Flat roof with minimal slope. Minimum slope and slope of a flat roof

It is necessary to determine the design of the roof at the design stage of the structure. If you have chosen a flat option, it is very important to represent all the positive and negative aspects of the operation of a building with such a roof. The choice of the type of roof also depends on the use of special materials and technological methods in construction.

Flat roof device

Not always a flat type of roof evoked positive emotions among builders. This was due to some prejudices in the construction and operation of a flat roof - lack of aesthetics, uneconomical, fragility.

Recently, there has been a trend to revive the popularity of flat roof structures, a significant role in this was played by new construction technologies and innovative materials.

A flat roof made of modern materials reliably protects the house and looks beautiful

A flat roofing device can be represented as a multi-tiered "pie" with several layers:

Reliable foundation. Most often, this role is played by a reinforced concrete slab or a metal profile structure.
Vapor barrier coating. The most popular bitumen or roll materials.
Thermal insulation layer. Mineral wool, expanded clay, expanded polystyrene, cement screed - the main components used by builders for thermal insulation.
Waterproofing. There are a lot of materials to protect the roof from moisture (bitumen-based mastics, PVC membranes, compositions for liquid fusing, etc.), the choice depends on the material and production capabilities of the developer.

The listed order of layers is not mandatory, it can be different in different flat roof structures.

All elements of the roof must be of high quality, a flaw in at least one of them can lead to problems in the normal operation of the roof.

Pros and cons of a flat roof

A flat roof, despite its apparent simplicity, has a number of useful features that attract builders. Such designs also have disadvantages that must be taken into account.

Advantages of flat roofs

Photo gallery: flat roof operating options

Modern technologies make it possible to plant grass on the roof and arrange a playground exactly like on earth. You can get to such a cafe by elevator. Only a flat roof can be decorated so beautifully and modernly. On the roof, you can place a table, benches, a hammock and enjoy your vacation. Swim in the pool. practically without leaving home - you can only dream about it

Disadvantages of a flat roof structure

No roof is perfect. There are significant disadvantages of a flat roof:

instability to snowfalls (with heavy snowfall, the likelihood of a roof break increases, with abundant spring thawing, leaks are possible);
the need to build additional drains for water;
increased requirements for the state of hydro- and thermal insulation of the roof.

If internal drains are made on the surface of flat structures, then they require constant monitoring of their condition (it is necessary to clean debris, eliminate freezing, etc.).

Types of flat roofs

There are two main types of flat roofs:

The structural differences between the two types of flat roofs are in the order in which the layers are laid. In an unexploited roof, the top layer is waterproofing, which quickly collapses under the influence of various natural factors - the sun, wind, precipitation, etc. This option is not suitable for the active use of the roof.

The inversion roof is “packed” differently. The sequence of layers here is as follows: concrete, waterproofing, thermal insulation, protective coating. The last layer is often made of drainage or geotextile. Such durable structures are in demand among designers who want to make the most of the entire roof space.

Holding concerts, building car parks, summer cafes and studios implies a high degree of load, so builders put additional reinforced materials between the insulating layers.

flat roof slope

A flat roof does not have to be absolutely flat, a minimum slope must be provided for. Otherwise, sewage disposal will be difficult, moisture from precipitation will accumulate on the roof and contribute to its rapid destruction.

In the absence of a slope, stagnant zones with negative aspects may appear:

accumulation of moisture;
germination of seeds carried by the wind;
lichen formation.

To prevent this from happening, a slope of one to four degrees should be made on a flat roof. With such a difference in levels, melt and waste water will not linger on the surface, which will extend the life of the roofing.

Work to create a slope on a flat roof is called slope.

To achieve the desired slope on a flat surface, you can use different materials:

Backfill components (expanded clay, perlite, etc.).
different layers of insulation.
Lightweight mixtures of concrete on various bases (polymers, bulk materials, etc.).

Each of these solutions has its own characteristics in relation to the slope. The use of backfill materials during long-term operation of the roof does not give a clear angle of inclination. Loose materials can slide off the roof, move, which leads to a change in slope. It is difficult to achieve a smooth height difference if large-sized expanded clay (more than 20 mm) is used.

Accurately leveling an inclined surface with expanded clay is quite difficult.

Lightweight concrete masses are devoid of such disadvantages, but they are quite heavy, not every roof structure provides for such additional weight. These materials cannot be used in cases where the building has already been built and its design is not designed for a large load on the frame and foundation.

Modern industry produces materials that help create the necessary and smooth slope on a flat roof. The polymer base of these mixtures makes them plastic, which is a big plus in the construction of flat roofs.

There are other possibilities for creating a slope on a flat roof:

installation of metal profile structures covered with flat slate;
construction of a crate (rarely used due to the cost and impossibility of creating small slopes);
installation of wedge-shaped heat-insulating plates.

The last of these methods is gaining popularity among builders, because this method of ramping has its advantages:

simple installation. Plates for thermal insulation are already cut at a certain angle. Their installation does not require any special skills, it is enough just to lay the wedge-shaped slabs on a flat surface of a flat roof to get the necessary slope.
light weight. During construction work, you will not have to resort to the help of any lifts. In addition, the insignificant total mass of insulation boards will not affect the performance of the roof in any way.
Independence from external conditions. Laying wedge-shaped thermal insulation can be done in any weather.

Video: flat roof flattening

Insulation and drainage for flat roofs

To avoid a quick failure of a flat roof, you should take care of its proper insulation and drainage.

Drainage

A drain on a flat roof is mounted outside or inside the building. The choice of water drainage method depends on climatic conditions:

Video: installation of a receiving funnel on a flat roof

Warming

The thermal insulation of a flat roof is carried out differently than the insulation of pitched surfaces.

This process includes two important points - vapor barrier and thermal insulation. Depending on the type of roof (classical or inversion), the order of the layers changes.

Used as thermal insulation:

mineral wool;
Styrofoam;
polyurethane foam;
ecological cotton wool;
foam concrete.

A good vapor barrier can be provided by a polypropylene film and a build-up mass with a bitumen base.

