Inversion roof – what is it?

An inversion roof, sometimes referred to as an upside-down roof or an inverted roof, is a special kind of roofing system that essentially turns standard roofing techniques on their head. An inversion roof arranges insulation above the waterproofing layer, in contrast to traditional roofs where the waterproofing materials are positioned above the insulation.

This non-traditional setup accomplishes a number of significant goals. By placing the insulation on top, it protects the waterproof membrane from UV rays from the sun and sharp temperature changes, greatly increasing its lifespan. Additionally, by keeping the roof structure’s temperature stable, this arrangement lessens thermal movement and potential long-term damage.

The waterproofing layer in an inversion roof system serves as a barrier against water intrusion and is usually composed of bitumen sheets or liquid-applied membranes. This layer must be strong and long-lasting because it will be directly exposed to weather conditions, foot traffic during installation, and maintenance tasks.

Reducing the possibility of mechanical and thermal damage to the waterproofing layer is one of the main advantages of an inversion roof. The roof is more stable and less likely to crack or deteriorate due to changes in temperature or physical impact when insulation is covering the membrane.

Technological features of inversion roofs

The high cost of these roofs should be considered when selecting the type of building covering. The best materials must be used when building the inversion roof, and only qualified and responsible workers should be trusted with this kind of work.

Professional installation of the operated roof is required.

If fixing a typical flat roof costs a lot, the same repairs for an inversion may occasionally cost much more and involve more financial resources. When designing a structure, it is imperative to include an inversional roof because, depending on its intended use, it can significantly affect how the most significant architectural elements change in size and how loads are distributed across them.

The functioning roofs are included in the building’s design.

There are some technological differences among the different kinds of inversion roofs, but they all share certain characteristics.

What is contained in the framework?

Utilizing overlap. Strong industrial reinforced concrete slabs are the best option; their technical attributes are chosen with the maximum computed loads in mind. Inversion roofs are occasionally supported by wooden beams, although these kinds of constructions have a lot of limitations.

Using overlap

Sloping layer. Using expanded clay is ideal for these kinds of uses. It holds well and has a high mechanical strength. As a result, it is feasible to address two issues at once: organizing roof water drainage and enhancing the coating’s ability to retain heat.

Expanded clay roofing

Lining up the screed. essential as a foundation for rolled roofing components. Concrete or cement-sand mixtures are used for screed. The loads on the inversion roof are taken into consideration when making a specific decision.


Layer of waterproofing. The materials and styling technology are the same as those found on typical flat roofs. However, there is one requirement: they must all be of the greatest caliber, dependability, and durability.

Layer of waterproofing

Layer of insulation. He needs to possess the best physical attributes imaginable. Based on these parameters, only the priciest extruded polystyrene foam should be utilized, and even then, only for inversion roofs with relatively low loads.

Polystyrene foam that has been extruded serves as insulation.

Geotextiles. It serves as a barrier between the insulation and water filtration and plant roots. It is therefore advised to use it exclusively on specific kinds of roofs that are exploited.

Pie on the roof

Ballast. This layer is the primary interface for users and contains all the underlying data. D. Ballast can take the form of gravel, pedestrian slabs, herbal lawn, etc.

Roof inversion at Ballas

Ballast filling

"Green" ballast

Synthetic grass on the ceiling

The above describes the general universal structure of the complex cake of the inversional roof; its components may vary based on the intended use and preferences of the client.

"Inversion roofs, in which the normal orientation of the waterproofing and insulation layers is reversed, are a clever roofing design solution. An inversion roof offers advantages such as improved thermal efficiency and protection against temperature fluctuations because it places the waterproofing layer above the thermal insulation, in contrast to traditional roofs. Because of this creative method, moisture buildup inside the structure is prevented, which makes inversion roofs especially useful in areas with a high frequency of extreme weather. Homeowners and builders can choose roofing solutions that prioritize longevity and efficiency by being aware of how inversion roofs operate and their benefits."

Types of coatings

We will only list the most frequently used ones, though there may be many.

Upper layer: Gravel sprinkling

The topmost layer consists of pedestrian tiles.

Lawn grass in the upper layer

Device for flat roofs Pies from a functioning roof Green roof pies

Prices for various types of artificial grass

Artificial grass

General advantages and disadvantages

Similar to other architectural designs, inversion roofs possess advantages and disadvantages. Reduced heat loss and multifunctionality are two benefits of coatings. Cons: Exorbitant price, intricate engineering and technical requirements, substantial weight.

Step -by -step instructions for the manufacture of an inversion roof

Take the technology involved in setting up the so-called "green roof," which has grass applied as a finishing layer. Subterranean parking structures in major cities frequently use these kinds of coatings. High-rise buildings are very difficult to put over these structures; the best way out of a tight spot is to arrange large green spaces.

Green roofs enhance the aesthetics of buildings, contribute to the growth of urban flora and fauna, reduce indoor noise levels, and prolong the life of pricey coatings. Furthermore, they enhance urban dwellers’ living conditions and boost the efficiency of passive energy conservation.

Green roofs’ advantages

The components of so-called "green roofs" include the following:

  • sloppy. Purpose – serves as the basis for flexible roll waterproofing and removes water in a given direction. It is made from a layer of expanded clay and cement-sand screed. To increase the viciousness, the screed can be reinforced with metal or plastic grids. Specific points of water drainage should be provided at the stage of development of the building project and take into account all the requirements of building codes and rules;
  • waterproofing. A special primer is applied to the surface of the screed to increase adhesion indicators between the base and waterproofing material. Then one or more layers of rolled roof are laid in the screed;
  • insulation. The thickness of the insulation is calculated separately and takes into account the purpose of the interior and individual requirements for the microclimate;
  • drainage. A special membrane is used to remove surface waters and protect the insulation layer;
  • Rolled lawn grass. Finish decorative and protective coating of the inversion roof.

