Contents
Many people like houses with hipped roofs. 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 although the truss roof system is one of the most complex, it can be developed and made by hand.
Types of hipped roofs
Four-pitched roofs are the most expensive and difficult to construct. But, despite this, they were and remain popular. And all because they look more attractive than all other types of roofs, have high mechanical strength, and resist wind and snow loads well. A house with a hipped roof or even a gazebo looks “more solid” than with any other.
There are two main types of 4-pitched roofs: hip and hip. Hipped is suitable for square buildings, hip – for rectangular. In a hipped roof, all four slopes look like triangles and they all converge at one point – in the center of the square.
The classic hip roof has two slopes in the form of trapeziums that converge on the ridge. These slopes are located along the long side of the rectangle. The other two slopes are triangles that adjoin the extreme points of the ridge beam.
For all that, there are four slopes in any case, the arrangement and calculation of these roofs are different. The assembly order is also different.
Half hip
The hip roof is much more common – after all, there are much more rectangular buildings than square ones. There are several other varieties of it. For example, half-hips – Danish and Dutch.
They are good because they make it possible to install full-fledged windows in the vertical part of the side slopes. This allows you to use the under-roof space as a living space. Of course, compared to a full-fledged second floor, there is less living space, but the construction costs are also not so high.
The slope of the slopes and the height of the roof
The angle of inclination of a hipped roof is determined based on the snow and wind loads in your area. The higher the snow load, the higher the skate should be raised – so that the slope is steeper and the snow does not linger in large volumes. In strong winds, on the contrary, the skate is lowered lower – in order to reduce the area of uXNUMXbuXNUMXbthe slopes and, consequently, the wind load.
Even when choosing the angle of inclination of the roof slopes, they are guided by aesthetic and practical considerations. With aesthetics, everything is more or less clear – the building should look proportional. And it looks better with fairly high roofs – 0,5-0,8 of the height of the first (or only) floor.
Practical considerations can be of two kinds. First, if the under-roof space is planned to be used as residential, pay attention to the area that will be comfortable for use. It is more or less comfortable in a room with a ceiling height of 1,9 m. And even then, this is for people of average height. If your height is higher than 175 cm, the bar will have to be raised.
On the other hand, the greater the height of the roof, the more materials will be required for its manufacture. And this is the second practical aspect that needs to be taken into account.
There is one more point that should be taken into account: roofing materials have a minimum and maximum slope angle with which this coating can “work”. If you have certain preferences for the type of roofing material, consider this factor. It depends on what height the truss system of the hipped roof should be raised (relative to the walls).
Hip roof truss system
If they make a hipped roof, most often it is a hip roof. Let’s talk about her first. The central part of the rafter system one to one repeats the gable roof system. The system can also be with layered or hanging rafters. Hanging rafters are installed “in place” – on the roof, two people are enough for such work. Rafter trusses, in the form of triangles, can be assembled on the ground, and then, ready, lifted and installed. In this case, there is less work at height, but in order to raise and install finished trusses, either equipment (crane) or a team of four or more people is needed.
The main differences between the rafter system of the hip roof are in those places where the rafters are shortened (truss half-legs) and the hip is formed – triangular slopes. Diagonal rafters are installed here, which are also called slanting. They rest on the outer or inner corners of the building, they are longer than ordinary rafter legs. Special attention should be paid to the diagonal rafters, since they have one and a half loads (when compared with neighboring rafters). Therefore, the corner rafter legs are made reinforced – they are assembled from two boards, splicing them in width with nails. Also, to support the diagonal rafter legs, additional racks and slopes are installed, which are called a trussed block.
Another truss system of a four-pitched roof of a hip type is different in that the mauerlat is laid around the perimeter of the building, and not just along the long sides of the box. This is understandable – the rafters are located along the perimeter, and not just on two sides, as in a gable roof.
Mauerlat – an element of the roofing system of the building. It is a bar or log laid on top along the perimeter of the outer wall. Serves as an extreme lower support for the rafters.
