How is a flat roof being repaired? Flat roof. Flat roof repair and reconstruction. How to calculate the cost of renovation correctly

The photo above shows a standard construction, the so-called ⇒ weld-on roof. Here, rolled bituminous materials are used as a waterproofing coating.
When installing such a roof, a gas burner with a propane cylinder is used, as well as a hose with a reducer to adjust the outlet pressure. When laying on a new base, they are covered in two layers, if on an old well-prepared one, then one layer can be dispensed with.
To increase the waterproofing properties and service life, a slope is arranged on flat roofs. It is needed in order to control the flow of rainwater, creating high points on the sections of the parapets towards the weirs.
Initially, the slope must be designed with respect to the funnels and create zones with a rise, slopes with a height greater than the main roof area. By following these instructions and the project drawings, it will be possible to prevent the appearance of stagnant zones where water will accumulate.
Large puddles on the roof are a good environment for the emergence of vegetation and at the slightest defect in the seams of the joint, the layer of water will eventually push moisture into the roofing cake, which will lead to a major overhaul.

A defect in the roof like swelling, air bumps on the surface appears due to the fact that the cement-sand screed of the base has not been sufficiently dried. The same defect can occur even after repair, if you do not dry the damaged area with opening the pie and immediately fuse new layers onto the old ones.

Installing aerators over the entire roof area will create exit points (ventilation) and remove moisture vapor from the under-roof space.

The slope can be created using a screed with the addition of expanded clay, while the given slope is formed by a metal profile or stone blocks cut along a string from a high point to the lower one.
Also, the slope can be formed from a wedge-shaped insulation of the Technonikol company from solid (dense) stone wool, then cover it with a primer based on bituminous mastic. This will allow the creation of an adhesive backing for a durable soft roof installation.
To maintain the correct geometry and dimensions of the overlaps along the side and end connections of adjacent rolls, it is necessary to spread the bitumen coating from the beginning and cut it according to the forms of abutting half-timbered houses, weather vans, parapets, chimney pipes and ventilation.
Further, when working with a gas burner, you need to heat the material to a temperature sufficient to combine the materials at the molecular level. To do this, the indicator on the underside of the roll material helps; when the flame is directed at it, the film is deformed.
The characteristic flowing out of the bitumen roll in front of the movement of the tooling with the roll is a sure sign of compliance with the "welding" technology of the coating.

The exploited flat roofs have a rigid base, since they are under significant load.
Much less rigid are unexploited flat roofs, where soft materials are used for insulation.
A flat covering that does not have an attic is most often surrounded by a lattice barrier so that the wind can blow away unnecessary debris from it. Such surfaces do not require cleaning from snow drifts, since the snow melts from the heat conducted by the roof.
A flat covering with an attic is a more expensive structure, but it has a number of advantages: the attic helps to monitor the tightness of the waterproofing and thermal insulation layer, and also contributes to the drying procedure of the roof.

Features of flat roofs

Repair of a flat roof can be done with the help of specialists or done by hand, since it is simple and does not require much effort.

Flat roofs have a slight angle of inclination (no more than 10 °). For their repair, it is recommended to use different types of soft roofs, iron and slate. You should make a choice in favor of this or that material, based on the purpose of the building: industrial, economic, residential.

For the repair of flat roofs, PVC membranes are often used. They can be laid on existing roofing material or old slate in one layer. Only one condition must be met: the surface must be clean, free of debris, water and oil stains. In this case, it is not necessary to use a flat surface - the elasticity of PVC membranes will hide any roughness.

A more budgetary option would be to repair flat roofs with euroruberoid. When using this material, it is necessary to thoroughly clean the surface from debris, irregularities and previous coating. Euroruberoid is applied in two layers: basic and decorative. Thanks to the top layer, roofs made of this material are heat- and frost-resistant, drought-resistant, immune to the effects of chemicals, and also durable.

Any coverings and roofing including - are not eternal. Even the most modern of them are subject to wear and tear and a gradual loss of their protective qualities. Under the influence of precipitation, temperature changes, mechanical factors, the roof material collapses, cracks, bubbles, delamination, faults, etc. appear on it. And then leaks are just a stone's throw away! Flat roofs are particularly prone to this type of damage due to their geometry and use as coverings for soft materials.