Roof Plan "Green"

Bitumen mastic prices

Bitumen mastic

Roof arrangement algorithm

This procedure is not required since it is not difficult to construct a sloping portion of the roof. We consider that the groundwork has already been done.

Step 1: Use a primer to make the screed swell. Any composition will work well; all contemporary materials are excellent at completing specific tasks. It is advised to perform impregnation twice, applying the second layer subsequent to the first. Make sure that all roller movements are perpendicular and without gaps.

Vital. The cement-sand screed must be completely dry before applying the primer.

Step 2: Begin adhering the layer of waterproofing.

As we previously stated, only the strongest and best materials ought to be utilized. No matter which manufacturer they use, they must have a sturdy base made of fiberglass fabric—not canvas—and only bitumen that has been altered with cutting-edge additives is used for impregnation. You should be very aware of this. Furthermore, it’s recommended to apply at least two coats of coating; this will greatly extend the roof’s lifespan. Tightness should be guaranteed for at least fifty years in modern constructions.

Complete the junction with caution. Nothing new here; you should just make sure to heed the advice of experts in the field and read the guidelines provided by roofing material manufacturers. Reputable businesses have their own labs where they thoroughly inspect materials before selling them. Every suggestion is made in light of the actual outcomes that were attained.

The metal protective caps on the inversion roof plume funnels are a need. Achieving the maximum is essential to guaranteeing each coating element’s functionality.

Certain roofing funnel varieties featuring both vertical and horizontal releases

Step 3: Get the thermal insulation installed. Use only robust extruded polystyrene foam.

Bulk insulation or reinforced foam concrete are used if the coating is subjected to an extremely high load. Such critical loads are not created by herbal carpet; instead, polystyrene foam can withstand them without any issues.

Sensible guidance. Sheets must be laid with the interference of the joints in order to remove the cold bridges. Half of the sheets are placed in the first row for this. The onlyists’ vehicles determine the insulation thickness by calculating a multitude of different factors.

The insulating material is applied in multiple layers, interfering with the joints.

The photograph’s crossing joints

Step 4: Begin setting up the drainage layer. Its production requires the use of a unique profiled membrane with upper protective geotextiles and pimples.

Make sure the material rolls are always parallel to the roof’s edges as you roll them up. Small displacements must be fixed as soon as possible, and this makes the work considerably more difficult.

Several techniques must be used in this process to ensure that the joints are tight. It is important to keep in mind that the creation of counterclaims is not permitted during the joint formation process.

When laying the material, it’s crucial to make sure the joints are tight.

Leaks will most likely occur in these types of locations.

  1. Spread the first drainage layer, level the membrane, check the correctness of its position.
  2. Spread the second layer over the first with an overlap at least 10 cm or four spikes. Again check the parallelity of the edges of both layers.
  3. Light a little protective geotextile width of bending 2-3 cm larger than sizes.
  4. Insert the pimples of the lower membrane into the deepening of the upper.

Take note of the acne on the membrane’s underside.

Assuming proper execution, there shouldn’t be a leak. However, manufacturers advise further joint protection.

The membrane is installed with parapets or climbing walls.

Step 5: Use a unique ribbon to glue the joints together. Cover both sides with modified bitumen. The tape is about 5 centimeters wide; align it precisely along the joint line and firmly press it against the membrane surfaces.

Junction tape

Step 6: Secure the geotextiles that were previously torn. Either unilateral or bilateral tape can be used to fix it. The effectiveness of operation and sanitation are improved because the Earth won’t clog the membrane due to the fixation of geotextiles.

Now that the preliminary work has been finished, you can begin laying the grass on top of the soil by inspecting the quality of the work. If the roof is intended for a pedestrian area, there will be areas where the ground is uneven and paths covered in gravel, which will have a screed layer beneath the paving slabs.

Diagram of the roof with paving slabs

Concrete slabs must be used on the upper coating of operated roofs for vehicle parking; durable bulk insulations, not polystyrene foam, are to be used instead. The use of polystyrene foam plates for insulation is permitted in situations where the upper slabs are supported by concrete.

Prices for extruded polystyrene foam

Extruded polystyrene foam

The conventional placement of roofing materials is reversed with an inversion roof, a less common but very powerful roofing technique. With an inversion roof, the insulation is positioned below the waterproof membrane rather than above it as is typically the case.

There are various benefits to this creative strategy. The roof membrane is shielded from temperature changes and UV rays by placing the insulation beneath the waterproof layer, which prolongs its life. This configuration also reduces the possibility of damage occurring during maintenance or installation.

Furthermore, through the utilization of the building’s thermal mass to stabilize interior temperatures, an inversion roof improves thermal efficiency. This makes it an economically and environmentally sound option for many buildings by gradually lowering heating and cooling expenses.

Notwithstanding its advantages, installing an inversion roof calls for skill and meticulous planning. Choosing suitable materials and ensuring adequate drainage are essential to avoiding moisture buildup and potential damage to the roof over time.

To sum up, an inversion roof is a technologically innovative approach to roofing. In addition to increasing longevity and energy efficiency, this conventional insulation placement is reversed, which advances long-term sustainability in building design.

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Alexandra Fedorova

Journalist, author of articles on construction and repair. I will help you understand the complex issues related to the choice and installation of the roof.

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