Inversion roof: types, materials used and device technologies

An inversion roof is a contemporary roofing technique that provides noticeable benefits in terms of longevity and insulation. Inversion roofs are different from traditional roofs in that insulation is positioned above the waterproof layer. In this instance, the waterproof membrane is covered with an insulating layer to shield it from temperature changes and mechanical harm.

There are various varieties of this roofing technique, each suited to various conditions and requirements. Insulation is positioned above the waterproofing layer in an inverted warm roof, which is a popular type. By protecting the waterproof membrane from temperature fluctuations and ultraviolet radiation, this configuration mitigates thermal stress and increases its lifespan.

While there are many different materials used in inversion roofs, stiff insulation boards composed of polyisocyanurate (PIR) or extruded polystyrene (XPS) are frequently used. Excellent thermal resistance and durability are provided by these materials, which are essential for preserving structural integrity and energy efficiency over the roof’s lifetime.

The efficacy of an inversion roof installation depends on the device technologies used. The insulation layer above the waterproof membrane is guaranteed to stay firmly in place by using proper installation techniques. This strategy is appropriate for both new construction and roof renovations since it improves thermal performance while lowering the chance of water intrusion and structural damage.

Type An inversion roof is a type of flat roof where the insulation is placed above the waterproofing layer.
Materials Used Common materials include rigid insulation boards like extruded polystyrene (XPS) or polyisocyanurate (PIR), and protective layers such as paving slabs or ballast.
Device Technologies The roof structure involves placing the insulation above the waterproofing layer, which helps protect the waterproofing membrane and improves thermal performance.

Inversion roof: Description and device

The term "modified soft roof" refers to inversion, where the insulation is on top of the roll waterproofing material. Further layers are incorporated into the design to guarantee intensive operation, resulting in the final roofing cake that looks like this (from the bottom up):

  1. The basis serves as a hollow or ribbed reinforced concrete slab.
  2. Waterproofing.
  3. Insulation.
  4. Drainage pillow. Cleans the water leaking through the upper coating. Thanks to this, the space over the insulation over the waterproofing carpet is not poured and the liquid flows through it freely.
  5. Finish coating. These are tiles, paved screed or soil with vegetation. In the latter case, the surface of the roof is a lawn or even a garden, which looks spectacular.

Since it is not required, there is no vapor barrier.

The specifications of SNiP 2.6-26-76* "Roof. Design standards," SNiP 3.04.01-87 "insulating and finishing coatings," and additions to this chapter "Roof. Guide to design, device, acceptance rules and quality assessment methods" are all taken into consideration when designing the inversional roof.

Pros and cons of the inversion roof

This kind of roof has a number of benefits:

  1. Ability to withstand significant loads. It is explained by the fact that an important and sensitive element of the roof pie – a waterproofing barrier – lies in the depths of the structure, therefore it is not subjected to mechanical effects.
  2. Durability. The reason is the same: the deep location of the waterproofing. It is protected not only from mechanical exposure, but also from other negative factors, for example, ultraviolet radiation, frosts (the material is destroyed from the outside when freezing the water that has penetrated the pores), temperature extremes. Inversion roofing serves 60 years or more.
  3. High thermal resistance. Inversion roof in comparison with the usual one is a more warm.

Additionally, there are drawbacks:

  1. Difficulty in the device. It requires lifting to the roof and laying of a large amount of additional material – for the drainage layer and the finish coating.
  2. The complexity of the repair. To patch up or replace the worn waterproofing material, you will have to dismantle overlying layers.
  3. Limited application. Inversion roofs are not suitable for regions with a rainy climate, since in conditions of constant damp, fungus and mold that destroy building materials can develop under the insulation.
  4. Visual inaccessibility of the waterproofing layer. This makes its preventive examination impossible.

Because of this:

  • There is no opportunity to prevent leaks by advance detecting and eliminating problems;
  • the requirements for the tightness of vulnerable areas – the roof adjustment to pipes, mines, walls, parapet and other vertical structures are increasing;
  • The detection of damage to the waterproofing layer in the case of leaks, which are far from always above the place of water, is complicated.

