Roof design and construction
In the process of planning the installation of the roof, you must first decide on its type. You can use the services of experienced craftsmen who will help you create a project and select the necessary consumables for it. Information for independent study is also available in various sources, including photo and video materials of roofs and roofs.
Roof construction stages:
- Installation of Mauerlat (timber laid along the perimeter of the outer wall to support the rafters);
- Assembly and installation of the rafter system, fixing them on the ridge;
- Installation of horizontal screeds;
- Installation of waterproofing material;
- Installation of the lathing;
- The final arrangement of the front surface of the roof.
Construction studs are used to fix the roof structure to the walls of the building. Under the rafter system, support roofing niches are located, which are fastened to each other with strong braiding or reinforcement.
In order to correctly design a roof device, you need to take into account the shape and volume of the building, the location inside the load-bearing walls, whether the attic will be arranged and what kind of appearance the building will have as a whole.
Installation of roofing
For a tent-roofed roof, the roof covering is not laid one degree at a time, for example:
- flexible shingles are mounted with a slope of 8-18 degrees;
- asbestos-cement materials are mounted at 14-16 degrees;
- metal tiles are installed with a slope of 30-60 degrees.
In addition to basic roofing materials, specific types can also be used, for example, reed and reed options. The reliability and durability of such a roof is minimized, especially if the region is in harsh climatic conditions.
Basically, flexible and metal shingles are used for complex roofs. The material is significantly more expensive, but has a long service life. In the first case, a special gas burner is used for installation. The material is fused by heating the shingles and the base of the roof. And in the second case, the sheets are fixed using a screwdriver and self-tapping screws. Coating is always done from bottom to top.
The waste of the roofing will be large, since the roof has a figured shape and you cannot do without trimming. This must be taken into account when calculating the consumption of material.
If the work will be carried out in one hand, then you should be patient and strong. Indeed, at all stages of the assembly of the roofing product, you will have to support the timber somewhere or submit a roof sheet. Therefore, it is advisable to include in the work one more person who will help in difficult situations. However, if such a roof is intended for a small gazebo, then in this case you can cope on your own.
Calculation of the angle of inclination and area of the hipped roof
For calculations, you need to know only two parameters: the angle of inclination of the roof and the length of the wall of the structure along its outer edge. Since a roof rafter system of this type in most cases consists of a certain number of isosceles triangles, the angle that the ramps form is calculated. It is necessary to calculate the area of one figure and multiply by their total number. So the area of the structure will be known, by which you can determine the amount of required roofing material. When the base is a rectangle and a hipped roof is planned, then the area of the triangle (slope) is first calculated. Next, the area of overhangs is calculated - cornices similar to trapeziums. The minimum overhang is 30 cm.
- The length of the central rafter C is calculated using the formula of a right-angled triangle, where the rafter acts as a hypotenuse, half the length of the wall of the house a is the known leg, α is the slope of the slope: C = a / 2 * cosα.
- The length of the slant rafter is calculated using the Pythagorean theorem, where one of the legs is a / 2, the other is C.And L (length of the slant rafter) is the square root of the sum of squares a / 2 and C: L = √ ((a / 2) 2 + C2).
- The height of the roof or the central vertical pillar is also calculated using the Pythagorean theorem. The area of one slope is calculated by the formula: S = C * a / 2.
The roof is calculated using formulas for simple geometric shapes.
You can also calculate the angle of inclination on the Internet - using an online calculator.
The choice of the angle of inclination of the roof
Usually, when choosing an angle, the following criteria are taken into account:
- Climatic conditions. With a high wind load, the slopes should be flat, since the lower the slope, the more reliable the main structure.
- The amount of precipitation. The more precipitation, the higher the slope must be so that they roll off the roof in time.
- Roofing material. Each species has its own criteria for the slope of the slope.
The higher the angle of inclination, the larger the roof area. This should be taken into account when calculating. The most wind-resistant roofs are considered to be with a slope of 25 degrees.
Step-by-step roof installation
This type of hip structure involves the assembly of all elements in turn:
- Mauerlat installation;
- installation of nipple beams;
- installation of middle supports and struts;
- installation of special handicrafts;
- roof sheathing with crate;
- vapor barrier film flooring;
- waterproofing layer flooring;
- in the last step, the roof covering is made.
