Roof slope angle for various conditions and roofing materials. Flat roof slope minimum and maximum - what SNiP say Flat roof slope SNIP

05.05.2020

A perfectly flat roof cannot be by definition. Otherwise, it will accumulate rain and melt water which will cause it to wear out quickly. 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 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. For this you can use wooden beam, 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 wooden rule with a handle, according to the principle of a rake, only instead of teeth - an even, wide bar. 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 provide good stock water.
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

Specially for flat roofs produce wedge-shaped insulation. 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.

Since the flat roof used to cover office buildings, industrial facilities and residential buildings, does not have slopes, high demands are placed on the quality of waterproofing. To avoid leaks, three to five layers of material are used, but a flat roof surface is not able to drain water as efficiently as a pitched one. Because of this, areas are formed on it where moisture accumulates, they dry out only in the hottest periods of the year. The rest of the time, non-evaporating puddles negatively affect the waterproofing layer, destroying it.

In addition, in places where moisture accumulates, particles of soil and dust settle, forming a kind of substrate. The wind brings seeds into this favorable environment, and they germinate. Destroying the roofing cake. In order to organize the removal of excess moisture and their movement to drainage system laying the slope of a flat roof. So the name "flat" is just a figure of speech, in fact, its surface is located at a slight angle, not noticeable to the eye, without the use of a special geodetic tool. What should be the slope and how it can be created, we will tell in this article.

building codes

The minimum slope of a flat roof is regulated by clause 4.3 of SP 17.1333, adopted and approved in 2011. It allows the angle of inclination of the roof surface in the range of 1.5-10% or 1-6 degrees. That is, the smallest slope allowed by the regulations, 1.5% or 1 degree, it creates conditions for the movement of water to downpipes and gutters, and prevents stagnation. Steeper angles are rarely used, as on a large roof area, rolled waterproofing materials slide off to the base.

The process of creating a slope is called flat roof slope. This task is performed in various ways, using:

Thermal insulating material;
backfill materials;
Light mixes of concrete with filling materials;
Lightweight mixtures of concrete with polymers.
Plastic panels

Important! The slope of the operated flat roof should not exceed 3 degrees, since its increase reduces the safety of use.

Razklonka thermal insulating materials

The structure of any flat roof implies the presence of a layer of thermally insulating material. To set the angle of the roof surface, adjust the thickness of the insulation. To prevent slipping and maintain a given angle, it is fixed to the base of the roof with self-tapping screws. If the base of the roof is well cleaned, the insulation can be glued to it or special plastic supports can be used that grab the layers of the thermal insulator together.

This method of unfolding has advantages, it is good because:

It is relatively cheap. Since insulation is already necessary for the formation of a roofing pie, costs increase only through the purchase of glue or fasteners.
Fairly accurate. Using this method, it is possible to set an angle of 1-4 degrees with great accuracy, which is quite sufficient for effective drainage.
A light weight. Unlike most other methods, flat roofing with insulation does not require strengthening the base, since the thermal insulating agent, most often mineral wool or polystyrene foam, has a low mass.

Razklonka backfill material

Creating a slope angle for a flat roof using backfill material begins with the installation of waterproofing material. This role is most often played by glass isol, it is modern based on fiberglass, due to which it has increased tensile strength, a service life of more than 20 years. Expanded clay or perlite is poured onto the glass isol so as to withstand the required slope angle. After that, the filling material is covered with a polyethylene film located in overlapping strips and the remaining layers of the roofing cake are laid according to the project.

However, this method of creating a flat roof slope has disadvantages:

Large granules (more than 20 mm) do not allow you to accurately observe the specified angle and make it smooth.
Backfill material cannot be rigidly fixed, which is why it shifts over time. Moreover, this can happen even at the stage of the formation of the roofing cake, if the claydite is not poured with cement milk. However, in this case, the time spent on drying increases.
Backfilling is done almost by eye, so it is impossible to maintain the exact angle of inclination.
Due to the heavy weight of the backfill, reinforcement of the concrete base of the roof is required.

Razklonka concrete mixtures

Concrete-based mixtures can be used to set the slope. This method is not suitable for reconstruction or partial repair, it can only be used for newly created roofs. In order to make a roof slope with concrete mixtures, special equipment and highly skilled workers are required. There are two types of concrete mixtures:

With the addition of expanded clay and perlite, slag.
With the addition of polymeric materials.

This method has only two disadvantages: high cost, consisting of the wages of highly skilled workers and the high cost of polymers, and the second is the large weight of concrete, which increases the load on the roof base.