Photo gallery: flat roof insulation

Flat roofs can be insulated in a well-known way - by filling expanded clay Large surfaces are easier and faster to insulate with mineral wool Modern materials, such as extruded polystyrene foam, are increasingly being used to insulate flat roofs. Foam glass provides not only thermal insulation, but also an excellent soundproofing effect. flexible hose, so you can handle this job alone

Flat roof ventilation

To begin with, let's denote the negative points that will arise on a flat roof without ventilation. A roof of a flat design, devoid of ventilation, will be “loaded” with condensate. Natural physical processes will lead to the fact that warm air, rising up, will settle not on the elements of the attic (like on a pitched roof), but on a reinforced concrete base. The result of such adverse processes will be the appearance of fungus and mold on the ceiling.

In the future, steam and heat insulation, other roofing elements will suffer. To prevent this from happening, it is necessary to equip deflectors and aerators on the roof. Their installation is provided at the design stage of the building.

Devices to ensure unhindered air circulation are provided at the design stage of the roof

The inflow and outlet of air is carried out due to different pressures outside and inside the building. A flat roof will "breathe" if artificial ventilation devices are placed on it. This will help keep the layers of hydro and thermal insulation from destruction, eliminate the spread of air bubbles and swelling of the roofing material.

Flat roof covering materials

As roofing materials for flat roofs are used:

mastics;
polymeric membranes;
roll materials on a bitumen basis.

They provide good waterproofing and excellent resistance to mechanical stress and temperature extremes.

Bituminous materials

The basis of many roll coatings is oxidized or modified bitumen. Ruberoid, stekloizol, rubemast, euroroofing material are the main types of bituminous materials used on a flat roof.

Table: characteristics of rolled bituminous materials

Material name	What is	Average service life	Characteristics
			positive		negative
Ruberoid	Cardboard impregnated with bitumen. The material also has a protective layer of backfill - talc, sand, granular expanded clay, etc.	5–10 years	Good waterproofing, resistance to atmospheric collisions and mechanical impacts. Low cost, easy installation.		Does not withstand temperatures of +50 °C and above. Cracks form on the roofing material even at large minus values.
Rubemast	Improved modification of roofing material with a thicker layer of bitumen.	15 years	High ductility and resistance to cracking (with temperature extremes and mechanical damage).	The need for certain skills when welding this material.
Stekloizol	The basis of the material is fiberglass with a bituminous top layer. For protection, there is an additional layer of backing at the top, and a special film at the bottom.	20 years	Doesn't rot, doesn't crack.	Requires professionalism when laying, bubbles and folds may form, burns through the bituminous coating when the gas burner malfunctions.
Euroruberoid	Bitumen supplied with various polymeric additives.	Over 20 years	All characteristics are an order of magnitude higher than those of any other bitumen materials	Assembly skills required. High price.

Polymer membranes

These materials have become popular relatively recently. The advantage of such flat roof coatings is plasticity, resistance to damage, resistance to temperature extremes, and simple installation. Another big plus of polymer coatings is their production footage. The length of one roll of polymer membrane is from 20 to 60 meters, so it can cover large areas of a flat roof very quickly.

Polymeric membranes are available in long rolls, so they can quickly cover large areas.

The operating period of roofs with polymer membranes is 30–50 years.

Mastics

The positive aspects in the use of mastic materials are the absence of seams and the integrity of the coating. The service life of such roofs is from three to ten years.

Applying a viscous and viscous mastic to the roof surface is a simple process, this layer becomes solid at normal air temperature. Mastics are also used as an adhesive base for mounting roll materials.

There are cold and hot mastics. The first type does not require additional manipulations during the preparation and installation, in the second case, the mixture will need to be heated to 180 °. It is safer to work with cold mastics, but hot materials set faster.

Flat roof repair

Any roof needs constant inspection, care and repair. On the roof, under the influence of various factors, cuts, damage, breakthroughs, swelling, delamination and other problems can occur that interfere with the normal use of the roof. To eliminate such negative conditions, it is necessary to carry out repair work. They can be current, emergency and capital.

Emergency repair is a forced, unplanned measure, emergency measures to restore the integrity of the roof. Current and capital repairs of a flat roof are provided in advance. The volume of work carried out during current and major repairs differs significantly. Major repairs require more time and costs, while the area of repaired coatings is also much larger.

Defects on roofs covered with rolled materials are most often eliminated by gluing patches.

During emergency and scheduled repairs of a flat roof, patches are most often installed on the damaged area. Materials for repair in each case are selected individually. One of the latest "assistants" when updating a flat roof is a self-adhesive tape with a bituminous coating. It is very convenient and effective to use it for roof repair. There is only one limitation: such a tape is not suitable for repairing damage over a large area.

Flat roof repairs are much easier and safer than pitched roofs. The repair time on such a surface is also much less.

Video: flat roof repair technology

Economic nuances of using a flat roof

If you are wondering about economic benefits, then you should consider some points when building a flat roof.

Of course, the construction of a flat type of roof is less expensive, since the cost of building a rafter system is not required. This will also be the case with operation, if repair of the rafter part of the pitched roof is required. In a flat roof, such an expense item is simply absent.

A pitched roof will require more investment also because it is clearly visible, being an integral part of the facade of the building. The materials used in the construction of the upper layers in a flat roof are not always appropriate for a pitched version. They can be simpler, uncomplicated, while on a pitched roof it is better to use not only reliable, but also beautiful finishes.

The costs of building, maintaining and repairing a flat roof largely depend on its intended purpose. The cost will be much lower if the roof is not in use.

The construction, maintenance and operation of a flat roof have their own natural features. There are advantages and disadvantages to using flat roofs. Given the purpose of using the building, a flat roof should be mounted with strictly defined materials.

A perfectly flat roof cannot be by definition. Otherwise, it will accumulate rain and melt water, which will lead to its early wear. Therefore, according to generally accepted standards, a flat roof has a slope of 1 to 11.5 degrees. At the same time, the average value fluctuates around 1-5 degrees, which in practice is 1.5 or more centimeters of slope per meter.

How to calculate the angle of inclination

In order to find out the angle of inclination of the roof, you must:

Know the height of the parapet.
Know the thickness of the roofing cake.
Know the exact location of the intake funnel.

