Inverted roof waterproofing

Green roofs are becoming more and more popular when it comes to building designs. An inverted roof system can be used to make them as efficient as possible. Nevertheless, it should be noted that a green roof does not necessarily have to be finished with green plants and shrubs, but the inverted roof solution itself is considered to be one of the best waterproofing solutions for usable terraces and roofs. Why is it called the “inverted roof”? Said system is based on the approach based on applying the waterproofing layer under the insulation layer, which is an exact opposition to solutions utilized in the case of traditional roofs. The traditional arrangement of layers on a flat roof, where the thermal insulation is covered with a waterproofing layer, has a significant disadvantage – the key layer, usually having the form of a roofing felt, may be exposed to direct weather conditions, reducing the resistance of the insulation to adverse weather conditions. Another disadvantage of such a system is the condensation of water vapor in the roof insulation layers. The spots allowing for its evaporation are ventilation chimneys, which do not always fulfill their task. In the said scenario, the condensation-specific moisture remaining is often mistaken for possible leaks.

Main advantages of the system:

removal of rainwater from the inverted roof takes place on two levels: some of the water flows to the drainage system, whereas the remaining part that has penetrated the insulation of the waterproofing layer flows through the profiled slopes into the inlets.
it is possible to increase usable roof load, mainly due to the fact that the waterproofing system made on a rigid surface is additionally secured from the top with a layer of thermal insulation made out of a sturdy XPS material that is resistant to water. Therefore, there is the possibility of creating not only green roofs, but also – parking lots and recreational spots above utility rooms.
It is possible to quickly and safely check the tightness of the cover by performing a water test. Leakage will always occur in places where the insulation is damaged. In a traditional system, water often leaks in spots that are rather away from the damaged insulation layer.
very high resistance to weather conditions.

Sequence of undertakings to be performed:

Preparation of a floor slab with a slope that will allow water to run off automatically. The slope should be no less than 2-3%. It should be made out of WB FAST FLOOR – a ready-made quick-drying screed
Alignment of the surfaces and the removal of dirt.
Priming the surface with WB PRIMER.
Laying the first layer of WB HOT MATE together with the extension to the facade to the height of about 0.6 – 0.7 m
Application of the second layer of WB HOT MATE
Covering the entire surface with geotextile
Laying out the dimpled film allowing for an easy drainage of water.
Laying a thermal insulation based on XPS boards with their density adjusted to the pressure.
Coverage of the surface of the XPS boards with a geotextile, which will protect the layer against the penetration of refuse from the pressure layers.
Laying a pressuring layer made out of scattered 8/16 or 16/32 washed pebble stones.
Laying a finishing layer, for example – concrete or stone slabs laid on brackets or directly on gravel.

CROSS-SECTION OF LAYERS OF THE INVERTED ROOF SYSTEM

Materials required for insulation:

WB Fast Floor
WB Primer
WB Hotmate
XPS insulation
Geotextile
Dimpled foil

Materials required for roof finishing:

Washed pebble stones
Concrete slabs

Please note!

If you are not sure how much material you may need to insulate your roof, you can always ask our professional support. Just contact our technical team via phone or e-mail.

IMPORTANT INFORMATION PERTAINING TO INVERTED ROOF WATERPROOFING:

VERTICAL INSULATION IS AS IMPORTANT AS HORIZONTAL ONEWielokrotnie rozmawiając z klientami While communicating with our clients, we explain how important it is to perform vertical insulation on the wall in terrace and balcony systems. It is a very vital element of the entire system, mainly due to the fact that it will protect the wall of the building against the so-called capillary action. Said phenomenon may quickly lead to the development to the emergence of types of fungi that are harmful to one’s health. The photos show a properly made transition of horizontal insulation to vertical one created by means of using the WB Hot Mate insulation material. Such insulation is made at the height of about 0.6 – 0.7 m. Afterwards, the missing fragment of wall insulation is supplemented, restoring its original form.