Hip roof- this is a type of hipped roof, in which two slopes are trapezoidal in shape, and the other two (end ones) are triangular (having the same name “hips”). If the end slopes occupy the entire area from the ridge to the eaves, it is a hip roof; if they do not reach the eaves, it is a half-hip roof.
The roof of a house performs a dual function - on the one hand, it is charged with protecting the building from external influences, and on the other, it is designed to decorate the structure and give it individuality.
Historically, in Russia preference was given to simpler one-, gable roofs, Europeans prefer a hip or hip roof, which has advantages and disadvantages under certain conditions.
Hip roof - advantages and disadvantages
Pros:
- greater structural rigidity. Achieved by corner ribs connecting near the ridge support beam;
- the possibility of arranging more protruding overhangs, which provides additional protection house walls;
- aesthetic appeal.
Cons:
- complexity of calculation and installation;
- higher cost of project implementation;
- reducing the area of the attic space (in particular at the installation site diagonal supports);
- impossibility of installing an attic;
- natural light is only possible by installing windows in the roofing pie.
Since the shortcomings are not critical - hipped roof hip type is actively practiced in modern construction private houses.
Varieties (types and types) of hip roof
Studying the device rafter system hip roof, it should be noted that within this type, there are several types of structures. In turn, this makes adjustments to the overall process of constructing the frame of the rafter system.
Classic hip roof
It is distinguished by the support of the diagonal ribs on the ridge support beam and the location of the overhangs at the same height. Individual elements hip roofs correspond to a triangle (gables) and a trapezoid (slopes).
Hip hip roof
It is distinguished by the absence of a ridge support beam. This leads to the fact that all the diagonal ribs converge at a single point, and ordinary short rafters are already adjacent to them. This type of roof is preferred if the house has a square frame. But forming a reliable ridge assembly is quite complicated.
Half hip roof
It is distinguished by the presence of vertical gables in which windows can be installed. The picture shows the difference between two types of half-hip roofs (Dutch and Danish).
Sloping hip roof or mansard hipped roof
The most complex design in terms of construction is the hip roof truss system, since in this case, all roof slopes have different areas and diverge at different angles. A sloping (attic) roof allows you to more rationally organize the internal roof space and, in addition to additional living space, give the house a spectacular appearance.
Hip roof design
Regardless of the type of roof, all types have the same elements of the hip roof rafter system:
ridge support beam or ridge beam - used for a classic hip roof, performs the function load-bearing element, to which the diagonal rafters are attached;
diagonal rafter (side, rib, slant or corner rafter) - a longer rafter leg that is attached to the end of the ridge beam under acute angle, forming one of the sides of the triangle;
central rafter - boards of the same length that adjoin the ridge beam and form the edges of the trapezoidal roof slope. Between them there are intermediate rafters;
intermediate or ordinary rafters - forms the plane of the trapezoidal slope, the distance between them determines the run of the rafter system;
raspnik or short rafter - a structural element that is attached to a diagonal rafter, forming a triangular overhang and corner parts of trapezoids.
Hip roof calculation
The calculation of the hip roof truss system is carried out taking into account the following prerequisites:
- wind load in the region. The higher it is, the flatter the slope should be, and the stronger the entire structure. To level out strong winds, the central and diagonal rafters are made thicker;
- amount of precipitation. Observed inverse relationship. The higher the amount of precipitation, the steeper the slope should be so that snow and rain do not create pressure on the rafter system;
- view roofing material. Each type of roofing material puts forward its own requirements for the sheathing, and also has a certain weight. These factors must be taken into account at the design stage;
- the need for roof insulation. In this case, the rafter installation step is calculated taking into account the width thermal insulation material. In addition, the distance between the rafters depends on the type and section of the wood.
The calculation of roofing material is carried out using formulas taking into account the angle of inclination of the roof. The optimal roof slope for different types of roofing materials is shown in the table:
The slope of the slope angle determines the position of the rafters. In turn, the position of the intermediate rafter is calculated as follows:
- first on top harness a center line is applied to the end wall;
- then half the thickness of the ridge beam is calculated, and the placement line of the first of the central intermediate rafters is drawn;
- then the end of the measuring rod is aligned with the placement line of the central intermediate rafter marked above;
- a line of the internal contour of the side wall is applied to the opposite end of the measuring rod;
- the resulting point is the position of the intermediate rafter.