As an example, take a parapet height of 500 mm; the thickness of the roofing cake, excluding the slope layer, is 250 mm, while 50 mm of the parapet should remain on top, above the roof plane; the water intake funnel is located 5 meters from one of the parapets. Thus, 500–250–50=200 is the thickness of the slope forming material at the parapet. The funnel is 5 meters away, which means that we need to go to zero for these 5 meters: 200/5=40. Thus, the slope of the roof will be 4 centimeters per meter or 4%. With a minimum value of 1.5%, this is a sufficient level.

If you consider this slope too large, it can be reduced to a minimum of 1.5%. So, if there are 5 meters from the funnel to the parapet, and we will rise 1.5 centimeters every meter, then the thickness of the slope-forming layer at the parapet will be 5 * 1.5 + 2 = 9.5 centimeters.

Provided that the water intake funnel is located not outside, but inside the roof, there are two options for organizing the slope:

The formation of a circular system. That is, make a slope in such a way that water flows evenly over the entire area of \u200b\u200bthe roof.
The formation of scarves. Draw a roof from the funnel like an envelope. So, improvised gutters are created.

Note that when two or more water intake funnels are located, the roof slope is organized exclusively according to the second option.

markup

To make it convenient to mark the future screed, you will need a laser level. The laser is aimed at an acceptable level of parapet thickness, in our case it is 200 mm, and a line is drawn with a construction pencil along the perimeter of the entire roof. In the absence of a laser level, you can use the usual, or hydraulic. Then we find the thickness of the parapet in one place and, adding a level, draw a line along the entire perimeter. You can check that the line does not crawl up or down using the hydraulic level.

Further, a lace is pulled from the parapet to the funnel. Beacons can be set along the cord, so it will be more convenient to work. If the unfolding occurs with the help of the formation of kerchiefs, the lace must be stretched along their border.

Roofing with polystyrene concrete

Polystyrene concrete is a type of lightweight concrete made from cement, water, mineral filler and various additional additives. For the purpose of weighting, the addition of sand is permissible. To produce polystyrene concrete at home, you will need:

Concrete mixer. Specialists use a special unit that allows you to supply concrete through a hose directly to the roof.
Cement 500 brand.
Polystyrene crumb. Manufactured from defective polystyrene boards.
Water.
Liquid soap.
Sand.

It is made at the rate of: 2 shovels of cement, a shovel of sand, 5 ten-liter buckets of polystyrene okroshka, 50 grams of liquid soap, water, until the mixture reaches the desired consistency. Concrete should not be liquid and not too dry.

The order of work is as follows:

Creation of markings on the roof. Use a bar or beacons. Please note that the beam subsequently needs to be delivered on time. That is, when one section is flooded, and the mortar has already solidified, the beam is removed so that it does not interfere with the pouring of the adjacent section. The lace in this case is a weak helper. From concrete, it will get wet and sag.
To create a slope of a flat roof, the resulting mixture must be delivered upward. We advise you to take care of creating a winch in advance. This will make lifting the concrete easier. Even better, initially bring all the material to the roof, as well as deliver a concrete mixer there. This will greatly simplify the work on the slope.
Polystyrene concrete is pulled together by beacons using the rule. It is desirable to leave as few irregularities as possible; subsequently, insulation will be laid on the concrete. The solution hardens in a day, and it is already possible to move freely on it.
A heater is laid along the slope-forming layer, and then everything is fixed with a cement-sand screed, for which a reinforcing mesh is necessarily laid. The thickness of the screed is approximately 6 centimeters.

Polystyrene concrete is used both on reinforced concrete bases and on bases made of profiled sheets.

The advantages of this material include:

Inexpensive cost.

To the disadvantages:

The complexity of installation, subject to independent work.

Razklonka with expanded clay

Creating a minimum slope of a flat roof is acceptable when using expanded clay. It is obtained by firing clay shale. Expanded clay is laid both on a base of reinforced concrete slabs or corrugated board, and on a heater.

The order of work is as follows:

Creation of markings on the roof. To do this, you can use a wooden beam, a metal profile or just a lace. It is more convenient to work with a beam and a profile, but closer to the end of the work they need to be taken out, and the resulting pits should be leveled. You don't need to do this when using laces.
Expanded clay backfill. To facilitate this process, you can order a manipulator that will deliver expanded clay directly to the roof. Otherwise, the material will have to be worn manually for a very long time.
Lighthouse alignment. Align with a rule. For convenience, you can make a wooden rule with a handle, according to the principle of a rake, but instead of teeth - an even, wide beam. Expanded clay is pulled from the parapet towards the funnel. If there is too much material, it can be stretched to the edges of the parapet to ensure good water drainage.
To fix expanded clay in the desired position, it is poured with cement milk. Prepared from cement and water, with the calculation of 200 kg of cement per 1 cubic meter of expanded clay. The consistency of the milk should be sufficient so that it spills to the base, but at the same time, flooding should not be allowed.

Fixing expanded clay is not necessary, but desirable, since during the installation of the roof you will often have to walk on it, violating the created level.

Dismantling markup. If a beam or a metal profile was used, the cavities fall asleep.
Next, you need to fully fix the slope with a cement-sand screed, about 6 centimeters thick. As in the previous case, a reinforcing mesh must be laid for it.

Expanded clay advantages:

Low cost. Even lower than when using polystyrene concrete.
Convenience of creating a slope of a flat roof according to SNiP. Expanded clay is lightweight, it is convenient to pull it apart, you do not need to remove excess from the roof. The only problem is to deliver the material to the roof.
Good thermal insulation characteristics.

Cement milk, like other fixing solutions, is not able to 100% ensure the safety of the level of expanded clay.
If it rains during the installation process, this can be a big problem. You can’t expel moisture from under expanded clay, which means you have to wait until everything dries out.

Razklonka with expanded clay concrete

Another popular material for creating a flat roof slope according to SNiP is expanded clay concrete.

To prepare it you will need:

Cement
Sand
Expanded clay

It is made according to the proportion: one shovel of cement, two shovel of sand, three shovel of expanded clay. Water is added until the solution reaches the desired consistency.

