Features of the device and installation technology of inversion roofing

For modern buildings, inversion roofing is a creative and useful solution with many advantages. Inversion roofing, in contrast to conventional roofing systems, reverses the usual order and positions the insulation layer above the waterproofing membrane. This special configuration offers improved longevity and resilience, which makes it the perfect option for flat roofs and other situations where durability and effectiveness are essential.

The ability of inversion roofing to protect the waterproofing layer from physical damage and temperature fluctuations is one of its most notable features. The membrane is protected from the weather by the insulation placed on top, which lowers the possibility of leaks and lengthens the roof’s lifespan. Better thermal performance is also made possible by this design, since the insulation is kept more effective by not being exposed to adverse weather.

An inversion roof installation calls for meticulous planning and attention to detail. The waterproofing membrane must be installed, the insulation layer must be placed, and the roof surface must be prepared, among other crucial steps in the process. A seamless and dependable roofing system requires careful execution of each step. For both residential and commercial buildings, inversion roofing can offer a reliable and cost-effective solution with the appropriate methodology.

Device

The term "inversion" for the roof implies that this kind of installation is a "in reverse" action. Here, the layers (roofing cake) are strictly numbered in reverse order: the waterproofing layer is numbered first, followed by the heat-insulating layer. More about flat roof pie is covered here.

The Latin word "inversion" means "rearrangement" or "turning over" when translated. The term "inversion roof" highlights the primary distinction from the traditional design—this is an actual "roof castling."

Experience demonstrates that the constant precipitation and temperature fluctuations cause the waterproofing applied on top of a standard roofing system to quickly wear out. Once beneath the waterproofing, water loses its ability to evaporate. The entire roof’s perimeter is rapidly affected by the destructive effects of emerging mold.

These issues are resolved by laying an inversion "pie" with a drastic alteration in the coating order. Additionally, the layer’s current maximum protected waterproofing will endure four to five times longer.

Installed on top of thermal insulation, mandatory ballast systematically shields the lower "important" layers and keeps them from shifting even a little. Ballast has made it such that fastening elements are now only needed at the intersections where walls and parapets join.

Crucial! Plant soil is used as ballast in the "green" roof version, and it is positioned on top of the drainage layer.

The waterproofing layer already performs the role of a vapor barrier, so there isn’t one in the inversion version. As a result, both the material cost and the overall structure’s installation speed are decreased. Here is information on the conventional vapor barrier.

Scope and conditions of application

The type of load determines the differences in the inversion roof.

• minimum – for private or small houses and unused roofs;
• average – with the arrangement of medium-sized recreation areas, playgrounds for children, a solarium, pedestrian “paths”, green flower beds;
• maximum – when creating sports grounds, parking lots, cafes, swimming pools, large gardens with trees.

Because a very heavy mass will be loading the load-bearing walls in the latter option, careful design and calculation are necessary.

Types of roof

The inversion roof’s design varies as well because there are two types available: one that is utilized and the other that is not. It can be both full and light. The lightweight version consists of gravel backfill, hydro-, thermal-, and finishing coating (construction materials in rolls). This design is suitable for building multi-story buildings, offices, and tiny homes without any extra external loads.

It saves money, withstands weather well, places less weight on load-bearing walls and ceilings, and is utilized for the intended purpose.

An inversion roof is built with an enlarged roofing pie when you want to add usable space on a flat roof or when there are more mechanical loads.

For recreational areas (which are placed on a bed of sand and gravel), paving slabs are chosen as the final layer; for landscape gardening, soil is used. However, in this instance, the insulation is covered with geotextile, drainage is applied, and then the filtration layer and finishing soil are fixed.

Take note! If you want to build parking spaces, use a sturdy intermediate layer to strengthen the base and a reinforced concrete slab for the finishing coat.

We examined the complete classification of flat roofs in a different article.

Advantages and disadvantages

Undoubtedly, an inversion roof offers many benefits.

Advantages

• Maximum wear resistance, durability (up to half a century) and reliability.
• Simple, understandable calculations for design work.
• Minimum costs for materials compared to pitched roofs.
• The installation process is simple and fast.
• Safety and environmental friendliness – the materials are not dangerous to the human body and do not emit harmful substances into the atmosphere.
• It becomes possible to arrange additional recreation areas on the roof – terraces or swimming pools, golf or tennis courts, a garden with flower beds and even trees, as well as parking lots.
• The appearance of the roof is aesthetic, status and noble.
• Simple and safe maintenance – it is impossible to fall from such a roof when cleaning or repairing compared to a pitched roof (at an angle).
• Repair work can be carried out at any time of the year.
• A large selection of ready-made standard roof options for various geometric shapes of houses, both single-story and multi-story.
• Availability of materials for improvement or replacement of damaged areas.

Citation! Construction of government buildings, commercial buildings, educational facilities, and private country homes, cottages, or dachas frequently uses inversion roofs.

Among the drawbacks are:

• The weight of the inversion roof is significant; taking into account the wind load and the height (number of floors) of the building, it can reach up to 90 kg/m2 – load-bearing walls must be strong and resistant to this weight.
• Special equipment is required to lift ballast onto the roof.
• Repair work is not difficult, but determining the location of the leak and its cause (under ballast) is already difficult and takes time. Read about flat roof repairs here.

