The height of the ridge and the area of the gable roof - methods of determination. Calculation of a gable roof Build a gable roof calculator
Aesthetic indicators, architectural specifics and specifications Houses. When developing a project, it is extremely important to correctly determine the correct size of the structure.
To get the perfect result, we invite you today to figure out how to calculate the height of the ridge gable roof, and which method is best to use in independent calculations.
The ridge is the horizontal edge of a gable roof, formed at the junction of the vertices of its inclined planes. Without the slightest doubt, the height of the ridge is considered one of the most significant parameters that determine the proportions of the roof.
Both underestimating and overestimating it can lead not only to disruption of the architectural picture, but also to operational problems. The ardent desire of the house owner to realize own ideas often goes against technical regulations, familiarization with which will help to avoid serious mistakes.
In order to make the process of studying the value being studied simpler and more understandable, let’s imagine the future roof in the shape of an equilateral triangle. This is the most common option. In addition, there are asymmetrical gable roofs with slopes varying in area.
However, the angle of inclination of both structural components is most often equal, therefore the height of the ridge is calculated according to the standard scheme.
For convenience, we will divide the equilateral triangle into two symmetrical parts. The line passing from the top of the triangle to its base is the axis of symmetry of the figure we have presented, it is also the leg right triangle and the height of the ridge.
Landmark No. 1: Atmospheric phenomena
It is pointless to argue with climate reality; it is necessary to adapt to its inexorable dictation and adapt. Atmospheric phenomena that influence the choice of ridge height include:
. In areas where weather conditions are characterized by frequent gusty winds, it is customary to construct flat and low-slope roofing structures with an inclination angle of up to 10º. In regions with weak and moderate winds, the height of the ridge can be any.The indicated characteristics will be indicated by the local weather service. You can independently find them in the collection with rules and tables on construction climatology SNiP 23-01-99 or using the zoning maps given in SP 20.13330.2011.
Landmark No. 2: Availability of an attic
In the family of gable roofs there are attic and non-attic representatives. In the first case, the attic space is separated from the frame of the house by a ceiling. They are also called “separate”, which confirms the architectural independence of the premises between the roof structure and the ceiling.
Attic representatives are either residential or non-residential. The height of the ridge of residential roofs is determined by the ease of movement. Structures with an usable attic are constructed mainly according to the construction method, which involves the construction of a rafter system of two tiers.
Operated ridge height attic roof consists of two values: the height of the lower part of the roof and the height of the top of the roof, installed on the lower tier. The height of the lower tier is usually taken from 2.0 to 2.3 m.
It is calculated by adding the height of the tallest future owner and a margin of 30 - 40 cm, necessary for the convenience and safety of movement. Top size sloping roof arbitrary, depends on the taste preferences of the owners.
The height of the ridge of non-residential attics is determined by fire safety standards. In addition, the size of the attic space should not create obstacles for Maintenance. The building code regulations indicate that the attic must have a through passage along the entire roof of at least 1.6 m in height and 1.2 m in length. In short sections of complex structures, the width and height of the through passage can be reduced by 40 cm in both directions.
In the second “atticless” case, the space under the roof is not separated from the box by a ceiling. Usually it is located below: at the level of the ceiling system of the previous floor. Attic roofs are called “combined”, which refers to the connection of the space under the roof with part of the space of the foot.
Prominent representatives of structures without an attic belong to. They are erected according to the usual gable scheme, but the mauerlat is laid on walls no less than 1.4 m high. The height of the ridge of a half-slope attic is measured from the bottom edge of the mauerlat.
The practicality of constructing a semi-mansard roof in regions with high wind loads is difficult to overestimate. Thanks to its construction, there is minimal lateral load on the roof, and the owners receive a comfortable and very spacious additional floor.
No attic and attic floor construct low, small domestic buildings and warehouses. The installation of a ceiling in such situations is neither economical nor reasonable from the point of view of access for maintenance.