The relationship between the length of the rafters and their position is calculated using a correction factor, the value of which depends on the angle of inclination of the roof slope. The length of the rafter leg is determined by multiplying the laying by the coefficient.
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Formulas for calculating a hip roof
| Ridge height |  |
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| Ridge beam length |
The length of the house minus its width |
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| Central length rafters (trapezoid) |
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Pythagorean theorem |
| Length of ordinary rafters | Calculated similarly to the length of the central rafters | |
| Rafter extension to form frame overhang |
 |
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| Tilt angle ordinary rafters |
 |
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| Diagonal length hip rafters |
 |
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| Narozhniki (short rafters) |
 First short rafter |
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 Second short rafter |
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| Square hip roof |
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How to calculate the area of a hip roof?
To know how much roofing material to buy, you need to know the total roof area.
To do this, you need to break the entire roof into simple components geometric shapes and make a calculation for each of them.
Calculating the area of a hip roof allows you to determine in advance not only the costs of purchasing roofing materials and installation, but also to determine the requirements for materials, as well as the need for arrangement and the exact configuration of the sheathing.
Hip roof rafter system drawing
The result of the project development and calculations will be a diagram-drawing of the hip roof rafter system. There are no similar drawings that are ready for use without taking into account the features of a particular structure and the place where it was built.
You can develop a preliminary design yourself (a simple sketch will help determine the direction of the project). But, it is better to entrust the drawing to specialists or use special programs for calculations. It should be remembered that the more complex the roof structure, the more accurately you need to calculate the rafter system: configuration and materials. This will also affect the cost and duration of installation work.
The hip roof drawing must include an indication of the purpose of the material, its installation location and method of fastening. It is advisable to include the key components of the hip roof rafter system, for example, the connection of diagonal supports to the ridge beam or the installation of rafter legs on the mauerlat, in a separate drawing and describe them in more detail.
Drawing of a hip roof (sloping rafters with emphasis on two purlins)
Drawing of a hip roof rafter system with a bay window
Having a schematic drawing will be a good help in the manufacture of blanks and subsequent installation of the roof.
Tools for building a hip roof
The design of the roof and the methods for arranging the components determine the set of tools that should be prepared before starting work.
To work with wood you will need: a level, a hacksaw, a hammer, a tape measure, a marking cord, and a stapler.
To work with metal structures you will need an electric drill, a riveter, and cutting shears.
Tool and consumables must be prepared in advance, because complex installation of the hip roof rafter system involves large number cuts and installation of nails.
To simplify measurements and be able to make all the details same size, experts advise replacing the tape measure with a measuring rod. The measuring rod is made of plywood 50 mm wide, onto which the main dimensions are applied.
Hip roof material
The species and type of wood have a direct impact on the durability and reliability of the roofing structure. Craftsmen advise giving preference to lumber or pine. All workpieces require pre-treatment with fire retardants and antiseptics.
In addition to wood, you will need metal fasteners, nails, screws, and anchor bolts.
Note. Forming a hip rafter system on wooden house, which can shrink, craftsmen advise using floating fasteners to connect the rafters to the Mauerlat. This method compensates for the movement of the crowns during natural shrinkage houses made of timber or logs.
Hip roof rafter system - installation technology
DIY rafter system devices step by step:
1. Preparation of blanks (rafters)
This is the most difficult and time-consuming part of construction, because... related to:
- the need to ensure a given angle of inclination of the rafter legs;
- different lengths of rafters (short rafters);
- the presence of diagonal rafters (sloping), which receive special attention. Due to their length, slanted rafters carry a greater load than the main rafters, and therefore require the use of more quality lumber with a large cross section. In addition, often the length of the diagonal rafters exceeds the standard length of the boards.
In order not to buy different lumber, in practice the splicing (mating) method is used. edged boards to obtain the specified length.
Advantages of rafter splicing technology:
- obtaining continuous beams of a given length;
- increasing the strength of the diagonal rafters of the hip roof due to the doubled cross-section;
- simplification of calculation and purchase of material (unification of dimensions: length and cross-section);
- the possibility of using boards designed to form ordinary rafters.