Screeding with panels

The most innovative way to set the angle of the roof is to use special plastic panels. They, like pieces of a children's puzzle, are collected and laid on a pre-prepared base, and then poured liquid rubber. Different thickness of the panels ensures the most accurate observance of the angle of inclination of the surface. But this method also has its own characteristics:

Decreasing Efficiency Control

To check whether the slope is well-done and whether water is efficiently drained from the roof surface, use one of two methods:

Sloping, carried out in accordance with building codes, protects the upper floors from leaks and extends its life.

Video instruction

Stagnant puddles with rain or melt water are a merciless enemy of flat roofs. With stubborn persistence, they destroy the coating and the components of the roofing cake. In order for atmospheric negativity not to create threats, it is necessary to foresee and carry out protective measures. The most effective and affordable way is to form slopes that contribute to the rapid outflow of water.

In the name of the long service life of the roof and located under it building structure you need to know how to flatten a flat roof. In order to create the most effective protection, you should familiarize yourself with the options used for its design.

The slope of the plane is necessary so that, under the action of standard gravitational forces, water is transported by gravity to the catchment points. It is required that the surface be freed from rain and melt water at the highest possible rate, all year round threatening the internal and external components of the roof structure.

The list of risk factors associated with stagnant water includes:

Damage and rupture of the coating. A phenomenon characteristic of periods of fluctuations in plus and minus temperatures, for sharp frosts. Water in the process of crystallization significantly increases in volume, which leads to delamination of the mineral protective dressing on bituminous roofs. Due to the violation of the protective layer, the material becomes vulnerable to UV radiation. On membrane and bulk roofs, due to the alternation of freezing with thawing of water, a grid of small cracks appears.
Overstressing the waterproofing mat. The temperature difference outside the building, inside and inside the building creates excessive stress on the coating. Around stagnant puddles, the stress state intensifies, resulting in gaps and cracks.
Deflection of a thin bearing base. A typical example is corrugated sheet roofing, on which the accumulation of precipitation can cause deformation and subsequent rupture of the coating.
Moisturizing insulation. Microscopic cracks unnoticed by the naked eye will let water into the body of the roofing system, which may not happen if the water is drained at a brisk pace. An equivalent trouble on roofs with poor-quality seams. Wet insulation loses half of its insulating properties and gains weight. Weighting is very undesirable for roofing systems arranged on corrugated board.
The origin of vegetation. Dust accumulated on a flat roof, coupled with stagnant water, is a wonderful environment for rooting and further prosperity of wind-blown plant seeds. Not all roof coverings are capable of steadfastly resisting life-loving roots invading them.

Flat roofs built from heavy-duty, but terribly expensive materials, are not afraid of horror stories from the specified list. Someday, when the hearts of their manufacturers tremble with sympathy for the average consumer and the price tag becomes more humane, the need for the construction of means to drain water from a flat surface will probably disappear.

However, while the method of preventing spoilage and premature aging is a device of slopes, thanks to which the currents of melt and rain water independently move to the water intake gutters and funnels or simply roll down from the roof to the ground.

Flat roof slope options

Spontaneously, without mechanical stimulation, water will not drain from a flat surface. In order not to wait for it to evaporate or destroy the roof, it needs to create conditions for movement - i.e. incline. Guidelines for the installation of systems with bitumen and polymer coating recognize the ideal angle for a flat roof as 1.5º, 1º-2º are considered acceptable, which in percentage terms means from 1.7% to 3.4%, respectively.

It is possible to tilt the roof plane of a small domestic facility during the construction period. To do this, according to pre-made calculations, the difference in the height of the walls is set, on which the two responsible sides of the slope will have to rely. This is a separate topic, acceptable for buildings with an external organized and unorganized type.

Now we are much more interested in the formation of a slope equal at all points to the roof plane, erected on load-bearing walls of equal height. Such tasks often have to be solved by the owners of suburban property and often implemented with their own hands.

The slope of the flat roof forms a barely noticeable relief with valleys and watersheds resembling ridge ridges. pitched roofs. The essence of its formation is to regulate the flow of water.

The lowering of the relief is always directed away from the elevated parts of the roof, including chimneys, skylights, roof aerators etc., in the direction of water intakes, which include drain funnels with gutters. If two or more drain funnels are installed to drain water from a flat roof, then there must be a watershed between them, cutting the flow into parts flowing in different directions.

Stagnation along the parapets of flat roofs is eliminated by installing a fillet. The design of a simple part is akin to floor plinth just no bulges. Along the junction line of the parapet walls or standard wall with a flat roof, a bar with a triangular section is installed, which can be made by longitudinally splitting the bar into two halves.

Instead of a split bar, a similar device made of basalt wool or expanded polystyrene is used. Fillet can be arranged directly on the object from a concrete solution.