Guideline No. 3: Type of roofing
We have already represented the gable roof as an equilateral triangle. And the height of the ridge was represented by the leg of its rectangular counterpart, obtained by dividing the structure into two symmetrical parts. In the created by us geometric figure all components are interconnected, including angles and side lengths.
As roof designers, we are interested in the angle of its slope, because... it is directly dependent on the type and technical characteristics of the roofing covering. This will help determine the optimal height of the designed structure.
There are several selection rules roofing material taking into account the height of the ridge and the steepness of the roof, this is:
- The smaller the roofing elements, the greater the angle of inclination of the pitched planes. Numerous joints of piece coverings create the prerequisites for moisture to penetrate under the roof, therefore it is necessary to speed up the precipitation.
- The lower the roof, the fewer joints and seams there should be on the covering. Large-sheet and roll roofing is a priority for construction.
- The heavier the covering, the steeper the roof should be built. The weight of massive elements will be distributed in projection per unit area of the base. As a result, the higher the ridge, the less load puts pressure on the rafter system and the ceiling.
True, installing a steep roof with a high ridge will cost more. The construction of a structure with a slope of 45º will require 1.5 times more material than covering a flat roof with a slope of up to 7 - 10º. And if the slopes are inclined at an angle of 60º, the costs will double.
Typically, the range of suitable inclination angles is indicated by roofing manufacturers in the instructions. Manufacturers' recommendations should be followed for the sake of long-term service of the structure.
Knowing the recommended angle of inclination, the width of the eaves overhangs and the dimensions of the house box, you can use simple geometric constructions to find the height of the ridge. However, not only the graphical method is used in roof design.
The slope of the slopes is indicated in degrees, percentages or a decimal fraction, the numerator of which indicates the height of the ridge, the denominator - half of the overlapped span. All three slope expressions are interrelated, but on a construction site it is more convenient to use the last option.
There are few people who want to set the angle of inclination of the slope with a construction protractor on site. Moreover, the process of installing layered rafters, for example, is carried out on an already installed ridge girder. Those. You need to know the height of the ridge girder in advance. This is another good reason that stimulates interest in calculating the height of the ridge.
There is a general attitude towards the percentage expression of roof slope both among craftsmen and among home craftsmen. Percentages will only help to confuse things. The most acceptable method of displaying the slope is the ratio of the height of the ridge to half of the span being covered. It is most often used on a construction site.
Knowing the height of the ridge, you don’t have to look at the design documentation every minute. Simply by measuring, the middle of the gable wall is determined. At the resulting point, a block or pole is nailed strictly vertically. From the top edge of the Mauerlat pre-installed on the wall, the size we are studying is laid upward. They are guided by it when constructing a rafter system.
Methods for determining the height of the ridge
To calculate the height of the ridge of a gable roof, the area of the planes and other dimensions of the designed structure, there are a significant number of calculator programs on the network. All calculations are carried out automatically, I am pleased with the speed and simplicity of the procedure. True, it is difficult to check the results of the calculations without a visual representation of the planned roof configuration. And if you accidentally enter an erroneous number, it will be possible to discover “amazing” sizes only at the construction site. Therefore, it is better to understand the features of construction and calculations in advance, so that a banal flaw does not cause extremely high costs.
Independent designers will need memories of a school trigonometry course and a desire to build scale diagrams using a monitor or a regular piece of paper.
Mathematical and graphical methods
To determine the height of the ridge roofing structure the following methods are used:
- Mathematical. It consists of calculating the size using the formula for calculating the length of one of the sides of a right triangle.
- Graphic. It consists of constructing a scale diagram of the roof and obtaining the height of the ridge.
To perform mathematical calculations, the formula a= b × tgα is used, where a is the desired height of the ridge; b – half the span width; tgα is the slope angle chosen by the house owner based on technical specifications and recommendations of the roofing manufacturer.
Graphically, the height of the ridge is determined at the intersection of the axis of symmetry of the roof and the slope line laid at a given angle from the extreme point of the eaves overhang. Let's look at one of them illustrative examples graphical construction to get an idea of the process.
