INSTRUCTIONS AND PROPHECIES OF THE Blessed MOTHER ALIPIA GOLOSEEVSKY, Kyiv...
The roof is a complex and important architectural element of any building. Its construction should be treated with special attention, it must be remembered that the installation of a truss system requires considerable experience in performing such work and a special tool. You should not take on the creation of a roof for those who hold a carpentry and measuring tool in their hands for the first time - the results of the activity can be very negative.
There are two types of roofs depending on the number and placement of rafter support points, but each developer can, at his own discretion, slightly change the specific design of the truss system. This takes into account the operating conditions of the building, the purpose of the attic, the climatic zone of location, the technical parameters of lumber and roofing. Of course, the type of truss system is influenced by the personal experience and preferences of developers.
Before proceeding with the manufacture of rafters, you should decide on their type, method of attachment and linear dimensions. Only in this case, you can be sure of the strength and safety of the structure.
How do various factors affect the parameters of the rafters?
| physical factor | Brief description of the influence on the parameters of the rafters |
|---|---|
| Rafters must withstand snow and wind loads. During the calculations, it is necessary to take the actual maximum values of snow cover from the tables of building codes and rules, take into account the strength and rose of the winds. The data allows you to find out the total load on the roof slope, depending on its area and angle of inclination. Further, it is already possible to determine the dimensions of the rafters, their number and step. In this case, a safety factor is necessarily laid down. The fact is that lumber does not have stable and identical strength values, too many unforeseen factors affect these indicators. For most cases, 50 × 150 mm or 50 × 200 mm boards are used for the manufacture of rafter legs. |
| Gable roofs can be layered and hanging. For hanging roofs, you need to make rafters from more durable boards. This takes into account the method of fixing the elements to the Mauerlat. If a cut is made, then the width of the boards should increase by the size of the cut. The fact is that the cut in this place automatically reduces the width of the material that receives the load. If a cross cut 60 mm long is made on a board with a thickness of 200 mm, then only the remaining width of 140 mm is taken into account. Accordingly, if rafters from 200 mm boards are selected when calculating loads, but unforeseen cuts of 60 mm are made during fastening, then the width of the blanks for rafters increases to 260 mm. This remark is made for those who like to abuse various notches and cuts for the thrust areas of the ends of the rafters. Currently, there are many special devices that allow you to firmly fix the rafter in the desired position without sawing. |
| For residential buildings, rafters must have a safety margin of at least 1.4 of the calculated values. For non-residential structures, the coefficient is reduced to 1.2. Conclusion - the dimensions of the rafters on the houses are larger than on garages and other outbuildings. |
| Residential attics (mansards) must have an insulated roof. The width of the rafters must correspond to the thickness of the insulation layer. At the same time, it is necessary to adjust the step between the rafter legs, depending on the standard width of the insulation. If in this climatic zone the optimal thickness of the roof insulation is 200 mm, then it is recommended to choose the same width for rafters. Various extensions of narrow rafter legs during roof insulation are not considered the right solution. |
This knowledge will help you make the right decisions both during the manufacture of rafters and during their fixation directly in place. Mistakes in the construction of the truss system are too expensive, you should not show excessive self-confidence.
What influences the choicesizes andwaysmountsrafter
A very important point. The task of any fixation is to ensure the stability of the connection node, while it can be fixed or have one or more degrees of freedom. This cannot be achieved without knowledge of the loads affecting the rafter legs. Loads can be permanent and temporary, dynamic and static, unidirectional and multidirectional.
- Constant vertical forces. Arise due to the impact of roofing and roof insulation materials. Due to the fact that the rafter legs are located at an angle to the vertical force, they are subject to bending and bursting loads. The magnitude of the forces is determined after the construction of the diagram, on the basis of specific bending and bursting forces, the thickness and width of the boards for the rafters are selected. Fasteners must prevent the spreading of the truss system.
- Variable vertical forces. Appear in winter, the value depends on the height of the snow cover.
- Lifting wind forces. As a result of gusts of wind, lifting forces act on the roof. They do not affect the dimensions of the rafter legs, efforts are taken into account only when choosing the type of fixation, it must provide for and hold such loads.
- Lateral efforts. The value depends on the windage of the roof. As a result of gusts of wind, lateral forces act on the truss system. They increase bending and tearing loads. This feature must also be taken into account during the manufacture and installation of rafter legs.
There are options for rigid fastenings of truss trusses; for this, metal plates, corners, self-tapping screws and nails are used.
Sometimes it is required to use floating rafter connections to compensate for changes in the size of wooden houses. For floating connections, special fasteners and bolts are used. The second allows the rafter legs at the top to turn a little.