Moreover, the first minor defects may appear literally after a couple of years of operation. Should we re-cover the roof? Not at all. You can eliminate damage by performing timely repair of a flat roof. Simple measures to restore the roofing will help to extend its service life, and, importantly, will not require large expenditures.

cracking of the surface;
local mechanical damage (holes, through cracks, cuts);
peeling of the roofing at the edges and in the seams;
the appearance of folds;
decay of the coating;
bloating, blisters;
wear (loss) of the top layer of the roofing carpet.

The causes of defects are various factors: errors during installation, insufficient insulation of attic floors, mechanical influences, environmental influences.

In any case, damage to the integrity of the roof will sooner or later lead to leaks, destruction of concrete floors. This has caused the need to carry out current local repair of a flat roof at a time when its complete replacement is not yet needed.

Repair of rolled bituminous roofs

Most often, flat roofs are covered with roofing felt or its analogs from a series of fused bituminous waterproofers (euroruberoid, rubemast, glass insulating material, etc.). So let's start with them.

Local damage (cuts, breakouts, penetrations)

Mechanical damage on the surface of the roof can occur as a result of its clearing from snow in winter, hail, and human movement. Other possible reasons: deformation of the base and initial defects allowed during the installation of the coating.

Local defects are eliminated by installing a patch on the damaged area. The patch is cut from the same material as the base cover. Its edges are rounded to reduce the likelihood of delamination, and the size is made so as to cover the defect by 10-15 cm in all directions.

Traditional repair work algorithm:

the place of damage is cleaned (including from protective dusting) and dried;
cut out the patch;
stick it on mastic or fuse it with a construction hair dryer;
smooth the patch with a roller or other suitable object to align the edges of the patch with the base surface.

If everything is done correctly, the integrity of the roof will be completely restored, and the patch will be almost invisible.

The process of installing a patch over a crack in a bituminous coating was filmed:

Extensive damage to bituminous roofing

It occurs most often if moisture seeps under the bituminous layer, a large area of the roof is damaged and begins to rot. To restore the integrity of the coating, perform the following actions:

the damaged area is cleaned of gravel (in the presence of dressing);
cut out a square or rectangular piece of fabric containing damage (layer by layer);
clean and dry the resulting gap;
using the cut out piece of canvas as a template, cut out as many patches from the bituminous material as it was decided to replace the layers;
smear mastic on the exposed area and glue the patch back to back, smooth it with a roller;
similarly, the next layers of patches are glued;
cut out another finishing patch, so that it overlaps the damaged area by 10-15 cm on all sides;
smear with mastic and glue a patch on it, smooth it with a roller.

When using the deposited material, the repair is carried out in the same way, with the exception of using bitumen mastics for gluing patches. The patch cut from the waterproofing is heated from below with a hot air gun until the adhesive bitumen layer melts. Then the patch is laid in place, fixed and smoothed with a roller.

Cracking of the bituminous surface

Bituminous materials are susceptible to the formation of small surface cracks caused by sun and heat.

To seal surface cracks, do the following:

the damaged area is cleaned of dirt, old mastic and dusting (if any);
dry;
cover with mastic in 2 layers;
the renewed area is covered with coarse-grained dressing.

It is also allowed to apply a patch of the same material as the base coat to the area with a network of cracks. Moreover, its size should overlap the area of the defect by 10-15 cm from all sides. The patch is glued on top of the mastic; when choosing a fusion method, the lower side of the patch is preheated with a hot air gun stream.

Air or water bubbles

Formed as a result of seasonal or daily temperature fluctuations in the summer, when the roof quickly cools and heats up. The air in the insulation layers of the roofing carpet expands and "blows" bubbles. The same happens if moisture has seeped into the under-roof space. When heated, it evaporates, forming swellings.

Repairs to eliminate bubbles:

remove layers of dusting from the place of swelling;
the place of the swelling is cut with a knife along or with an envelope (criss-cross), the edges are folded back to dry parts;
dry the inner surface;
cleanse it of dirt;
the cavity is treated with bituminous mastic;
glue the folded edges back onto the mastic, press down and roll the restored fabric with a roller;
a previously prepared patch is glued with mastic or fused onto the cut site with its overlap by at least 10-15 cm, pressed with a roller.

