The first thing to do before starting roof construction is to make accurate calculations. Necessary detailed description all connections and assemblies, accurate drawing of all rafter system and approval of all this by an experienced person.

It sounds complicated, but in reality everything is simpler - no more complicated than a children's construction set, it is only important to do everything correctly. And, if you are looking for how to calculate the rafter system hip roof, you will find all the information you need here!

So, what is a hip roof truss system? This hipped design, i.e. one that has four planes. Such a roof is much more complex than a gable roof, but stronger and more reliable in operation. And her appearance is recognized all over the world as one of the most successful and aesthetic.

Here are the main advantages of this design:

  • Due to the presence of triangular end slopes in the hip roof, it is possible to install ordinary roof windows.
  • Due to the absence of a sharp protrusion, a hip roof has a higher resistance to various atmospheric phenomena.
  • The hip roof is considered economical - due to the fact that it does not have gables.
  • Temporary deformations of such a roof are reduced to zero - all thanks to its special design.
  • Insulating such a roof is much simpler than a gable roof (there are no such problematic gables).
  • Greater resistance to wind loads of the area due to low tilt angles.
  • The ability to more easily and easily convert an attic space into comfortable attic. And this is already a valuable increase in the living space of the house.

Among the disadvantages, we highlight the main one: the rafter system of a hip roof is more complex than that of a conventional one, and therefore its installation will cost you more, although you will save on brickwork.

Types of hip roof construction

So, let's figure out what types and subtypes of hip roofs are being built today:

  • Hip. This is a traditional hipped roof with triangular slopes on all end sides.
  • A roof in which the hip does not reach the eaves is called half-hipped.
  • A hip roof is a hip roof in which identical triangles are connected together by one upper point. By the way, once upon a time in Rus' they built just such roofs.
  • Cross-shaped hip roof - more rare view due to the high cost of execution and high labor intensity of work. Usually it is built on houses with complex layouts or separately just above the entrance doors.

Our diagram will help you understand in more detail:

As we have already said, if the hip does not reach the eaves, the roof is called half-hip. Just in these places they put dormer windows, which completely solves the problem of the need for inclined attic windows. But in terms of complexity and cost of construction, the half-hip roof is higher than others.

The simplest example of a hip roof (quite aesthetically pleasing, we note) is the roof triangular shape. All slopes here are the same size, and all angles are equal. If this height and design suits you, then give preference to this option - you will avoid many pitfalls and nuances!

The only point: the hip roof in its classic version is bad because it does not have vertical planes and dormer or attic windows have to be placed on sloping walls. As a result, such elements become the most vulnerable in terms of leaks during rain.

Hip roof architecture in detail

To construct a hip roof specifically, experienced builders recommend taking rectangular beams from coniferous trees, and strengthening the stability of the entire system with additional steel elements. After all, in addition to the rafters themselves, you will in any case need the following building elements:

  • Mauerlat is the lower support for the rafters.
  • A purlin is a beam that needs to be placed parallel to the Mauerlat as another additional support.
  • Racks and struts are supporting elements for a so-called multi-span structure.
  • Crossbars are special elements that help cope with spacers (a common occurrence when installed incorrectly).
  • Sprengel is another additional element of the rafter support.
  • A bench is a special support for racks and struts.

So, construction material purchased? Now put all the parts in a stack or dry them further. The main thing is to think about protection from rain.

How to avoid errors in calculations?

Now let's avoid the very first and most annoying mistake of designing a hip roof - the lack of measurements of the house itself. The problem is that even trained craftsmen manage to start work by drawing up a plan and drawing of the roof, but do not work with the base - the walls. But only at first glance it seems that the walls are perfectly even, everything is parallel to each other and the like, but in reality it is far from ideal, even completely new house. And then, only during the construction process are certain errors discovered that prevent the first supports from being installed correctly.

Therefore, first of all, before making any calculations on the hip roof, we arm ourselves with a ruler and level. We check elevations, parallelism of walls, diagonals (correctness of rectangular walls) and draw up a measured plan of the house. Let's say you will be surprised by some of the inaccuracies. And now we decide how we will fix it:

  • We correct a minor error in parallelism with a Mauerlat.
  • Minor difference in heights different walls fix it with gaskets.
  • We correct significant differences with additional elements of the rafter system, which we must include in the calculations.

