Methods Of Flat Roof Insulations | Flat Roof Insulations

Similar to the common types of roof insulation, also the flat roof insulation is not an easy task. When insulating a flat roof, different variants can be carried out: insulation warm roof, insulation cold roof and insulation inverted roof.

In any case, special attention must be paid to the roof construction for flat roof insulation. The most commonly encountered roof structures are roofs made of solid reinforced concrete, wooden constructions or lightweight trapezoidal constructions.

The flat roof insulation – three different methods

Depending on the design of the flat roof, different methods of flat roof insulation arise. Here you will find all three methods explained clearly. If you have any questions, please do not hesitate to contact us.

Flat roof with cold roof insulation

The name of this for a flat roof insulation sounds confusing at first, because you do not really want to have it cold by Dam measures. The term “cold roof” can be attributed to a cold air layer which remains between the insulation layer and the roof seal as rear ventilation. This form of insulation is particularly suitable for flat roofs with a low slope, where there is sufficient space (30 – 50 cm) between the ceiling and the roof seal.


In this space then the insulation is blown through a vapor barrier film on the ceiling completely or if the roof is open at the top with clamping felt designed. If no vapor barrier is present, it can also be retrofitted from below, which, of course, significantly increases the expense. Again, it is important again that the vapor barrier is properly sealed against the outer walls and the insulation is laid without thermal bridges.


It should be noted that above the insulation an air gap of at least 10-15 cm remains as a ventilation level in order to remove any accumulating moisture from the wooden construction. Suitable insulating materials are mineral or rock wool, as well as organic insulating materials such as cellulose. This type of insulation is intended for flat roofs with wooden construction, with concrete ceilings, the two following variants are more likely to be used.

Flat roof with warm roof insulation

For a flat roof insulation with almost horizontal roof, the so-called warm roof offers. Unlike a cold roof, there is no air layer between the ceiling and the outside of the roof. The insulating material is enclosed airtight between these two layers.


The high demands on the tightness of the roof must be taken into account, since penetrating water is difficult to escape and thus leads to mold growth or insulation destruction. The first layer (from inside) of a warm roof forms the vapor barrier film, on which the pressure-resistant insulation boards, for example of XPS or PUR, are applied.


If necessary, a formwork made of wood is integrated into the insulation system above the insulation boards, on which the so important roof waterproofing is applied. In most cases, bituminous sheets, which are welded together, are used. About the roof seal can then follow a loose gravel bed landfill. However, this is not absolutely necessary. During the inspection or use of the roof, care must be taken that the seal is not damaged.

Flat roof with inverted roof insulation

The simplest type of flat roof insulation is the inverted roof, in which the insulation is applied to the existing roof seal. As with the hot roof, pressure-resistant insulation panels made of XPS or PUR are recommended. Before applying the printing plates, the substrate should be thoroughly cleaned to avoid destroying the old seal with sharp objects.


On the insulation boards then the new sealing layer is applied. This can again consist of welded bituminous membranes. As with a warm roof, a loose gravel fill can then be laid over the new sealing layer. It is advisable to add a protective fleece between the sealing layer and the gravel pack to ensure that the new sealing layer is not damaged.

Our energyheld tip for insulating the flat roof

In the insulation of a flat roof usually offers a blow- in insulation . This is mainly known from the core insulation, but also gives very good results in flat roof insulation.


In all types of insulation for flat roof insulation, it must be ensured that the edge of the roof and the wall connections may need to be enlarged and sealed.


Some types of flat roof insulation, such as the inverted roof, sound simple in principle, but a variety of mistakes can be made here as well. So watch out for quality.


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