The order of work is exactly the same as in the case of polystyrene concrete:

Markup.
Delivery of solution to the roof.
Stretching by level.
Laying insulation and forming a fixing screed.

Advantages of expanded clay concrete:

Low cost. Comparable to polystyrene concrete.
Good thermal insulation.

Very difficult installation for independent work. The main problem is the delivery of concrete to the roof.

Razklonka insulation

Especially for flat roofs, wedge-shaped insulation is produced. It is made in the form of mineral wool and extruded polystyrene foam.

Three main elements are used to create the main slope:

Type A slabs, creating a slight slope.
Type B slabs complementary to A slabs.
Additional plates needed to raise the height.

The order of work is as follows:

Marking is not needed, therefore, after laying the vapor barrier film, they proceed immediately to the installation of plates. Start from the lowest point, type A plates are laid first.
Behind the first row, type B slabs are laid.
Then additional slabs are laid, 40 mm thick, and slabs A are placed on them.
Again additional slabs with a thickness of 40 mm and slabs B. These operations are repeated until the parapet is reached. At the same time, the flat roof has a slope of 1.7%.
If necessary, mechanical fasteners use special dowels "mushrooms". Average consumption - two dowels per sheet.
On top of this ramp, another layer of insulation is laid to evenly distribute the load.

To create a counterslope along the resulting gutter, use:

Plates J
Plates K
Additional plates

The counter-clone is made in the form of a rhombus, with sequential laying of sheets J and K parallel to its lines.

Simple and fast installation.

The high cost of wedge-shaped insulation.

When creating a roof, all details are taken into account. It is especially important to determine the slope of the surface, since not only the appearance, but also the durability of the structure depends on it. This indicator depends on many factors, including the climatic conditions of the area. In this case, it is taken into account that the roof provides protection from environmental influences, but it itself is exposed to all these negative factors. That is why it is important to calculate the slope of a flat roof even before construction begins.

The nuances of choosing a slope angle

To begin with, the effect of wind on the coating is considered. In regions with strong winds, roofs with a slight slope are preferable. In this case, if there is a high roof, the likelihood that gusts of wind will tear off part of the material increases. To prevent this, it is necessary to make the truss system more massive, which causes an increase in the cost of installing the structure, and also negatively affects the weight of the entire structure. In areas where precipitation is especially frequent in winter, it is enough to make the roof slope within 45 °. This will provide a free slope of snow and eliminate the increase in the load on the roof surface.

In the event that there is little snow in winter, you can limit yourself to a low-slope roof, that is, the slope in this case will be minimal. According to SNiP, when creating such a design, it is recommended to use membrane materials to prevent leaks. When creating a flat surface, importance is also given to drainage, it is on it that the function of draining water and eliminating its accumulation on the surface is assigned. To reduce exposure to sunlight, bituminous covers, green, turf or pebbles can be used.

In regions where a harsh climate often prevails in winter, it is recommended to combine external and internal drainage. The latter will no longer be exposed to negative factors of nature.

The choice of materials depending on the angle of the slope

Each material has its own requirements for use. The rough surface of the roof will prevent the removal of the gadfly, and the smooth one will contribute to this. Equally important is the design of the truss system. When creating a flat roof, it can be lighter, but designed for a powerful load from water and snow. From a roof with a slope, water rolls off faster, and snow does not linger, but it itself must be more durable due to the complexity of the design. The choice of roofing material also affects the type of rafters and the step of the crate.

The choice of material for the roof should be based on the level of slope. To create high roofs, the range of roofing is wider, and outwardly such buildings are particularly attractive. In order to properly perform installation work on the roof, you must adhere to the following rules:

Grade Angle Measurement

For the correct choice of materials and the design of the truss system, it is important to calculate the angle of the slope. This action is performed using a goniometer or by mathematical calculations and is expressed in degrees, percentages and the ratio of indicators.

The simplest is the mathematical calculation. To do this, you need to know the width of the blood and its height. Using trigonometric formulas, the angle is calculated in the form of cosine, sine or tangent. The result obtained using the table is converted into percentages.

It can also be calculated by another method. To do this, divide the height of the future roof by half the width of the room, and multiply the result by one hundred. The result is compared against the table to determine the slope and it is also expressed as a percentage.

In the presence of a goniometer, all actions consist in determining the angle and selecting materials to create a roof. Only after that you can make the right choice, be sure to compare it with the requirements of SNiP.

Features of creating a low-slope roof

The most common flat roof slope is carried out using the following methods:

backfill insulation, that is, perlin, expanded clay and others;
concrete mixtures based on heaters;
polymeric materials and concrete mixtures based on them with the obligatory addition of fillers;
using only insulating materials.

Each of the above methods has its own advantages and disadvantages. Expanded clay and perlin can change position over time and break the slope of the roof. As a result of this, the minimum slope after a while can become a flat roof. The size of the material also matters, since large components do not allow the slope to be sufficiently uniform.

For a flat roof, concrete mixtures are especially often used. The main disadvantage of these materials is their weight. That is, it is necessary to calculate the additional load when developing the design of the truss system. Given this disadvantage, it can be concluded that concrete mixtures can be used to create a flat roof at the construction stage or during major repairs. They are not suitable for partial repair of a flat roof, as they cause additional stress.

According to SNiP, polymeric materials are ideal for such work. Given their wide range, they should be chosen not only depending on the angle of the slope, but also take into account the features of the truss system.

The nuances of choosing a slope angle

In regions where a harsh climate often prevails in winter, it is recommended to combine external and internal drainage. The latter will no longer be exposed to negative factors of nature.

The choice of materials depending on the angle of the slope

Grade Angle Measurement

Features of creating a low-slope roof

The most common flat roof slope is carried out using the following methods:

backfill insulation, that is, perlin, expanded clay and others;
concrete mixtures based on heaters;
polymeric materials and concrete mixtures based on them with the obligatory addition of fillers;
using only insulating materials.

