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The foundation and roof are the two most important and difficult to calculate architectural elements of any building. Load-bearing elements roofs are a rafter system, and its performance largely depends on the angle of inclination of the slopes. Ordinary developers choose optimal angle roof slope, based on criteria other than those of the designers.
They are not entirely interested in calculations of the strength of load-bearing units; they are of little interest in the influence of the angle of inclination gable roof on cost and complexity rafter system etc.
What do ordinary developers pay attention to?
| Roof angle selection options | Short description |
|---|---|
| Every owner wants to have beautiful house with their own individual differences. On appearance At home, the angle of inclination of the slopes has a great influence. Architects have their own requirements for buildings; houses must organically fit into the style of existing buildings. This parameter is especially strictly applied when the house is located within the city. Quite often organs local government make decisions prohibiting violation of traditional architectural view. It is impossible, for example, to build a house with a roof slope of 45° if all buildings on this street have a slope of no more than 20°. |
| This factor has very little effect on the optimal angle. Roofing materials have only general recommendations for installation on flat and sloping roofs. Flat roofs have a slope angle of less than 10°; all structures with a slope angle exceeding these values are considered inclined. The technology for installing roofing materials with a slope angle of 15° is no different from the technology roofing works on slopes with a slope of 45°. There is, however, a limitation for piece tiles; they can be installed on roofs with a slope angle of at least 22°. |
| The greater the angle of inclination of the slopes, the higher attic spaces. Such roofs are built for buildings with attics. Developers pay a lot of attention to this factor, but not everything is as simple as it might seem at first glance. |
These wishes are taken into account by architects during the design and calculation of rafter system elements. But to these are added a fairly large number of purely engineering factors that have a decisive influence when calculating the parameters of the rafter system. And the angle of inclination of the slopes is not the only one among them; all values depend on each other and cannot but be taken into account when developing the project.
How designers choose the optimal angle
Calculations are made based on SNiP 2.01.07-85. The posted standards are used during calculations taking into account permanent, temporary and special loads and their various combinations.
SNiP 2.01.07-85. The PDF file will open in a new tab.
What loads are taken into account when determining the roof pitch angle?
Loads are divided into several categories depending on the duration of their impact: long-term, short-term and special.
- Long-term (constant) loads on the rafter system. These include the weight of roofing materials, insulation, wooden elements truss structure. This category should include loads arising due to thermal expansion and changes in linear dimensions due to changes in the relative humidity of lumber. Standard temperature changes are determined using formulas separately for heated and unheated premises. The weight of the snow cover is also considered a long-term load on the rafter system and is necessarily taken into account when determining the optimal angle of inclination rafter legs.
- Short-term. The rafter system is influenced by the weight of workers, stored building materials, mass special equipment and tools used during construction, and wind loads.
- Special loads. Efforts arising during natural disasters, earthquakes, explosions, with a sharp loss of the load-bearing capacity of one or more loaded nodes of the rafter system.
Special stresses include earthquakes and natural disasters
When determining the roof slope angle, the maximum possible combination of loads is taken into account. Both of these parameters affect the thickness and length of the rafter legs. The calculation of the rafter system and the angle of inclination of the slopes is done according to limit states, taking into account all unfavorable factors.
The maximum deflections and movements of the rafter legs are regulated regardless of their linear dimensions and should not lead to partial depressurization of the roof. The following conditions apply to all types of roofs, regardless of the angle of inclination:
- The safe operation of buildings must be guaranteed;
- the integrity of the structure cannot be compromised even during short-term peak loads;
- the appearance of the roof should not change throughout the entire period of operation.
Moreover, each requirement must be fulfilled regardless of the others. The maximum deflection values of the rafters are limited taking into account performance characteristics roofing materials. If the standard values do not have a noticeable effect on the appearance, then they are not adjusted.
Practical advice. It is much easier to ensure the integrity of the roof pie not by increasing the strength of the rafter system, but by using special structural compensators.
Choosing the optimal slope angle for a roof is not only an aesthetic issue, but, to a certain extent, a practical one. The functionality of the coating and the protection of the building from various kinds atmospheric influences (precipitation), durability of the structure and consumption of roofing materials.