It is important to follow the sequence of work and not jump from one stage to another. Otherwise, the quality of the roof structure may decrease.
Do-it-yourself system installation
Installing a rafter system for such a roof is considered difficult. Therefore, it is necessary to calculate everything accurately. In this case, the ceiling is made only after the construction of the structure, but not earlier. Phased installation is as follows:
- First, a Mauerlat is installed on the surface of the walls. It is fixed with anchors. But under the base is a flooring of waterproofing material. For these purposes, a roofing material made on the basis of mastic will serve. For wooden walls, a special strapping is performed.
- The fastening of the overhead rafters is carried out, which are installed in the corners. To do this, you need to cut off those edges of the boards, which will be in the upper part of the roof, so that they create a sharp point. To install the slant rafters, you must use the cut-in beam. If the wall is made of brick, then metal clamps from reinforcement are used to fix the Mauerlat, and ordinary brackets are used for wood.
- In the middle of the entire system, the installation of supports is done.
- In those parts where the slopes are located, the installation of diagonal rails, braces and struts is carried out. This will help to avoid breaking the roof from strong gusts of wind.
- Further, the installation of trusses, braces and struts is carried out.
- Boards are stuffed.
To install diagonal beams, it is recommended to maintain a right angle. The correct calculation of the rafter beams should be made in order to obtain an overhang for arranging the box. To lengthen the rafter legs are used "filly", which lengthen the bars.
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Hip roof options
Under the name "hipped roof" several roofing options are combined that have structural differences.
Classic hipped roof
A single-level four-pitched roof is geometrically a four-sided pyramid. A two-level roof is a more complex structure: the upper part is a pyramid, the middle is a cube or parallelogram, and the lower is a truncated pyramid. As if the top of the roof had been cut off from the base and raised. The middle part is sometimes made in the form of a glass lantern or finished in the color of the walls.
Two-level hipped roof
A hipped roof can have not only four slopes, but also six and eight slopes. This shape looks more like a cone than a pyramid, and is most common in the construction of gazebos with a round base. The most difficult thing in the implementation of such a structure is the connection of the rafters in the center.
Six-sided roof
Roof rafters of eight gentle slopes
- hanging;
- layered.
The hanging truss system rests exclusively on the walls of the house, the layered one has a support located in the center of the building and rests on a load-bearing wall or on a pillar specially erected inside the house.
a - the structure of the hanging rafters; b - the construction of the layered rafters; 1 - rafter; 2 - crossbar; 3 - tightening; 4 - rack; 5 - brace; 6 - run; 7 - bed
The choice of design depends on the size of the span (8 m - a hanging system is suitable, 12 m - a layered system is required) and the maximum length of the timber for construction (when connecting the rafter leg in length, the installation of a vertical support is required).
In practice, the layered system is often used, as it is more reliable and maintainable. If the house does not have a suitable load-bearing wall or pillar for support, the base can be created from a bar by dressing at the Mauerlat level.
Necessary calculations
Before going to the store for the required materials, familiarize yourself with the procedure for performing calculations and draw up a roof project that is suitable specifically for your case.
Basic information
Hipped roof for the gazebo
Traditionally, the roof under consideration includes 4 inclined slopes.
If the base of the structure is in the shape of a regular square, the area of the structure is calculated by multiplying the area of one roof slope by 4.
Hip roof frame
However, if the base of the system looks like a rectangle, then first you need to determine the total value of the areas of two different rectangles, and then double the resulting number.
To establish the area of the roof slope, which is an isosceles triangle, it is necessary to multiply the length of the base of the figure by the value of its height, and then double the resulting number.
When performing calculations, you need to find out the value of the area of the eaves overhangs in the form of isosceles trapezoids. This calculation is done by multiplying the height of the shape by exactly 50% of the sum of the base lengths of the trapezoidal shape.
The calculation of the hipped roof system can be done in two ways. The first involves a calculation using the value of the ridge height and the length of the base of the roof structure. In accordance with the second calculation method, it is necessary to take into account the value of the length of the diagonal rafter, as well as the length of the perimeter of the base.
In addition, in the calculation process, it is imperative to pay attention to the parameters of various additional components that make up the roof structure. These elements include:
- diagonal rafter legs;
- lie down;
- support bars;
- racks;
- mauerlat, etc.