Regardless of how the slope will be carried out, it is important to pay attention to the drainage system. These can be gutters, outdoor catchments and other systems. You can calculate and select the appropriate option by evaluating the material used, as well as the requirements for the roof. On roofs with a slope of less than 10°, additional membrane materials should be used. Due to them, a reliable waterproofing coating is provided.

In addition to drainage, ventilation is also of great importance when creating flat roofs. There is a dependence of the size of the roofing space on the angle of the slope. The lower the slope, the greater the height of the ventilation gap.

Considering all the above requirements, it is possible to create a roof with a minimum slope angle, which will freely withstand the negative influence of natural factors and retain its qualities as much as possible.

Minimum flat roof pitch, flat roof slope

Required minimum slope for a flat roof. Methods for flat roof slope and minimum roof slope according to SNiP

Flat roof slope according to SNiP

A flat roof, which is built in accordance with the requirements of building codes, always has a slight slope. If it is minimal, an inexperienced observer will not notice. But if there is no slope at all, it will be visible immediately. The fact is that in the absence of at least some slope of the structure, rain or melt water will necessarily collect on it.

Even if the surface of a flat roof is created perfectly flat, and, it would seem, there can be no talk of any puddles, the reality is different. Under the influence of wind, solar radiation, rains of various acidity, temperature changes, the roof deforms over time, zones are formed on it, in which water or dirt brought by the wind can linger. If there is a minimum slope, the chances that water or snow will linger on the roof for a long time are much less.

What's the point in dodging

It would seem that sooner or later the snow lingering on the roof will melt, and the water will either dry up or the drainage system will cope with it. The experience that eventually resulted in the recommendation of the Building Code suggests otherwise. Water tends to destroy the structure of the roof in a variety of ways.

Firstly, the water on the roof is not completely distilled, its chemical analysis will show the presence of dissolved oxygen and a whole range of substances that will actively destroy the roof material. Secondly, in the cold season, water can change its state of aggregation several times a day. Among other things, it is also a change in volume, which carries a powerful destructive force.

The slope of a flat roof is also needed so that dust does not accumulate on it. Many saw vegetation on the roofs of residential and industrial buildings. It would seem, where does the grass and trees come from? But wind, water and sun do their work steadily. And the roots of plants, as you know, are able to destroy even very strong materials.

What is measured and how the slope is determined

The parameters of a flat roof, which include the minimum slope, are regulated by the set of rules SP 17.13330.2011 SNiP II-26-76. A document so complex in designation is easier to distinguish by name. It is called the "Code of Roofing Rules", or Theroofs in English.

The scope of the document is the design of roofs using rolled, bituminous and other roofing materials, several types of tiles, slates and tiles, galvanized steel and copper sheets, profiled sheets, aluminum, zinc-titanium and other structures.

Before considering the table available in the set of rules, it should be clarified that the slope of a flat roof can be measured either in degrees or as a percentage. There are also relative units like 10/12, but they are rarely used.

Slope Table

In paragraph 4.3. of the set of rules mentioned above, there is a table in which the norms are prescribed that determine the slope of a flat roof, that is, its minimum size. The values depend on the type of materials used for the arrangement of the roof, as well as on some other factors.

So, if the roof is made of rolled materials or bitumen-based mastics, it should be sloped in the range from 1 ° to 6 ° (1.5-10%) if gravel or other coarse-grained substances are poured on top. If the top layer is foil, the slope of a flat roof varies from 1° to 16° (1.5-25%).

When using polymer roll materials, the slope should not exceed 1° (1.5%) without a protective layer and 2° (3%) with a protective layer.

Quite different values are provided for piece materials, metal sheets and concrete structures. For shingles and slates, the minimum slope of a flat roof is between 12° (20%) and 22° (40%). Metal sheets can be placed at a minimum of 7° (12%), reinforced concrete trays - 3°-6° (5-10%).

The norms allow the use of significant slopes, but some additional requirements are required.

How slopes are created

The process of creating roof slopes is commonly referred to as sloping. This process uses:

bulk materials, in particular perlite and expanded clay;
lightweight concrete compositions based on the same perlite and expanded clay;
lightweight concrete compositions based on polymeric materials;
insulating materials.

Which material will be used depends on the design of the building, on the required slope and on some other factors. For example, lightweight concrete in some cases may be too heavy, creating a significant load. On the other hand, when using bulk materials, it is impossible to create a large angle. In general, different materials have their own advantages, disadvantages and scope.

The slope of a flat roof will help protect the structure from premature destruction, significantly extend its service life and make maintenance easier.

The minimum slope of a flat roof according to SNiP

The slope of a flat roof according to SNiP A flat roof, which is built in accordance with the requirements of building codes and regulations, always has a slight slope. If it is minimal, an inexperienced observer will not

What should be the slope of a flat roof + minimum sloping as a percentage

There are many types of roofing, the most popular being flat. It has a number of its advantages, such as: its installation will take less materials, ease and simplicity of installation and additional useful territory.

For many, the phrase flat roof is in no way associated with a slope. Although this is far from true. Even the most even roof has its slope, even if it is minimal.

At a minimum, this is necessary so that melt water, and water after rain, can safely drain into the installed funnels, which are part of the internal catchment area, or into the gutter of the external system.

In addition, it is easy and simple to install additional, necessary equipment on such a roof. To date, There are several types of flat roofs:

Operated roof;
unused roof;
Traditional roofs;
Inversion roofs.

Flat roof slope - why is it needed

The slope that should be on this type of roof, is about 1-5 degrees, if you neglect this, then water, both rain and melt, will accumulate, which in turn will damage the roof.

In summer, you may not encounter such a problem, since rainwater dries up under the rays of the sun. In winter and autumn, such water can freeze at night and melt during the day.

Puddles form, which ultimately leads to the fact that moisture gradually penetrates the insulation. The essence of the mechanism is that moisture penetrates the waterproofing layer, which means that inevitable leaks occur.

But this is not the only problem. In addition, puddles on the roof can be covered with dust, which at one time settles on the bottom. Seeds of various herbs and plants can fall into this puddle and germinate there.

Often on the streets you can find houses on the roofs of which there is grass or thin trees. It is logical that this spoils the roof, and also spoils the aesthetic appearance of the entire building.