Additionally, we recommend that rather than just a simple 2D roof drawing, you create a 3D model that will give you a clear picture of your hip roof. At first glance you will be able to understand whether you like the result or not. Remaking something is quite difficult. And modern computer programs, of which there are quite a lot, will help you with this.

If you are looking for finished drawing roof that fits the required parameters, do not take too detailed drawings with Latin abbreviations and formulas: they are needed only by the master who can read them. And so that you have an idea of ​​what exactly awaits you, we offer you a simple master class on building a hip roof, where all the elements are clearly visible:

What data is needed for construction?

Here are the parameters of the future roof you should know before you start building it:

  1. The angle of inclination of the roof, on each side of the hip slopes.
  2. The angle of the roof from the sides.
  3. The exact area of ​​the entire roof surface
  4. Weight of the future roof and exact load roofing material on the roof truss system.
  5. Length of diagonal rafters.
  6. The cross section of the rafters takes into account regional wind and snow loads, the pitch of the rafters and the weight of the roofing material.
  7. The required volume of all rafters in cubic meters.

You will need to know the area of ​​the entire surface in order to purchase the required amount of roofing material and calculate it in advance future weight:

Next are the rafters. On hip roofs, rafters are placed directed towards the corners of the walls - internal and external, and are called slanted or diagonal. The second ones are longer than ordinary rafters, and the shortened rafters rest on them - narozhniki. As a result, such rafters carry a load 1.5 times greater than usual.

The length of the diagonal rafters is longer than the standard length, so they are made in pairs. Their advantage is that the double cross-section is designed for increased load and ultimately represents a solid, uncut board. As a result Constructive decisions Such roofs turn out to be quite simple. And in order to ensure the multi-span of the hip roof, one or two supports will need to be placed under the sloped leg.

If you have already purchased scaffolding for the construction of the roof, then calculate the pitch of the rafters based on the cross-section of the finished boards. If you haven’t purchased it yet, look now, before drawing up a project. After all, it’s not uncommon for a project to be ready, but good wood it turns out to get completely different parameters than planned.

We bring to your attention a special free one.

What should be taken into account when calculating?

The hip roof project is one of the most difficult. Here it is extremely important not to make mistakes in the calculations, because the hip roof is a large number of a variety of elements, and each of them has an important function.

So, the slope of a hip roof usually varies from 5 to 60°. Based on this, the roofing material is chosen: roll coverings for small slopes and tiles for steep planes. But immediately expect that the greater the angle of inclination of such a roof, the more roofing material you will end up using. With what smaller angle- the stronger the frame will have to be built, because it will now bear a considerable load.

To make your final decision, you will have to consider all these factors:

  • The total weight of the planned roofing material.
  • Additional weight of waterproofing and insulation.
  • Local climate features (check with your neighbors).
  • Type of rafters and availability additional elements to maintain the strength of the roof.
  • All devices and equipment that you are going to install on the roof.

It is important to take into account wind and snow loads so that your roof is not broken through by tons of snow or torn off by a stormy wind, and the weather conditions of a particular area will indicate what possible deformations of the rafter system over the years (for example, dampness, sea air, etc. .).

Note that a hip roof usually has no problems with wind loads, but almost always with a snow roof. The reason is that a hip roof has all inclined planes. Bad for wind, but good for snow.

Have you decided on the project? We've done everything necessary calculations? Then get started!

A fairly popular type of roof is. This variety is classified as hipped structures.

For slate, an example calculation is as follows:

  1. Typically seven sheets are used to cover wave slate, the useful area of ​​which is 1.335 m 2.
  2. If 8 sheets of such material are used, then the usable area is 1.56 m2.
  3. Next, the value of the total roof area is divided by the value of the usable area of ​​the material. If the roof area is, for example, 26.7 m2, then the number of slate sheets required for roofing is 20 pieces.