More details:

Peeling the waterproofing carpet from the backing

It occurs if, during the installation of the roll cloth, the base (concrete slab or screed) was not sufficiently cleaned of dust and dirt. Or the installation was carried out without priming the base with a bituminous primer. All this leads to a low degree of adhesion between the waterproofing material and the substrate.

To eliminate the described trouble:

the exfoliated part of the canvas from below is cleaned of mastic;
remove dirt from the base, dry it;
put mastic on the base and stick the exfoliated area on it;
press the restored site with a roller;
if the web of material in the place of delamination was torn, then a patch with a width of 20 cm or more is applied along the gap line.

Repair of membrane roofs

Polymer membranes are more durable than any bituminous waterproofing. Their service life reaches 50 years. But even membrane roofs are not insured against various types of mechanical damage, including punctures, ruptures, and depressurization of the seams. Most often, coverings are damaged when performing various works on the roof, for example, when clearing snow or installing equipment.

Restoration of a damaged membrane usually involves sealing the defects with polymer patches, and if the seams diverge, they are re-sealed.

Mechanical damage

Tears and cracks on the surface of the polymer web can occur as a consequence of careless movement on the roof, cleaning from snow and ice using sharp tools, falling objects or dragging them.

The sequence of restoration work:

the repaired section of the web is cleaned and degreased;
cut out a patch from the membrane, preferably of the same type and manufacturer as the base coat; its dimensions should be such as to cover the defect by 5-10 cm on each side;
the patch is soldered with a stream of hot air using a welding machine;
roll the sealed place with a roller.

The whole technology looks like this:

When installing a patch on an EPDM membrane, you can use the adhesive fastening method, without using welding.

Depressurization of seams

The separation of adjacent blades at the seam joints occurs when the blowing force and welding temperature are incorrectly selected during installation, the speed of the welding machine. Another possible reason is the installation of the membrane with an initial "interference", with the help of which inept installers visually compensate for unevenness in the base.

Depressurization is eliminated as follows:

the place of delamination is treated with a special cleaner;
seams are soldered with a welding machine;
in some cases, to strengthen the places of delamination, a patch of membrane is applied over the problem seam.

There is another way to get rid of damage without using welding machines and expensive components. These are modern Eternabond technologies used to restore tightness of seams and minor damage.

Eternabond repair material is a roll tape with an adhesive layer on one side. The tape is capable of forming a uniform surface with the membrane, which is not inferior in strength to a solid sheet.

Repair work using EternaBond tape is carried out as follows:

the surface of the defect is treated with a special solvent;
cut off the necessary part from the tape roll;
remove the protective film from the adhesive side of the tape;
press the tape to the place of the defect and roll it with a roller.

More details:

Repair of mastic roofs

Flat roofs are not always covered with roll materials or polymer sheets; quite often in recent years, liquid waterproofing has been used for these purposes. A special mastic is applied to the base of the roof, which, under the influence of air, hardens and takes the form of a polymer membrane.

After several years of operation, cracks may appear on the mastic roof. They should be cleaned of dust and dirt, and then filled flush with mastic or polymer-cement mortar. An additional continuous layer of mastic is placed if the area of damage is more than 40%. In this case, first, the damaged areas are restored locally with mastic, and then another layer of mastic with a thickness of at least 3-4 mm is applied over the entire surface, and after it has hardened, a protective layer is applied.

Features of overhaul

All measures for the partial restoration of the roof belong to the current (planned) repair, during which only minor damage can be eliminated. If the service life of the coating comes to an end, and defects make up more than 50% of its area, a flat roof is overhauled.

It consists in replacing the entire roofing covering, and, if necessary, all components of the roofing pie (thermal insulation, vapor barrier).

The complex of works carried out during the overhaul of the roof:

the old coating is dismantled;
if the base was a cement-sand screed, then, in most cases, it is also removed - with the help of seam cutters, bumpers;
all layers that make up the roofing cake are inspected (insulation, waterproofing membranes, vapor barrier films);
upon detection of damage, the problem layer is replaced;
a new cement-sand screed is poured (if it was originally provided);
a new roof covering is being laid.

In addition, overhaul may include the replacement or installation of roofing aerators, the installation of drainage funnels, the device of abutments and eaves.

When performing a major overhaul of the roof, there is a possibility of its complete reconstruction. For example, by including a layer of insulation in the structure, an ordinary roof can be converted into an insulated one. Or, by adding a top durable layer, make an exploitable roof from an unexploited roof.