Diagonal rafters
As already mentioned, slanted (corner) rafters carry an increased load: from the shortened rafters of the side slopes and from the hips. In addition, the length of the diagonal hip roof rafters usually exceeds the standard length of lumber – it is more than 6 meters, so they are made spliced 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 can withstand greater loads than a solid beam of the same section. And one more thing: spliced beams for rafters are made of the same material as ordinary rafter legs. It’s cheaper, and you don’t need to look for special material.
If spliced beams are used, diagonal rafters are usually insured by installing struts and / or trusses (racks).
- If the length of the beam is up to 7,5 m, one strut is enough, which abuts against the upper part of the beam.
- With a length of 7,5 m to 9 m, an additional rack or sprengel is installed. These supports are placed at the bottom, 1/4 of the length of the rafter.
- With a length of an inclined rafter of more than 9 meters, a third, intermediate support is needed – a stand that supports the middle of the run.
Sprengel – a special system that consists of a beam supported by two adjoining external walls. A rack rests on this beam, supported on both sides by slopes (the slopes are set if necessary).
A truss truss is usually not considered, but is made from the same materials as the truss system. For the beam itself 150 * 100 mm, racks – 100 * 100 mm, for cuttings – 50 * 100 mm. This can be a beam of a suitable section or spliced beams.
Supporting the sloping rafter leg
Diagonal sling legs with their upper end rest on a ridge beam. The exact execution of this node depends on the type of system and the number of runs.
If there is only one run, the consoles are made 10-15 cm longer than the sub-rafter frame. If such an issue is too large, then it is cut. But you shouldn’t make it shorter – growing it is much more difficult and expensive. The oblique diagonal legs will rest at this point.
The rafters are cut at the right angle, joined on the console. Fasten with nails. You can strengthen the connection with metal patch plates.
If there are two ridge spans (they are done if an attic-type living space is planned), the connection method depends on the material from which the rafters are made:
- If spliced boards are used, a truss is needed, which relies on the extensions of the ridge runs. Diagonal rafters are cut and rest on a trussed post.
- If a beam is used, a surf is installed in the place 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 there are already rafter legs that will form a hip.
The lower part of the rafter legs is cut horizontally and attached to the Mauerlat or strapping board. For greater reliability of the assembly, you can install an additional oblique beam and fix the corner beam to it (in the figure below).
Fastening – nails on both sides, if necessary, can be additionally fixed with wire twists or clamps.
How to attach sprigs and semi-legs
To the installed diagonal rafter legs, on the one hand, shortened rafters of the side slopes (also called half-legs) are attached, on the other – rafters – rafters that form a hip. They must be arranged in such a way that the joints do not coincide. Sometimes for this you have to change the distance between the outdoor rafters (better – in the direction of decreasing the step).
Usually shortened rafters are cut and fastened with 2-3 nails on both sides. This attachment is sufficient in most cases. But, if you want to do it “correctly”, you need to make a “cut” for each rafter – a recess no more than half the thickness of the beam. The rafters are cut, set to the desired position, the desired contour is circled on the beam (an uneven trapezoid is obtained due to different connection angles). A notch is cut out along the resulting contour, into which the half-leg is inserted, after which it is fastened with nails on both sides. This is a complex knot, and it takes a long time to do it. But the bearing capacity of such a connection is much higher. There is another option, which is much simpler in execution, but differs little in reliability.
The best way to fasten sprigs and semi-legs to the slanted beam can be considered to be their fastening on nails with the additional installation of cranial bars (see the figure above). For this, a beam with a section of 50 * 50 mm is used, which is nailed along the lower edge of the beam between the fixed rafters. In this embodiment, the beam becomes an I-beam, which greatly increases its elasticity, and the bearing capacity increases.
How to fix the lower ends of the rafters
The method of attaching the lower ends of the rafters depends on what type of truss roof system is chosen – with hanging or layered rafters, which scheme is used. A system with sliding rafters (usually used for buildings that are contraindicated for spacer loads – wooden, frame, lightweight concrete) is implemented using special metal fasteners. They consist of two parts. One is installed on the mortgage board, the second – on the rafters. Between themselves, they are connected movably – with the help of a long slot or plate.