Another example of a free rafter connection is a sliding one. It is used on wooden log cabins and makes it possible to compensate for the natural shrinkage of the house.
What elements are used to increase the stability and bearing capacity of the rafters
As a result of the correct choice of the truss system and methods of fixing its elements, the structure must be stable, compensate for natural fluctuations in linear parameters and withstand various loads that occur during operation. To fulfill the conditions during the fixation of the rafters, additional fixation elements can be used.
Runs
Most often they are mounted in the ridge part of the system, the upper ends of the rafter legs rest on them. To increase stability, cuts may be provided. The top connection is rigid or floating on bolts. On large roofs, girders can be installed in the middle of the rafter legs or in other places with critical loads.
vertikaflax racks
They are installed to strengthen the rafters; due to the use of racks, elements can be made from thinner lumber. Vertical racks with their upper end abut against the rafters, and with their lower end against the bed or ceiling beams.
corneraboutpores
Retain bending and expansion forces, universal use. Corner stops can be placed in any places of the rafter leg that cause concerns about strength. Due to such stops, the resistance of the rafters to bending and tearing forces is significantly increased.
Puffs(crossbars)
Purpose - to keep the rafter legs from sprawling, they are used on hanging rafter systems. Most often they are placed in the upper part of the truss; boards with a thickness of about 20–25 mm can be used for manufacturing. The fact is that they work in tension, lumber holds such efforts well. Boards do not work well in compression, quickly bend and lose their original strength indicators.
Knuckleadki
They are used in the upper ridge part of the rafters, due to the use of puffs, the strength of the knot connection increases. Puffs can be made of wood, plywood, OSB or metal.
Bosses(stops)
They have many specific names. They are ordinary pieces of boards 30–40 cm long and 40–50 mm thick, fixed at the bottom of the rafters. They rest against the Mauerlat and do not allow the structure to slip. The use of bosses allows you to perform a rigid connection of elements without sawing the rafters. We talked about the problems that arise in connection with sawing in this article above.
Prices for various types of timber
Options for connecting the ridge knot of the rafter legs
The horse is one of the main and most loaded elements of the truss system. The node has several connection options, you should choose a specific one depending on the general parameters of the roof.
With a large length of slopes, it is better not to use a ridge beam, but instead to put two parallel runs and puff crossbars. This design is easier to do, it is more stable and safe.
For a hanging roof, you should choose the most reliable ways to connect the rafter legs, these systems have a minimum number of additional stops.
Prices for various types of fasteners for rafters
Fasteners for rafters
step by stepWithtruction of the mouthanew rafters
For rafter legs, coniferous boards 50 × 200 mm, first-class lumber, are used. The boards must not have traces of rot or fungus, significant malformations and deep cracks. It is strictly forbidden to use low-quality lumber for the manufacture of the truss system.
To increase the protection of roof elements from decay, it is recommended to use fire protection.
Rafter blanks should be impregnated at least twice, while the material must be dry and clean. Processing is done on a flat area in dry and clear weather.
It can be impregnated with a roller, brush or air gun. It is not recommended to use household hand sprayers - too long and hard. Boards can be lifted up after complete drying of the impregnation.
Our gable roof has a ridge run, vertical supports rest against a bed located on a load-bearing wall in the middle of the building.
Practical advice. If the house is quite high and the boards are heavy, then it is recommended to make an elementary device to protect window openings from damage. To do this, two boards are knocked down in the form of a square, the length and width are selected taking into account the parameters of the opening. The device is installed on the windowsill, and the rafter boards do not damage the foam blocks during lifting.
Prices for fire-retardant impregnations
Preparatory operations
The manufacture of rafters begins with preparatory operations.
Step 1. Raise the rafter boards into the attic. For convenience, place them evenly along the length of the building, put one end on the Mauerlat, and the other on the run bed. First you need to install the extreme rafters on both sides of the roof of the house, pull a thread between them and install and align all the remaining ones along it.
Step 2 Check again the position of the ridge run. It should be located exactly in the middle of the roof. Its displacement by 1–2 centimeters will not affect the strength of the roof as a whole, but it will somewhat complicate the manufacture of rafters and the laying of roofing materials. In addition, an experienced builder may notice a mismatch in the size of the slopes and, accordingly, the asymmetry of the roof. It is recommended to achieve a situation so that the ridge run is located along the line of symmetry, if this is not associated with great difficulties. The final decision is made by the foreman on site and depends on the magnitude of the offset and the amount of work to correct the error.
How to straighten a run?
- Attach a batten board to the Mauerlat, it is lighter, easier to lift and fix. The second end should lie on the run. The board is nailed to the Mauerlat with an ordinary smooth nail or screwed with a self-tapping screw.
