mineral wool. The waterproofing material can be bitumen or plastic, and it can be laid in one layer or two layers.

The material of the single-layer PVC/EPDM insulation is welded together in the width of the overlaps. In the case of two-layer bitumenous insulation, the bitumen washer membrane is loosely spread over the RAVATHERM SW SC slope elements, which are welded together in the width of the overlaps. Finally, the sealing layer is laid with a half overlap and welded to the washer membrane at full width.

Slope elements

RAVATHERM SW Roof slope elements ensure optimal roof drainage. The proper design of drainage is of paramount importance, as this is the only way to ensure the long life-span of the flat roof structure and to protect the vulnerable waterproofing membrane. It must be protected from the ever-changing heat effects caused by precipitation and the sun, from the harmful effects of the root system of micro-organisms and vegetation or from effects of acid rain.

The roof surface shall be constructed with slope towards a point or linear drainage depending on the structure. RAVATHERM SW SC and RAVATHERM SW SF products can be used constructing the proper slope design.

RAVATHERM SW RIN

RAVATHERM SW RIN is also available in several sizes for different trapezoidal plates in industrial buildings to improve the slab's fire safety and acoustic properties.

RAVATHERM SW SA

RAVATHERM SW  SA is a specially pre-cut mineral wool product that ensures an even, smooth transfer of waterproofing between the horizontal and vertical surfaces of the roof structure (e.g. parapet wall).

In all cases, the flat roof must have a minimum slope, which may be a slope towards a point or line drainage, depending on the design or use. Proper operation and longevity are essential for proper slope design.

When designing the roof, care must be taken to ensure a 2% slope even when the structure is under full load. At the junction of different roof planes, we also need to create suitable valleys and ensure the free drainage of rainwater towards the drains.
WARNING! The minimum slope of the valleys (due to their larger lengths for the same level difference) in the fields results in larger slopes due to geometric reasons.

According to the international standards, the slope of the waterproofing layer must be at least 1,0% in the valleys, and at least 2,0% in general areas. Special attention should be taken when constructing the slope, as defects in construction can cause the surface of the waterproofing to be dimpled, in which water can stop permanently after a rain or snow. Stagnant bodies of water must not be formed anywhere (even temporarily)! RAVATHERM SW high-density, pre-cut slope-forming stonewool boards are easy to install and are an excellent solution for the slope of the industrial flat roof, for which the slope design is carried out by our experts.

Flat roof accessories

In certain areas of industrial flat roofs, in some places we need to use additional elements for the sake of a complete. Examples of such areas include the junction of parapet walls and roof plane at vertical angle. In the case of a bitumenous waterproofing membrane, this is a sensitive area, since along the bend the waterproofing membrane can weaken and break over time. The special mineral wool additional element is designed to ensure the unfractive transfer of waterproofing between these surfaces.

The fire resistance of the trapezoidal plate is also a pivotal point of the industrial flat roof. Our special rib filling elements are a solution to this problem, which can significantly improve the fire protection and acoustic properties of the slab.