Calculation example
Tilt angle and rafter length
To make the calculation principle clearer, we present to your attention a simple example of the implementation of the basic calculation activities. Initial data:
- house dimensions - 6x6 m;
- the length of the diagonal rafter is 521 cm;
- ridge height - 297 cm;
- slope of roof slopes - 35 degrees;
- the width of the eaves overhang is 600 mm.
Using the first of the two previously mentioned methods, determine the value of the height of the roofing triangle. To do this, use the Pythagorean theorem, according to which to calculate the square of the height, you need to subtract from the value of the square of the length of the roof slope half the width of the base, also squared.
In this example, the calculation will show that the square of the height is 4.24 m squared. Using a simple formula, you can determine that the area of one triangular slope will be 12.72 m2.
Due to the fact that the base of the roof is a square with a side of 6 m, the calculated value of the area must be increased by 4 times. As a result, you will determine the total area of the roof slopes, equal in this example to 50.88 m2.
Determine the area of the cornice light. You already know the value of the length of the shorter base of the trapezoidal figure - 6 m. To establish the length of the larger base, you need to use the simplest form that is relevant for such figures.
Hipped roof (hip roof)
According to the calculations, the length of the larger base will be 704 cm, and the area of the figure as a result will be equal to 4.76 m2.
To set the total area of the overhangs, multiply the value calculated in the previous step by 4.
As a result, the total amount of the hipped roof structure will be 69.91 m2.
Comparative characteristics of frame types: hip and hip
The four-slope roof category includes 2 types of framing systems, which schematically look like square (hipped roof) and rectangular (hip roof) envelopes. In our country, the roof envelope is quite popular. The main feature of hipped roofs is the absence of gables. For the construction of the rafter system of a hipped roof, in both cases, hanging and layered rafters are used. Their assembly methods are standard for roofs with any number of slopes.
Distinctive features of hipped roofs of various designs:
- In the case of a hipped roof, the roof consists of four isosceles triangles, which are in contact with their vertices at one point. In this case, the functions of the ridge are assigned to the central support beam in layered structures, or to the upper point of the truss of the hanging rafters.
- A hip-type roof assumes the presence of two triangular and two trapezoidal slopes. In this case, the trapezoidal slopes adjoin the ridge beam with their upper ribs, and the triangular ones with their tops. In this case, all four slopes are in contact with each other with lateral ribs.
Studying the plan of the rafter system of the hipped roof, we can conclude that the choice of the configuration of the hipped roof depends on the shape of the structure. That is, square houses are covered with hipped roof structures, and rectangular ones with hip roofs. In this case, you can use any roofing materials, both hard and soft.
When drawing up the drawings of the rafter system of the hipped roof, the geometric shape should be clearly indicated, as well as the position of the individual elements and the projection of the slopes with exact dimensions.
To support the four-slope structure, you can use the Mauerlat, which is the upper strapping on concrete or brick walls, as well as the upper crown of a log frame. Slab technology is used in cases where it is possible to install an upper and lower support under each rafter leg.
Some recommendations for installing layered rafters:
- The Mauerlat must be reinforced to withstand the bursting forces in the case of rigid fixation of the rafter legs with wooden pads or metal corners.
- If the upper part of the leg is fixed rigidly, and the lower one is hinged, the Mauerlat can be fixed in the usual way. In this case, with increased loads on the frame, the rafters can move slightly.
- The bursting load and pressure on the Mauerlat will be leveled by using rigid mounts on the lower part of the rafters and articulated mounts on the upper heels.
When constructing hip and hip frames, the following specific nodes of the rafter system of a hipped roof are used:
- Diagonal legs from which the ridges of the slopes are made. In hipped-roof frames, such slant legs align the corners of the roof with its upper point. Hip frames involve joining the ridge beam consoles with the corners by means of diagonal rafters.
- Narozhniki (half-legs) - elements mounted at an angle of 90 degrees to the cornices. Since they fit into the diagonal rafters and are parallel to each other, their length will vary. Roof slopes are created from such elements.
The same structural elements are used to create valleys, with the only difference that the corners are made concave.
It is the installation of the overhead rafters that is the most difficult. Moreover, these elements will have an increased load, since they serve as a supporting element for fastening in the upper part of the wedges, that is, they perform the functions of a ridge. Therefore, before starting work, it is necessary to calculate the rafter system of the hipped roof.