2. Mounting the Mauerlat
Mauerlat for a hip roof is wooden beam large section (100x100 or 100x150 mm) mounted along the perimeter of the walls. First grade wood is used for the Mauerlat.
The peculiarity of laying the Mauerlat is that the timber is connected along the length only with an overlap, but not end-to-end, using many connection points with the base of the wall. The connecting nodes are additionally reinforced with metal brackets.
Since the purpose of the Mauerlat is to serve as a support for the rafter legs, it needs protection from moisture. For this purpose, a hydraulic barrier is placed between the wall and the beam (for example, roofing felt is used).
Note. Under the mauerlat in brick houses (or made of aerated concrete, foam concrete, wood concrete), a reinforced concrete belt with pre-installed studs for mounting the timber is poured. The pin has a diameter of 10 mm or more and should protrude beyond the plane of the Mauerlat by 20-30 mm. The stud installation pitch is 1000-1200 mm.
3. Purlin installation
A purlin is a beam installed parallel to the sides of the mauerlat. The purlin serves as the basis for installing additional supports under the rafter legs. The installation of a purlin is not a mandatory stage of work and is performed only for hip roofs of a large area or having a configuration increased complexity. The location of the purlin is shown in the diagram.
It should be taken into account that the point of maximum load will vary depending on the location - on the ridge of the hip or on the edge of the valley.
Note. The hipped hip roof is mounted without support, and a complex assembly is formed at the junction of the diagonal rafters.
4. Installation of support posts
The racks serve as a support when installing the ridge beam ( orange in the picture).
5. Installation of the ridge beam
Installation of the hip roof ridge is accompanied by precise measurements. Since the entire roof structure will rest on the ridge, the correctness of its installation is checked in terms of height and level.
6. Attaching rafter legs
Regarding the sequence of work at this stage, the opinions of the craftsmen differ. This makes it possible to distinguish two directions for performing work:
- The central rafters are mounted, and then the diagonal ones. This procedure is simpler;
- diagonal rafters are mounted, and then the rest.
During installation, the lower part of the rafter leg rests on the Mauerlat.
The support of rafters on a hip roof is shown in the diagram. The first option (with a cutout) is simpler, but the second (with a support beam) is preferable, because in this case, the fastening does not weaken the rafter.
Forming a knot on a ridge beam is possible in different ways.
Options top mount diagonal rafters are shown in the diagram.
Advice. For rigidity, it is advisable to reinforce all nodes with metal elements (staples, plates, corners).
Since diagonal rafters bear a significant load, they can be strengthened using such means as:
- installation of the rack. Mounted vertically on the ceiling;
- installation of the strut. Mounted at an angle. The angle of inclination is not decisive. The ability of the brace to strengthen the diagonal rafter is important;
- truss Essentially, this is a T-shaped short beam rotated 180°. It is used on long spans and is installed so that its base is oriented perpendicular to the diagonal rafter.
7. Installation of ordinary rafters
The rows are installed similarly to the installation of the central rafters, which form the edges of the trapezoid. Their lower part rests and is attached to the mauerlat, and the upper part rests on the ridge beam. It is important to maintain the same distance between row rafters.
8. Installation of roof trusses (short rafters)
Spawners are made only from solid lumber. At the junction of the spigot and the long rafter, notches are made or support beams are installed. The installation site is additionally reinforced with metal elements.
Note. Installation of hip roof extensions is possible in staggered intervals to simplify installation.
In any case, the frames are installed after the roof’s load-bearing frame has been formed. Their installation completes the work on installing the hip roof rafter system.
DIY hip roof step by step - video
The program shows the process of installing a rafter system for a gable hip roof with a central bay window along a short wall.
Once the rafter system is ready, you can begin installing the roofing covering, the specifics of its fastening determine the need to install the sheathing on the rafter legs.
Installation of a hip roof truss system is a long process that requires attention to every stage of the work - from calculation and selection of material, to installation of parts and strengthening of fastening points. But, if all stages are carried out correctly, the result will be a beautiful and reliable roof for a private home.