Calculation example for metal tiles:

  1. When choosing a similar material for coating, it is worth knowing that the smaller the size of the material, the larger size joints must be applied.
  2. Initially, the value of the total area is multiplied by a correction factor equal to 1.1.
  3. After this, the resulting area value is divided by usable area tiles, depending on its size and, accordingly, the size of the overlaps.

If the roof covering structure is combined and complex, then the cost overrun can reach 60%.

Roof calculation calculator

Rafter pitch

The distance that forms between two rafters is called the pitch. Most of the structures are made in such a way that the step is 1 m. The minimum permissible value of this parameter is also set at 60 cm.

The process of calculating the distance between the rafters is as follows:

  1. Initially, you need to select the approximate expected pitch of the rafter system. You can build on the above values, i.e. the distance is 1 m.
  2. The next value you will need is the length of the ridge.
  3. After this, the length of the rafter is divided by the approximately selected pitch value. The resulting result is rounded up and then increased by 1.
  4. The last thing in the calculation is dividing the total length of the slope by the value from the previous paragraph. This will be the required distance that must be maintained during the installation process.

Using an example, we can consider the design, the length of the slope is 12 m, and the approximately selected step distance is 0.8 m:

  1. 12 / 0.8 = 15. If the number in the calculation is not an integer, then it should be rounded to the nearest integer value.
  2. 15 + 1 = 16. Increase by one for more accurate calculations number of legs in the structure.
  3. 12 / 16 = 0.75 m. This value will be the optimal step distance for the truss structure.

Rafter pitch

Selecting the roof slope angle and determining the height of the ridge

As in previous calculations, the process of determining the height of the ridge depends on the selected slope angle. Despite the fact that the hip roof structure allows you to build slopes with different angles, it is best to make a structure with the same angles.

This will allow the load to be distributed evenly and the roof to have an aesthetically pleasing appearance.

ATTENTION!

The angle of inclination relative to the hip version of the structure varies between 20 and 45 degrees.

A more specific definition of such a parameter is influenced by:

  1. The factor of increased snow load suggests the construction of a structure with a steeper slope.
  2. If the wind in the area where the house is located is strong and gusty, then it is recommended to make the slope no more than 30 degrees.
  3. The intention is to use the attic space as a living space. In this case, the ease of movement around the attic and the ability to provide all communication structures in such a way that they can be easily accessed if necessary are taken into account.
  4. The coating chosen for the roof also plays an important role. When choosing a specific material, you need to inquire about the minimum permitted characteristics regarding the angle of the slope.

Regarding the height of the ridge, it is very simple to determine it, knowing the value of the angle of the slope. In the design, it is necessary to conditionally select a right triangle, in which one of the sides will be the desired height.

Formula: h = b / 2 * tanA.

Roof angle

Conclusion

The stage of designing a house and all its structural elements is quite complex and painstaking. It is very important to carefully carry out all calculations and double-check them each time. A visual representation on a smaller scale of the entire future structure can make this task easier.

In contact with

Using a calculator for calculating a hip roof, you can determine the angle of inclination, the amount of sheathing and calculate the rafter system. You will also be given detailed information about the required amount of building materials. Perform an online calculation of the hip roof of a house.

Specify roofing material:

Select a material from the list -- Slate (corrugated asbestos cement sheets): Medium profile (11 kg/m2) Slate (corrugated asbestos cement sheets): Reinforced profile (13 kg/m2) Corrugated cellulose-bitumen sheets (6 kg/m2) Bitumen (soft , flexible) tiles (15 kg/m2) Galvanized sheet metal (6.5 kg/m2) Sheet steel (8 kg/m2) Ceramic tiles (50 kg/m2) Cement-sand tiles (70 kg/m2) Metal tiles, corrugated sheets (5 kg/m2) Keramoplast (5.5 kg/m2) Seam roofing (6 kg/m2) Polymer-sand tiles (25 kg/m2) Ondulin (Euro slate) (4 kg/m2) Composite tiles (7 kg/m2) ) Natural slate (40 kg/m2) Specify the weight of 1 square meter of coating (? kg/m2)

kg/m 2

Enter roof parameters:

Base width A (cm)

Base Length B(cm)

Roof angle α (deg)