During reconstruction, some materials may be replaced with others more suitable for specific operating conditions. A common situation: replacing a bituminous coating with a polymer membrane. In this case, it is not necessary to dismantle the old material. PVC membranes are mounted on a bituminous roof through geotextiles, which act as a separating layer. If TPO or EPDM membranes are used, then they are laid without geotextiles, directly on the bituminous coating.

Overhaul is an expensive undertaking, in most cases complicated by the dismantling of the old coating. Therefore, you should not bring the roof to a deplorable state before the end of its service life. And for this, it is necessary to periodically carry out preventive inspections of the roof and, if defects are found, carry out timely maintenance.

Flat roof reconstruction problems

Reconstruction of flat roofs of industrial and civil buildings on the territory of the Russian Federation is one of the most frequent and natural types of construction work. Despite the appearance of modern roofing materials, a clear improvement in the culture of work in the device of welded waterproofing, huge amounts of money are spent annually on current and overhaul repairs of roofs of this type. Leaks, bulges, folds, cracks and other defects in the roofing carpet lead to a significant increase in the cost of building maintenance.
As part of the current repair of roofs, which is carried out either when the first signs of roof leakage appear, or according to the results of an assessment of the condition of the roof, one or two layers of roll-on materials are glued. The durability of such repairs, as a rule, is not great - only 2 - 4 years and it is necessary to re-apply the next layers of roof waterproofing. As a result of such permanent repairs, the waterproofing roof carpet can have a thickness of more than 200 mm (see Fig. 1)

Fig. 1. Flat roof waterproofing carpet after numerous renovations.

One of the main reasons for such a short period of maintenance-free operation of roofs is the saturation of various elements of the roof with water, both in the process of direct installation of the roof and in the process of their subsequent operation. Excess moisture appears in the elements of the roof during work in the autumn-winter period, during precipitation, and the elements of the roof also get wet when the roofing carpet is damaged, in the absence or violation of the continuity of the vapor barrier membrane. When water or water vapor gets inside the structures of the roofing cake, the heat-insulating layer of the roof, laid under the layer of roll waterproofing, gets wet. This is also facilitated by those building solutions that are most popular today. Backfilling with expanded clay gravel, thermal insulation of roofs with fibrous mineral wool slabs with high water absorption are widely used. These materials can be saturated with water both during construction, during precipitation; and during operation, with all kinds of damage to the roofing carpet. It should be noted here that heaters with high water absorption are prone to water accumulation under the waterproofing layer. In this case, water can concentrate not in the place of leakage through the waterproofing, which significantly complicates the search for the place of damage to the roof. When the roof is heated by solar energy (in summer up to 85 degrees C), moisture from the heat-insulating layer evaporates with the creation of excess pressure under the waterproofing membrane and, as a result, swelling, bubbles, tearing of the roof carpet appear. (see fig. 1). This damage forms subsequent damage to the waterproofing layer, leading to water leaks. Roof repair, which consists in re-sticking waterproofing, is not effective insofar as it does not eliminate the cause of roof defects, which is the increased water content of the roof insulation layer.

Existing options for the reconstruction of flat roofs

Only the decision to overhaul the roof, in which the roofing cake is completely dismantled, can radically correct the situation. But the overhaul of the roof is a complex of expensive construction work, including a large amount of financial investment in dismantling and removal of construction waste. In addition, during the overhaul of the roof, there is a risk of causing significant financial damage to the interior decoration and equipment of the building, since when precipitation falls when the roofing waterproofing is removed, water is likely to get into the building.
To some extent, it is possible to find a solution to this problem with the construction of so-called "breathing" roofs. In this case, in the lower layer of the waterproofing carpet, due to its partial fixing to the base, a network of channels is created through which there is a subsequent release of excess pressure under the waterproofing membrane. This solution has several significant drawbacks:

High labor intensity of the device of the elements of the roof. Sophisticated units for the output of the vapor-air mixture.
If the roof is damaged in one place, moisture spreads along the system of under-roof channels over the surface of the entire roof. In this case, it is almost impossible to find the place of leakage; often it is necessary to dismantle the entire roofing carpet.
When installing a breathable roof over an old waterproofing carpet, stagnant water is not eliminated, which almost always occurs on old roofs. Especially with increased thickness of the waterproofing carpet.

