Houses with gable roofs like many. Despite the fact that they require the most materials, and therefore the most money, they are popular. Firstly, because they give even a simple "box" a more interesting look. Secondly, because they are strong and reliable. And let the rafter system of a four-slope roof is one of the most difficult, it can be developed and made by oneself.
- 1 Types of gable roofs
- 2 The angle of the skates and the height of the roof
- 3 Ramp system of a gable roof of a hip type
- 4 Danish semi-royal roof
- 5 Device 4 pitched tent roof with an example of a gazebo
Types of gable roofs
Four-roofs are the most expensive and complex in the device. But, despite this, they were and remain popular. And all because they look more attractive than all other types of roofing, have high mechanical strength, resist the wind and snow loads well. The house with a gable roof or even a gazebo, looks "more solid" than with any other.
There are two main types of 4-pitched roof: hip and hipped roof. The hip frame is suitable for square buildings, the hip is suitable for rectangular buildings. In the hipped roof, all four slopes have the appearance of triangles and they all converge at one point - in the center of the square.
The classical hip roof has two slopes in the form of trapezoids, which converge on the ridge. These rays are located along the long side of the rectangle. The other two slopes are triangles, which adjoin the extreme points of the ridge beam.
For all that, although there are four skates in any case, the arrangement and calculation of these roofs is different. The order of assembly differs.
Hip roofs are much more common - still there are much more rectangular buildings than square ones. There are several more of its varieties. For example, semi-royal - Danish and Dutch.
They are good in that they make it possible to install full windows in the vertical part of the side ramps. This makes it possible to use the under-roof space as a living space. Of course, compared to a full-fledged second floor, the living space is less, but the cost of construction is also not so great.
The angle of the skates and the height of the roof
The slope of the gable roof is determined by the snow and wind loads in your area. The higher the snow load, the higher it is to raise the skate - so that the sting is steeper and the snow does not linger in large volumes. In strong winds, on the contrary, the skate is lowered lower - to reduce the area of the rays and, consequently, the wind load.
Even with the choice of the angle of slope of the skate roofs are guided by aesthetic and practical considerations. With aesthetics, everything is more or less clear - the building should look proportionate. And it looks better with high enough roofs - 0,5-0,8 of height of the first (or only) floor.
Practical considerations can be of two kinds. First, if the under-roof space is to be used as a residential area, pay attention to the area that will be comfortable for use. More or less comfortable is in a room with a ceiling height of 1.9 m. And then, this is for people of medium height. If your height is higher than 175 cm, you will have to raise the bar.
On the other hand, the higher the height of the roof, the more materials will be needed to make it. And this is the second practical aspect that must be taken into account.
There is one more point that should be taken into account: roofing materials have a minimum and maximum angle of slope with which this coating can "work". If you have certain preferences for the type of roofing material, consider this factor. On this depends on what height should be raised rafter system of a four-slope roof (relative to the walls).
Ramp system of a gable roof of a hip type
If you make a gable roof, most often it's a hip roof. About it and talk for a start. The central part of the rafters system one by one repeats the system of a gable roof. The system can also be with pylon or suspended rafters. Hanging rafters are installed "in place" - on the roof, for this work, two people are enough. The roof trusses, in the form of triangles, can be assembled on the ground, and then ready, raised and installed. In this case, work at altitude is less, but in order to raise and install finished farms, you need either a technique (crane) or a brigade of four or more people.
The main differences of the hip roof system in those places where the rafters are shortened (rafter halves) and the hips are formed are triangular slopes. Here are installed diagonal rafters, which are also called oksnymi. They rely on the outer or inner corners of the building, they are longer than ordinary rafter legs. On diagonal rafters it is necessary to pay special attention, since they have a one and a half load (if compared with neighboring rafters). Therefore, the corner truss legs are made reinforced - they are assembled from two boards, having joined them along the width with the help of nails. Also, to support the diagonal rafter legs, additional racks and slopes are installed, which are called a sprung block.
Another rafter system of a four-slope roof of the hip type is characterized by the fact that the Mauerlat is laid along the perimeter of the building, and not just along the long sides of the box. This is understandable - rafters are located along the perimeter, and not only on two sides, as in a gable roof.