- Climb to the top of the run and use a tape measure to check the distance from the edge of the run to the Mauerlats installed on opposite walls. Work very carefully, it is advisable to use insurance. Unfortunately, in practice, few people follow the safety rules, but in vain. Falls from height can cause very serious injury.
- Align the purlin to the center and secure the board. To increase rigidity, fix the same board on the other side of the run.
Now everything is ready, you can proceed to the manufacture and installation of rafters.
Installationrafter legs
If you work alone, then you need to fasten a piece of rail to the run at the place where the first rafter is fixed. A rafter board will be temporarily fixed to it to prevent it from slipping down.
And at this time, you can perform work on the manufacture and preparation for connecting the upper part of the rafters.
Step 1. Lift and install the rafter board in place, clamp it to the previously fixed rail with a clamp.
Step 2 Draw lines to cut out the thrust pad. This is done in two stages. First, draw a horizontal line. To do this, press the rail, square or other even object firmly against the horizontal surface of the run.
Second, draw a vertical line. Now the ruler or square should be pressed against the side surface of the run.
Important. The width of the ruler should be no more than 2-3 cm, it is not necessary to make deep cuts and significantly reduce the width of the rafter leg, it loses its maximum design strength.
Make the same markup at the bottom of the rafter. Only now the ruler needs to be pressed against the Mauerlat surfaces.
Step 3 Remove the board and carefully cut out the seats. You can work with a hacksaw or an electric circular hand saw.
Practical advice. If the cuts are made with an electric circular saw, then it is better to cut in two steps. First cut to the mark, then turn the board over and cut again to the mark. Knock out the cut piece with a hammer, and remove the remaining protrusion with a chisel or chisel. No need to go behind the line with a saw and try to cut off the ledge in one go. This method increases the cut by 3–5 cm, depending on the diameter of the disk, which significantly reduces the bearing performance of the rafter.
Step 4 Install the prepared rafter in place and check the correctness of its manufacture. Do the same operations with the second leg of the farm.
Step 5 Place the rafters with an emphasis on the Mauerlat and the run, pull them together with a clamp in the upper part. Find the middle of the run and transfer the line to the rafters, use a level or building square (only if the plane of the run is strictly horizontal).
Step 6 Saw through two rafters at the same time along a vertical line. The boards must be tightly clamped with a clamp. Pay maximum attention, the saw blade should be perpendicular to the plane of the rafters. If you cut it obliquely, then the ridge joint will not fit tightly, and this reduces the stability of the truss system and is considered an obvious construction defect.
Step 7 Remove the clamps, connect both elements in the ridge, check the correct position.
With a lack of practical experience in performing such work, the first leg may have a gap in the ridge part, if it is within 1–2 mm, then there is nothing to worry about. If it is more than 4 millimeters, then you need to correct the element. See which planes of the thrust pads do not allow the upper cut to fit tightly. Approximately indicate the amount of additional cut. Remove the rafter and remove the interfering protrusions. Check the connection again, if there are gaps, repeat the operation. As practice shows, experience appears on the second or third rafter and no further corrections need to be made.
Step 8 Secure the rafter legs firmly in place. For this, it is recommended to use metal plates and corners, it is simple and easy to work with them, the strength fully meets the requirements for the truss system.
For each pair of rafters, you will need one large reshaped plate to connect the ridge knot, two 50x50mm corners for fixing to the run and two 60x80mm corners for screwing to the Mauerlat. The thickness of the metal is at least two millimeters.
In the same way, install the extreme rafters on the other side of the house, pull the threads between them. One at the top and bottom and one in the middle. So that they do not interfere during the manufacture of rafters, make a gap between the thread and the plane of about one centimeter.
Real professionals never make one rafter in the attic of a house. Such an algorithm of work significantly increases the construction time, complicates the process itself and makes it unsafe. It is very dangerous to work with electric tools on unsuitable sites, injuries from them are severe, often causing disability.
If the house is delivered with high quality with exact observance of dimensions and rules, then the rafter legs are made according to one template on the ground. Finished elements are assembled on the roof. This technology increases labor productivity by 3-5 times, at the same time the quality of the rafter system is improved, it is more reliable and durable. Of course, the wages of builders also increase proportionally. They work from the development and receive money not for the time spent in the attic, but for the assembled roof.
Prices for popular models of screwdrivers
Screwdrivers
Video - Manufacturing and installation of rafters on a gable roof
The gable roof truss system is considered one of the simplest in purely constructive terms. It consists of only a few elements, the number of which decreases or increases due to the size of the roof itself. But with apparent simplicity, the process of erecting a gable roof itself requires knowledge of some of the nuances that affect the quality of the final result.