To avoid such a nuisance, and thereby extend the life of your roof, Roof sloping needs to be done.. Such complex manipulation is carried out at the time of construction itself.

The process itself is quite complex, and includes many activities of different structure. The purpose of this procedure is for the roof itself to acquire the necessary slope..

But before you start the slope of the roof, you need to find out what a flat roof consists of.

In fact, it is a pie with several layers:

Immediate foundation, which is reinforced concrete slabs that have a certain wave height;
Vapor barrier, which can be made from different materials, such as bitumen, or rolled materials;
The next layer is insulation, which can be made of mineral wool or other durable material.

The ingredients of this pie can be changed if the builder wants to do the whole roof with the new building materials. It should be understood that such a procedure as a bias, carried out directly at the time of laying the insulation.

It is important that in addition to such main layers of the roof, there must also be water intake funnels or gutters.

The angle of the roof slope is very important, and it depends on many parameters. The first thing to pay attention to is wind effect. If you live in an area where there are frequent strong winds, then it is worth making a small angle of inclination.

Obviously, the steeper the slope of the roof itself, the faster the outflow of water.

Percent slope

Minimum angle and roof slope calculation

The minimum slope angle can be determined based on the materials of the roof itself:

If the roof is made of corrugated board, then its minimum slope must be at least 12 degrees(according to SNiP). If the roof is made of metal, angle increases up to 15 degrees. It is important to understand that the gaps of the material, and other joints, must be treated with a special sealant - frost-resistant / waterproof. If the angle of inclination is 15 degrees, then the sheets of material should overlap by about 200mm., if the angle is smaller, then the overlap should increase;
The minimum slope angle may be in cases where if the roof of your house is made of artificial materials. These, in turn, include membrane coatings, ondulin, bitumen-based materials. It is logical that by the value of the slope angle, affects the number of layers of the roof. If, for example, the roof is carried out in two layers. then an angle of inclination of 15 degrees is quite enough;
Having covered the roof with soft tiles, it is worth understanding that quite enough and 11 degrees of inclination angle, but at the same time you need to make a crate of a solid type.

Such a process as a flat roof slope, made from these materials.:

Extruded polystyrene (technonikol);
Wool, both mineral and glass/basalt based;
polyurethane foam;
foam concrete;
Foam glass;
Various types of backfill materials.

Each of the materials has its pros and cons. Before starting work, it is necessary to correctly calculate the angle of inclination itself. In fact, it is quite easy to carry out this calculation, for this you need to use a goniometer, or with fairly simple mathematical formulas.

The instructions for using bituminous and polymer coatings for sloping indicate that the optimum angle of inclination should be 1.5 degrees. An inclination of 1-2 degrees is acceptable.

Everything is very simple here. You need to know the height of the roof and its width. Further, simple trigonometric formulas will help calculate the direct angle (sine, cosine, tangent). And according to the existing table, which was calculated earlier, you can find out the value as a percentage.

There is another way to calculate - the value of the height of the roof must be divided by half the width, and the already obtained result is multiplied by one hundred, after that, in the table, you can find out the percentage value of the future angle of inclination. This option is faster, but they are both correct in terms of accuracy.

Sloping a flat roof with bulk materials

If you decide that the slope procedure will be carried out using bulk materials, then the first thing worth noting is the scheme by which such a procedure must be carried out:

First of all, on the concrete base itself, it is necessary to lay a layer of glass insulation. This material not only has a long service life (30-35 years), but also has a high waterproofing performance;
Farther, it is necessary to pour the main material on it - expanded clay. But at the same time, everyone needs to create the right slope;
Necessarily it is necessary to cover the layer of expanded clay with a special polyethylene film. It is important to note that it must be overlapped;
Further, it is necessary to apply the prepared sand-cement screed doing it smoothly, slowly. Its essence is to level the layer of poured expanded clay;
After these events, you can start carry out the formation of the roofing "pie", according to the developed project.

Remember that when laying each layer, you need to ensure that the previously prepared angle of inclination is maintained.

If you want to create a minimum angle of inclination, and the roof area is not particularly large, then a sand-cement mortar is quite enough.

Thermal insulation materials

Another good material for roof slopes are thermal insulation materials. Experts claim that this is the most affordable option.

Its advantage is that it is quite light and quite cheap which plays a very important role in construction. Mineral wool, the best material. The scheme of the process is quite simple.

It is necessary to attach the material to the base itself, using self-tapping screws or dowels. Some prefer sheets of such cotton wool to be glued to a previously cleaned base with special glue. Such a process can be performed both during the repair and during the installation of the roof.

A good material that can be used to flatten a flat roof is foam concrete. It should immediately be noted that this procedure must be carried out using special equipment.

On the base itself, a layer of foam concrete is poured, but at the same time the angle of inclination itself is noted, and after make a special screed of foam fiber concrete. Next, it is important to apply waterproofing material.

A huge plus of this kind of razuklonka - high rate of thermal insulation, as well as other mechanical characteristics. For example strength and durability.

Speaking of cons, they are here too, or rather one. This is the price. She is high enough. And again, to carry out such a procedure on your own will not work. Therefore, in this case, it is worth contacting professionals.

If the roof has a minimum slope, then it is important to note that in this case, proper drainage systems must be installed. The slope itself is made exclusively in the direction of the drain (funnel, gutter);
If your roof is bituminous tiles, it is worth making the slope angle less than 6 degrees, while the bottom layer of waterproofing must be made of membrane materials;
It is important to know that with small values of the slope angle, it is necessary to carry out ventilation of the under-roof space itself, with all the slopes. The thickness of the gap also depends on the value of the angle (the larger the angle, the smaller the thickness, and vice versa).

Flat roof slope: minimum roof slope in percent, with technonicol according to SNiP

In this article, you will find out what the minimum slope of a flat roof should be, what is the correct slope with technonikol material according to SNiP.

flat roof slope

How to calculate the angle of inclination

In order to find out the angle of inclination of the roof, you must:

Know the height of the parapet.
Know the thickness of the roofing cake.
Know the exact location of the intake funnel.