Materials for the device of inversion roof

Prior to beginning construction, the following needs to be ready:

  1. Polystyrene concrete foam, expanded clay concrete or other similar material. This mixture is performed by a rampant – on the base, a surface with a slope of 1.5-5% is formed for giving a liquid into the drainage system.
  2. M150 brand cement, sand, reinforcing rods or nets. This set is necessary for the manufacture of screed, which serves as the basis for the waterproofing carpet. It can also be laid on top if it is decided to use ceramic tiles or asphalt concrete as a finish coating.
  3. Roll waterproofing. Bituman-polymeric materials (for example, Euro-Ruberoid) are suitable for the inversion roof, which are laid in 2-3 layers, oilopolymer (PVC and others) and rubber membranes-the latest materials, durable and resistant to all negative factors, are laid in one layer. In inversion roofs with vegetation, special root rolled waterproofing is used.
  4. Insulation with high strength and moisture resistance. This requirement meets only extrusion polystyrene foam, capable of withstanding loads up to 50 t/m 2 without significant deformations . Unlike foam (granular polystyrene foam), the extrusion has a homogeneous structure.
  5. Geotextiles, crushed stone or gravel in size from 16 to 32 mm. Used for the manufacture of a drainage pillow: geotextiles are laid on top of the insulation and then crushed stone is laid with a layer of at least 50 mm. Both materials together are a filter, so pure water flows along the waterproofing carpet. Geotextiles are also used as a dividing barrier between layers, when elements of one can damage the second. Under the finish coating with low water permeability (asphalt concrete or a tile -faced screed), it is allowed to lay a special membrane – a plastic mesh poured on two sides by geotextiles as a drainage layer.
  6. Ruberoid or Pergamine. With these materials, a drainage pillow is covered if the finish coating requires laying the screed or reinforced concrete. The substrate will not let cement milk leave the solution and score drainage.
  7. Asphalt concrete, paving or ceramic tiles, soil compositions (mixture of compost with expanded clay, perlite or vermiculite). These materials are used as a roofing, depending on its purpose.
  8. Two -level drainage funnels. The fluid is collected simultaneously from the waterproofing carpet and the surface of the inversion roof.
  9. Fence. The operated roof is blocked according to the requirement of the standards in order to prevent a random fall of people.

Types of inversion roofs

The inversional roof’s cake design may change based on the claimed loads.

Roof with gravel

The most basic type that doesn’t allow the roof to function. The gravel backfill serves as drainage instead of finish coating, and the ballast crushes the insulation. The latter is actually positioned without fastening in the inversion roof, allowing water to freely run along the waterproofing carpet.

Large stones, measuring 25–32 mm, are used. The backfill is between 30 and 50 mm thick.

Pedestrian roof

There are cafes, terraces, sports fields, and other spaces set up on these roofs. Paving slabs placed over a spray of small gravel (5–10 mm), sand, or a combination of these materials perform the function of the finish coating. A heater that is strong enough to support pedestrian weight in addition to a standard snow load is chosen.

Roof with landscaping

Double filtration is used in this type of inversion roof: on top of the crushed stone backfill, another layer of geotextiles is placed. On top of the latter is the layer of soil where plants will be planted. In this capacity, experts recommend using a compost mixture with either perlite, expanded clay, or vermiculite.

Special root material is used to create the waterproofing carpet’s top layer.

Video: Principles of building the right pie for a green roof

Roof for car parking

An apartment building’s roof is becoming more and more outfitted. Features that set this design apart:

  • A heater with maximum bearing capacity is used;
  • A monolithic or prefabricated reinforced concrete slab is laid on top of the backfill (stones in size 25–32 mm);
  • Asphalt concrete is laid as a finish.

Pie "Technonikol"

The Technonikol company manufactures a broad variety of materials, such as roller bitumen-polymeric-polymer waterproofing materials, for the installation of inversion roofs for any purpose.

