When constructing any modern building, one of the main factors is the aesthetic appearance. Like nothing else, the type and structure of a roof affects the overall appearance of a structure. But the functions of the roof are much wider than just decoration. The roof protects the house from moisture and retains heat. There are a large number of types of roofs and roof systems.
The hip roof truss system is very popular with private house owners. The scheme by which roofs of this type are erected allows for high reliability, durability and versatility. These three factors are an indicator of a good roof.
The choice of material for the rafter system
Before the assembly of the structure begins, it is necessary to pay attention to the quality of the raw materials used, which will be used for the manufacture of the main load-bearing elements, because all the weight load will be concentrated on them. In residential houses, it is preferable to use wood of the first grade, in sheds, temporary huts and other outbuildings, the second and third grade are suitable.
Workpieces with defects (knots, cracks) should be set aside for stock or not used at all.
According to GOST, 3 healthy knots per linear meter are allowed. The presence of small surface cracks is acceptable if their number is small.
Wooden load-bearing elements must be at least 5 cm thick and a maximum length of 6.5 m. If the materials are not long enough, they can be joined with special grooves or with the help of overlays.
Hip Roof Features
If the roof project involves two large trapezoidal slopes and two short slopes - this is a rafter system of a hip roof, the drawing will help to better understand all the nuances.
A rafter structure of this type includes several types of rafters: central, diagonal and angular. It is worth considering climatic features before the rafter system of a hip roof begins to be erected. The scheme should take into account the strength of the winds, atmospheric pressure and material for sheltering the roof. The height and angles of the roof slopes depend on these factors. For maximum accuracy of calculations, you can use a special program or consult a specialist.
Hip Roof Benefits
- This type of roof has maximum wind resistance. This effect is achieved due to the absence of pediments, the wind glides over the surface.
- Corner rafters abut the beam of the ridge and prevent even the slightest deformation.
- Overhangs can be made large to protect the walls from rain.
- The roof has an attractive appearance and is able to decorate any building.
Types and features of hip rafter systems
As a kind of pitched roofs, hip roofs are divided into several types:
- Tent. Roofs of this type have four equal slopes and are suitable only for square buildings.
- Broken. Consist of different slopes at different angles. Installation of such structures is a rather difficult task.
- Half-hip. With this design, the hips do not reach the bottom, and only the pediments are covered. Thus, small slopes reach half of the structure.
In addition to standard types of roofs, the design of the rafter system may include additional design features:
- Raised hip roof system with attic - allows you to use the attic as a living room. This solution is very relevant for owners of one-story houses. The attic allows you to increase the functional square meters of the house up to 2 times. When drawing up the design plan, the location of the windows should be taken into account and ensure that this does not affect the overall rigidity of the structure.
- The rafter system of a hip roof with a cuckoo gives the roof not only a decorative look, but also additional square meters on the attic floor. Often in such a protrusion they have a window, and this is an additional source of lighting. Work on the creation of such a “cuckoo” should be carried out carefully, it is especially necessary to control the angle of inclination and the depth of cut.
- The rafter system of a hip roof with a bay window involves the use of additions to the main rafter structure. A bay window is a ledge from a wall in the form of a balcony or an extension of a room, often built to improve indoor lighting. If the height of such an extension is equal to the height of the building, this must be taken into account when building the roof. In the form of a bay window, the entrance to the house or porch can also act.
Proportions
Measurement rail is an indispensable thing, especially when the rafter system of a hip roof is being built. The scheme for using such a tool is quite simple, it is enough to outline frequently used dimensions on the rail.
Spending 5 minutes on manufacturing will eliminate the need to take a tape measure every time. You can make it from plywood or a slat about 5 cm wide. A measuring slat will help to maintain maximum accuracy and the required proportions.
Fabrication of the hip roof truss system
Before starting the manufacture of the rafter frame, it is very important to delve into the main elements and study the features of their installation:
- the skate is located strictly in the center of the building;
- the forming elements are rafters, one end of which is attached to the ridge, and the other goes beyond the boundaries of the structure, forming an overhang;
- the central frame goes from the ridge and goes to the walls;
- the intermediate frame also goes from the ridge beam and leaves along the slopes;
- short rafters are used when arranging additional elements and dormers.