Rafter system for a gable roof Source tues.ru
What is a gable roof
From the name it becomes clear that the roof structure is two slopes that have a rectangular shape in the plane. More often, the slopes have the same dimensions, but there are so-called asymmetric designs in which the slopes differ in size from each other.
In this case, the slopes are set to each other at a certain angle, which is called the slope. The line of contact is the ridge beam, which is part of the truss system. In a simple way, it is called a ridge, and it is the highest point of the roof.
The side planes formed by the slopes are called gables. They are triangular in shape. After the construction of the roof, the sidewalls are lined with sheet or panel materials: plywood, OSB, even boards, etc.
What is a gable roof truss system
The basis of the structures of the slopes are rafter legs, they are also rafters. They are made either from lumber (beams, boards), or from a steel profile (corner, channel). In private housing construction, wood is used. It is easier to work with, plus lumber is cheaper.
The device of the gable roof truss system is not only rafters. In addition to them, there are several other mandatory elements. The photo below shows all the elements of a gable roof. Let's designate them.
Each of the elements of the roof has its own purpose. Source lestorg32.ru
Elements of the gable roof truss system
Mauerlat. In fact, this is a beam on which the rafters rest. Its purpose is to evenly distribute the load from the rafters on the walls of the house. If the Mauerlat is not used, then the rafters will put pressure on the walls pointwise, that is, large stresses will arise at the installation sites, which will lead to cracking of the walls.
rafters installed at an angle.
Skate, he is a ridge beam or run. Its task is to form a place for joining the rafter legs. A ridge beam is an optional element of a gable roof. There are designs in which it is not installed. But more on that below.
Puffs. They are not always used, but only on hanging rafters or if the rafter system is installed on a wide house.
floor beams that form the ceiling in the room and the floor in the attic.
One of the floor beams, which is called lying down. It additionally functions as a base for the support posts that support the rafters. Not always used.
Support legs, they are grandmas supporting the rafter legs. They are installed only if the span of the house is at least 6 m.
Struts, they are also diagonal props. They are used only if the support posts cannot ensure the overall reliability of the truss system.
There is another element that is clearly visible in the photo below. These are support posts for the ridge run. They are installed if the design of the truss system is heavy. That is, the entire structure is assembled under heavy roofing material, for example, under ceramic tiles.
Sloped rafters with support posts under the ridge run Source seaside-home.ru
You might be interested! A warm roof is an important detail in the construction of an energy-efficient home. From the article at the following link you can find out.
Types of rafters
The roof truss system (gable) can be assembled from layered or hanging rafters.
Layered
They got their name because the lower ends rest on the walls of the house, the upper ends on the ridge run. In this case, the truss elements are subjected to loads that bend them. The design is reliable, durable, with a large bearing capacity.
The photo above just shows the rafter system of a layered view. It is clearly seen that the legs rest in the upper part on the skate. In this case, there are two types of fastening of the rafters themselves in the upper part:
fastening is made to the ridge:
fastening is made between each other with an emphasis on the ridge (photo above).
hanging
It is necessary to immediately indicate that this type of rafter system can be used if the distance between the walls of the house does not exceed 12 m. Because the rafters abut the lower ends against the walls, and the upper ends only between themselves (there is no ridge run in the structure). Hence the low bearing capacity with a large spread.
Hanging rafters for the roof have one purely design flaw - a large support load on the walls of the house. To reduce it, puffs are installed between the legs to form a rigid triangle. Often, the functions of the puffs are performed by the load-bearing floor beams.
If necessary, strengthen the hanging rafters, install racks and struts under them.
Hanging rafters of a gable roof Source postila.ru
Installation of a gable roof truss system
Two types of truss system determine two types of their assembly technology. Let's consider each separately.
Installation of layered rafters
There is a certain sequence for assembling layered rafters.
Two extreme support posts are installed under the ridge beam. They will not only support the beam, but also be the elements that form the gables of the building. Attach them at the bottom to the Mauerlat. At the same time, they are strictly set vertically, and the upper ends are in the same horizontal plane. To do this, a strong thread is pulled between the racks, the level is checked for horizontalness. If there are deviations, then one of the supports (low) is raised using wooden supports.
Intermediate support posts are mounted along a horizontally stretched thread in increments of 2-2.5 m. To prevent the beams of the racks from moving, they are supported with temporary fasteners: props or puffs.
A ridge beam is laid on the racks, which is attached to them.