The hip roof is one of the varieties of hipped roofing structures. In terms of complexity of arrangement, hip roofs are superior to classic and gable roofs, - placing four slopes on a house, exactly coordinated with each other and docked at the same angles, is not very easy. But with a strong desire, even the most difficult activities become understandable and simple. Read the guide and get started.
A hip roofing system has a number of distinctive features. Thus, a hip roof includes a pair of long slopes, which have a pronounced trapezoidal shape, as well as a pair of short slopes, made in the form of inclined triangles.
The main difficulties in arranging a traditional hip roof arise at the construction stage truss structure, consisting simultaneously of sloped, ordinary and external rafters.
Hip roofs are excellent at resisting wind loads and generally have high performance characteristics. To finished roof served as long and efficiently as possible, at the design stage it is necessary to resolve a number of important issues, namely:
- choose the optimal material for arranging the roof structure;
- determine the intensity of precipitation characteristic of the construction region;
- set average and maximum wind loads.
Taking into account the above indicators, you can calculate the optimal values for the slope angles and the height of the roof structure.
To perform calculations and draw up a project, you can contact a specialist or find a suitable project in one of the many open sources. If you have the proper skills, you can handle the mentioned activities yourself.
The roof in question, as already noted, has a very interesting design. And if large slopes can be seen on almost all roofs, then short slopes make the system in question truly unique.
The design of the roofing system is such that the slopes do not cover the length of the house area and the remaining free space filled with two short hips.
When drawing up a diagram of a hip roof structure yourself, you will need to use a marking strip and Pythagorean tables.
It is important that the roof design is as accurate as possible - this is the only way you can make the correct cuts from the rafter elements yourself and install all the components of the system yourself.
What do you need to know before starting work?
To ensure that the system fully meets all the requirements, remember the following recommendations:
- the intermediate components of the hip roof rafter system are steeper when compared with the corner parts, therefore the boards used for arranging the intermediate elements must have a size of at least 5x15 cm;
- fastening of short elements is carried out to the corner rafter components, and not to the ridge board. Intermediate boards must be fixed with the same slope as the short beams;
- ridge roof system and rafter elements must be made from the same material;
- intermediate rafter legs are fixed at the edges of the ridge board. They must simultaneously connect to the upper end of the trim and to the ridge board;
- rafter elements and ridge beams must be of equal thickness. Only if this rule is observed can you count on the reliability and strength of the roofing system. If any rafters are thinner, over time the roof frame will deform and the integrity of the system will be seriously compromised;
- hip roofing system can be almost any height. However, when arranging a roof that is too low, it is necessary to use additional supports;
- To ensure the longest possible service life of the hip roof, it is necessary to use thoroughly dried and quality timber coniferous species. Before assembling the structure, all wooden components must be treated with antiseptic impregnation.
Guide to constructing a hip roof
Start arranging the roof. Start by creating a construction site layout.
Marking
Well-done markings correct drawing and the most reliable calculations - these are the three fundamental factors for successful construction. Carry out markings in accordance with the drawings. Follow the following sequence.
First step. Mark the axis along the highest trim on the end side of the building;
Second step. Calculate 50% of the thickness of the ridge and determine the location of the first element of the rafter system.
Third step. Place one edge of the measuring stick against the previously marked line. Place the second end along the line of the side wall. This will establish the placement point for the intermediate rafter element.
Fourth step. Determine the length of the rafter overhang. To do this, place the beam with one edge on outside corner walls, and install the other on the roof overhang.
Fifth step. Calculate the next component of the central rafters. Move the batten to the edge of the side wall and mark where the rafter will be attached. The element will be located between the top roof trim and the side wall.
Repeat for the remaining three corners. This way you will know where the intermediate rafter legs and ridge ends will be installed in the future.
Calculation
First step. Take the marking strip and determine the value of the horizontal projection of the intermediate rafter element. Using standardized documentation, find the appropriate roof slope for your situation and multiply the determined values.
Second step. Measure the length of the rafter. Do this from the sampling at the roof ridge to the sampling at the place where the support is fixed. Measure along the bottom line.