Note important nuance. Using the described methods, the rise of the roof is calculated, and not the total height of the ridge. The actual value depends on the technology of fastening the top of the rafters. In hanging systems, the height of the ridge remains unchanged. Similarly in layered versions, if the top of the rafters does not protrude above the line of the ridge girder.
If the tops of the rafter legs rise above the purlin, then 2/3 of the thickness of the board or timber used in the construction of the rafter system should be added to the rise of the roof. It is believed that the depth of the cut reduces the thickness of the material by a third.
The sheathing built over the rafters and the thickness of the roofing are usually neglected in calculations. Minor deviations during roof construction are practically unavoidable; in fact, 5-7 cm of roofing with sheathing has almost no effect on anything.
Practical calculation example
Let us use a specific example to analyze the procedure for calculating the height of the ridge. This is how sizes are calculated gable roof North American carpenters specializing in low-rise construction frame houses. Fundamentally, the process is no different from the actions of craftsmen in other countries.
The example has a purely technological specificity: the attachment point for the lower heels of the rafter legs to the base is attached with a notch. The rafters rest on the ridge board. If this is not taken into account when drawing up the diagram and performing calculations, the slope will change, which is extremely undesirable when choosing the limit value of the slope angle recommended by the coating manufacturer.
The independent constructions are based on the same equilateral triangle, divided into two symmetrical halves. We know the width of the span of the house box and the angle of inclination, because it is selected according to the type of roofing.
The algorithm for calculating the height of the ridge comes down to the following steps:
- Let's build a scaled diagram and plot on it the exact dimensions of the box being equipped. The most convenient and understandable scale is 1: 100, according to which 1 cm is displayed on a scale of 1 m. If working with such a reduction is uncomfortable, you can choose a smaller or larger scale.
- Let's find the middle of the span and draw the axis of symmetry of the roof upward from the resulting point.
- Using a protractor, we plot the slope of the designed roof from the corner of the box. We draw a slope line according to the marked angle.
- The intersection of the axis of symmetry of the roof and the slope line of the slopes, i.e. diagonals, will give us the opportunity to estimate at what height the ridge board will be located.
- We outline schematically the outline of the ridge girder and the support post on which the girder will be laid. Their axis of symmetry must coincide with the axis of symmetry of the roof. You just need to put half the thickness of the ridge board on both sides of the axis and draw arbitrary lines.
- The base line of the triangle, the diagonal and the nearby side face of the ridge girder, together with the post, define the required triangle, the vertical leg of which is the rise of the roof.
- We reduce the rise by 1/3 of the thickness of the board, i.e. to the cutting depth of the lower rafter assembly.
- From the resulting height, we set aside the width of the ridge board and draw the ridge purlin, then the ridge post.
- Draw to scale rafter leg, not forgetting that it will sag by 1/3 of the width due to the notch. To simplify the work, we draw a straight line parallel to the diagonal at a distance of 2/3 of the thickness of the rafter board.
Simply put, the height of the ridge is the sum of the rise of the roof and 2/3 of the thickness of the rafter board. In practice, there will still not be impeccable accuracy, but the error can be considered insignificant and quite acceptable according to building construction standards wooden structures, prescribed in the collection SP 64.13330.2011. Ideally, the processes of compression and crushing of the wooden parts of the system should be taken into account.
Video example of a skate device
The video will introduce you to the option of constructing the ridge of a gable roof, similar to the design described in the example:
A well-designed roof with a correctly calculated ridge height will look great. Its components will not create conditions for leaks and premature wear of the structure. It is not difficult to master the calculation methods we propose.
The roof is the first protective barrier of the house, which prevents cold air, melt or rain moisture from entering the living space. If you correctly calculate and then correctly determine the height of the roof ridge, it will independently remove atmospheric moisture and snow mass from the surface of the slope, preventing an increase in the load on the rafter system. In this article we will tell you how easy it is to calculate the height of the roof of a house, as well as how this parameter affects the quality of the roofing structure.