Produced in pairs installation of gable roof rafters. Installation can be started from either side. Fastening is immediately carried out to the Mauerlat and to the ridge. The main thing is to maintain the distance between the legs, which is determined depending on the severity and bearing capacity of the roofing material. Usually this parameter is indicated in the project of the house.
If necessary, intermediate support posts and struts are mounted.
Installing rafters on a ridge along a stretched thread Source kbumb.ru
Installation of hanging rafters
The technology for installing hanging rafters is different. To do this, the entire structure, assembled from two rafters and puffs, is assembled on the ground. That is, roof trusses are prepared in the required quantity, which then rise to the roof. Sometimes craftsmen assemble trusses on the roof. Collected one - installed, collect the next.
It should be noted that such farms have a significant mass. Lifting them manually is difficult and dangerous, so they use the services of a crane. And this increases the cost of construction.
Hanging trusses assembled on the ground Source moydom-irk.ru
The most difficult thing is to set farms. All of them are installed at the installation site with a planned step, where they are temporarily fixed with jibs and props. Then a thread is pulled between the extreme farms. It must be set so that, firstly, it is stretched strictly along the horizon, and secondly, according to a design that is higher than the rest.
It remains only to raise the truss structures, which turned out to be below the stretched level. And the last - the installation of the crate, which will secure all the trusses into one truss system. Please note that at the bottom of the rafters will be fixed to the Mauerlat.
You may be interested! When the installation of the truss system is completed, the turn of roofing comes. From the article at the following link you can find out.
Rafter calculation
length of rafter legs;
the step of their installation;
section of the lumber used.
Everything is simple with the length, for this you will have to use the Pythagorean theorem, which is based on the formula: c 2 \u003d a 2 + b 2, where c is the hypotenuse of the triangle (this is the rafters), a and b are the legs. The latter are the height of the roof and half the width of the house. All parameters can be easily measured.
The length of the rafter is l 2 + H 2 Source remontik.org
It is more difficult with the installation step, because a lot will depend on the mass of the roofing material and the loads from natural precipitation. The larger both loads, the smaller the installation step. But, as practice shows, this parameter varies from 60 cm to 2 m. The latter indicator is used if corrugated board with large corrugation parameters, for example, H75, is used as a roofing material.
As for the section of the rafter legs, here, as in the case of the installation step, loads are taken into account, as well as the length of the legs and their installation step. Here the dependence is as follows: the greater the load, step and length, the larger the cross section.
Video description
In the video, the installation process of the truss system:
And one moment. Rafters for a gable roof are laid at a certain angle (indicated by the letter “a” in the photo). The slope is selected with the calculation of the choice of roofing material. That is, some coatings cannot be laid on roofs if the angle of inclination is less than required. Here are some ratios:
the minimum angle of inclination of the truss system for slate is 22 °;
for corrugated board - 12 °;
for metal tiles - 14 °;
soft tiles - 15 °.
The ratio of the roof slope to the type of roofing material Source arhplan.ru
On our website you can find contacts of construction companies that offer a turnkey roof design and repair service. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".
Generalization on the topic
Gable roofs are traditional designs. But from the article it becomes clear that there are two truss systems that form the basis of the construction of roofs. The one that fits the size of the house is selected. As a selection criterion, the loads that put pressure on them are also taken into account. Therefore, it is important to correlate everything correctly, taking into account the nuances of construction processes.
Roof installation is a complex multi-stage process. In order to independently assemble and install the truss system, it is necessary to carefully study the methods of connecting the elements, calculate the length of the rafters and the slope angle, and select the appropriate materials. If you do not have the necessary experience, you should not take on complex designs. The best option for a small residential building is a do-it-yourself gable roof.
A standard roof of this type consists of the following elements:
Mauerlat is a beam laid on top of the walls along the perimeter of the building. It is fixed with threaded steel rods immured into the wall or anchor bolts. The beam must be made of coniferous wood and have a square section of 100x100 mm or 150x150 mm. Mauerlat takes on the load from the rafters and transfers it to the outer walls.
rafter legs- these are long boards with a section of 50x150 mm or 100x150 mm. They are attached to each other at an angle and give the roof a triangular shape. The design of their two rafter legs is called a truss. The number of farms depends on the length of the house and the type of roofing. The minimum distance between them is 60 cm, the maximum is 120 cm. When calculating the pitch of the rafter legs, one should take into account not only the weight of the coating, but also the wind load, as well as the amount of snow in the winter.
It is located at the highest point of the roof and most often represents a longitudinal beam connecting both slopes. From below, the timber is supported by vertical racks, and the ends of the rafters are attached to the sides. Sometimes the ridge consists of two boards, which are nailed to the top of the rafters on both sides and connected at a certain angle.
