Inversion roofs are so called due to a change in the classical order of the elements of the roof structure. In the traditional version, the waterproofing is placed above the thermal insulation layer. The need to "hide" the waterproofing coating arises when the mechanical stress increases. In most cases, this occurs during the operation of the roof, therefore, the operated roofs are usually inverted and, accordingly, inverted roofs are most often used.
Roof operation options
The roof of the building can be used both for the development of your business and for recreation. For example, on the roof of a hotel or a shopping complex, you can arrange a summer cafe, sunbathing areas, playgrounds, etc. You can plant a garden, set up a small square, organize a lawn for summer holidays.
Variants of using roofs with higher operational loads are being practiced today. Modern designs of inversion roofs are used not only for roofs of buildings, but also for stylobates and parking lots. For example, in business centers and shopping malls, the roof of the stylobate part is often equipped for parking. This is possible if the roof structure is made of strong and reliable elements. Fortunately, today the building complex has at its disposal thermal and waterproofing materials with high strength and other characteristics, which make it possible to provide reliable technical solutions for inversion operated roofs.
Modern roofing materials
We are talking about the products of the PENOPLEX company, which have found wide application for the arrangement of roofs due to the unique combination of technical characteristics.
PENOPLEX brand thermal insulation® made of extruded polystyrene foam. If we consider the running heaters, then this material can be considered uncontested for use in inverted roofs. The explanation is found in clause 5.4.3 of SP 17.13330.2017, which prescribes for inversion roofs to use thermal insulation with water absorption of less than 0.7% in 28 days. Of the common thermal insulation materials, only extruded polystyrene foam meets this requirement: this figure is 0.5%. In the same paragraph, there is a limitation on the compressive strength: not less than 100 kPa. Minimum compressive strength of PENOPLEX boards® at 10% deformation is 150 kPa, for the most durable mineral wool this figure does not exceed 70 kPa.
It is important to note the high heat-shielding properties of PENOPLEX® (thermal conductivity does not exceed 0.034 W / m ∙ ° С in the most unfavorable conditions), as well as a combination of high strength and lightness, which is important for the roof (density depending on the PENOPLEX brand® varies from 20 to 50 kg / m3).
Special requirements are imposed on the waterproofing of inverted roofs, because in the event of leaks, it is much more difficult to determine the place of damage than on a traditional roof, where the waterproofing layer is the finishing one.
Waterproofing PLASTFOIL® produced by the PENOPLEX company meets the highest requirements: the material is sealed, durable, resistant to chemical aggression. For the arrangement of inverted roofs, an unreinforced waterproof PVC membrane PLASTFOIL is used® GEO signal yellow.
It should be noted the common advantages of both materials: and PENOPLEX®, and PLASTFOIL® are distinguished by environmental safety, biostability, wide temperature range of application, resistance to temperature extremes, durability from 50 years.
Technical solutions for inverted roofs using PENOPLEX® and PLASTFOIL®
Consider two options for the design of inverted roofing systems: with landscaping and without green spaces.
Inverted roof with porcelain stoneware top layer
In all roof structures, including inversion ones, between PENOPLEX thermal insulation® and waterproofing PLASTFOIL® a separating layer of geotextiles with a surface density of 80 g / m2 is laid2 or fiberglass (from 50 g / m2) to avoid diffusion or chemical interaction between the two polymers. As a protective layer between the waterproofing and the screed, geotextiles with a surface density of 300 g / m2 are used2.
Inversion roof with green spaces
When designing green roofs, specialists are faced with a lack of federal regulations in this area. Developed GOST "Greening and maintenance roofs of buildings and structures. Technical and environmental requirements ", but so far it is in the status of a project and awaits its approval in 2019. A valid guideline document may be the "Recommendations for the design of landscaping and improvement of roofs of residential and public buildings and other artificial foundations", developed by JSC "Mosproekt" and published in 2000. If necessary, the document can be downloaded from the PENOPLEX official website.