An important criterion for choosing a roof slope is the climate of the area where you are building. In regions where there is a lot of rainfall, and in winter time There are heavy snowfalls, it is more logical to choose a large roof slope (from 45 to 60 degrees). This angle will reduce the load of snow on the roofing system, since large masses of snow will not accumulate, but will begin to slide from it to the ground, gaining a critical mass. If the region where construction takes place is characterized by strong winds, you should choose the minimum roof slope, as a result of which its windage will be reduced. IN in this case you should choose a roof inclination angle in the range from 9 to 20 degrees.
From the above it follows that the most universal and common is a roof slope of 20-45 degrees.
Secondly, when choosing the angle of inclination of the slope, it is important to take into account the properties of the roofing material itself. Therefore, you should take a closer look at how to determine the minimum slope for various materials roofs.
The third criterion for choosing an angle is the purpose of the building itself. Those. if it is planned that the roof will also play the role of an attic, then the slope will have to be significantly increased.
Roof inclination angle made of corrugated sheets
The most popular roofing material is corrugated sheet. This material has a number of advantages: it is light in weight, can be installed quite easily and quickly, and lasts a long time.
As a roofing material, corrugated sheets have found their main use in industrial construction in the manufacture of roofs for workshops, hangars, trade pavilions and other industrial facilities. The steel base of the corrugated sheet and stiffening ribs provide the roof and load-bearing structures necessary rigidity. The corrugated sheet does not weigh down the building and has excellent tightness.
Sheets of corrugated roofing are made of metal 0.4-1 mm thick, then formed by cold rolling. Corrugated roofing sheet differs from other types by the presence of a water seal (grooves along the edge of the sheet that prevent water from flowing under the longitudinal joints). The profiled sheet for roofing has the index “R” in its marking.
The minimum slope of a corrugated roof, as recommended by manufacturers, is 12 degrees. It should be remembered that at small angles it is necessary to additionally seal the joints with sealants to avoid leaks. According to SNiP, it may be even less, but not less than 6 degrees. At such small angles, it is necessary to reliably seal the longitudinal and transverse joints with sealants, for example, silicone, and the transverse joints themselves must be increased to at least 25 cm. The basic principle here is this: the size of the joints must be such that the wind cannot blow water under them. In this case, a number of disadvantages appear: firstly, the corrugated sheet will be more difficult to install, and secondly, dirt will accumulate much more strongly on the surface, therefore, maintaining such a roof will become more labor-intensive. In this case, the roof must be cleaned more often, otherwise the service life of the corrugated sheet will be significantly reduced.
Laying of the profiled sheet is carried out on wooden base. The pitch of the base sheathing varies depending on the slope of the roof slope and can range from 300 to 4000 mm. By increasing the angle of inclination of the corrugated sheet, its pitch also increases. By building regulations, the slope may differ from the specified level by no more than 5%. On roofs with a slight slope, it is more rational to use continuous sheathing.
The small angle of inclination of the roof simplifies the process of installing corrugated sheets, because there is no need for additional devices, such as mobile ladders or other devices for securing the installer to the roof. Accordingly, labor costs are significantly reduced and work completion time is reduced. In addition, by choosing a small slope angle, you make it more resistant to mechanical stress due to more frequent lathing and a significant reduction in windage.
The reliability of the building and the comfort of living in it depend on the quality of roof construction. Its design is selected optimal for local operating conditions. Of particular importance is such a parameter as the slope of the roof, which will be discussed further.
The angle of the roof slope depends not only on its design and the features of the facade of the house, on the selected roofing material, but also on other factors. It is necessary, first of all, to take into account the climatic conditions of the area where the building is being erected. Where the amount of precipitation falling in winter is high, a large roof angle (within 45-60 degrees) is preferable: this contributes to better snow melting, which means reducing the load on the roof. It also becomes less likely that the surface of the floor will freeze due to compaction of snow covers.
If a building is being erected where weather with strong winds prevails, it is advisable to choose a minimum roof slope angle to reduce the windage of the structure. Otherwise, the structure is in danger of rapid destruction. Most often, the tilt range in this case is 9-20 degrees.
The greater the slope of the roof slope, the easier the snow cover comes off it.
But basically, the optimal roof slope angle is selected in average values, that is, from 20 to 45 degrees. It is suitable for almost any type of roofing material, for example, corrugated sheeting or metal tiles, which are very popular today.
In an area with warm climate, where there are much more sunny days than cloudy ones, flat roofs will be more acceptable: their area is smaller than that of other types of structures, which means heating from sun rays will occur to a lesser extent. But such a structure should not be absolutely horizontal: the slope of a flat roof should be at least within 3-5 degrees. The minimum slope of the flat roof will ensure normal drainage of rain and melt moisture.