To appearance the roof was harmonious and organically complemented the architectural design of the house, it is necessary to correctly calculate the ratio of the width and length of the building. According to construction terminology, the height of the ridge is the distance from the middle of the base of the roof to its highest point. The following design qualities depend on this parameter:
- Roof slope angle. The higher the ridge, the steeper the slope of the roof of the house should be. In the territory middle zone Russia, which is famous big amount winter precipitation, prolonged downpours in autumn, it is recommended to choose a slope angle within 20-50 degrees.
- Area of slopes. The higher the roof, the large area have slopes, which increases the cost of roofing, as well as the material for the manufacture of the rafter frame.
- Bearing capacity of the frame. As the height of the roof increases, the weight and, consequently, the load from the roofing pie increases, which is why it is necessary to strengthen the structure frame with additional elements.
Important! There are 2 methods for calculating the height of the roof: you can calculate this parameter based on the desired slope, or, conversely, determine the height of the roof, and then calculate the angle of inclination of the slopes.
Factors influencing choice
The height of the roof of a house has a significant impact on the technical characteristics and operational characteristics of the structure. If you correctly calculate and then make a roofing design that meets the climatic conditions and the nature of the structure’s use, then it will last longer and will require less care and maintenance. When designing the roof of a house, the following factors are taken into account:
- Amount of precipitation. The higher the average annual precipitation in the construction region, the higher the ridge should be.
- Wind strength and direction. In windy regions, it is recommended to build low-rise buildings with a low, sloping roof so that it is not torn off by rapid gusts of air.
- The nature of the use of the premises. If the house design involves the installation of a residential attic, then the height of the ridge should be at least 2.5 m.
Note! The height and slope of the roof are calculated before drawing up the project, since these indicators have a strong influence on the design of the rafter frame and the choice of roofing.
Calculation procedure
Calculating the height of the roof is quite simple, even if you do not have a special calculator program at hand. The calculations are based on the assumption that the vertical section of the roof is an isosceles triangle, the base of which corresponds to the width of the pediment. Knowing the geometric formulas, we can find the height of the ridge using the calculation formula valid for a triangle:
- First we need to measure the width of the structure and then divide this value by 2.
- Then you need to determine the slope of the slope, that is, calculate the angle between the base of the roof and the surface of the slope.
- The next step is to use the Bradis table or an engineering calculator to determine the tangent of the angle formed by the base of the roof and the slope.
- Then we multiply half the width of the structure being covered by the tangent of the angle between the slope and the base of the roof, obtaining the height of the ridge.
Video instruction
Please indicate the required dimensions in millimeters
X- width of the house
Y- roof height
C- overhang size
B- roof length
Y2- extra height
X2- extra width
Reference
The program is designed to calculate roofing building materials: the amount of sheet material (ondulin, nulin, slate or metal tiles), roofing material (glassine, roofing felt), the number of sheathing boards and rafters.You can also calculate some useful roof dimensions.
The program works in two modes: a simple gable roof and a roof with two side gables (side roofs), type 1 and type 2.
Attention! If you have a roof with one side gable, then for the calculation use first type 1, then type 2. And from the data obtained, calculate the amount of building materials: rafters, sheathing boards, roofing and sheet materials.
Otherwise there may be an error in the calculation. After all, the program takes into account the cutouts in the main roof for the roofs of the side gables.
In the calculation you will see several numbers: the size or volume of the building material of half the roof and in brackets - the full size or volume.
In the calculation of an additional roof - the full size and volume, and in brackets there are two numbers: the size and volume of one and two additional roofs.
Attention! When calculating sheet roofing material, keep in mind that the program calculates by roof area.
For example, 2.8 rows times 7.7 sheets per row. During actual construction, 3 rows are laid.
To more accurately calculate the number of roofing sheets, you need to reduce the sheet height in the calculation until you get a whole number of rows.
Don't forget to set the amount of overlap more precisely.
When calculating the volume of material for the rafters of the main roof, in mode type 2, the program does not take into account the cutout for the side gable. This is due to some implementation difficulties in the program.