The following proven methods are used for flat roof slopers:

The use of backfill thermal insulation: most often expanded clay or perlite, less often vermiculite. To create a ramp with a filling insulation, the roof area is divided into segments. Guides are installed at the required angle, between which the material is poured. On top of the backfill, a concrete mix screed with the M150 marking is arranged. Concrete pouring without fail should be reinforced with a road mesh. Finishing layer concrete can be replaced by a dry screed made of plywood or flat slate sheets. The uniquely time-consuming method is not accurate due to the inherent displacement of loose particles. In addition, it is difficult to form a slope rise in this way.
Pouring lightweight concrete- mixtures with the inclusion of expanded clay, polystyrene chips, perlite and similar aggregates. It is carried out according to the traditional scheme of the screed device, only the guides are installed at the required angle. The disadvantage of the method is in weather restrictions, tk. the screed can not be poured at minus thermometer readings. The concrete ramp will dry for at least 28 days, during which the screed will need to be moistened and protected from rain and wind.
Installation of metal structures. They are made of profile PP nomenclature 75×50×05 or similar material according to the dimensions of the increase and decrease. Distances between structures are calculated depending on the upcoming load. Sheets of flat slate are laid on top of the formed relief. The disadvantages of the method lie in significant material costs and labor investments.
Lathing construction. It is used extremely rarely, because. the application is unprofitable, besides, it is too difficult to implement such minor deviations, but among other methods it is still mentioned.
Application of wedge-shaped thermal insulation boards produced from basalt wool, foam glass, expanded polystyrene, polystyrene specifically for slopes on flat roofs and for creating an outflow of water from parapets.

Wedge plate tilting leads the way with numerous impressive benefits. They were developed and introduced into the construction industry purposefully in order to eliminate the shortcomings of all the previously listed methods.

Wedge-shaped heat-insulating plates are recognized for a reason optimal way solving problems of drainage from a flat roof. This is the most convenient, cheapest and simple circuit, which does not require in-depth skills and fundamental knowledge in roofing from the performer.

Wedge-shaped plates are cut at the factory, which guarantees the accuracy of the result of the upcoming work. The set of material must be accompanied by practical installation instructions.

Advantages of using wedge-shaped plates

Expanded polystyrene and mineral wool boards for the formation of slopes have an equivalent set of advantages, these are:

Insignificant weight, due to which the slope made of insulation creates the least load on the supporting building structures.
Transportation to the place of laying without the use of lifting construction equipment.
Independence of technology from weather conditions. Possibility to carry out successful laying, despite unfavorable forecasts for builders.
Perceptible relief and acceleration of actions for the formation of inclined planes. There is no need to postpone finishing work due to the need to withstand technological breaks. For example, wait 28 days for the cement-sand screed to gain the required hardness parameters.
A significant reduction in the cost of building slopes, necessary and sufficient for the unhindered flow of rain and melt water.

Important: despite the thermal insulation qualities traditional for materials, wedge-shaped plates cannot replace the insulation layer. Elements of different thickness do not have equivalent thermal properties at all points. Therefore, a layer of real insulation is constructed and calculated separately. Its thickness has nothing to do with the forthcoming hoisting of wedge-shaped slabs.

SNiP II-26-76 prescribes to install the slope of the finishing coating of a flat roof after laying the insulation, if thermal insulation was provided for by the project. If there was no need to insulate the roof plane, the wedge-shaped slabs are laid on a base covered with steam or hydroprotection.

Wedge-shaped thermal insulation is used in the construction of new roofs and in the performance of repair and restoration work. With the help of lightweight, convenient module slabs, you can create literally any relief in order to direct the flows in a given direction.

How to make a slope with plates?

Wedge-shaped slabs are supplied in kits that allow you to gracefully and quickly form slopes and counter-slopes on a flat roof. The sequence of laying the rake elements does not depend on what type of insulation they are made of. However, the composition of the slabs has an impact on the structure of inclined planes.

For example, between the finishing polymer membrane and polystyrene foam or foam boards a layer of geotextile must be laid. Without a separating layer, the roof carelessly says goodbye to plasticizers and will definitely become unusable. But on the basalt wool, the finish coating can be laid without fear, without using a separating layer, due to which costs will be significantly reduced.

The polymer membrane is strictly prohibited from direct contact with bitumen and bitumen-polymer waterproofing. They can coexist only if the same separating layer is laid between them.

Another geotextile substrate is required when laying plates immediately on a rough concrete pavement, i.e. if they are used exclusively to form a slope on an uninsulated roof.

Marking of ramp elements

As part of a single manufacturer, wedge-shaped plates are produced according to general principle regardless of the composition of the product. The elements are marked to facilitate the laying procedure, they have identical dimensions.

The Russian manufacturer of building systems TechnoNikol, for example, offers wedge-shaped ramping kits made of expanded polystyrene and mineral wool. In both cases:

Plates marked with letters A and B are intended for assembling slopes with a size of 1.7%.
If the material is marked with the letters J and K, then it is used in the construction of slopes of 3.4% and 4.2%.
Flat insulation boards with the letter C are used for climbing. Elements marked C can be laid both under and on top of the ramp.