Types of roofing structures
Utility and utility buildings are often built with a pitched roof: it is easy to install and does not require large expenses. In fact, such a building has walls of different heights with a ceiling laid on them. The slope of the ceiling is selected within the range of 9-25 degrees, which is well suited for corrugated sheets and metal tiles. This design requires ventilation of the under-roof space.
But the most popular is the gable one: two planes located at an angle are connected along the ridge line. Other (end) planes are vertical and are called pediments. They may have doors to access the balcony or external staircase.
There are many options for roofing structures
Hip ceilings, the most popular representatives of which are hipped ones, are aesthetically very attractive. In such cases, especially in more complex structures, the slopes can be any: it depends on the chosen design and personal preferences of the developers. Dignity hip roofs– in the absence of restrictions on the use of roofing material.
A variant of the hip design is attic: the attic space is used as a living space, so the requirements for insulation are very high. The free space under the ceiling is formed due to the high angle of inclination of all slopes, in which the presence of skylights.
Dependence of roof structure on floor material
Before choosing a roofing material, you should study it specifications: this will help you optimally approach the issue and choose the most reliable one. In addition, there is a rule that determines the dependence of the slope angle on the roofing material used.
We list the main ones:
When choosing the slope value, you should take into account the strength characteristics of the roofing structure: the safety margin should be enough not only to withstand its own weight and the weight of the roofing material, but also for external loads (gusts of wind, snow). Also, the type of sheathing for laying most materials also depends on the slope of the slope: for small values of this parameter, either a continuous sheathing or with a small pitch (350-450 mm) is installed. When constructing any roof, especially a flat one, it is necessary to install a system of slopes and drainage. If the area is particularly large, additional drainage will be required.
Calculation of the angle of inclination
The design must meet the following requirements: be strong enough, provide reliable protection from atmospheric precipitation, have good thermal and sound insulation. It is also important that there is access for repairs and maintenance. How to calculate the angle of the roof so that all these conditions are met? Experts recommend using simple options its devices, which include single-pitch, gable, hip (and half-hip), and attic.
Roofs can have a design of any complexity, with different slope angles
Single-pitch roofs are most convenient for verandas, outbuildings and outbuildings. The principle of creating a single-pitch roof is the same as other types: rafters and sheathing are installed, after which the roofing material is laid. The latter plays a decisive role: for corrugated sheeting an angle of 8-11 degrees is required (it is better to do 20), for metal tiles - at least 25, for slate and seam roofing - 35 degrees.
If climatic conditions allow, it is better to make a roof with a slope of 45 degrees: this will allow you to neglect calculations related to the mass of snow. This is an almost ideal pitched roof: the angle of inclination will not complicate its installation and will facilitate maintenance (snow will not accumulate on its surface). But in this case, it will be necessary to strengthen the rafters and sheathing, since the wind pressure on the structure increases 5 times. It should also be taken into account that this will require high costs for materials - approximately 1.5 times.
Roofing material must be selected depending on the roof slope
As can be seen from the graph, each slope corresponds to a certain group of roofing waterproofing materials. There are 11 of them in total, with the inclined lines corresponding to the angle of inclination of the slope. The thick line indicates how the height of the ridge relates to ½ of its depth. It can be seen that the segment h is equal to half of the horizontal segment, designated by the fraction ½. The numbers at the tops of the semicircular scales correspond to the angle of inclination (in degrees), the vertical scale also indicates in percentage. When choosing any roof configuration, you should adhere to these recommendations and purchase roofing materials suitable for your chosen option.
In order to make it clear how the roof slope angle is calculated, we will give an example of calculating the smallest slope angle of a roof with tile waterproofing. On the graph we find a semicircular curve corresponding to this covering: this will be the curve indicated by the number 2. Tracing it to the point of intersection with the vertical scale, we find that the minimum slope of such a roof is 50%.
Taking into account the fact that the slope of the slope is the ratio of the height of the ridge to ½ of its depth, we calculate the slope. That is, with a ridge height h = 4 m and a slope equal to L = 15 m, the slope will be determined as h: (L/2) = 4: (15/2) = 0.53. To display it as a percentage, multiply the result by 100 and get 53%. This value of this parameter guarantees good drainage of rainwater. The minimum slope in the valley is 1%.