Fig. 2. Sectional view of a flat roof after conventional renovation (applying a new waterproofing carpet).

1. The base of the roof is usually a reinforced concrete slab.
2. A layer of vapor barrier.
3. A layer of old, damp insulation due to leaks (mineral wool, expanded polystyrene, expanded clay, lightweight concrete, etc.)
4. The path of migration of the vapor-air mixture in the heat-insulating layer when the roof is heated.

6. Overpressure created by migrating water vapor.
7. Bulges on the surface of the new roofing carpet laid during the roof reconstruction.

Buffer layers of a flat roof made of monolithic foam concrete.

An effective solution for the reconstruction of flat roofs is the use of monolithic roofs. At the same time, foam concrete screeds are arranged on the surface of the old waterproofing carpet. Next, a new roofing carpet is fused onto the surface of the foam concrete screed. Fully flat roof reconstruction technology is a series of next steps.
... Assessment of the condition of a flat roof: determination of stagnant water zones, the presence of damage to the roof carpet, etc.;
... Preparation of the base for the installation of a buffer foam concrete screed. Cutting folds, detachments, bubbles - to the base, removing debris, peeling off dressing, removing air pockets;
... Acceptance of hidden works;
... Installation of buffer foam concrete screeds with a thickness of 40 - 100 mm;
... If necessary, the device of vertical transitions (fillets) also from monolithic foam concrete;
... Priming the base with bituminous primers, according to the recommendations of the supplier of the waterproofing roof covering;
... Installation of a roof waterproofing carpet in two layers;
... Installation of roof fans (weather vans) at the rate of 1 piece per 150 - 200 sq. M .;

Fig. 3. Section of a flat roof during reconstruction using monolithic foam concrete.

1. The base is a reinforced concrete slab.
2. Vapor barrier.
3. Old thermal insulation layer.
4. Paths of migration of the vapor-air mixture in the heat-insulating layer of the roof.
5. Damage to the old waterproofing carpet.
6. Distribution of migrating water vapor in the pore space of the foam concrete layer.
7. A layer of new waterproofing, installed during the reconstruction.

With this roof structure, the layer serves as a buffer space for water vapor. The increased pressure created by water evaporating from the heat-insulating layer of the roof is evenly distributed within the vast pore space of the foam concrete, without leading to damage to the roof waterproofing carpet. It is this effect that explains why the layers of roll waterproofing on foam concrete roofs have been without repair for more than ten years in the complete absence of blisters and other damage. A similar mechanism has the effect of frost resistance of cellular concrete - only when freezing into the pore space of foam concrete, not steam is squeezed out, but ice crystals grow without damaging the material itself.
A separate line should be noted the effect that we called "self-drying" of foam concrete. Physicochemical binding of water during hardening of Portland cement by hydrated neoplasms ensures a decrease in the water content of non-autoclaved foam concrete even inside hermetically sealed spaces. This happens when laying monolithic foam concrete in buffer heat-insulating screeds, well masonry, filling other building cavities with non-autoclaved foam concrete. When water is absorbed, the processes of hardening of foam concrete are intensified, thus, when dry, foam concrete increases its strength characteristics. It is a well-known fact of the possibility of long-term hardening of cement concretes in general, and cement foam concretes in particular. This allows the foam concrete screed, even with subsequent ingress of water, as a result of damage to the waterproofing coating, to dry independently during the hydration of the cement matrix of the foam concrete. It should be noted that the practice of working with monolithic foam concrete when installing flat roofs convincingly shows that in roofs using non-autoclaved foam concrete, a vapor barrier is not necessary. This can also be explained by the "self-drying" effect.

Description of the properties of monolithic foam concrete and equipment for its production.

The production of aerated concrete mixture was carried out by us using the so-called one-stage technology for the production of aerated concrete mixture. This excludes the preliminary preparation of two-phase foam (L - G). The equipment prepared three-phase foam (Zh-T-G) in one redistribution, the foam generator and the pump for feeding the foam concrete mixture at a distance are excluded from the technological chain. When producing foam concrete at a construction site, a fundamental requirement is the minimum required set of equipment. A foam generator is a device that requires a high work culture during operation, its presence significantly complicates the technology of foam concrete production. At the same time, the presence of a foam generator does not give any tangible advantages in the production of monolithic foam concrete. The foam concrete mixture was supplied by injecting pressure into the working chamber of the foam concrete mixer. This method allows you to abandon the use of pumps (gerotor, peristaltic) when transporting foam concrete, at a height of the foam concrete mixture up to 30 meters. Thus, the production and supply of monolithic foam concrete was carried out by one unit - a foam concrete mixer, which combines the functions of a foam generator, a foam concrete mixer and a pump.