Mauerlat - the element of the roofing system of the building. It is a bar or log, laid on top of the perimeter of the outer wall. Serves as an extreme lower support for rafters.
As already mentioned, the canted (angled) rafters carry an increased load: from the shortened rafters of the side ramps and from the hips. In addition, the length of the diagonal rafters of the hip roof usually exceeds the standard length of the sawn timber - it is more than 6 meters, so they are made paired and doubled (paired). This solves two problems at once: we obtain a beam of the required length, we increase its bearing capacity. Two paired boards withstand greater loads than a solid bar of the same section. And one more thing: lathing beams for nasal rafters are made of the same material as ordinary rafter legs. It's cheaper, and you do not need to look for special material.
If you use girders, diagonal rafters, as a rule, insure the installation of struts and / or stitches (racks).
- If the length of the beam is up to 7.5 m, one single strut is sufficient, which rests against the upper part of the beam.
- With a length of 7.5 m to 9 m, an additional rack or spigot is installed. These supports are placed below, 1/4 of the length of the rafters.
- With the length of the inclined rafters more than 9 meters, you need a third, intermediate support - a post that supports the middle of the run.
Sprengel - a special system, which consists of a beam, supported by two adjacent external walls. On this beam is supported by a stand, backed from two sides by stalks (the stakes are put if necessary).
Sprungel farm is usually not considered, but made of the same materials as the rafter system. For the beam itself 150 * 100 mm, racks - 100 * 100 mm, for cuttings - 50 * 100 mm. This may be a beam of suitable cross-section or elongated beams.
Supporting the foot truss leg
Diagonal stropile legs rest on the ridge beam with the upper end. The exact execution of this node depends on the type of system and the number of runs.
If the run is one, the consoles are longer than the rear frame by 10-15 cm. If this issue is too large, then it is cut. But do not be shorter - it's much more difficult and expensive to grow. At this point, the diagonal legs will be supported.
The rafters are cut at the right angle, they join the console. Strengthen with nails. Strengthen the connection by using metal overlaid plates.
If ridge flights are two (do, if a mansard-type dwelling is planned), the method of connection depends on the material from which the rafters are made:
- If you use rug boards, you need a sprinter, which rests on the outsides of ridge runs. The diagonal rafters are cut and supported by a spar.
- If a bar is used, a surf is installed at the point of support - a piece of board with a thickness of at least 50 mm. The board is fastened with nails to two runs, and to this board already - rafter legs that will form a hip.
The lower part of the foot trimmings is cut horizontally and fastened to the Mauerlat or the plank. To increase the reliability of the unit, you can install an additional oblique beam and fix the corner beam to it (in the figure below).
Fastening - nails from two sides, if necessary, you can additionally fix with wire twists or clamps.
How to strengthen narozhniki and half-legs
To the established diagonal rafter legs on one side are fastened truss rafters of side rajids (called still half-legs), on the other hand - workers - rafters forming a hip. They must be arranged in such a way that the joints do not coincide. Sometimes for this purpose it is necessary to change the distance between narodnye rafters (better - in the direction of reducing the pitch).
Usually truncated rafters pruned and fastened with 2-3 nails on both sides. This fastening is sufficient in most cases. But, if you want to do "right", for each rafter you need to do "cutting" - a notch not more than half the thickness of the beam. The rafters are cut, set to the desired position, a necessary contour is traced on the beam (an uneven trapezium is obtained due to different joint angles). On the resulting contour, cut out a notch into which a half-leg is planted, after which nails are attached from two sides. It's a complex knot, and it's time to do it. But the carrying capacity of such a connection is much higher. There is another option, which is much easier to execute at times, but it differs little in reliability.
The optimal way to fix the craftsmen and the half-leg to the foot beam can be considered to be their attachment to the nails with the additional installation of cranial bars (see the figure above). To do this, a bar with a cross-section of 50 * 50 mm is used, which is nailed along the lower edge of the beam between the fixed rafters. In this case, the beam becomes an I-beam, which greatly increases its elasticity, increases the bearing capacity.
How to fix the lower ends of the rafters
The method of fastening the lower ends of the rafters depends on what type of roof rafter system is chosen - with hanging or nylon rafters, which circuit is used. The system with sliding rafters (usually used for buildings that are contraindicated in the spacer load - wooden, frame, lightweight concrete) is realized with the help of special metal fasteners. They consist of two parts. One is installed on the mortgage board, the second - on the rafters. Between them they are connected by means of a long slot or plate.