Features of calculating a gable roof
The gable roof is the most successful and common design. There are several reasons for this: high reliability, relative simplicity, low cost design. When constructing a roof, not everyone correctly chooses the optimal angle of inclination of a gable roof.
In the areas strong winds, it is necessary to calculate the gable roof so that its slope does not cause too strong wind loads. The greater the angle of inclination of the structure, the higher its windage.
You cannot reduce it to values less than 25 degrees: precipitation will be less easily removed from the roof, and dampness may appear in the under-roof space. Making it larger than 60 degrees is also not recommended: a strong impulse of faith can destroy the roof. The roof does not have to have symmetrical slopes: if you orient the building with a more gentle slope to the south, the roof will dry better after rain.
Conditions for using roofing materials depending on the slope angle
Useful attic area and drainage system
The usable area of the attic space depends on the roof structure: the greater the slope angle, the larger the area and vice versa (this is clearly shown in Figure 2). When constructing an attic, you have to make a compromise between the area that can be easily used, the cost of building a roof and the strength of the structure.
The method of removing precipitation can also be different. There are external or internal organized and unorganized - only external. The latter involves the installation of drainpipes and gutters, while wall and suspended systems are installed on roofs with a slope greater than 15%. The gutters are attached with minimum slope at 3 degrees, their sides are made with a height of about 120 mm.
It depends on the angle of the roof effective area attics
The distance between the pipes should be no more than 23 m. The cross-section of the pipe should ensure normal drainage of water and is selected depending on the area of the slope. External drains of an organized type are more suitable for areas with a warm climate. Internal drains used for cold climatic conditions. Such systems consist of a funnel for receiving water, a riser, an outlet and a discharge pipe. The main condition is that water drainage must be ensured at any air temperature.
Installing a roof is a very important task that requires the participation of highly qualified workers. Installation errors can cost home owners dearly. To avoid troubles, roofing work should be entrusted to specialists with sufficient experience: this will guarantee the reliability of the building and the comfort in it.
One of the most painstaking tasks during the design of a corrugated roof is choosing its angle. No aesthetic considerations play a role here: the ratio of the height of the roof to its total area will in the future affect how much usable space remains in the attic, will there be problems with snow accumulation, and even whether the wind will blow your roof away in a strong storm.
But this is not uncommon! Shall we figure it out? So, what is the minimum slope of a corrugated sheet roof? And how to build a roof with a minimum slope - all the pros, cons, recommendations and subtleties of construction are here!
Let's look at the official data. So, according to SNiP, building codes and regulations, any roof can be covered with corrugated sheeting, the slope of which has a slope of at least 8°. This is the only way that precipitation will not be able to penetrate through joints and screws. The sheathing step in this situation should be 40 cm.
But 8° is the minimum angle of inclination for the roofs of utility and industrial buildings, and for residential buildings this threshold is 10°. And if the roof is laid in two or more layers, then the minimum threshold will be even higher. That's why modern construction companies They give guarantees for their work only on the condition that they cover a roof with a slope of at least 12° with corrugated sheeting. And here maximum angle for a roof made of corrugated sheets it can be at least 70°, and even more.
Therefore, for profiled steel sheets as roofing material, SNiP recommends a 20° slope as the most best option. But what if you need to build an almost flat roof? For a garage, outbuilding or gazebo? Then just follow our advice - and no problems will arise!
Degrees, percentages and ratios
The roof slope is 8°, which corresponds to a value of 1:7 - this is the minimum value that can be when installing corrugated sheets. And after completing all the work, it is necessary to carefully check the roof for ventilation. But why do roofers, when determining the angle, talk not only about degrees, but also about percentages and even coefficients? All this is the same thing, the only difference is for design documents and when ordering materials. We have prepared a table for you that will help you figure out what's what:
Now let's look into construction terms. So:
- Flat roofs are those whose slope angle does not exceed 5°.
- Sloping ones are those that are usually more than 20°. It is natural that pitched roofs more waterproof, and therefore more popular in private construction.
- Roofs with a slight slope– up to 25°. Here you can already equip attic spaces, but without windows.
- Steep - those that have a slope of more than 40°. Cool ones allow you to arrange a good residential attic, which is never superfluous.
- Large is the roof slope that falls between 45-60°.
- But today the ideal roof slope angle is 38-45°.
So, the minimum angle of inclination of a corrugated roof is 8°. Here detailed video master class on how to build such roofs:
If you need to build a roof with an even smaller slope, then the profiled sheet should already be at the bottom of the roofing cake - like a ceiling. The design principle simply changes.