Rice. 4. Equipment for the production and supply of foam concrete is placed on the body of a truck. Most of the workplace is occupied by a warehouse of binders and fillers.

Rice. 5. Production of foam concrete mix is carried out by one worker-plasterer. In the foreground is a foam concrete mixer SPBU-500M and a tank for mixing water.

Since the requirements for the economic efficiency of the repair of flat roofs require the installation of buffer foam concrete screeds of minimum thickness, this imposes a number of special requirements on the physical and mechanical properties of foam concrete. The presence of a complex modifying additive in the composition of foam concrete is mandatory, in the composition of which water-retaining additives are introduced. Otherwise, it is impossible to provide a guaranteed set of strength, especially in summer with intensive heating of the base for pouring foam concrete. Thin-layer laying requires mandatory volumetric reinforcement to prevent the development of shrinkage deformations. Volumetric mesh reinforcement of the cement matrix of foam concrete is carried out with hydraulically active silicate fibers. As part of a complex additive, it is desirable to use water-reducing additives. Sometimes it is necessary to use additives, accelerators of setting and hardening of the foam concrete mixture. The selection of a complex additive should be carried out by a construction laboratory, taking into account the fact that many types of modifying additives have a pronounced defoaming effect, for example, naphthalene-formaldehyde-type superplasticizers.

Table 1 Physical and mechanical properties of foam concrete.

Medium density foam concrete grade	Compressive strength, MPa	Thermal conductivity coefficient, W / m * deg.	Thermal resistance of a layer of foam concrete 100 mm thick.	Weight 1 sq. a layer of foam concrete 100 mm thick. (taking into account operational humidity), kg	Notes (edit)
					It is used only as a thermal insulation material, as well as for filling cavities

					Can be used as a base for soft roofing

Based on the results of many years of work related to the reconstruction of flat roofs using buffer foam concrete screeds, the following positive effects of such a structure and such material can be distinguished:
1. The period of maintenance-free operation increases to 10-20 years.
2. Laying of monolithic foam concrete is carried out by industrial methods, a team of two people can lay up to 700 meters of square foam concrete screeds per shift.
3. Foam concrete screeds provide additional thermal insulation of the roof. See table 1.
4. When laying monolithic foam concrete screeds, the unevenness of the roof is eliminated, there are no places of stagnant water.
5. The technology of gluing rolled bituminous materials is simple and does not differ in any way from the technology of gluing these materials onto a conventional cement-sand mortar.

Rice. 6. The photo shows one of the stages of flat roof reconstruction using monolithic non-autoclaved foam concrete.

You can see a foam concrete screed lying on an old waterproofing carpet. The next and last stage of the work is the installation of a waterproofing carpet made of bitumen deposited materials on top of a foam concrete screed.

Flat roof repair is becoming more and more in demand these days, since such a roof structure is very widespread not only in multi-storey, but also in individual construction. Its benefits are quite obvious. A flat roof with a small angle of inclination allows not only to save heat energy, reducing the heat transfer area. It allows you to use it for domestic and economic purposes, thereby increasing the usable area of the entire structure.

Before proceeding with the repair of a flat roof, it is necessary to study all the rules and requirements, since mistakes can lead to a reduction in its service life.

However, this use also has a negative side. It greatly increases the risk of damage to the roofing, primarily by mechanical means. Meanwhile, a flat roof, despite its external simplicity, is a rather complex structural system.

That is why the repair of a flat roof should be carried out with the strict observance of a number of rules and recommendations. Their violation can lead to a radical reduction in the service life of the roofing, up to its complete destruction.

Flat roofing and possible types of damage

Before proceeding with the repair of a flat roof, you need to know its structure. Then the weakest points of this particular structure will be clear, and it will be easier to identify the cause of the roof leak. Usually its construction consists of several layers. This is a load-bearing surface, in the role of which is a reinforced concrete floor slab, on which a vapor barrier layer is placed, and on it, in turn, a heater.