Maybe I'll solve this in the future.
However, the excess rafter material is unlikely to disappear, or make some adjustments to your calculations.
There will also be a separate program for more intelligent calculation of sheet roofing materials.
And don't forget what to buy Construction Materials it is necessary with some reserve for waste.
Designing any roof is a rather painstaking task, since most of the impacts of bad weather - snow, rain and strong winds - fall primarily on the roof slopes and rafter frame. Even though, in terms of stability and strength, a gable roof is considered the most the best option for any low-rise building.
Specialists have to repeatedly calculate the height of the ridge of a gable roof in order to find the golden mean between the angle of inclination of the slope, the volume of the roof space and the windage of the building.
What does the height of the ridge affect?
Anyone unfamiliar with the features of planning and calculating a gable roof can intuitively guess that the height of the ridge cannot be chosen. This is true. The height at which the joining line of the two slopes is located determines two main factors that determine the viability and price of the roof truss frame:
- Rafter length. The higher the ridge is raised, the longer the rafter beams;
- As the height of the ridge increases, the cost of beams, strut boards and struts increases;
- The higher the ridge, the greater the consumption of roofing, film vapor and waterproofing, insulation, and lining material;
- The windage of the building increases, if the height of the ridge exceeds the limit value determined by the calculation, a situation is possible when the building box is not able to hold the roof.
When calculating roof parameters, the factor of the influence of atmospheric phenomena is taken as one of the most important. An equally important characteristic depends on the height of the ridge - the angle of inclination of the roof slopes; the higher the ridge, the greater the slope.
For your information! A gust of wind of medium intensity creates a dynamic pressure normal to the surface of the roofing pie, reaching 20 kg per square meter.
An increase in the angle of inclination by 5° will mean that the height of the ridge and the length of the roof slope will increase by almost 10%, respectively, for 10° the increase will be almost 30%. It would seem that the flow of rainwater has improved and the volume of heat-insulating roof space has increased. But at the same time, the force of wind pressure increased by 30%. Calculations show that the pressure of high-speed air flow on the plane of an ordinary gable roof measuring 8x8 m is more than 1200 kg, which in itself is significant, given the strength of the rafter beams. Under these conditions, an additional 400 kg can be fatal for the roof plate.
Builders don't like high skates. This usually means that rafter beams will have to be purchased at an inflated price. It turns out that the greater the height of the ridge, the more expensive the material for a gable roof is. For timber longer than 6 m, the price per meter increases almost in arithmetic progression. In addition, the rafter beams have to be spliced, and due to the change in proportions they become excessively flexible. To prevent too much deflection, it is necessary to perform a control calculation of the deformation of each beam and be sure to use struts.
The height of the ridge cannot be increased arbitrarily for reasons of stability of the roof covering. Before calculating the height of the ridge of a gable roof, you need to decide on the type of roofing. Most manufacturers give recommendations about optimal angle slope of a gable roof for a specific type of roofing material. For example, flexible tiles cannot be laid on a roof slope with a slope of less than 16 o and more than 40 o, and ondulin and metal tiles are not used on slopes with a slope angle of 60-65 o.
Positive aspects of increasing the height of the ridge
There are only three main advantages with a plus sign that arise when increasing the height of the ridge:
- Reduced snow pressure;
- Increase usable space attic due to higher ceilings;
- Improving the ventilation of the under-roof space, reducing the risk of rainwater flowing under the roofing pie, reducing the cost of insulation due to a more voluminous air cushion.
A roof with a high ridge is ideal for dense urban areas, if available large quantity precipitation in the form of snow, rain and fog. Such a roof is often not even equipped with full thermal insulation, since the air pocket of the attic reduces heat loss 3-4 times more effectively. But for gable roofs with a high ridge, a special design of gables will be required. A more effective solution would be to replace the gable roof with a half-hip Danish scheme.
Before making a choice which angle is most suitable for a gable roof, it would be appropriate to compare the advantages and disadvantages that an increase in the height of the ridge entails.
