Hanging rafters: varieties, montage

In any construction, the most important stage is the creation of a roof. It accounts for the mechanical pressure of snow in winter, significant wind loads and the influence of precipitation. That is why the process of making the roof requires close attention and execution of all works with special precision and accuracy.

Differences

The construction of the roof, like most other works on erecting a house, is divided into several stages. The device of suspended rafters is one of them. It is worth noting that the rafter systems can differ significantly in their technological characteristics.

The main difference between the suspended version is the support of the structural elements on the Mauerlat one on top of the other and from below or on the upper ridge part. That is, they are located without a vertical support, without which you can not do with the formation of a nasal system.

It is advisable to use this option in the absence of load-bearing internal walls in the building. It is also possible to use, if necessary, an attic space. In the form of an example, we can mention the construction of a mansard roof.

The construction of the suspended rafters carries the mechanical load on the walls of the building - this is the inevitable cost of the absence of vertical supports in the structure. Therefore, the construction of such a rafter system can not do without the so-called screed. It is a horizontally placed element, pulling the rafter's legs, due to this, the walls are subject to smaller bursting loads. It is worth noting that when the level of screed mounting decreases, the application efficiency increases.

Advantages

A rafter system manufactured with a hanging arrangement has a number of operational positive characteristics. A qualitative and competent execution will give sufficient strength to the roof and reduce the impact of the loads exerted on it. In comparison with the collapsible system, it has less weight, which reduces the overall load on the wall structures and, accordingly, on the basis of the house.

Due to the use of fewer parts, less material is needed to create the rafters.

Layered and suspended rafters

If the house has a large internal wall, when building a roof in the role of a supporting structure, the most commonly used system is used. It has the main difference, which consists in the presence of an internal additional element, which has an emphasis on the column or internal supporting wall. Due to this, the transfer of load only to bending is transferred. Among the advantages of this design is its relatively low weight and the need to use a small amount of material for the construction.

For certain cases, for example, in the arrangement of a single roof over several spans, simultaneous use of both layer systems and hanging systems is required. Rafters, knots of a stratified structure in this version are used in that part of the house where there are internal supports, respectively, where they do not exist, another system is being arranged.

Stages of erection

After determining the type of rafters can be taken for the construction itself. First, a schematic drawing is executed. It should be noted immediately that it is desirable to entrust it to professionals, since it requires special knowledge and experience in this field. Drawing up calculations at the level of the layman is a rather dangerous measure, since errors can be made in the design, which can lead later to a change in the integrity of the roofing system or to its destruction.

After the drawing is created, the further tasks are started, that is, the installation of the Mauerlat. It is used for this wooden beam, which has a section of 20x20 cm, it is placed along the perimeter of the walls and strengthened. It is necessary to pay attention to the fact that protection against dampness is necessary for the Mauerlat, therefore special material, for example, roofing material, is mounted under it.

When using blocks or bricks for the construction of walls, it is required to perform a concrete leveling screed along their perimeter, only after this can be put Mauerlat.

As a material for rafter legs, it is best to use a wooden beam with a cross-section of 20x5 cm. If necessary, it is sawn to a suitable length, special cuts are made from the underside, ensuring their firm support in the Mauerlat.

Hanging rafters can be installed using a ridge beam, which gives the structure additional rigidity. When organizing a roof without it, the rafters' connection in the upper part should be made with an emphasis, and not overlapping.

There are two options for installation: the installation of the first two pairs of legs using a ridge beam, after which the rest are placed, or in order. More preferable is the first option, because it can provide time savings, as well as a more reliable design that is resistant to many kinds of loads.

For the manufacture of puffs, the same material is used as for rafters. The tightening is in the horizontal position. As noted earlier, the lower its location, the better its characteristics become. It is necessary to take into account this circumstance, which is of particular importance if it is planned to operate the attic space. In the absence of a suitable size bar, overlapping cuttings can be used to create a tightening.

Hanging rafters: construction and components

When installing a suspension system, the way to connect the nodes is important. In addition to fixing screws or nails, there must be a connection with nuts and bolts, for this purpose holes are drilled in certain places.

Technological cuts are compulsorily performed. For each connection point of the elements of the rafter system, at least two fasteners must be manufactured. As an example, you can fix the tightening with two screws or nails, followed by pulling the threaded stud.

Cornice elements

When installing a system of suspended rafters, it is worth remembering the formation of eaves. It is desirable that initially their length was laid in the size of rafter legs, but the cost of construction because of this increases. For a more budgetary production of overhangs, an edging board is used , the parameters of which are 10x5 cm. Forms of "filly" are formed from it, their length should be chosen so that the overlapping of the trussed legs in the upper part is at least 50 cm. The parts are fixed using threaded parts .

In the Mauerlate, cuts of the required size are made for a more dense connection. To give increased mechanical strength in the middle, the "mare" is also fastened with a small-sized supporting bar that is fixed to the side of the overhang and on the top of the mauerlat.

The joints of the rafters are overlapped and butt-jointed. In the first variant, the suspended rafters are fixed to each other by means of a bolted joint. In the second, efforts are made to knots with pads, which are metal plates or boards.

The cornice joint of the rafters and the tightening is performed by an outline orthogonal cut, having a single or double tooth, as well as plates or boards.

Hinged triangular arch

This version of the truss is the simplest. The arch is based on three elements: a horizontal beam (tightening), which fixes the suspended rafters in the center of the span or at the base, as well as two rafter sloping legs combined at the top. The tightening, formed from steel rods or wooden beams, takes over the supporting force, so only the vertical load is transmitted to the outer walls of the house. Due to this, it becomes much easier to install a truss support unit on a wall structure: it is replaced with a regular board instead of a Mauerlat, which is used to redistribute the existing load.

In the place of foundation rafters are puffed up if necessary to create a mansard floor. It is used to support interfloor overlappings. In other situations, the tightening is mounted at a higher level. So increases the tensile stress, which is accounted for by it, but at the same time in the span of the rafters the bending forces decrease.

Articulated arm with bolt

This farm visually looks like a gable roof with suspended rafters, described above, in the form of a triangle. The main difference lies in the used support on the wall. In the crossbar, the base of the rafter's feet is fixed in the grooves that are in the Mauerlate. On the walls, apart from vertical forces, there are also spacers. In the middle of the span, a tightening (in this method it is called a bolt) is mounted and used for compression. As a consequence, it simplifies the assembly of the rafter and crossbar.

Hinged arch with suspension

In case the roof with suspended rafters has a width of more than 6 m, it is quite difficult to equip a three-element simple farm. Firstly, to produce a tightening of this size, it takes a long time to find the bar. Secondly, because of the large weight, a long pivot hangs in the center. Therefore, as a supplement to the arch, a suspension is used - it is a part that unites the center of the tightening and the upper part of the arch. The pulling element is made up of two parts, using a bolted connection. Wooden suspension is often called a grandmother, and metal - weights.

Swivel arch with struts

To reduce the deflection, which is present in the rafters, to the arch with suspension there are added struts, which are inclined elements for supporting the rafter legs in the center of the span. In this case, for the abutment of the struts themselves, a suspension is used.

Conclusion

In conclusion, it is worth noting that due to competent execution of calculations and the total amount of work, the hanging rafters for operational properties will not yield to the layered rafters. In addition to stability and high strength, the use of this design will create an attic space suitable for use in economic or other purposes. In the case of an attic roof, such a rafter system becomes an ideal option.