Length of side overhangs C (cm)

Length of end overhangs D (cm)

Rafters:

Rafter pitch (cm)

Type of wood for rafters (cm)

Lathing calculation:

Sheathing board width (cm)

Sheathing board thickness (cm)

Distance between sheathing boards
(cm)

Calculation snow load:

Select your region using the map below

1 (80/56 kg/m2) 2 (120/84 kg/m2) 3 (180/126 kg/m2) 4 (240/168 kg/m2) 5 (320/224 kg/m2) 6 ​​(400/280 kg/m2) 7 (480/336 kg/m2) 8 (560/392 kg/m2)

Wind load calculation:

Ia I II III IV V VI VII

Height to the ridge of the building

5 m from 5 m to 10 m from 10 m

Terrain type

Open area Closed area Urban areas

Calculation results

The angle of inclination is suitable for this material.

It is advisable to increase the angle of inclination for this material!

It is advisable to reduce the angle of inclination for this material!

Lifting height: 0 cm

Ridge beam length: 0 cm

Roof surface area: 0 m.

Approximate weight of roofing material: 0 kg.

Number of rolls of insulating material with 10% overlap (1×15 m): 0 rolls.

Rafters:

Load on the rafter system: 0 kg/m2.

Side rafter length: 0 cm

Length of diagonal rafters: 0 cm

Number of hip rafters: 0 pcs.

Reduce the pitch of the rafters!

Number of side rafters: 0 pcs.

Lathing:

Number of rows of sheathing (for the entire roof): 0 rows.

Uniform distance between sheathing boards: 0 cm

Number of sheathing boards with a standard length of 6 meters: 0 pcs.

Volume of sheathing boards: 0 m3.

Approximate weight of sheathing boards: 0 kg.

About the calculator

An online calculator for a hip roof will help you calculate its parameters: the volume of roofing and insulating materials, sheathing, the strength of the rafter system, the correct angle of inclination of the roof slopes. The calculator database contains information about most roofing materials. These are metal tiles, bitumen, ceramic and cement-sand tiles, bitumen and asbestos-cement slate, ondulin and other materials. Therefore, by using this calculator you can more accurately calculate the structure and decide on future construction. This calculator considers classic version hip roof with equal slopes and equal slope angles relative to the base of the roof.

Before constructing a hip roof, familiarize yourself with regulatory documents, such as SNiP 2.08.01-89 “RESIDENTIAL BUILDINGS”.

A hip roof is a unique version of a gable roof, but in profile it has the shape of a trapezoid. At the ends of the hip roof there are slopes shaped like triangles (the so-called hips). The roof has a total of 4 slopes (two side and two end) and 4 ribs (so-called diagonal rafters).

This design, although more complex than usual gable roofs, but has its advantages, and the hip roof looks great.

There are also half-hip roofs, in which the hip slopes are shorter and do not reach the eaves.

All kinds of roofing materials can be used to finish a hip roof. When choosing them, you should take into account the climate characteristics of your region and pay attention to the performance characteristics of the materials.

When filling out the fields of the calculator, you can find out Additional information, located under the sign.

If you have any questions or suggestions about this calculator, you can write to us using the comment form at the bottom of the page. We'd love to hear your opinion.

Additional information about the calculation results

Roof angle

Here you will see a message indicating whether the specified roof angle complies with roofing material standards. If the angle does not match, you will be advised to change it.

Lifting height

The height of the roof from its base to the ridge (overhangs are not taken into account).

Ridge beam length

The ridge beam will have given length between the hips.

Roof surface area

The area of ​​the entire surface, including existing overhangs. This parameter will help you calculate necessary materials for construction.

Approximate weight of roofing material

The total mass of the selected roofing material required for a roof of a given size.

Number of rolls of insulating material

The required amount of insulating material. The quantity indicated in rolls is based on the standard - 15 meters long, 1 meter wide. The calculation also took into account an overlap of 10%.

Load on the rafter system

The maximum weight exerted on the rafter system. The wind and snow loads of the selected region, the angle of the roof, as well as the weight of the entire structure are taken into account.

Side rafter length

Estimated length of rafters taking into account overhangs.