Third step. Determine the length of the overhang in the same way. To do this, multiply the horizontal projection value by the appropriate correction factor. You can use the Pythagorean theorem, known since school days: c2=a2+b2. In the situation under consideration, a is a vertical projection, and b, accordingly, a horizontal projection.
Fourth step. Proceed to the calculations of the angular components. On one side of the rafter legs there are oblique cuts, due to which it is ensured reliable fixation elements to the roof ridge. Directly at the ridge there is an undercut with a special double bevel, used for attaching corner components.
Corner rafter legs are calculated in the following order:
- The length of the rafter element is measured from any corner of the house;
- a projection is established equal to the squares of the length of the projections of the central rafter legs used, multiplied by each other;
- the resulting value is multiplied by a correction factor, which allows you to determine the length of the corner rafter leg.
Installation of rafters
First step. Proceed with the installation of vertical posts that will support the ridge beam. Attach the elements to the central beam using a miter system.
Second step. Install diagonal rafters. All elements must be the same length. In the case of roof overhangs, the figure will vary from 500 to 700 mm. Pay special attention to the correct joining of the hip, diagonal rafter elements and the ridge.
Third step. Install slanted rafters, and then ordinary rafters with a pitch of about 600 mm. Attach ordinary rafters to the mauerlat and ridge beam using the cutting method. To strengthen the fixation, use crossbars and ties.
It is important that ordinary rafters do not come into contact with the studs that secure the Mauerlat to the walls of the house.
Fourth step. Attach splices to each side of the diagonal strips, due to which the slanted rafters will be connected to the mauerlat.
Both ordinary rafter elements and frames must be mounted strictly perpendicular to the ridge.
Strengthening the truss structure
When choosing a method for strengthening rafters, focus primarily on the size of the building. Among the most popular methods of amplification, the following options should be highlighted:
- At the corners of the roof, trusses with a special stand are fixed, which serves as a support for the diagonal rafter element. The sprengel in this situation is a beam that you need to throw between the two corner arms of the support mauerlat. If the truss installation has to be done at a great distance from the mentioned corner, professionals recommend installing a reliable truss truss;
- By reinforced concrete floor or the racks are filled by tightening. They will perform the function of the so-called. “shelf” supporting the rafters in the middle;
- if the diagonal rafter elements are too long, double beams should be used instead of one beam.
Ventilation
For device required level To ventilate the under-roof space, make a hole in the windproof film for air entry. It must be placed on top, closer to the roof ridge.
If the wind sheathing is made of wood, it is enough to simply fasten the boards with a gap of 2-3 mm. If, however, for the manufacture of filings they are used plastic products, the elements must first be perforated.
If the wind roof lining has already been assembled, you can install ordinary ventilation grilles. The standard diameter of such gratings is 50 mm. The mesh of the product can be of any color. Place the gratings along the entire length of the wind tunnel with a pitch of about 800 mm.
At the end, all you have to do is lay the insulation, arrange the waterproofing layer, fill the sheathing boards and install the selected finishing coating.
Now you know the main features and procedure for arranging a hip roof yourself. The work can hardly be called too easy, but using the knowledge gained in practice, you will be able to cope with all the related activities yourself.
Good luck!
Video - DIY hip roof
Hip roofs are becoming increasingly popular among owners of private houses. This is not surprising, since such a scheme has a number of undeniable advantages. operational properties, and besides, it looks very original, giving the house a special aesthetics.
Some homeowners leading self-construction, perhaps, it is frightening that the rafter system of the hip roof looks too complicated. Yes, it is certainly not as simple as a regular gable gable roof. However, this rafter system is completely subject to the laws of geometry, and it is quite possible to make a preliminary calculation. Installation, of course, will require some experience in carpentry work, nose good helpers, and even better - with a qualified consultant, you can take on this large-scale event.
What are the advantages of a hip roof?
The hip roof refers to hipped structures, the rafter system of this type of roof forms four slopes, two of which are in the shape of a trapezoid with their upper edges connected at the ridge girder, and the side slopes form triangles. These triangular slopes are called hips.
The hip roof design has a number of advantages:
- Convenience for creating an attic floor;
- Cost-effectiveness (in terms of consumption of building materials);
- Interesting appearance.
At the same time, the arrangement of this type of roof is associated with a number of difficulties and requires special calculations when planning the rafter system.