With such a device, when the load changes, the roof “wins back” – the rafters move relative to the walls. There are no spacer loads, the entire mass of the roof and precipitation is transferred vertically down to the walls. This fastening allows you to compensate for uneven loads that occur with a complex roof structure (with adjunctions in the form of the letter G or T).
A rigid mount can be made in different ways – with a cutout for a power plate / strapping board or with a hemmed support bar. Fastening is usually with nails, it can be reinforced with metal plates and corners.
A connection with a cutout is made if a hipped roof with an outlet – overhangs. Usually the overhangs are quite large and, in order not to buy long beams, they grow them – add boards that are nailed through to the bottom of the beams. This allows you to make overhangs as long as you want without a lot of overspending on materials.
Danish half hip roof
The truss system of a Danish-type four-pitched roof differs from the classic hip roof. The difference in the design of the hip – here, at some distance from the ridge, a supporting board with a thickness of at least 5 cm is stuffed. Diagonal double rafters are attached to this board. How low to lower the base board is your choice. But, the lower the board is lowered, the smaller the angle this slope will have, and the worse the precipitation will go. With a large area of uXNUMXbuXNUMXba half-hip, you will have to consider the load and select the thickness of the rafters.
But a low-lying support board allows you to put a horizontal window of sufficient area. This is beneficial if a residential area is located under a hip hipped roof.
So that the surf (a board connecting two opposite rafter legs) does not bend from downward loads, a shorty is installed – a piece of the same board, which is nailed to the stand supporting the ridge beam. The same stops are made on the edges of the surf, having well fixed the short ones with nails (the installation step is in a checkerboard pattern in 5-10 cm).
With such a device, it is necessary to strengthen the attachment points of the layered rafters, since the load from them is transferred to the extreme pair of rafter legs. There are two amplification methods:
- The extreme rafters are made double.
- Install struts from double boards. The lower part of the strut rests against a bed or rack. They are fastened with nails, the joints are reinforced by installing scraps of boards.
If the house has a rectangular shape and the hip is not too wide, you can either install struts or make extreme rafters from double beams. Otherwise, the truss system of the Danish-type four-pitched roof is assembled in exactly the same way as described above.
Device 4 pitched hipped roof on the example of a gazebo
For a square gazebo 4,5 * 4,5 meters, they made a hipped roof covered with soft tiles. The slope angle is chosen “floor material”, taking into account snow and wind loads – 30 °. Since the structure is small, it was decided to make a simple system (in the figure below). The distance between the rafter legs is 2,25 m. With a rafter length of up to 3,5 m, a board of 40 * 200 mm is needed. A bar 90 * 140 mm was used for the strapping.
They assembled the rafter system on the ground, fixed it on the support pillars, then installed a solid OSB flooring, after which they covered it with flexible tiles.
First, we assembled the harness, which will be attached to the supporting pillars. Next, they installed rafters that rest on the middle of the strapping. The procedure here 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 only need it 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 a board of the desired section, lean it against the rack in the place where they will be connected (depending on the desired angle of inclination). We note how it should be cut (above, at the junction and where it joins the harness). We cut off everything superfluous, try it on again, adjust if necessary. Further on this blank we make three more of the same.
Now the hipped roof truss system can begin to be assembled. Most questions arise about the junction of the rafter legs in the center. The best way – reliable and not too complicated – is to take a piece of timber of a suitable section, make an octagon out of it – for joining eight rafter legs (four corner and four central).
Having fixed all four central elements of the truss system with nails, we perform the same operations with the corner rafters: we take one, try it on, cut it out, make three copies according to the template made, mount it.
By the same principle, we make semi-legs (shortened rafters). If desired, all connections can be further strengthened with corners or metal plates, then the truss roof system will be more reliable and you will not be afraid even in the heaviest snowfalls.
We put the assembled system on the racks of the gazebo, fasten it with nails, corners, and fix it with mowing. After that, you can mount the crate (in this case, solid) and lay the roofing material.