Racks - vertical bars with a section of 100x100 mm, located inside each farm and serving to transfer the load from the ridge run to the load-bearing walls inside the house.
The struts are made from timber scraps and set at an angle between the uprights and the rafters. The side faces of the truss are strengthened with struts, the bearing capacity of the structure is increased.
Puff - a beam connecting the lower parts of the rafters, the base of the truss triangle. Together with struts, such a beam serves to strengthen the truss, increases its resistance to loads.
Lying is a long bar with a section of 100x100 mm, laid along the central load-bearing wall, on which vertical racks rest. Lying is used when installing layered rafters, when the run between the outer walls is more than 10 m.
The crate is a board or timber stuffed on the rafters. The crate is solid and with gaps, depending on the type of roof. It is always attached perpendicular to the direction of the rafters, most often horizontally.
If there is no more than 10 m between the outer walls and there is no load-bearing wall in the middle, arrange hanging rafter system. With such a system, the upper ends of adjacent rafters are sawn at an angle and connected to each other with nails, excluding the installation of racks and ridge timber. The lower ends of the rafter legs rest on the outer walls. Due to the lack of racks, the attic space can be used to equip the attic. Very often, floor beams perform the function of puffs. To strengthen the structure, it is recommended to install the upper puff at a distance of 50 cm from the ridge.
In the presence of a central supporting wall, the arrangement is more justified layered truss system. A bed is laid on the wall, support posts are attached to it, and a ridge beam is nailed to the posts. This installation method is quite economical and easier to perform. If the ceilings in the interior are designed at different levels, the racks are replaced with a brick wall dividing the attic into two halves.
The installation process of the roof includes several stages: fastening the Mauerlat to the walls, assembling the truss trusses, installing the rafters on the floors, installing the ridge, fastening the batten. All wooden elements before assembly are carefully treated with any antiseptic composition and dried in the air.
For work you will need:
- timber 100x10 mm and 150x150 mm;
- boards 50x150 mm;
- boards 30 mm thick for lathing;
- ruberoid;
- metal studs;
- jigsaw and hacksaw;
- a hammer;
- nails and screws;
- square and building level.
in wooden houses Mauerlat functions are performed by logs of the last row, which greatly simplifies the workflow. To install the rafters, it is enough to cut grooves of the appropriate size on the inside of the logs.
in brick houses or buildings from blocks, the installation of the Mauerlat is as follows:
Mauerlat bars should form a regular rectangle and be in the same horizontal plane. This will facilitate further installation of the roof and provide the structure with the necessary stability. In conclusion, markings are made on the bars for the rafters and grooves are cut along the thickness of the bar.
When choosing a hanging truss system, it is necessary to assemble the trusses on the ground, and then install them above the floors. First you need to draw up a drawing and calculate the length of the rafter legs and the angle of their connection. Typically, the roof slope is 35-40 degrees, but in open, heavily ventilated areas, it is reduced to 15-20 degrees. To find out at what angle to connect the rafters, you should multiply the angle of the roof by 2.
Knowing the length of the run between the outer walls and the angle of connection of the rafters, you can calculate the length of the rafter legs. Most often, it is 4-6 m, taking into account the cornice overhang 50-60 cm wide.
The upper ends of the rafters can be fastened in several ways: overlap, butt and "in the paw", that is, with cut grooves. For fixing use metal pads or bolts. Next, the lower and upper puffs are mounted, and then the finished trusses are lifted up and installed above the ceilings.
The extreme trusses are attached first: with the help of a plumb line, the rafters are set vertically, the length of the overhang is adjusted and attached to the Mauerlat with bolts or steel plates. So that during the installation process the farm does not move, it is strengthened with temporary jibs from a bar. After installing the extreme rafters, the rest are exposed, keeping the same distance between them. When all the trusses are fixed, they take a board with a section of 50x150 mm, the length of which is 20-30 cm longer than the length of the eaves, and nail it along the upper edge of the slope. Do the same on the other side of the roof.
The first option: on the rafter leg, at the place of contact with the Mauerlat, a rectangular groove is cut out 1/3 of the beam width. Stepping back from the top of the box 15 cm, a steel crutch is driven into the wall. The rafter is leveled, the grooves are aligned, then a wire clamp is thrown on top and the beam is pulled close to the wall. The ends of the wire are securely fixed on the crutch. The lower edges of the rafters are carefully cut with a circular saw, leaving an overhang of 50 cm.
The second option: the upper rows of walls are laid out with a stepped brick cornice, and the mauerlat is placed flush with the inner surface of the wall and a groove is cut in it for the rafter. The edge of the rafter leg is cut at the level of the upper corner of the eaves. This method is simpler than the others, but the overhang is too narrow.