Pros and cons of a roof with a minimum slope
And now about what you will have to face during the construction of a minimum slope roof and what to expect from it in the future.
Advantages
Let's list the benefits first. The main advantages of building such a roof:
- Less material consumption.
- Easier and safer roofing work.
- No ridge or problems associated with its sealing.
Consider another point: the higher the ridge, i.e. The greater the angle of inclination of the roof, the heavier the roof itself will be. There will be more material available. And this is significant pressure on the house and foundation. In this case, the load will be insignificant.
Flaws
And so we moved on to annoying disadvantages. The minimum roof slope is bad because rainwater will drain much more slowly, and will quickly find small cracks and joints to seep into the roofing pie. The threshold in this regard is considered to be an angle of 12°, at which it is still possible to do without additional measures sealing. Therefore, if you are building a flatter roof, the slope angle of which is less than 12°, the overlapping areas of the corrugated sheets will have to be sealed with special roofing sealants.
The chosen angle of inclination will determine what material you can use for the roof. So, for a flat roof and a roof with a slight slope, only durable load-bearing corrugated sheeting with high corrugation is suitable. But on roofs with a steep slope it is allowed to cover them with both a universal and a wall profile - because now the pressure on the sheets will be minimal. In other words, the same snow will easily slide off, and the water will not linger either.
Second point: material consumption will also increase, because The overlap of the sheets on each other will have to be made a little larger. So, if you are going to build a roof with an angle of 12° to 14°, you will need to increase the overlap of the sheets, but you can still do without sealant; if less, you will need both. This is why a slope of 15-30° is considered optimal for a corrugated roof. Here is a more detailed table of this data:
Although to install steep roofs from corrugated sheets you will have to build quite long rafters, and more bars will be needed, but you will save a lot on roofing material. It will be possible to take corrugated sheeting that is cheaper, with a lower wave height, because now it load bearing capacity will play a lesser role than with flat roofs
In addition, if the angle of inclination is insufficient, it is impossible to equip a residential attic, which reduces the heat loss of the house through the roof by up to 9%.
And finally, roofs with a slight angle of inclination require the construction of a much more complex rafter system that could withstand a lot of weight. The smaller the angle of inclination, the more additional support elements there are.
And now we will disappoint you a little: even after weighing all the advantages and disadvantages of a roof with a minimum angle, and giving our preference to the value of 8° as more suitable, it may not be possible to build just such an option. Or rather, it will not even be safe! Why? Read on!
Wind and snow loads
Determining the angle of inclination of a corrugated roof is actually influenced by many initial data. First of all, this is - climatic features the area where your house is located. Therefore, find out in advance what the usual depth of snow cover is on the winter days, how often it rains, how strong the wind is and what its predominant direction is:
After all, the slope of a roof made of a material such as corrugated sheets is calculated not for aesthetic reasons, but based on weather factors. Thus, the slope of the roofs of those houses that are located in areas with strong wind loads tends to a minimum value. In these areas, the so-called “roof windage” is dangerous. Have you heard or seen how sometimes powerful ones torn off by the wind “walk” through the fields? polycarbonate greenhouses? But they were also not placed on the ground without fastening. And now imagine possible consequences, if part of your roof is already literally ripped off. Remember which one is the most main drawback corrugated sheets? "Sail"!
Here are the SNiP requirements in this regard. With an average wind load, the slope angle should be 35-45°, and with strong winds - 15-25°. In places where strong winds are the norm, make the roof angle made of corrugated sheets close to the minimum in order to minimize wind resistance. But almost flat roofs from this material there is a risk of being easily torn off, and therefore the complete lack of steepness in this case is also no better. Here is a rather impressive recording from a DVR, where the wind tears off a flat roof made of corrugated sheets:
Therefore, do not think that wind load is more harmless than snow load. In the Novgorod region, for example, the average value is 23 kg/m, where snow cover is about 75 kg/m.
Then shouldn't all roofs be flat? Not at all. In Russia, as everyone knows, there is snow up to the neck in winter. But snowflakes that seem so fragile at first glance actually weigh a lot. For example, in one unremarkable winter on flat roof so much snow can accumulate as if a whole company were standing closely on it. No rafters can withstand this, and therefore in areas with significant snow loads the roof slope has to be made up to 45° - so that the snow does not linger. Then there is no need to strengthen the rafters - precipitation on such a foundation will no longer be retained at all. After all, snow slides easily only from steep roofs.