With this device, when the load changes, the roof "wins" - the rafters move relative to the walls. Spacious loads are absent, the entire mass of the roof and sediments is transferred to the walls vertically downwards. Such fastening allows to compensate for the uneven loads that arise when the roof structure is complex (with G or T contiguity).
Hard fixing can be done in different ways - with a cutout under the Mauerlat / binding board or with a hem support plate. Fastening is usually by means of nails, it can be strengthened by metal plates and corners.
The connection with the cut is made if the four-slope roof with outlet - overhangs. Usually the overhangs are quite large and, in order not to buy long beams, they are dug up - add boards that nail through to the bottom of the beams. This allows you to make the overhangs as long as you want without a large overrun on materials.
Danish semi-royal roof
The Danish roof type roof rafter system is different from the classical hip roof. The difference in the design of the hip - here, at some distance from the ridge, is packed with a support board with a thickness of at least 5 cm. To this board are fastened diagonal double rafters. How low to lower the support board is your choice. But, the lower the board is lowered, the smaller angle this slope will have, and the worse the precipitation will go. With a large area of the half-shaft, it is necessary to consider the load and choose the thickness of the rafters.
But the lowly lowered support board allows you to put a horizontal window of sufficient area. It is beneficial if a dwelling is located under the hip gable roof.
In order for the surf (the board connecting the two opposite rafter legs) from the loads directed downwards, do not bend, a short one is installed - a piece of the same board that is nailed to the pillar supporting the ridge bar. The same stops are made on the edges of the surf, also fastening the shorts with nails (the step of installation is staggered after 5-10 cm).
With this device, reinforcement of the fastening points of the liner rafters is necessary, since the load from them is transferred to the last pair of rafter legs. Two methods of amplification are used:
- The outer rafters are made doubled.
- Install the struts of the double boards. The lower part of the strut rests against a leg or stand. They are fastened with nails, the joints are strengthened by installing scraps of boards.
If the house has a rectangular shape and the hip is not too wide, you can either set the struts, or make the outer rafters of twin beams. Otherwise, the truss roof system of the semi-dwarf Danish type is assembled exactly as described above.
Device 4 pitched tent roof with an example of a gazebo
For a square arbor 4,5 * 4,5 meters made a tented roof covered with soft tiles. Angle of gradient is chosen "floor material", taking into account snow and wind loads - 30 °. Since the structure is small, it is decided to make a simple system (in the figure below). The distance between the rafter legs is 2.25 m. When the length of the rafters is up to 3.5 m, a board of 40 * 200 mm is needed. On the harness used a bar 90 * 140 mm.
They assembled the truss system on the ground, fixed it on the supporting poles, then installed a solid flooring from the OSB, then - covered with flexible tiles.
First we gathered the harness, which will be fastened to the pillars. Further, rafters were installed, which rest on the middle of the strap. The procedure is as follows: in the middle we put a rack on top of which the rafter legs will join. In this version, this rack is temporary, we need it only for a while - until we connect the first four rafters in the center. In other cases - for large houses - this rack can remain.
We take the board of the desired section, we lean against the rack in the place where they will be connected (depends on the desired angle of inclination). We note how to cut it (above, at the junction and where it joins with the strapping). Cut off all unnecessary, try again, correct if necessary. Further on this preparation we make three more same.
Now the rafter system of the four-hipped roof hood can begin to be assembled. Most questions arise about the junction of the rafter feet in the center. The optimal way - reliable and not too difficult - is to take a piece of timber of a suitable cross-section, make an octagon from it - to connect eight rafters (four corner and four central).
Fixing all four central elements of the rafter system with nails, we do the same operations with corner rafters: we take one, try on, cut out, we make three copies according to the template, and mount it.
By the same principle, do the half-legged (truncated rafters). If desired, all the connections can be further strengthened with corners or metal plates, then the roof gable roof system will be more reliable and it will be possible not to be afraid even of the strongest snowfalls.
The assembled system is installed on the racks of the arbor, fastened with nails, corners, fastened with cuttings. After that, you can mount the crate (in this case - continuous) and cover the roofing material.