Provided that the water intake funnel is located not outside, but inside the roof, there are two options for organizing the slope:

The formation of a circular system. That is, make a slope in such a way that water flows evenly over the entire area of \u200b\u200bthe roof.
The formation of scarves. Draw a roof from the funnel like an envelope. So, improvised gutters are created.

Note that when two or more water intake funnels are located, the roof slope is organized exclusively according to the second option.

Roofing with polystyrene concrete

Concrete mixer. Specialists use a special unit that allows you to supply concrete through a hose directly to the roof.
Cement 500 brand.
Polystyrene crumb. Manufactured from defective polystyrene boards.
Water.
Liquid soap.
Sand.

The order of work is as follows:

Creation of markings on the roof. Use a bar or beacons. Please note that the beam subsequently needs to be delivered on time. That is, when one section is flooded, and the mortar has already solidified, the beam is removed so that it does not interfere with the pouring of the adjacent section. The lace in this case is a weak helper. From concrete, it will get wet and sag.
To create a slope of a flat roof, the resulting mixture must be delivered upward. We advise you to take care of creating a winch in advance. This will make lifting the concrete easier. Even better, initially bring all the material to the roof, as well as deliver a concrete mixer there. This will greatly simplify the work on the slope.
Polystyrene concrete is pulled together by beacons using the rule. It is desirable to leave as few irregularities as possible; subsequently, insulation will be laid on the concrete. The solution hardens in a day, and it is already possible to move freely on it.
A heater is laid along the slope-forming layer, and then everything is fixed with a cement-sand screed, for which a reinforcing mesh is necessarily laid. The thickness of the screed is approximately 6 centimeters.

The advantages of this material include:

Inexpensive cost.

The complexity of installation, subject to independent work.

Razklonka with expanded clay

The order of work is as follows:

Creation of markings on the roof. To do this, you can use a wooden beam, a metal profile or just a lace. It is more convenient to work with a beam and a profile, but closer to the end of the work they need to be taken out, and the resulting pits should be leveled. You don't need to do this when using laces.
Expanded clay backfill. To facilitate this process, you can order a manipulator that will deliver expanded clay directly to the roof. Otherwise, the material will have to be worn manually for a very long time.
Lighthouse alignment. Align with a rule. For convenience, you can make a wooden rule with a handle, according to the principle of a rake, but instead of teeth - an even, wide beam. Expanded clay is pulled from the parapet towards the funnel. If there is too much material, it can be stretched to the edges of the parapet to ensure good water drainage.
To fix expanded clay in the desired position, it is poured with cement milk. Prepared from cement and water, with the calculation of 200 kg of cement per 1 cubic meter of expanded clay. The consistency of the milk should be sufficient so that it spills to the base, but at the same time, flooding should not be allowed.

Fixing expanded clay is not necessary, but desirable, since during the installation of the roof you will often have to walk on it, violating the created level.

Dismantling markup. If a beam or a metal profile was used, the cavities fall asleep.
Next, you need to fully fix the slope with a cement-sand screed, about 6 centimeters thick. As in the previous case, a reinforcing mesh must be laid for it.

Low cost. Even lower than when using polystyrene concrete.
Convenience of creating a slope of a flat roof according to SNiP. Expanded clay is lightweight, it is convenient to pull it apart, you do not need to remove excess from the roof. The only problem is to deliver the material to the roof.
Good thermal insulation characteristics.

Cement milk, like other fixing solutions, is not able to 100% ensure the safety of the level of expanded clay.
If it rains during the installation process, this can be a big problem. You can’t expel moisture from under expanded clay, which means you have to wait until everything dries out.

Razklonka with expanded clay concrete

Another popular material for creating a flat roof slope according to SNiP is expanded clay concrete.

To prepare it you will need:

It is made according to the proportion: one shovel of cement, two shovel of sand, three shovel of expanded clay. Water is added until the solution reaches the desired consistency.

The order of work is exactly the same as in the case of polystyrene concrete:

Markup.
Delivery of solution to the roof.
Stretching by level.
Laying insulation and forming a fixing screed.

Low cost. Comparable to polystyrene concrete.
Good thermal insulation.

Very difficult installation for independent work. The main problem is the delivery of concrete to the roof.

Razklonka insulation

Three main elements are used to create the main slope:

Type A slabs, creating a slight slope.
Type B slabs complementary to A slabs.
Additional plates needed to raise the height.

The order of work is as follows:

Marking is not needed, therefore, after laying the vapor barrier film, they proceed immediately to the installation of plates. Start from the lowest point, type A plates are laid first.
Behind the first row, type B slabs are laid.
Then additional slabs are laid, 40 mm thick, and slabs A are placed on them.
Again additional slabs with a thickness of 40 mm and slabs B. These operations are repeated until the parapet is reached. At the same time, the flat roof has a slope of 1.7%.
If necessary, mechanical fasteners use special dowels "mushrooms". Average consumption - two dowels per sheet.
On top of this ramp, another layer of insulation is laid to evenly distribute the load.

To create a counterslope along the resulting gutter, use:

The counter-clone is made in the form of a rhombus, with sequential laying of sheets J and K parallel to its lines.

The high cost of wedge-shaped insulation.

Flat roof slope: what is the minimum slope according to generally accepted standards

What is the minimum slope of a flat roof according to generally accepted standards? The slope of a flat roof as a percentage and SNiP.

A flat roof with a slight slope will be considered built in accordance with building codes and requirements. In this case, the correct bias will not be noticeable to the layman. In case of non-compliance with the standards on a flat roof, precipitation will certainly accumulate. You can read more about the device of a flat roof in the article below.

How is this roof made?

The device of a flat roof is a simple task. The basis for the construction can be reinforced concrete slabs or profiled metal sheets.

The layers of a flat roof are as follows:

cement-sand base or concrete;
vapor barrier materials using modern roll bases or bituminous mastics;
insulation: mineral wool, slabs, expanded clay bedding, concrete pouring.

All components of the roofing pie are made taking into account the materials used.

If it is a built-up base, then the surface is mounted with one type of material.

A flat roof is simple in configuration, but its construction technologies are quite diverse. If you correctly decide on the technology, the construction process will take a maximum of two days. Load-bearing walls are of great importance when choosing components for a roof. Since beams are mounted on them, which can be either made of wood or steel.