More details on the diagrams:

The material manufacturer's instructions usually include a laying plan that clearly shows the sequence of the wedge-shaped slabs. The construction of one plane directed to the gutter, or two adjacent planes directed to the catchment funnel, will not be a serious problem for the home master. Laying should start from the lowest point of the roof and continue up to the created watershed.

It is somewhat different if a complex relief is being constructed with several valleys and watershed ridges. You will have to draw a plan and think over the course of action in advance. In plan, a complex relief usually looks like a combination of rhombuses and triangles. Laying in such cases starts from the edge of a rhombus or triangle, and finishes the process in the center of conditional figures.

The required height is achieved by means of a set of plates with the required thickness. When constructing a rhombus, it is as if divided into quarters, and a triangle into halves. Each segment is assembled separately, after which, in fact, trimming is performed.

Mounting rules

The installation of wedge-shaped slabs on the base without preliminary thermal insulation is carried out by methods commonly used or by bituminous coating. The priority is the mechanical method of fastening to the base, according to which the telescopic plates are fastened with self-tapping screws with a telescopic nozzle.

Fixation of wedge-shaped parts made of mineral wool is carried out simultaneously with the main layer of insulation. It is recommended to install two fixing units on a 600×1200mm slab. If both linear dimensions of the plate are more than a meter, 4 fixing points will be required.

The wedge-shaped ramp must be positioned so that its joints do not coincide with the joints of the underlying thermal insulation, i.e. the principle of seam spacing is observed both in relation to the multilayer insulation system, and in relation to the insulation layer with slope-forming material. If the elements of the heat-insulating ramp are laid on the base without insulation, they are glued or simply loaded.

Note that polystyrene boards cannot be glued with bituminous glue containing a large amount of organic solvents. The material is "not friendly" with organic solvents and gasoline. Therefore, their neighborhood should be excluded.

For the duration of the installation operations, it is recommended to glue the polystyrene foam plates together with double-sided tape so that they do not move from careless touches. It is desirable to place a load on the assembled segment of the composite slope so that it maintains its location.

The type of fastener must correspond to the type of base to which the panels are fixed:

For installation on corrugated board, self-tapping screws Ø 4.8 mm are required.
For fastening to concrete screeds strength B-15 and cement-sand screeds with strength M150 require pointed roofing screws Ø 4.8 mm together with a polymer anchor sleeve.
For fixing on concrete bases of class B-25, it is necessary to stock up on driven anchors.

The size of the self-tapping screws is selected taking into account the thickness of the layer so that the screw enters the concrete by 5 cm, and protrudes at least 1.5 cm beyond the back side of the corrugated board. When laying down on old repaired roofs with bituminous coating, a plate-shaped category of fasteners is used. The age of the repaired bituminous roof must be more than a year.

The use of insulation fillets

Triangular in cut, a long piece made of basalt wool is used to redirect atmospheric water currents from the junctions of vertical and horizontal surfaces. They are laid along the joining line of the roof with the parapet, the adjoining wall, the sides of the rooflights, chimneys, etc.

The material cut with impeccable geometric accuracy contributes to an increase in the speed of work on the arrangement of a flat roof. Fillet laying allows you to quickly create a smooth transition from a vertical surface to a horizontal plane.

Video lesson on the device slopes

For those who want to know how to competently make an ideal ramp on a flat roof, the video will help to get acquainted with the specifics of the work in detail:

The list of options for slopes on a flat roof rightly tops the wedge-shaped insulation boards. They are designed to make work easier and significantly speed up processes. With the assigned duties, the wedge-shaped ramp does an excellent job.

When creating a roof, all details are taken into account. It is especially important to determine the slope of the surface, since not only depends on this appearance but also the durability of the structure. 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 the impact environment, but she herself 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 the snow winter time little falls, 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. The design is also important 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 then can you do 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 overhaul. 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.

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. Calculate and choose suitable option possible 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 that will freely withstand Negative influence natural factors and retain their 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.

First, 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 equipped with roll materials or bitumen-based mastics, it should be sloped between 1° and 6° (1.5-10%) if gravel or other coarse-grained materials are placed 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 has its 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, on such a roof it is easy and simple to install an additional, necessary equipment. 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, because under the rays of the sun rainwater dries up. 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 components of such a pie can be changed if the builder has the desire to make the entire roof with 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 result already obtained 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 its own concrete base, 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 very large, then a sand-cement mortar is quite enough.

Thermal insulation materials

Another good stuff, for the roof slope 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, must be installed correct systems drain. The slope itself is made exclusively in the direction of the drain (funnel, gutter);
If your roof is shingles, 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

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.

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 bar. 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.