How to connect the rafters to each other in a skate with
A large load is created on the roof support frame created by the roofing material, thermal insulation layer and the weight of snow lying on the surface of the slopes. To prevent the structure from collapsing, a roof system is designed taking into account all the forces potentially affecting it. In the process of calculating determine the required number and size of the cross section of rafter legs, on which the bulk of the roof falls. However, it is equally important how well the connection of rafters is performed in the ridge. This article will tell you what types of connections exist, how to make them correctly and what the choice of one or another method of fastener depends on.
Types of connecting nodes
The basis of the roof frame is the roof trusses, into which the individual elements are interconnected in the construction of various geometric shapes, for example, triangular or pentagonal. One of the most durable and resistant to external influences of the figure is a triangle, this kind of look is given to farms of gable and half hipped, hipped and hipped roof. Connecting node is called the place of splicing or fastening rafters with each other, with a power plate, additional supports. In the construction of the truss system, the following types of nodes are used:
- Attachment to the power plate. Each truss foot has an attachment point to the base of the frame, called a mauerlat bar. Its task is to evenly distribute the load from the weight of the roof and pass it through the load-bearing walls to the foundation of the structure. Violation of the integrity of the mauerlat reduces its strength, so the connection is performed using bars, metal corners or making saws at the ends of the rafter legs.
- Knot connection rafters among themselves. The connection of the rafters of the roof among themselves perform in the ridge of the roof. In addition to the weight of the roofing material, the legs of the frame are subjected to stress on the flex and on the deflection. Therefore, the ridge knot is under constant pressure. Reliability and carrying capacity of the truss system depend on the strength and accuracy of this attachment.
- Docking unit with additional supporting elements. To reduce and redistribute the load from the stop, use bolts, tightening, struts and racks. They are connected to each other with a half-wood fastener, metal plates or nails.
- Splice node. For the manufacture of rafters for roofs with a slope width exceeding the standard length of boards of 6 m, use the method of splicing lumber of 2-3 fragments.
Important! During the construction of the truss frame, two types of connecting nodes are used: rigid and mobile. Hard fixings are called when the elements are fixed between themselves motionless. Mobile connections have the ability to change their position; special metal “sliders” are used for them.
Ways to connect rafters in the ridge
The ridge knot of the truss system is located at the top of the roof and is formed by the connection between the legs of one truss pair. Not this section of the frame lays a huge load so that the horse endures it, experienced roofers use the following mounting options:
- Butt. In order to perform the butt-joint connection, one end of the boards used for the manufacture of the legs is sawn at an angle so that when combined they form an angle. To fix the rafters in this place use nails, hammering into the end of the foot at an angle so that it passes through both legs. To strengthen the end-to-end mounting use special metal plates with holes for screws. From impose on a junction of rafters from two parties and fix self-tapping screws or nails.
- On the beam. Another end-to-end mounting method involves the use of a bar, called a ridge girder. By choosing this method of connection, the rafters are also cut at an angle along the pattern, but not fastened not with each other, but fixed onto a timber. When mounted on a beam, the ridge has a not pointed tip, but a flat one.
- Overlap. To fasten the truss legs overlapped in the ridge knot, the ends of the legs are joined and fixed with a metal stud or bolt and nut. For reliability on both sides, large diameter washers are put on the bolt, and some craftsmen additionally use a rubber seal.
- In the groove. The connection of rafters into the groove is suitable for skilled, experienced carpenters. It consists in manufacturing in one rafter leg drank, and in the other a spike, joining which, the rafters are fastened with a wooden dowel or nail.
- At half a tree. Fastening in a half-tree a little easier than the connection in the groove. Since, in order to perform it, it is necessary to cut a notch at the end of the rafters equal to half the thickness of the board. By connecting these grooves as a jigsaw puzzle and securing it with a nail or nail, carpenters get a strong ridge knot.
Attention! Working with wooden houses from timber and logs requires a special approach. As the natural wood changes the size in the course of change of percent of humidity, the house constructed of this material sits in the first 5 years of operation. To compensate for shrinkage, the size of which sometimes reaches 20 cm, special movable mounts are required. It is a plate for fixing rafters, connected by a metal rod.
Mounting principles
In order to connect the rafters to each other in a ridge knot, it requires the most common tools: a pencil, tape measure, saw, building level, screwdriver and fastener. The quality of work depends on the following rules:
- The type of fastener used for each connecting sheet is determined in the calculation and design of the truss system. To avoid confusion, this information is reflected in the drawing.
- In order for all attachment points to have the same size and angle, a pattern will be made from one pre-marked and made.
- If a bolt or screws are used in the fixing process and holes must be made, their diameter must exceed the dimensions of the fastener. This prevents the wood from cracking, warping and warping.
- Tightening bolts, self-tapping screws or nails, they do not deepen below the surface of the boards, but on the contrary, leave a small gap so that the wood will not be damaged when humidity changes.
- Each connection of truss feet in a skate should be tight, but not tight. After installation is completed, a check for tight fit of all nodes is performed.
Ridge knot of the roof - the area on which the biggest burden. Therefore, the bearing capacity of the entire truss system depends on the correctness of the calculation and the quality of the connection of the rafter.