Length of diagonal (sloping) rafters

The length of each of the four diagonal rafters (ribs).

Number of side and hip rafters

The total number of rafters for the side and hip slopes, not counting the four diagonal rafters.

Minimum section of rafters / Weight of rafters / Volume of beams

  1. The first column shows the cross-sections of the rafters according to GOST 24454-80 Softwood lumber. Here are the sections that can be used when building a hip roof with given parameters. The starting point for calculations is the total load on the structure. After which the corresponding section of the rafters is determined, presented in this table.
  2. The second column indicates the total weight of the rafters, which would be obtained if they were used to construct the entire roof.
  3. The third column indicates the total volume of rafters in cubic meters. This indicator may be useful to you when calculating the cost.

Number of rows of sheathing

The number of rows of sheathing that will be needed for the entire roof with the given parameters. Be sure to check the required number of rows of sheathing for the selected roofing material; you can do this from roofing material sellers.

Uniform distance between sheathing boards

To evenly space the sheathing, use the step shown here. It will provide the necessary strength to the roof and save material.

Volume of sheathing boards

Volume of boards per sheathing (for the entire roof). This value will help you when calculating the cost of lumber.

A classic roof with its two slopes and end gables rarely suits a modern developer. More often country cottages decorated with a hip roof - spectacular, but more difficult to manufacture.

In our article we will deal in detail with this important issue how to calculate the rafter system of a hip roof. The data obtained will help to optimally use building materials and will significantly simplify the installation process itself.

What is a hip roof

The hip structure is a complex hipped roof shaped like a trapezoid. There are slopes (hips) at the end of the roof; outwardly their shape resembles a triangle. In total, the roof has 4 slopes - 2 side and 2 end, and 4 ribs (they are also called diagonal rafters).

The roof truss structure is based on a complex frame. The central rafters, due to the nature of their structure, create extra load. In addition, the rafters must withstand snow and wind loads (in areas with frequent snowfalls this is doubly important).

During installation, the structure is labor-intensive, but outwardly it looks more advantageous than a conventional gable roof. To finish this type of roof, you can use any roofing material. When choosing a coating, it is important to take into account the characteristics of the climatic zone in which construction will take place.

About the calculator

To calculate a hip roof, you can use several methods: manually or using special construction programs (calculators). For manual calculation you will need good knowledge in algebra and geometry. The formula for calculating a hip roof consists of the sum of the areas of 2 triangles (hips) and 2 trapezoidal side slopes. The area of ​​the hip slopes is calculated using the well-known formula of an isosceles triangle. The area of ​​a trapezoid is more complex and is subtracted using the formula presented in the figure below.

The calculator database contains information about the most popular types of roofing materials - metal, ceramic, cement-sand, bitumen shingles and other coatings. To get the result, the user must note the required roofing material, the dimensions of the roof base, the length of the overhangs, the planned pitch of the rafters, the type and parameters of wood for the sheathing, and mark the region of construction. Next, the system will provide a complete calculation of the hip roof of the house according to the selected parameters.

Important: the calculator will prepare a report taking into account data from the meteorological service of the development area, the average wind speed and strength, and precipitation intensity will be taken into account.

Calculation results - explanations

The online calculator report includes the following items:

    Roof. The calculator, according to the specified conditions, will recommend the angle of inclination of the side and hip rafters. This value directly depends on the selected development area. The calculator will also determine the approximate weight of the roofing material and the required amount of roofing felt (indicated in rolls);

    Rafters. The length of the side, diagonal and hip rafters will be given.

Important: the size of the side rafters is calculated taking into account the overhang!

The required number of side and hip rafters required for the entire roof.

Important: this value does not include diagonal rafters (+4 pcs.)

    Lathing. The Hip Roof Calculator will determine how many rows of sheathing are needed for a given roof area and will also determine the number of sheathing boards (each 6m long).

Important: the program takes everything into account important points: length and width of the roof, the size of the gable overhangs and roof eaves on all sides and the angle of the hips.

