Do-it-yourself rafter roof system - device and diagrams

In Russia, where a strong attachment to the traditional tower with a triangular roof, a lean-to roof is considered unrepresentative and unsuitable for a residential building. But for the construction of outbuildings and farm buildings there is no easier and more economical option. Therefore, if you have conceived the construction of a garage, bath, shed, carport, be sure to study the structure of the truss system of a shed roof to mount it with your own hands, without attracting hired workers.

Design features

The rafter roof system of the single-slope type is a simplified half of the double-slope. Its advantages:

•  Low weight The low weight of the structure allows you to build from scratch or reconstruct the roof, without making changes to the foundation without strengthening it. This is a big plus, as the cost of building the foundation, even with their own hands, account for about a third of the cost of the entire building.
• Availability of materials. Since the roof system consists mainly of wood, inexpensive material that is harvested and sold everywhere in central Russia, so the distance from the store to the construction site is minimal. The price of construction is acceptable for any budget.
• Easy installation. Usually the salary of professional roofing masters is 50% of the cost of the roof construction. Therefore, such a design with an elementary truss system makes it possible to minimize costs by refusing to hire third-party workers and mount the rafters of a shed roof with your own hands.

Despite the obvious advantages, one can not fail to mention the shortcomings of this type of roof:

•  Low energy efficiency. Due to the fact that the air gap of the lean-to roof, which serves as a natural thermal insulation layer, is less than the same distance from the dual-slope roof, it is not enough to prevent heat loss. The roof is made of materials with high thermal conductivity, so in summer it is very hot, it cools in winter, transferring heat or cold to the roofing rooms. To eliminate this shortcoming, it is necessary to organize more thorough insulation and ventilation of the premises with your own hands.
• The inability to equip the attic. For some homeowners, an attic is necessary, but it is difficult to equip it under a single-sided roof. But on the surface of the slope with a small slope it is convenient to place solar batteries, tanks for heating water and even a small platform for relaxing and sunbathing.
• The formation of snow drifts and snow drifts. This problem is relevant for farm buildings adjacent to the main residential building. The snow slides off the steeper slopes of the roof of the house and lingers on the shallower garage. However, if you carry out the calculations correctly, choose the appropriate material, this disadvantage will not worry the owners.

Construction truss system

Single Shed Roof System не представляет из себя ничего сложного, особенно для тех, кому знакомо устройство двухскатной. Она состоит из тех же основных опорных элементов, которые демонстрирует схема:

1. Mauerlat The strong, massive basis made of a bar with a section of 150х150 mm. Mauerlat is fastened to the upper part of the walls so that he takes the weight of the roof over himself and redirects it to the foundation. It is not installed only in the houses of logs and timber, in which the tasks Mauerlata performs the upper crown of the log house. In brick structures or gas silicate silt, formwork is established along the upper edge of the wall and a concrete screed is poured.
2.  Rafter legs. Rafters are smooth, durable bars of wood section 50x150 mm or 100x150 mm. They lean on the walls, forming the geometry of the slopes. The step between two truss legs is chosen between 60-120 cm. It is necessary to take into account that both too rare and too frequent a step is undesirable: if the rafter is unreasonably much, the design will be too heavy, if not enough, it will not sustain the weight of the roofing material. rafters define engineering calculation.
3. Strut Also called subrafter leg element additional support. It departs from the stand at an angle, supporting the middle part of the rafter, preventing its deflection. The struts are also made of wood, boards with a section of 50x150 mm.
4. Rack. A vertical support, which on one side stands on the supporting partition, while the other supports the rafter leg, transferring its weight to the foundation of the building. The pitch between racks should be 1.2-1.5 m, the greater distance does not provide adequate support.
5. Sill. They are made of the same material as the mauerlat, it performs the same functions as just the difference, which is installed on the internal supporting walls.
6. Scramble A horizontally positioned board that tightens two pillars to prevent them from spreading.
7. Filly. Used if the length of the truss legs is not enough to build a roof overhang. These are boards of smaller section, with the help of which the rafters are extended. The distance from the stands to the end of the filly should be at least 40 cm.

Types of roof systems

Depending on the layout of the structure, various types of truss systems are used for the installation of single-sided roofs, the most appropriate to the specified conditions:

•  Outrageous The peculiarity lies in the fact that suspended rafters are mounted only in constructions with internal bearing supports. It is relevant for the construction of their bricks or blocks, but if a timber-like or log house is made into a partition with a bearing wall inside, then it is suitable for it. The overhanging scheme includes additional supporting elements: racks, purlins, contractions, bent pads, and struts. The larger the area and weight of the single-pitch roof, the more auxiliary parts. Thus, it is possible to block the construction, the distance between the walls in which is more than 12 m, if there are two bearing supports inside it.