Here's a map to help you find the parameters for your area:
Let's scare: in Yakutsk the snow load on the roof sometimes reaches 550 kg per person square meter. And this is already half a ton! This is why the roofs of houses in this region are always so high and steep. But in southern countries They can even be covered with straw in a horizontal position.
Even a small layer of snow is much heavier in weight than you can even imagine. And, unlike rain, snow lingers on the roof, and in some regions of Russia its height on roofs sometimes exceeds more than a meter. And the worst thing in this regard is precisely the minimum slope.
Therefore, you need to make a decision about whether to make the roof angle of corrugated sheets so small.
How to calculate the angle of inclination yourself?
First of all, pay attention to what kind of roofs your neighbors have. We mean the place where you are going to build. Usually they have almost the same slope, the value of which has been hard-won over centuries and tested by hurricanes. And calculate the exact angle of inclination finished roof This can be done either with the help of special graphs and matrices, or armed with a regular square.
Professional builders, for example, calculate the slope of a roof using a device such as an inclinometer, or using some geometric formulas. The result is written in degrees or ratio:
Or even simpler. As you probably remember from your school geometry course, the first thing you need to do is find out the length of the hypotenuse and leg. The hypotenuse is the straight line of the roof slope, and the distance from the ridge to the ceiling is the opposite leg. The distance from the middle of the ceiling to the eaves slope is the adjacent leg. Now let's use it trigonometric function or arm yourself with an engineering calculator:
The second no less common and reliable method: we determine the ratio between the height from the ridge to the ceiling and half the width of the ceiling. Divide the height by half the width of the building, and multiply by 100. Simple!
So decide what the slope of your roof will be based on four main factors:
- Planned budget.
- Estimated snow loads.
- Average wind value.
- The need for useful under-roof space.
And, if you finally come to the decision that you need a roof with a minimum angle, we will tell you how to avoid mistakes in construction and what you need to do.
Other important aspects of construction
Typically, minimum roof slopes with reinforced rafters are made in the roofs of those houses that are located in areas with frequent sunny days and little rainfall. To reduce heat interior spaces, in the roofing pie provide thermal insulation materials and a ventilated gap. Otherwise, all that remains to be taken care of is that no water gets into the house.
Leak protection
On flat roofs, when installing corrugated sheets, be sure to use sealing tapes and mastics for overlaps and joints of sheets. And such a roof is protected from leaks and damage by special membranes. waterproofing materials. Here is a standard pie of this design: corrugated board => rafters => insulation => waterproofing => sheathing.
There is still such a moment. If you are making a roof with a slope of less than 10°, use a modern three-layer membrane as waterproofing. Only this material can protect roofing pie from dampness inside.
And finally, no matter how minimal the roof slope is, drainage system you still have to build one for it. Moisture, like snow, lingers on such surfaces longer than many expect. Therefore, plan the slope so that it goes towards the water intake funnels, if the collection system is internal, or towards the gutters, if external.
Rafter system and sheathing
As in conventional projects, with a minimum slope, the corrugated sheeting is also laid on the sheathing and secured with self-tapping screws rubber gaskets. But clamp the overlap, from 10 cm to 20 cm, with steel rivets. We recommend making an overlap of two waves.
There is such a dependence: the smaller the angle of inclination of the roof, the wider it is necessary to overlap the sheets. And the smaller the effective area of the material:
- Within 15-30° of inclination, make an overlap of 15-20 cm.
- But when building a steeper roof, with an angle of 30°, the overlap should be from 10 to 15 cm.
- If the angle of inclination of the roof is already less than 14°, then the sheets must be laid horizontally with an overlap of 20 cm.
- With a minimum angle of inclination of a metal profile roof of 8°, the joints between the sheets must be made double, carefully sealing them with sealant to prevent water from getting inside.
The usual rafter system is installed in increments of 60 cm to 1 meter, but with a minimum roof slope it is better to reduce this increment to 40 cm. The base will be stronger and will more easily withstand the accumulation of snow on the roof.
In addition, with minimum slopes between the rafter system and the corrugated sheeting, a ventilated gap is required - this is also a measure to reduce heat loss. More specifically: the smaller the angle of inclination, the wider you will have to make the gap for ventilation - and this is at least 50 mm.
Installation subtleties
Here detailed master class How to install corrugated sheeting on such a roof:
Follow the technology, follow our advice - and everything will work out!