Fill in the dimensions in millimeters:

Y– roof height, this is the distance from the attic floor to the ridge unit (top of the “tent”). Meaning Y affects the angle of inclination of the roof (for a hipped roof from 5 to 60 degrees). The angle of inclination of the roof slope is determined taking into account the type of building, purpose attic space, snow load and type of roofing material (for example, for roofing felt - 8-18°, slate or metal sheets–14-60°, tiles – 30-60°). If the attic is non-residential, you should choose a small height (saving material for rafters, waterproofing and roofing), but sufficient for inspection, maintenance and repair (approximately 1500 mm). It is imperative to take into account the requirements of SP 20.13330.2011 “Loads and impacts” (updated edition of SNiP 2.01.07-85*). It should be remembered that on a roof of low height (tilt angle up to 30 degrees) snow can accumulate, which increases the load on the roof truss system and negatively affects its tightness and durability. The high roof (tilt angle 45-60°) makes it possible to equip a living space under its arch and does not allow precipitation to linger, but is vulnerable to strong gusts of wind. The optimal angle of inclination of a hipped roof is often in the range of 30-45 degrees.

X– The length of the roof (excluding overhangs), in fact, is the length of the front wall of your house.

Z– The width of the roof is determined by the width of the building.

C- size eaves overhang, (necessary to protect walls and foundations from precipitation) is determined taking into account the climatic characteristics of your region (SP 20.13330.2011) and the general architectural design.

For one and two-story houses with drainage system minimum size C– 400 mm (according to SNiP II-26-76*), without organizing external water drainage, not less than 600 mm. The optimal overhang is approximately 500 mm.

U- Width of the rafters.

W– Thickness of the rafters.

S– The pitch of the rafters, i.e. distance between adjacent rafters.

U And W– important parameters that determine the reliability of the entire rafter system. The required rafter section ( U X W) depends on: loads (constant - the weight of the rafter system, sheathing, roofing pie; temporary - snow, wind; special - seismic impacts, dynamic loads from industrial explosions), the quality and type of material used (boards, timber, laminated veneer lumber), length rafter leg, distances between rafters. Approximate section of timber and step ( S) for rafters different lengths shown in the table.

Rafter length, mm Rafter pitch, mm Rafter section, mm
Up to 3000 1200 80x100
Up to 3000 1800 90x100
Up to 4000 1000 80x160
Up to 4000 1400 80x180
Up to 4000 1800 90x180
Up to 6000 1000 80x200
Up to 6000 1400 100x200

When choosing a rafter section, be sure to follow the recommendations given in SP 64.13330.2011 “ Wooden structures"", SNiP II-26-76* "Roofs" taking into account SP 20.13330.2011 "Loads and impacts".

O1– Width of sheathing boards.

O2– Thickness of sheathing boards.

R– Sheathing pitch (i.e. the distance between adjacent boards).

The sheathing of the roof rafter frame performs supporting functions; its cross-section (width O1 and thickness O2) is determined by the weight, rigidity of the roofing material and the angle of the roof. The lathing should provide sufficient support, but at the same time not weigh down the structure. Determine approximate width values ​​( O1), thickness ( O2) boards for sheathing and step ( R) is possible using table data.

Filling out the fields online calculator and a palm roof, you need to choose optimal cross section lathing and its spacing in a particular case will be helped by the recommendations given in SP 64.13330.2011 “Wooden Structures”, SNiP II-26-76* “Roofs” and SP 20.13330.2011 “Loads and Impacts”.

If you need a drawing close to GOST requirements, check the “Black and white drawing” box; this will save color ink or toner when printing.

Hip roof calculation results:

Our online calculator with drawings will help you calculate the materials for arranging a hip or hip roof and create detailed drawings (with exact dimensions of all parts of the rafter system). You can find out for free the area, width, height of the roof, the length of lumber for eaves, ridges, rafters, sheathing for each side of the roof and the required volume of wood for each item. Such data will allow you to form an idea of ​​the cost of a hipped roof (make an estimate) and purchase the required amount of lumber for the rafter system. It is also recommended to obtain advice from a qualified specialist (roofer builder with experience in implementing successful projects) on roof installation, since the comfort and coziness of your home largely depends on its quality and reliability.