In general, the process of erecting a roof with four slopes includes the following stages:
- Laying Mauerlat on brick or concrete walls. In log houses, this element is the upper crown.
- Installation of a central support beam under a hipped roof frame or assembly of support structures for a hip roof.
- Installation of layered rafter legs under one or another structure.
- Fastening diagonal rafters that align the corners of the roof with the center top or ends of the ridge.
- Layout and installation of handicrafts.
If a hanging type of rafter system is assumed, then the first stage in creating a hipped structure will be the placement of a central truss in the shape of a triangle. When creating a hip-type structure, several trusses are attached at the starting stage.
Roof device and scheme
Before building a roof, it is advisable to choose the optimal design option in terms of reliability and reasonable consumption of timber. To do this, you need to perform some calculations and develop your own project with drawings and dimensions. But first, let's understand the terminology and find out which elements are part of the rafter system of the pitched roof, shown in the diagram:
- Mauerlat - a support beam for rafters, laid on the walls along the length of the building;
- rafter legs - inclined beams that form slopes and load-bearing roofing;
- puffs (crossbars) - horizontal jumpers installed to increase rigidity;
- vertical posts are used to create additional support points;
- ridge beam and girders connect adjacent rafters into a single frame;
- brace - inclined stiffener;
- bedding - the same as the Mauerlat, is used on concrete floors as an additional structural element;
- filly - lengthening of the rafter leg, forming a cornice overhang.
In the round part of the wall, grooves are cut out for mounting the roof
In frame, chopped and other wooden houses, the role of the Mauerlat is played by the upper wall beam or log.Each section, consisting of 2 rafter legs (upper chord) and tightening (lower chord), is called a truss. These elements are connected to each other by purlins.
On top of the farms, a crate is made of boards, where the selected roofing material is then laid - metal, corrugated board, slate or a budget option - ondulin. Ventilation gaps are provided under the coating, and, if necessary, insulation.
How to correctly combine waterproofing and ventilation of the roof space
Hip roof structure
At the heart of the design, there is always a Mauerlat (a powerful bar or log), knocked into a solid frame in the shape of the base and laid on top of an armored belt. The entire rafter system is tied to the Mauerlat. It looks like four inclined beams with a section of 50 by 100 mm, fastened in the center of the roof (the size of the beam depends on the dimensions and weight of the future roof). If the house is built of stone or brick, the upper trim of the wall panel acts as a Mauerlat, in wooden buildings - the upper crown of the frame. Mauerlat must be waterproofed (for example, with roofing material). Then it is fixed on the inner upper part of the prepared and aligned walls.
The ridge knot of the hipped roof is connected at one point
The construction of a hipped roof requires the use of a large number of wooden elements. They should be treated with a fire-fighting and antiseptic agent before use.
For the construction of buildings with a bay window, a hipped roof is not suitable, since the shape of the box is square. Therefore, a semi-hip type of roof is usually used.
Types of truss systems for a hipped roof
In terms of its structure, the rafter system of the future hipped roof is either layered or suspended. The hanging truss system is distinguished by the fact that its beams rest directly on the walls. It is most often used for large spans, when there is no other support, and supports are not provided. With this option, a horizontal expanding force is formed, and in order to reduce it, puffs are used.
The pitched system is not recommended for use with slope angles over 40 °.
The process of building and repairing such a roof is complicated, so a layered rafter system is usually preferred. It is more convenient in terms of installation and operation, and there is practically no load on the walls. For its installation, a roof with a slope of no more than 40 degrees is suitable. For installation, a load-bearing inner wall or additional supports in the center of the roof is required. In this case, spacers on the walls are not needed, since the roof has supports at the peak and on the rafter legs.
Thanks to additional supports, the layered rafter system is more convenient for installation and operation
The allowable span size is about 4.5 m. If it is more and it is impossible to limit oneself to one central support, then struts are installed.