  

• Sliding. Used sliding rafters in the construction of log and log log buildings. Experienced builders say that wooden buildings shrink during the first 5-6 years after assembly; in the first year of operation, it loses up to 15% of the height. Therefore, if you equip them with a roof with a rigid mount, the roof will twist, over time it will have to be redone. However, the sliding rafters at the bottom have fasteners of the slider type, therefore, when a log house settles, the roof is not deformed, but adjusted.

  

• Hanging. This roof system does not rely on internal partitions, only external walls are used. Most often, for such a construction, a building framework with the same walls in height is constructed. In order to set the slope of the slope using a rack of wood. Rafter trusses are devices consisting of a stand, tightening, rafters and, if necessary, struts that are assembled on the ground. They look like a right triangle, in which the hypotenuse is the rafter, the small leg is the strut, and the large one is the inhaling. In order to install trusses, temporary flooring is constructed on the joists of the floor, capable of supporting the weight of the worker and the truss. Suitable if the distance between the walls does not exceed 4.5 meters.

Design options

In order to understand which elements the rafter system of your lean-to roof should have, what should be the step between them, you need to measure the length and width of the building, determine the distance between the supporting walls. If Dina facilities:

• 4, 5 meters and less. If the distance between the partitions is small, you can choose the simplest option, consisting of firmly fixed Mauerlat and rafter legs. Installation does not cause significant difficulties, can be made by hand. This method is used for small-scale outbuildings: garages, sheds, street toilets.
• 4.5-6 m. If the distance exceeds the recommended values, six-meter rafters that do not have support on the internal partition will sag under their own weight. Therefore, the truss system needs to be strengthened with struts resting on the floor mounted on the floor beam.
• Up to 12 m. If the length of the roof exceeds 12 meters, install at least one rack on which the struts rest. The step between rafters and racks shall not exceed 1.2-1.5 m.
• Up to 16 m. For structures, the distance between the walls in which exceeds 16 m, it is necessary to install at least two racks, fastened with a scrim, of multidirectional struts. This rafter system is used extremely rarely, it is suitable for arranging large sheds for keeping livestock or warehouses.

It should be understood that the larger the building, the more complex the truss system it requires, the smaller the step between the rafters. Since the standard length of sawn timber is 6 meters, structures whose width exceeds 4.5 require the manufacture of composite truss legs consisting of one or two planks connected by overlap of 50 cm.

Drafting

So a single-sided roof has the shape of a triangle, some of the lengths of which we know, the rest can be calculated using trigonometric formulas known to everyone from school. Suppose that the hypotenuse is a truss leg, we denote it by Lc. Then the Lbc segment is the leg, the height of the wall from the floor beams to the ridge. Hence, Lcd is the width of the house, A is the slope of the slope (selected or calculated). Now it all depends on which sides we know:

• If the width of the house and the height of the wall from the ceiling to the ridge are given, then we calculate the slope angle using the calculator: tgA = Lbc / Lcd;
• If the angle of the slope and the width of the structure are known, then we calculate the height of the wall raising: Lbc = tgA * Lcd;
• When the width of the building and the angle of inclination of the slopes are determined, the length of the rafter foot can be calculated: Lc = Lcd / cosA.

After the calculations have been made, a scheme is drawn on which the obtained dimensions are applied. The simplified drawing also reflects the step between the trusses.

Build a truss system

Since the sequence of work depends on the type of truss system, let us analyze how to build a shed roof for a garage with a width of 4.5 m with your own hands.

1. After erected gable walls, having the end in the form of a right-angled triangle, the partitions on which the slope will rest will be waterproofed before installing the power plate. For this purpose, a ruberoid folded in two or three times or a special film is used.
2. A reinforced belt is fitted on the wall: formwork is being installed, reinforcement is being installed, and viscous concrete is poured. Prefabricated holes for mounting Mauerlat. Before fixing the support bar, it is treated with fire-bioprotective composition. Attach the power plate with anchor bolts.

   

3. Then prepare the rafters. Purchased boards are sawn with their own hands, taking into account that the rafter leg must form a roof overhang of 40-50 cm on both sides. One rafter lift up and mark the place for tie-ins under the power plate. The remaining legs are made according to this pattern.
4. They set up the rear and front rafters with their own hands, stretching the fishing line between them, along which the remaining rafter legs are set and leveled. Optimally, if the step between them is 50-80 cm.

   

5. This is followed by the device obreshetki, solid or lattice. Solid is suitable for soft types of roofing and is made of sheet plywood. Lattice consists of unedged boards, mounted perpendicular to the rafters, used for metal flooring and profiled metal sheets. The pitch between the elements of the batten depends on the weight of the roofing material.

Video instruction