Mineral wool is most often used as the latter. A layer of waterproofing is laid on it, in the role of which, in most cases, rolls of roofing material act.

If the roof surface is occupied for household or domestic needs, a concrete screed is made on top of the waterproofing layer, designed to protect it from mechanical damage. In addition, to prevent moisture condensation from the insulation layer, ventilation holes are brought out, covered with special caps. Their connections to the top layer of waterproofing must be sealed carefully.

The main reason for the penetration of moisture under the waterproofing layer, in addition to mechanical damage, is the effect of temperature drops in the surrounding atmosphere. The second most common cause of roof leakage can be considered a violation of technology during the initial installation of the roof covering.

It is worth remembering that the service life of a roof covered with roll materials such as roofing felt is limited to a maximum of 5 years.

In winter, under the influence of severe frosts, it begins to lose elasticity and crack. In summer, due to its black color, it attracts solar thermal energy and heats up to 70 ° C.

As a result, the resin impregnating it begins to melt, and gradually slides down a slope towards the edge of the roof.

The base remaining in place largely loses its waterproofing properties and begins to gradually let moisture through.

Modern waterproofing mastics and resins have a significantly longer service life, but they are also much more expensive.

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Roof repair with roll materials

Rolled bitumen materials are the most common and popular roofing product, primarily due to their affordable price. Another reason for their popularity can rightfully be considered that their use does not require dismantling the old coating. However, do not immediately lay new rolls on top of the old coating. It must be prepared in advance.

First of all, it is necessary to remove the debris and dust accumulated on the roof. After that, the formed air bubbles are detected on the roof. They are opened with a knife, like an envelope, and, if necessary, dried. After that, they are heated with a blowtorch until the bitumen impregnation has melted and closed, eliminating air bubbles.

Only then can the next layer of rolled roofing material be laid. The roll is rolled out on the roof surface, one edge is heated and glued at the lower edge of the roof.

After that, it is folded back, winding on a piece of pipe slightly longer than the width of the roll.

Then they begin to slowly unfold it, heating the surface with a blowtorch. An indicator of the quality of heating is a small puddle of molten bitumen on the way of unrolling the roll.

The next roll in the longitudinal plane must be laid on the previous one with an overlap of at least 10 cm.

The adjacent roll should go to the edge of the previous one by at least 5 cm. As a result, if the technology is followed correctly, after the molten bitumen cools down, a monolithic waterproof membrane is formed that covers the entire roof surface.

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Application for the repair of polymer materials

Most modern waterproofing materials are made on the basis of polymers. If it is a mastic, then its main component is liquid polyurethane. Its first layer is applied directly to the prepared surface using a paint roller. It adheres tightly to the bituminous base. Then a reinforcing layer of non-woven synthetic fabric with a density of 20 to 60 grams per m² is placed on the not yet hardened mastic so that it is completely recessed. After that, a second layer of polyurethane mastic is applied on top. The process of its solidification lasts from 3 to 5 hours.

Another effective modern waterproofing material is liquid rubber. It is applied by spraying using special portable knapsack spray guns. The main advantage of this method is that it is not afraid of any irregularities on the surface of the roof. To obtain a rubber coating with a thickness of 3 mm, it is necessary to spray from 4 to 4.5 kg per 1 m². The resulting membrane is resistant to temperature extremes, but in severe frost it loses its elasticity, which makes it more susceptible to mechanical damage.

Another tool that is gaining more and more popularity these days is polymer tension membranes. They are assembled with hot air welding machines and are only attached to the edges of the roof. Therefore, if the foundation of the house begins to sag, the coating will retain its integrity. However, as in the case of previous materials, membranes are also vulnerable to mechanical damage, therefore, if the surface is intensively used, a protective coating must be put on top of the waterproofing.

The simplest protective coating, especially for roll-to-roll coatings, is a concrete screed. Unfortunately, over time, it begins to crack and crumble. Quite good reviews are received about the high-strength polyurethane coating "Marisil 400", but many are discouraged by its high price

In general, it can be noted that the repair of a flat roof, unlike its other varieties, is practically not associated with a risk to life and health, and therefore it can well be done by hand, without the help of hired specialists.