For example, how important is a large attic space for owners? A simple geometric calculation shows that an attempt to arrange a living space on the second floor of a building with a conventional gable roof is, as a rule, ineffective. In this case, less than half of the workspace is used.
For your information! If the height of the walls of the attic room of a gable roof exceeds 120 cm from the level of the ceiling, the construction inspectorate may classify it as a second floor and prohibit construction or refuse to register the building.
At the same time, the cost of constructing a roof truss system due to the additional amount of lumber and insulation will increase by more than 70%. It will be necessary to calculate the estimate again, calculate the cost of the workers’ services, and most importantly, recalculate the strength of the rafter beams for the new height of the ridge.
As a result, it turns out that a gable roof with a ridge height of more than twice the height of the building walls is beneficial primarily for country houses, when the attic is not insulated and is used only as a utility room. But even in this case, the height of the ridge for a gable roof must be calculated scientifically.
How is the height of the ridge determined?
If the choice of the type of roofing has already been made, then to determine the height of the ridge you will need to make a calculation or assessment of the roof’s resistance to weather factors in a given climate zone.
You may not have to independently check the stability of the rafter frame at different ridge heights; this is the job of professional designers. But you need to know that the calculation is performed based on meteorological service statistics on three determining factors:
- The predominant direction and average wind speed at the surface of the earth and at a height of 7-10m;
- Average and maximum thickness of snow cover in a given area over the past 70 years;
- Average daily, maximum plus and minus temperatures in the area.
For the calculation, you will need tabular data from the set of rules SP 20-13330-2011, according to which the country’s territory is divided into eight zones, with approximately equal amounts of snow falling maximum during the control period of winter. The first belt includes a snow load of 80 kg/m2; for the last, eighth belt, the amount of snow on one square can reach 560-600 kg.
If we compare the pressure of snow on the roof and the dynamic pressure of the wind, it becomes clear that the calculation of the height of the ridge and the angle of inclination of the gable roof should be carried out primarily based on the snow load. For snowy areas, the height of the ridge is chosen so that the angle of inclination of the gable roof is in the range of 30-60 degrees. At large angles, snow pressure can be ignored.
But this does not mean that the dynamic wind pressure can not be taken into account at all. For example, consider the gable roof system of a gable roof. With a ridge height of 3 m and a base width of 6 m, the surface area of one pediment is 9 m2. According to calculations, at a wind speed of 10-12 m/s, a horizontally applied force of 200 kg will act on the roof gable. This means that even with a small ridge height, the rafter system has a chance to be folded like a house of cards if the frame calculation does not include the installation of struts and wind boards.
Geometry of the ridge of a gable roof
Often, everyone who comes into contact with the topic of calculating a gable roof for the first time has a logical question: why do you need to calculate the height of the ridge if the main characteristics are determined by the angle of inclination of the slopes?
In fact, the angle of inclination is used primarily to take into account external climatic factors, and the height of the ridge is a purely structural value. The selected height of the ridge determines the length of the rafters and the length of the struts and posts holding the ridge beam.
To calculate the height of the ridge, two methods are used:
- Using trigonometric functions;
- Tabular method, based on pre-calculated lengths of rafters and base.
If the gable roof is made according to a symmetrical design, then for the calculation it is enough to know the length of the laying or half of the base of the roof and the angle of inclination. Next, we determine the height of the ridge using the tangent, as in the diagram.
It is clear that trigonometric functions very inconvenient and, most importantly, not visual for practical work. Therefore, in construction reference tables you can see the designation of the angle of inclination as 5:10. It doesn’t matter how many degrees it is, to make the calculation it is enough for the master to know that 5 is the height of the ridge, and 10 is the length of the ridge.
In addition, you can determine the height of the ridge using a graphical or practical method. In the first case, drawings or precise sketches of the design of the future gable rafter frame are used. For construction calculations, sometimes it is enough to simply measure with a ruler and recalculate the values to the scale of the drawing. Despite the external primitiveness, this is the most reliable and proven method of calculation. In the second case, you have to climb onto the roof with a tape measure and a plumb line and measure the height of the ridge in practice.