At the same time, it is these details that transfer the load from the roof to the walls and the base of the house:

flat roof beams support the weight of the remaining floors;
weight of people serving structures;
atmospheric loads accumulating on the roof.

Beams must be correctly selected and installed. Then the finishing coating is selected and installed. It should also have good performance properties. Equally important for a flat roof is the stage of laying vapor barrier and waterproofing.

According to the rules, the vapor barrier is laid on the surface first.

The material must prevent the ingress of moisture.

As the first layer, a reinforced bitumen film is often used, based on fiberglass.
The second stage of installation is the laying of insulation, which is often used for flat roofs expanded clay. If a flat roof cannot withstand a lot of weight, then options for polymer insulation are considered.
The third stage is the installation of waterproofing. As a basis for these works, polymeric or bituminous materials are used.

Experts distinguish between flat roofs for heated houses, as well as roof options for utility unheated premises. If there is no experience in the construction of roofs, then the construction associated with the installation of ceilings over a barn, gazebo, veranda will be a good experience.

It does not require special skills, since for a roof of a small area it will be necessary to create a single slope in one direction.

A flat roof for a house will require thoroughness and division of work into stages.

Laying flooring on laid beams. Boards on top are covered with roofing material.
The roofing material is covered with insulation (expanded clay, slag).
Mounting the slope by leveling the insulation.
Mounting the screed over the insulation. The thickness of the screed is at least 2 cm.
The screed is additionally covered with roll material or treated with a primer.

According to the regulations, the slope of a flat roof is calculated as a percentage. Next, we consider in more detail the calculation technology

What is slope for?

In addition to operated and non-operated types of roofs, there are two more options:

traditional;
inversion.

Traditional roofing maintains the order of the layers of the roofing pie when the waterproofing is laid on top of the thermal insulation. However, in this case, loads and constant pressure quickly disable the waterproofing layer, all other layers also suffer.

The idea of an inverted roof is to protect the waterproofing, which fits freely under the insulation. A vapor barrier device is optional in this variant.

In any type of flat roof, it is important to create the correct slope. The correctness of the slope is associated with many parameters. The first important definition is the effect of the wind. In regions with frequent and strong winds, it is worth making a small angle of inclination. With the wrong large slope, gusts of wind will simply tear off the roofing material. In addition, the truss system and crate will suffer.

The slope of a flat roof is needed so that precipitation does not cause premature damage to roofing materials. It is clear that in the summer period there may not be a problem with excessive moisture on the roof.

However, the danger is that in winter and autumn, the moisture accumulated from snow and rain will thaw during the day and freeze at night. This will lead to the fact that moisture will gradually penetrate into the insulation or waterproofing, and leaks will occur. In addition, dust will get into the materials, which carries the seeds of various herbs.

If there is enough moisture inside the materials, the plants will germinate. On some improperly designed roofs, not only grass can be observed, but also trees that will cause damage to the truss system.

It also spoils the general appearance of the entire building. Therefore, the procedure for flattening the roof must be carried out, and even at the initial stage of construction. Despite the fact that there seem to be a lot of steps to create a slope, the process is actually simple.

The calculations should take into account the materials that will be used in construction.

Calculation

For professionals, let's calculate the slope in degrees or percentages. The drawing will help determine the correct size. To create it, you need to know the height of the roof, as well as its width. Direct mathematical calculation is carried out using trigonometric formulas. The value can also be found from the existing table, which has already been calculated by professionals.

The slope of the roof can be formed according to pre-made calculations, which define the wall height difference. Two sheer sides of the ramp will rest on these walls. You can also form a slope on an equal footing at all points of the roof plane.

That is, the beams are initially erected on walls of equal height.

The calculation is permissible on the basis of the information specified for specific building materials. For example, for a corrugated roof, the minimum possible slope according to SNiP is less than 12 degrees. For a metal roof, it is worth increasing the figure to 15 degrees. In this case, both those and other sheets must be treated with a sealant.

Smaller angles of inclination are possible for roofs made of artificial materials. These can be membrane bases, ondulin, bituminous bases. The number of layers of the roofing cake will also affect the amount of slope. For a roof that includes two layers, an angle of inclination of 15 degrees should be provided.

If the roof covering is soft tiles, then 11 degrees is enough for a slope. But when laying soft tiles, it is worth considering a continuous crate. Consider the options for laying some types of materials in more detail.

Options

If you have chosen bulk options (expanded clay) as demolition materials, then it is worth considering the features of this scheme of work.

The concrete base of the roof will be better protected if a layer of glass isolator is laid on it. It is a good waterproofing material. Expanded clay is poured over the waterproofing. At this stage, you need to create a slope. The expanded clay layer is covered with a film material, and if this layer is not a single one, the film is overlapped.
The next step is to apply a screed, including sand and cement. The layer of bulk material is leveled with a screed. Next, a roofing pie is formed taking into account the existing project.
Razklonka from a profiled sheet of 6 meters should be equal to 12 degrees. At the same time, in order not to spend money on sealant, it is enough to adhere to the recommended conditions for overlapping. The choice of a roof slope from a profiled sheet is beneficial, first of all, from a financial point of view. This is the most economical and easiest way to install a roof.

There are also options for materials that will add maximum comfort not only to the builder, but also to the owners, since they will not create trouble during operation. Such materials include the products of TechnoNikol. It is the largest manufacturer of roofing materials, recognized as reliable and efficient throughout the world.

If the traditional method of spreading with bulk materials is not suitable, modern methods can be considered.

These methods are worth considering, as bulk insulation can:

move, which threatens to break the ramp;
not ensure a smooth transition;
not ensure the accuracy of work at sub-zero temperatures.

To ensure the accuracy of the slope, you can consider ready-made insulation boards with an existing slope. Boards may include mineral wool or expanded polystyrene. An economical and reliable method is the use of polystyrene. The process of working with plates coincides with the stages of the thermal insulation device.

Plates are laid under:

roofing;
waterproofing layer.

To fix the plates, self-tapping screws or glue are enough.