The third option: ceiling beams are extended beyond the edge of the outer wall by 40-50 cm, and roof trusses are installed on the beams. The ends of the rafter legs are cut at an angle and rest against the beams, fixing with metal plates and bolts. This method allows you to slightly increase the width of the attic.
The device of layered rafters
1 shows the cutting of the struts of the rafters into a bed laid on intermediate supports, and in Fig. 2 - supporting the rafter leg on the Mauerlat
The procedure for installing a layered truss system:
When the main elements are fixed, the surface of the rafters is treated with flame retardants. Now you can start making the crate.
A beam of 50x50 mm is suitable for the crate, as well as boards with a thickness of 3-4 cm and a width of 12 cm or more. Waterproofing material is usually laid under the crate to protect the truss system from getting wet. The waterproofing film is laid in horizontal stripes from the eaves to the roof ridge. The material spreads with an overlap of 10-15 cm, after which the joints are fastened with adhesive tape. The bottom edges of the film must completely cover the ends of the rafters.
It is necessary to leave a ventilation gap between the boards and the film, so first wooden slats 3-4 cm thick are stuffed onto the film, placing them along the rafters.
The next stage is the sheathing of the truss system with boards; they are stuffed perpendicular to the rails, starting from the roof eaves. The step of the lathing is affected not only by the type of roofing, but also by the angle of inclination of the slopes: the larger the angle, the greater the distance between the boards.
After the installation of the battens is completed, they begin to sheath the gables and overhangs. You can close the gables with boards, plastic panels, clapboard, waterproof plywood or corrugated board - it all depends on financial capabilities and personal preferences. Sheathing is attached to the side of the rafters, nails or self-tapping screws are used as fasteners. Overhangs are also hemmed with various materials - from wood to siding.
Video - Do-it-yourself gable roof
The roof of the house is one of the main components of the house. It is the upper structure of the building, without which it is difficult to imagine a comfortable stay. The main functions of the roof are protection from snow, rain and other precipitation, as well as keeping warm in the cold season and protecting against overheating in the summer months. In our years, there is a wide variety of roofs for every taste and budget. However, the most common and popular at any time are gable roofs, which are versatile, inexpensive and easy to install. We will talk about how to properly make a gable roof with our own hands in today's article.
The design of a gable roof is the most common in private construction. As the name of this type of roof implies, it is made in the form of two slopes or, more simply, in the form of a triangle. Such roofs are easy and quick to mount, they are quite durable and their appearance finds many fans, as it combines the look of a Russian hut and a modern building. With the necessary knowledge, you can do it yourself using the available tools.
The device of the truss system of a gable roof
The rafter system of a modern gable roof consists of many elements, each of which evenly redistributes the weight of the structure and correctly transfers it to the walls of the house. The figure below shows the construction of a gable roof of a house with its main nodes and elements of the truss system.
Let's analyze each of the elements shown in the diagram separately:
- The rafter leg is the main part in the design of the gable roof truss system, which is an inclined element laid through the entire roof. To create it, the most durable bars are selected, since the rafter leg, in addition to the weight of the roofing material and the batten, can bear the weight of precipitation in the form of snow;
- Mauerlat - the so-called "foundation" of the roof, which is the main support for the entire structure, which distributes the load on the walls. It is a bar or a thick board on which the rafter legs rest and which is a “gasket” between the wall and the roof;
- Puff (screed) - a spacer that lies at the base of the triangle, reinforcing strength. The puff performs a dual function, since the ceiling is mounted to its lower part;
- Runs - ridge ones are attached in the upper part, side ones in the center of the rafter legs. The task of the runs is to keep the rafter legs from falling and "folding";
- Rack - located in the central zone, directly under the ridge. Serves as a support, transfers the load to the tightening;
- Lying - an additional element on which the rack rests;
- Sheathing - boards that are mounted across the rafters. The crate is designed to lay roofing material on it (in the simplest case) and to provide additional rigidity to the entire truss system.
This roof scheme is universal for many buildings, but depending on the complexity of the structure, special elements can be added here to give stability and rigidity to the entire truss system.
The slope of the gable roof
Choosing an acceptable roof angle is a significant task, but for many builders it fades into the background, which is not true. The so-called gable structures with straight slopes are considered standard. The optimal angle of inclination of a gable roof is on average 30 ° -45 ° (the angle at the base of an isosceles triangle is taken as the basis).
The choice of the angle of inclination will determine how well the upper part of the house will withstand the following factors:
The first two points must be taken into account with particular care, since a miscalculation in the choice of roof slope can cost large financial and health losses in the event of a collapse.