For example, when assembling a gable frame, it is necessary to accurately cut the length of the rafters and cut down for the support pads on the ridge beam and on the mauerlat. In practice, the theoretical length calculation data is used only as a reference. To make a cut, the master climbs onto the roof, uses a plumb line and a tape measure to measure the height of the ridge and the length of the base, and only after that calculates the location of the cut.
Conclusion
With the development of software packages for the development and design of roof truss frames, it is possible to obtain complete detailing of all structural elements of the truss system with dimensions and materials. But practical skills in calculating heights and sizes will always come in handy, at least to check the results produced by the machine.
All parameters must be specified in millimeters
B- Roof length.
Y- Height.
C— Overhang distance.
X— Roof width.
Y2- Extra height.
X2— Additional width.
This program will help you perform an accurate calculation of building materials for roofing: the number of rafters and sheathing boards, roofing material (roofing felt, glassine), the amount of sheet material (metal tiles, slate, nulin or ondulin).
Our online calculator will also calculate other useful roof dimensions.
The presented program performs calculations in two versions: type 1 - simple gable roofs, type 2 - gable roofs with 2 side gables.
If the designed roof has only one side gable, then in this case we perform calculations according to type 1, and then according to type 2. Based on the calculation results, you will be able to determine the required volume of materials: roofing, sheet, rafters and sheathing boards.
Otherwise, you will make a mistake in the calculation, since the program takes into account the cutouts for the side fronts when calculating the parameters of the main roof.
Based on the calculation results, you receive the volume and size of the material for one roof slope, and the entire volume and size will be indicated in parentheses.
When calculating the volume and useful dimensions of an additional roof, you receive two parameters in brackets: the volume and size of one or two additional roofs.
Important! It is worth considering that the program performs calculations over the entire roof area when determining the number of sheets of roofing material.
For example, it takes 7.7 sheets per row, and only 2.8 rows. Based on the calculation results, you will receive 3 real building rows.
If you want to get the exact number of sheets for the future roof, you need to reduce their height until you get a whole number of rows.
Don't forget to set the exact length of the overlap.
Important! In type 2 mode, when calculating the volume of material for the rafters of the main roof, the program does not take into account the cutouts for the side gables. This calculation of the gable roof truss system is related to the design of the program itself.
You can also use the remaining building material for the rafters to build or repair a house, otherwise you can make corrections to the calculations.
An accurate calculation of the approximate cost of a roof depends on correct basic measurements.
Important! Don’t forget to purchase building materials with a 5-10% reserve for waste.
DIY gable roof
First of all, we need a diagram (drawing or design) of a gable roof, according to which we will make all the calculations (indicated above).
The procedure for constructing a roof is quite simple, but the sequence of certain steps must be followed.
Before installing beams or transfers for the future floor, you need to determine whether the attic or just an attic space will be built. As a rule, for a simple attic it is enough to choose a 150x150 mm board. If you are planning to build an attic, then it is best to choose a beam with the same size. To increase the strength of the frame, beams or boards should be mounted exclusively on the walls.
The process of fixing the beams is carried out taking into account the release from the outer edge of approximately 400 mm to prevent precipitation or wind from getting under the roof.
We will use a board cut to 50X150 mm when arranging the attic frame, and fixation is carried out with roofing nails. To give the gable roof stability, it is necessary to carry out all measurements correctly, trying to eliminate errors.
Now we move on to assembling the truss structure, starting with the installation from the gables, using the method already described above. At the same time, we saw off the lower parts of the boards, which will give our rafter structure additional stability.
When the structure is completely erected for a gable roof, we begin to cover it with roofing materials.
Advantages of a gable roof:
- This design is quite simple to construct, which allows you to do all the work yourself without the expensive help of specialists;
- The building materials used are affordable;
- The large angle of inclination of the roof perfectly drains water during precipitation;
- Absence complex structures and kinks, greatly facilitate the construction and cladding of the roof.