In this article
Features of the rafter system
The rafter system of a hip roof involves a number of distinctive elements that determine its distinctive design. Knowledge of these features is necessary for carrying out calculations of the rafter system and its construction.
Types of hip roof rafters
Rafters in a hip roof design are divided into several types:
- Corner rafters. One edge stands on the mauerlat, the other should rest on one of the ends of the ridge beam.
- A symmetrical hip roof has 4 corner rafters that form the hip. Corner rafters have the longest length and therefore often need strengthening and support;
- The central rafters are mounted on the mauerlat and the edge of the ridge girder. The scheme of this roof uses 4 such elements, a pair for each trapezoidal roof slope;
- The central hip rafters divide the roof hips into two equal parts. The design of the hip roof rafter system implies the presence of 2 similar elements.
- The intermediate rafter legs are similar to the central ones and are mounted to the same support points. Their number varies depending on the size of the roof and the length of the ridge. If the roof is small, they may be missing.
- Shortened rafter legs take their place in the corners of the roof. Supported by the mauerlat and corner rafters, they are smaller in size compared to other rafters, with a size that becomes smaller towards the corner.
System reinforcement elements
The hip roof is a complex roofing structure; its rafter system requires special reinforcement. The elements responsible for the strength of the roofing object are divided into several types:
- Long corner rafters require special reinforcement. They can be strengthened with a sprengel - a corner beam, which represents an inverted letter “T” and the lower part is installed on the mauerlat, and the upper part rests on the corner rafter. The diagonal rafter legs can be supported by struts supported by floor beams or a central beam;
- Tie-rods hold pairs of rafters together. They can additionally serve as floor beams or be placed closer to the ridge and serve as the basis for forming the attic floor;
- The posts strengthen the ridge beam. Bottom support the racks can be laid down if there is a main wall in the center of the building for laying it, or they can be installed on floor beams;
- If the length of the intermediate rafters is more than 4 m, they are also reinforced with diagonal posts at an angle of 45-60° with the rafters supported on the floor beams;
- When constructing a roof in a region with a strong wind load, it is advisable to use a wind support, which is pressed to the rafters on the side of the greatest wind impact.
Calculation of the rafter system
Installation of a hip rafter system should begin with calculations of design parameters and drawings. The main purpose of this event is to select the right materials, capable of bearing the weight of all materials, the load of wind and precipitation. The main quantities that you need to know to build a hip roof are the angle of the slopes and the height of the roof ridge.
Calculation of slope angle and ridge height
The angle of inclination of the roof truss system can be in the range of 20-60°. However, an angle of less than 35° will not allow creating a room under the roof with a sufficient ceiling height. Therefore, a roof slope of 20-35° is suitable for outbuildings.
Roofs residential buildings It is advisable to arrange it at an angle of 40-60°. The choice of a specific value depends on the weather conditions of the region. During snowy winters, it is better to choose a sharper design - the snow will slide off its slopes better. Under high wind loads, it is better to make the roof flatter to avoid overturning.
The greater the angle of inclination of the roof, the more complex its design and the greater the consumption of materials for its construction.
Calculating the angle of inclination and height of the ridge, which are directly dependent on each other, is possible in two ways:
- If the angle of inclination is selected in advance: the height of the ridge is calculated as the tangent of the angle multiplied by half the width of the roof;
- For a given height of the ridge beam: the angle of inclination is equal to the height of the ridge, multiplied by 2 and divided by the width of the building.
Rafter length
The dimensions of all types of rafters are calculated using the Pythagorean theorem: the square of the hypotenuse is equal to the sum of the squares of the legs. It remains to figure out which values of the elements of the rafter system in each specific case will be the legs and which will be the hypotenuse.
- The central rafters act as the hypotenuse in a triangle with legs equal to the height of the ridge beam and half the width of the roof. The intermediate rafters, located on the trapezoidal slope, have the same length;
- The size of the central hip rafters depends on the location of the ridge. As a rule, the ridge is equidistant from all three walls;
- To find the length of the corner rafters, you must select a triangle in which this element is the hypotenuse, and the legs are the central hip rafter and half the size of the roof;
- To calculate the length of shortened rafters, you need to know the pitch of the rafters.