  1. "Technoelastmost b" and "Technoelast EPP". Rolust waterproofing general purpose. Due to the polyester basis, it has high moisture resistance. Has a layer of spray of small sand.
  2. "Technoelastmost with". It is used in the upper layer of the waterproofing carpet when asphalt concrete is laid directly on it (in unleashed inversion roofs).
  3. "Technoelast-Grin". Material that is not amenable to the destructive effect of plant roots. This property is due to two factors. The outer layer is represented by a thick polymer film, and an additive that blocks the growth of the roots is added to the composition of the astringent. When arranging a techno-seal “technoelast-grain”, only the upper (external) layer is laid, the underlying (internal) is made of ordinary bitumen-polymer waterproofing, for example, “technoelastmost b” or “technoelast EPP”.
  4. "Technoelast ECP". The material on the one hand has a shale add -on, which makes it resistant to solar radiation. Apply "Technolast ECP" in the places of release of the waterproofing barrier to the outside, that is, when designing junctions to pipes and other vertical surfaces.
  5. "Technoelast-Fix EPM". The material is intended for free styling, when it is not possible to glue water protection to the base. In places of the waterflower, it is connected by welding.

All pay materials have a polymer film attached to them (Technoelast-Fix is not one of those materials). It displays the pattern on it once it reaches the necessary temperature.

Additionally, the business provides:

  • bitumen primer is used as a primer before gluing roll waterproofing on a concrete or cement base;
  • Hot mastic No. 41 is used to seal cracks, chips and temperature seams;
  • Cold mastic No. 23 is applied under the edge of the waterproofing carpet adjacent to the vertical surface (above the clamping rail).

Drainage membranes and builders are recognized for:

  • The compositional Planter-Plast membrane-a polymer grid pasted on both sides with geotextiles can be used on paved roofs as a drainage layer instead of a crushed stone pillow;
  • Polymer Planter-Geo membrane for pedestrian roofs.

The Planter-GEO and Standart waterproof polyethylene membranes from Technonikol completely stop moisture from penetrating insulation. Because even extruded polystyrene foam, which has a low water absorption rate, gradually deteriorates, this lengthens its lifespan.

The Technonikol brand’s geotextiles are offered separately. It has a 350–400 g/m 2 density. Additionally, this manufacturer sells extruded polystyrene foam under the Carbon Prof 300 and Technoplex 45 brands.

Tile pie

If a coating in the form of a cement-sand screed pasted with ceramic tiles is applied, pedestrian roofs are less likely to leak. At least 50 mm of screed is used, and cement bearing the M150 brand or higher is used. The road mesh, which has a maximum cell size of 150×150 mm, can be readily obtained or the reinforcing mesh can be bound using individual rods.

Use tiles to perform an inversion cake as follows:

  1. A roof or peramin is laid under the screed in order to hold cement milk in the solution.
  2. It is coated with polyurethane mastic in two layers (it is a protection from water).
  3. Then sprinkled with sand to improve adhesion. It should be dry. It is applied to mastic immediately after laying the second layer (the maximum allowable thickness is 1.5 mm), until the composition has managed to harden.

An inversion roof is a contemporary roofing method with special advantages and difficulties. Inversion roofs reverse this arrangement, placing insulation above the waterproofing layer, in contrast to traditional roofs that place insulation below it. This design contributes to the waterproofing membrane’s longevity by shielding it from mechanical damage, UV rays, and temperature changes.

Inversion roofs can be built using a variety of materials, contingent on particular needs like longevity, insulating efficacy, and environmental concerns. Mineral wool, polyisocyanurate (PIR), and extruded polystyrene (XPS) are examples of common materials. The selection of these materials is based on their ability to withstand heat, resist moisture, and work well with the waterproofing layer.

Because of the importance of the waterproofing membrane, installing an inversion roof usually requires careful attention to detail. The waterproofing layer is installed after the insulating boards have been laid over the structural deck. To protect the roof’s integrity from water infiltration, all joints and penetrations must be carefully sealed and fastened.

Inversion roofs have advantages, but during design and installation, they need to be carefully considered. Carefully planning elements like drainage, load-bearing capacity, and maintenance access is necessary to avoid problems like ponding water or damage to the insulation layer. In order to spot possible problems early on and take immediate action, routine maintenance and inspections are essential.

"Inversion roofs, which use cutting-edge methods to improve durability and energy efficiency, represent a contemporary approach to sustainable building practices. This article examines several kinds of inversion roofs and describes the materials and technologies typically utilized in their construction. Through an analysis of the advantages and difficulties related to inversion roofs, readers will acquire a thorough comprehension of how these systems support long-term cost savings in construction projects as well as environmental sustainability."

Video on the topic

The device of the inversion roof. SK alliance of modern construction.

Roller rolled device device

The device of the roof is technonic. Flat roof. VACATION HOME.

Inversion roof.

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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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