View this video to learn the benefits and drawbacks of inversion cables:

Rules for carrying out work

The selection of the roof is done even in advance of the design process. Professional calculations are necessary for inversion roofing. Acquire all required supplies and equipment in full. When assembling this roof, the following guidelines and recommendations must be followed:

1. On the roof surface, a drain is made for precipitation towards valleys, water intakes and drains. In this case, the slope of a flat roof cannot exceed more than 3% (1.8 degrees).
2. The slope depends on the purpose of the roof. If it will not be used, then the slope is equipped in an inexpensive way – in the form of metal structures or heat-insulating boards (in the form of a wedge), then flat slate. With the type in use, an even layer of expanded clay is applied, then a reinforced screed is poured.
3. Bitumen carpets from rolls are laid with a propane torch.
4. It is necessary to assemble the structure strictly in stages, without disturbing the order of layers.
5. Geotextile flooring is laid in overlapping strips and welded with hot air.
6. The polymer membrane is laid and butt welded from the inside and outside, also in strips.
7. The load for the non-operational option is calculated taking into account the weight of the materials used, the volume of snow precipitation (maximum) and the rose and strength of the winds.

The weight of furnishings and equipment, as well as the potential number of people or cars, are added to the aforementioned indicators for an operational roof.

Reference: Flat roofs with parapets can have inversion roofing installed, both operationally and non-exploitively.

One novel approach to roofing for contemporary structures is inversion roofing, which is distinguished by its unusual design that positions the insulation layer above the waterproofing layer. This technique increases the roof’s resistance to weather, increases its lifespan, and boosts energy efficiency. Careful planning and precise layering are necessary during installation to guarantee adequate insulation and drainage. The advantages that inversion roofing offers for both residential and commercial properties can be reaped by homeowners and builders by being aware of these essential features and the detailed installation procedure.

Installation technology

When installing an inversion roof, cover the roofing pie in the following order:

1. The basis for assembling an inversion roofing pie can be a reinforced concrete slab (of any structure – solid or hollow). The material is extremely resistant to heavy loads.
2. Form a mandatory slope of fine gravel (ceramic), up to 5 g.
3. Lay out a thin layer of cement and reinforced screed (with a thickness of more than 5-6 cm). and fix the angle of inclination.
4. The next layer of waterproofing from bitumen primers is a primer made from petroleum bitumen with the addition of the necessary components. Reliably protects premises from moisture, is durable and wear-resistant, since it itself is perfectly protected from the effects of bad weather, being in the middle of the pie. We wrote more about flat roof waterproofing here.
5. Layer made of modern technoelast.
6. Geotextiles – to create filtration. The material is made from polypropylene and polyester (used plastic bottles). It perfectly allows moisture to pass through and protects the lower layers from the penetration of heavy, solid particles (pollution).
7. Thermal insulation – extruded polystyrene foam is currently considered the best material. EPS is durable, wear-resistant, has high thermal conductivity and moisture absorption. Laying is carried out in several layers with overlapping joints. We talked about insulating a flat roof in a separate article.
8. The drainage layer (even from 5 cm) ensures maximum drainage of water from the roof surface, at the same time eliminates possible movements of layers, protects from the destructive effects of precipitation and temperature changes. For greater effect, use a drainage membrane.
9. Ballast additionally and thoroughly strengthens the layers of the structure, immobilizing them. This ensures that the layers of the pie will not “ride” and fray, damaging each other. Thanks to ballast, there is no need to create numerous holes for fixing fasteners at the joints (in the middle of the roof). It also provides a solid base for laying roof finishes.
10. A layer of cement mortar (marked 150 or more) for reliable installation of finishing coatings (rubber/silicone non-slip).
11. Paving slabs are supported on special supports (made of plastic), paving stones on a cushion of sand/crushed stone. If the roof is not in use, then the finishing coating will be in the form of a backfill of gravel (up to 50 mm).

Crucial! Rolls of waterproofing can be applied in two ways: first, by fusing the bottom layer together to cover the seams, and then applying the waterproofing in two layers.

The cost and installation of an inversion roof in Russia vary greatly depending on the region, kind of building (its size, number of stories), meteorological conditions, and chosen materials.

In small towns, it can range from 1200 rubles per square meter to 2,500–3,000 rubles (and beyond) in Moscow. The kind of roof and the pie’s component parts will determine the cost of materials in each unique situation. Read about the price of a turnkey flat roof in a different article.

The video demonstrates how to construct an inversion roof:

Useful video

An extensive synopsis of the inversion flat roof is given in the video:

For both residential and commercial buildings, the inversion roofing device and installation offer a cutting-edge and effective solution. Because of its special design, which places the insulation above the waterproofing layer, this kind of roofing system has a number of important advantages, such as better thermal performance and increased protection for the waterproofing membrane.

The longevity of inversion roofing is one of its main benefits. The waterproofing layer is protected from mechanical damage and thermal stresses by being positioned underneath the insulation. As a result, the roofing system lasts longer and requires fewer repairs or replacements, which eventually results in cost savings.

Inversion roof installation technology is comparatively simple to use, but it does need close attention to detail. Crucial actions include making sure the roof surface is properly prepared, applying the waterproofing and insulation materials precisely, and making sure there is enough drainage. These procedures, when carried out correctly, produce a roofing system that is incredibly effective and offers superior weather protection.

Furthermore, by minimizing heat gain in warmer climates and reducing heat loss in colder ones, inversion roofs improve energy efficiency. They can therefore reduce energy costs and be considered an environmentally friendly option. They also give you the option to add green roofing components, like plants, which can improve insulation even more and increase urban biodiversity.

In conclusion, inversion roofing is a reliable and flexible material for use in contemporary building. Its capacity to safeguard the waterproofing layer, along with its thermal efficiency and potential for use in green roofing applications, makes it a desirable choice for individuals seeking to make an investment in a durable and environmentally friendly roofing system.

Video on the topic

Installation of insulation on a flat roof.How to properly install thermal insulation?

Inversion roofing as it is.

Modern exploitable inversion roofing

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Inversion roofing device. SK Alliance of Modern Construction.