Calculation of the pitch of the rafter system
The distance between the rafters depends on the width of the house and plans for the under-roof space.
The longer the rafter legs, the shorter the step.
When planning warm room the pitch of the system will depend on the selected insulation, since it is supplied in certain sizes:
- Mineral wool implies a distance of 58 cm;
- Expanded polystyrene requires a step of 60 cm;
- Polyurethane foam can be used at any pitch.
The choice of pitch is also influenced by the presence of dormer windows: the distance between the rafters should be 5-6 cm greater than the width of the window opening.
Selection of rafter section
Depending on the data obtained, the material for the rafters is selected. In any case, it is preferable to choose boards and beams from coniferous trees, with a moisture content of no more than 22% without knots and cracks. All wooden elements future roofs must be treated with a special antiseptic to protect the wood from rot and pests.
The cross-section of the rafters depends on the distance between them and the length of the spans. Let's give general information, calculated for a step of 90 cm:
- The length of the rafter leg is less than 3 m – section 50*150 mm;
- Less than 4 m – 50*200 mm;
- Less than 5 m – 75*175 mm;
- Less than 6 m – 75*200 mm.
As the step increases, these values will increase. All reinforcing elements are always taken with a larger cross-section. Corner rafters are made double, as they carry a much greater load than the rest.
Roof area
When creating a roofing scheme, it also requires taking into account the roof area and the weight of the roofing material. The area of the hip structure is the sum of the areas of its simple figures (triangle and trapezoid). To calculate the area of the latter, it is more convenient to divide it into its component parts (a square or rectangle and adjacent triangles).
The area of figures is calculated using simple geometric formulas: the area of a triangle as half the base multiplied by the height of the figure, the area of a rectangle as the product of its two sides. Since the dimensions of all elements of the system have already been found, this step will not cause any difficulties.
Data on the area will allow you to buy the required amount of roofing material (do not forget to add 15% to the resulting number for reserve) and the weight of the roof. The cross-sections of the rafter structure elements will also depend on the last value.
Roof sketch
Before proceeding with the installation of the roof structure, we recommend making a sketch to scale. This sketch will be a kind of layout and instructions for creating a hip roof:
- We draw the house in two projections (full face and profile) observing all proportions to scale;
- We mark on the frontal projection the height of the ridge and the selected angle of the slopes;
- We determine the length of the ridge girder on the profile projection of the house;
- On the diagrams we plot the pitch of the rafters, draw out all the rafter legs;
- We supplement the sketch with the necessary marks for the reinforcing elements of the system.
This sketch will not only help to visualize the future roof, but will also become a kind of instruction for its construction. In addition, this drawing will help determine required quantity building materials.
Complex hip roof
Schemes of complex hip structures, which provide for the presence of additional elements such as roof windows or a bay window, do not differ much from the one presented above. The basic calculations and procedure for forming the truss structure remains the same.
If there are dormer windows in a hip roof, it is important to take into account the pitch of the rafter system and subtract the area of the windows from total area. When creating a roof with a bay window, that is, a roof over an extension, a tower to a house, the hip structure is joined with some other one: gable, hipped, etc. To do this, the necessary additions are made to the rafter system in the form of additional supports for this extension.
Any complex multi-component roof is designed and installed as a connection simple elements And this case is no exception. All additional elements of connections to the hip roof must be calculated separately and included in the general plan.
The design of a hip roof is based on fairly complex calculations. The success of its construction and performance characteristics depend on their accuracy. Therefore, it is so important not to neglect the creation of diagrams and drawings when accessing this type roofs.
The hip roof is perhaps the most popular view hipped roof. It is suitable for covering large and small private houses, bathhouses, even gazebos. A recognizable geometry is given to it by the rafter system, the combination supporting elements, working as a frame.
The complexity of this design lies in the large number components and attachment points requiring special skills and experience. This article will answer questions about what it consists of, what materials are used for construction, and how installation work is performed.
Hip roof design
The hip roof is of the hipped type, that is, it is formed from four slopes, planes that have one common side. The two slopes that replace the pediments are called hip or end slopes; they have a triangular shape. And the other two, in the form of trapezoids, are designated by the term façade. The line where all four slopes converge is the ridge, the highest part of the roof. The hip type design consists of:
- The hip slopes, which have the shape of a triangle, are located in the place belonging to the pediments.