The braces are supports for the rafter legs
Elements of the rafter structure
The rafter system of the hipped roof includes the following main elements:
- Mauerlat - support frame for the bottom of the rafters;
- diagonal or oblique rafters installed at the corners of the main frame;
- rafters - shortened rafters attached to mowing rafters;
- racks and struts - supports for rafter legs;
- beds - stacked on brick posts as supports for struts and racks;
- crossbars for resting rafter legs against each other near the peak;
- girders - beams parallel to the Mauerlat (used depending on the type of structure and available supports);
- sprengels - additional supports to give the building rigidity.
Metal profile rafter system
Rafters made of metal trusses have great strength and withstand significant loads, which makes the building more durable. Metal trusses can be operated for over 100 years. Usually they are used if the length of the slopes exceeds 10 meters. It is easier to assemble such a structure than a wooden frame, since you can purchase elements ready for installation. The only disadvantage of metal trusses is that they are more difficult to insulate. Condensation appears on them, which has a devastating effect on the roofing cake. Therefore, wood is preferable for residential buildings. You can also combine metal and wooden rafters. But at the same time, the wooden parts must be well treated with antiseptic agents.
Metal rafters are more commonly used for industrial buildings.
Gazebo with a hipped roof
A gazebo with a hip roof will become the standard of design solutions, and, provided that it is correctly calculated and arranged, it will be distinguished by its reliability and durability of operation. It will be easy to assemble a hipped roof with your own hands. This design is suitable for a gazebo in the form of a rectangle or square. The first option is an assembly of a hip structure with two triangular and the same number of trapezoidal slopes. The second option is a hip hip roof, consisting of 4 isosceles triangular slopes.
The hip roof for a square gazebo consists of four identical triangular sections
A four-pitched roof is an excellent choice when building a gazebo, since it allows the use of any roofing, and a convenient design provides a free viewing angle, it can be easily equipped, for example, in the Chinese style, adding lengths to overhangs and several curved diagonal rafters.
At the preparatory stage of the work, a drawing of the future roof is made, taking into account the main factors:
- the weights of all rafters and their additional elements;
- roofing and waterproofing masses;
- the level of climatic loads, the layer of snow masses;
- the weights of the builders serving the roof;
- loads from equipment that is planned to be installed on the rafter system.
The features of the installation directly depend on the slope of the slopes and what materials are chosen for covering the roof, for example, the pitch of the battens of the sheathing and the rafter system. And all this affects the total weight of the building.
You can extend the service life of a wooden gazebo by pretreating all its elements with special antiseptic impregnations, as well as a fire retardant. All these compositions are applied quite simply with an ordinary brush or roller.
The support for the hipped roof of the gazebo can be wooden, brick walls or support frame racks. If a brick is used in the work, then the structure will turn out to be capital and will require the construction of a solid foundation that can withstand heavy loads. The construction of a hip roof on such a gazebo is generally similar to installing a roof on a residential building or other large-sized structure.
Small hip roofs can be assembled on supports from pillars, which must first be well fixed
If the gazebo is installed on wooden pillars, then you should first check the strength of the fastening of its supports, they should be strictly vertical, and for the rigidity and stability of the frame from below they are tied with jumpers. Jumpers are also mounted on top, which will be a strapping for a pitched structure. Due to the high load, the supports may gradually disperse, therefore it is recommended to fasten them in advance at the upper ends using diagonal jumpers, and lay wooden or steel plates at the joints.
Step-by-step instructions for installing a hip roof for a gazebo
- First, a ridge beam is attached with special struts and vertical supports.
- Further, diagonal rafters are laid to form the roof slopes. This stage assumes the possibility of increasing the length of the overhangs with the help of overhead boards - "filly", which lengthen the overhang rafters.
- Then the installation of central and intermediate rafters and rafters is performed.
- To protect wooden elements from moisture, a waterproofing membrane covering is laid on top of the rafters.
- A crate is mounted on the waterproofing layer, and, if additional ventilation equipment is required, a counter-lattice is also installed.
- At the final stage of the work, the roofing material is attached.
The hip roof is assembled in the same way as a regular hip roof, excluding the installation of a ridge bar. In this case, a bunch of diagonal rafters is made into a ridge knot.
Video: building a gazebo and barbecue with your own hands
Lack of experience in the construction of roofing structures can adversely affect the quality of the future roof and the degree of protection of the entire structure, therefore, to perform this kind of work, it is recommended to contact professional construction teams. With the right approach, a hip roof will be an excellent architectural structure for a house, a gazebo and any other building.