If you well understand the nuances and subtleties of the process, even with independent erection, you can get a high-quality rafter system of a hip roof. Photos of the finished frame are given in the article.
Markup
Design marking is carried out sequentially and depends on the stages of the work performed:
- First of all, the axes are marked from the end of the building along the upper harness.
- Half the width of the ridge beam is measured and the position of the first part in the rafter system is determined.
- The measuring rail is fitted with one end to the marked line, and the other along the line of the wall.
- To calculate the length of the overhang, one end is installed on the outer corner of the wall, and the other is released on the overhang. The remaining elements are calculated using the measuring bar with a marked distance for the intermediate rafters.
- At the other corners, the same actions are performed. So the location of the end rafters and the ridge beam is calculated.
Payment
When a rafter system of a hip roof is planned or is being built, calculation and correctly drawn up schemes will be the main factors of a successfully completed project. When building it yourself, you should turn to the services of a professional for calculations, if this is not possible, you will have to use a calculator to design hip rafter systems.
When calculating the project, an indicator such as the slope angle is taken. To calculate the distance at which the intermediate rafters will be fixed, select one rafter as the reference point. The distance from the reference point to the corner of the house should fully coincide with its length.
The intermediate rafters are attached in a uniform manner, and the hip beams are attached right up to the corner.
Practical calculation
Here is an example of how component sizes are calculated. This should be done before or during the time when the rafter system of the hip roof is planned. The roof scheme is just an example, for each house only an individually created project is suitable.
- Measurement rail measures the horizontal distance of the inclined intermediate rafters. According to the table of roof calculations, select the optimal angle of inclination and look at the result of the product of the obtained data.
- We measure the length of the rafters from the ridge to the attachment point, given the protrusion.
- The length of the overhang is determined by the sum of the correction factor plus the horizontal projection.
The correct cutting angles of the rafters for fastening to the ridge are also calculated mathematically, the tight fit of the corner to the ridge board is the key to a strong design.
We calculate the length of the corner rafter:
- The rafter length is measured without taking into account the overhang.
- The erection of the projections of the ordinary rafters in a square will be a common projection.
- The result obtained is multiplied by a correction factor, and the length of the angular rafters is obtained.
Installation sequence
The beginning of the construction of the rafter system begins with Mauerlat fasteners, the rafter system of the hip roof is no exception. Features of Mauerlat installation are the same for all types of rafter systems:
- Mauerlat should be laid closer to the inner side of the wall, at least 5 cm from the outer edge.
- The beam itself must be securely attached to the wall of the building.
- Fastening is done using holes and anchors.
When the Mauerlat is firmly fixed, you can proceed to the installation process of the ridge beam. It is necessary to accurately calculate its height and correctly position it relative to all slopes, this is the key to the durability of the roof as a whole.
After that, we are taken for fixing the racks. They are attached with the help of jibs under the ridge beam. All these works can be called the initial stage.
After completing the initial stage, we proceed to the implementation of the intermediate stage, when constructing the four-sloped roof, we begin with the formation of side slopes. At this stage, it is important to monitor the parallel installation of sprigs (half-legs) in the same plane as the ramps. The final stage is the installation of jumpers and preparation for the processes of sheltering the roof. These are the main stages by which the rafter system of a hip roof is erected . With your own hands, this type of roof can be erected only with professional drawing up of drawings and calculations.
Structural reinforcement
Typically, the hip roof structure is quite reliable and able to withstand heavy loads. But in cases where the roof project involves a slight slope, then the snow load will be several times greater than with a steep slope, then it is worth taking care of strengthening the entire structure. Strengthening occurs due to trusses or trusses.
Sprengel is a beam laid on two walls connected at an angle. Such a beam serves as the basis for uprights that support the rafters. This method strengthens the lower part of the structure. To strengthen the upper part, truss trusses are used.
Conclusion
The hip roof is suitable for all types of houses; the main difficulties in its construction are caused by the rafter system of the hip roof. Photos and diagrams will help to understand in detail the issue for those who independently perform the installation. The main thing is to understand the process technology and the terms used in construction.
It is worth paying attention to the choice of material. One defective part will sooner or later negatively affect the condition of the rafter system.
For the proper functioning of the roof, in addition to installing the frame, you need to make high-quality insulation, steam, waterproofing and choose the right material for the final installation.