- Facade slopes are trapezoidal in shape.
- Ridge, the line that forms the upper connection rafter pairs, peaks .
- An overhang, a part of the roof protruding beyond the perimeter of the house, formed by the length of the rafters or fillies. It protects the surface of the walls from melt and rain water.
- The rafter system of the hip roof, the frame supporting and distributing the weight of the roof structure.
- Roofing material, a covering that is laid on the rafters of a hip roof to protect against precipitation.
- Gutters, systems for removing water accumulating on the roof. It consists of a gutter, a water intake funnel and drainpipe and transfers moisture from the surface of the blood to the storm drain.
- Snow retainers, elements that prevent snow masses accumulated on the roof from collapsing and injuring people passing by.
Types of rafter system
The hip roof rafter system can be of three types, depending on how the rafters are positioned:
- Hanging. This means that the rafters are supported by two points: in the upper part on the ridge girder, and in the lower part on the mauerlat. A hanging rafter system experiences deflection, compression and expansion loads. All these forces have a destabilizing effect on it, so additional compensating elements are needed - tightening, crossbars, headstocks. They complicate the design and installation of a hip roof, so experienced roofers advise against hanging rafters, if possible.
- Naslonnogo. With this type of hip roof rafter system, the rafters are supported at three points: at the top on the ridge, in the middle on the post, and at the bottom on the mauerlat. The racks are installed on the internal load-bearing walls. Additional vertical supports reduce the deflection of the rafter legs and eliminate the bursting force. Therefore, the layered system is considered more reliable and stable than the hanging system, and also easier to install.
- Combined. This term means that the rafter system consists of alternating layered and hanging elements. This is possible if a pillar or column is used as support for the rack rather than an internal load-bearing partition. The roof is of an open type, that is, all the beams and racks are not hidden by the cladding, but are visible.
Important! Using a hanging rafter system, you can cover a structure no more than 6 meters wide. The use of layered rafters with one additional support increases this distance to 12 m, with two – up to 18 m.
Material used
The hip roof truss system consists of many components, which are reflected in the drawing; they are made from the following materials:
Properly processed and prepared wood is an excellent material for making a rafter system. It is much easier to work with, it does not require special tool. And a reasonable price will reduce costs. Especially metal frame roofs can only be afforded by those who are confident in the safety margin of the foundation.
System elements
Depending on the area and features of the layout of the house, the rafter system of the hip roof acquires various types, but it is based on the following elements:
Pay attention! Some elements of the hip roof rafter system are of considerable length. And the standard size of timber lumber is limited to six meters. To get out of this problematic situation, roofers make glued or stacked rafters, made up of two or three parts.
Mauerlat installation
Installation of the Mauerlat is the starting point for creating a rafter system for a hip roof. Correct installation will provide a reliable base for the rafters. During the construction of a house made of timber or logs, the role of the Mauerlat is played by upper crowns. In buildings made of bricks and gas silicate blocks, it is secured as follows:
- On the upper section of the walls, formwork is installed and a concrete belt reinforced with reinforcement is poured into which metal studs are embedded.
- The Mauerlat timber is treated with a deep penetration antiseptic and holes are made in it for the studs. Moreover, the location of the holes is calculated in such a way that they do not coincide with the places where the rafter legs are attached, but are located between them.
- After hardening concrete belt which occurs within 2-3 days, waterproofing is installed on it. These functions are usually performed by roofing felt folded into two layers.
- The Mauerlat is laid on the waterproofing and secured with metal pins.
Please note that a large number of holes reduce the strength of the Mauerlat, provoke the appearance of cracks and defects, reducing its supporting functions. Remember, cuts under the rafters are never made in the mauerlat; its integrity must not be violated!
Assembly steps
The result of the calculation, made manually or by program, is recorded by creating a drawing that reflects the dimensions and relative position elements of the rafter system, and then begin to assemble it according to the following plan:
Competent calculation, detailed drawing and quality installation– the key to long service and reliability of the roof truss system.
Video instructions