Example: the larger the angle, the lower the load on the roof from precipitation, but the threat of wind damage increases due to the windage created (the roof can simply be blown off). The noise effect will also increase if metal is chosen as the roofing material.
- Roll materials: the number of layers is pre-calculated. The more of them, the lower you can make the roof. Double flooring - from 10-15°;
- Type-setting elements: these include tiles (including soft ones) and slate. The angle of inclination of the rafters is set from 20 °;
- Metal tile: adhere to a slope of 14 °;
- Decking: its sheets should be placed at an angle of 12 °;
- Ondulin: it is allowed to adhere to an indicator of 6 °.
Thus, when designing a roof and choosing the angle of inclination, it is important to know in advance what kind of roofing material you will cover it with. As you can see, the minimum angle of inclination of a gable roof can be 6 °.
Types of truss systems for gable roofs
Most truss systems for gable roofs are divided into two main types - hanging and layered. The first type is the most common. Let's take a closer look at both types.
Hanging rafter gable roof system
This type of roof structures is used exclusively when the walls of the house are at a distance of up to 10 m from each other and there are no supporting floors between them. Rafters (legs) are joined only with the side parts of the house in the form of a Mauerlat. The downside of a gable roof with hanging rafters is the possibility of damage due to bursting load, since stretch marks are not provided between the rafters in this case.
Sloping roof truss system
The difference between layered structures is the presence of an additional support in the form of a wall or other support. The layered truss system is installed with supports that are attached to the intermediate walls. This design allows you to close large spans without compromising the rigidity of the entire truss system.
Separately, it is worth talking about several more types of gable roofs. By design, a gable roof can be made in the following versions:
- symmetrical gable roof;
- asymmetric gable roof;
- double pitched roof.
The differences between these designs are clear from the name. Depending on the project of your house and design solutions, the roof can be asymmetric, that is, have different angles of inclination at the base. Such a roof is a little more difficult to install than a conventional symmetrical roof, which has an isosceles triangle at its base, but it will not be difficult for an experienced craftsman to build such a structure.
A gable sloping roof is also very common. The rafters of such a roof seem to be slightly broken off at the base. Such roofs practically do not retain precipitation and allow you to win in the attic space for.
Often, novice builders, before designing and calculating the purchase of material, have questions about how to find out the length of the gable roof rafters. To do this, it is important at the design stage to know what the width of the building will be in order to select standard-sized rafters so that they do not have to be spliced, sacrificing their bearing capacity. Along with this, you must not forget about the angle of the roof. All of these factors will eventually affect the length calculation.
So, to calculate the length of the rafters of such a roof, you need to divide the triangle formed by the rafter system into two right-angled triangles. Further, knowing the width of the building and the angle of the roof, you can determine the height of the gable roof ridge. Knowing the two legs of a right triangle and using the Pythagorean theorem, we can calculate the hypotenuse of each right triangle, which is the required length of our roof rafters.
As a result, to determine the final length, another 30-50 cm must be added to the obtained value to ensure roof overhangs.
All calculations made to determine the height of the ridge (it is also the height of the pediment) and the length of the rafters are clearly shown in the image:
From the foregoing, we can conclude that a gable roof is the cheapest and most versatile type of roof for a private house. There are examples when, with the help of improvised means, people erected a gable roof on their own alone. But still, we advise you to use the help of specialists in such matters, because a well-made roof over your head is comfort and coziness in the house.
Designing the construction of a gable roof of a house
The first and fundamental stage in the construction of a gable roof is its design. We have already said that the load perceived by the roof will depend on the choice of the angle of inclination of the roof, and, as a result, the choice of roofing material that can withstand precipitation and loads from these precipitations and winds.
At this stage, drawings of the design of the future roof are created and all necessary calculations are carried out. This is necessary, first of all, in order to have an idea about the general appearance of the roof and its dimensions, as well as to take into account all the expected maximum loads.
After designing, you will have the entire package of documents in your hands, which will indicate all the dimensions of the future roof, its area for the purchase of roofing materials, and the full range of lumber used in the construction. The presence of a list with the nomenclature of lumber will allow you not to spend extra money on its purchase, since lumber is the main expense item during the construction of the roof.
After all the design work is completed, they proceed directly to the construction work. Do-it-yourself work saves half the budget that could go to pay the builders. At the same time, it is important to remember that all norms and rules are observed so that the end result meets expectations.
Construction of a gable roof step by step
Mounting the Mauerlat of a gable roof
Mauerlat takes over the entire load from the roof and transfers it to the walls, therefore, a fairly thick and strong beam is chosen as a Mauerlat. The thickness is chosen based on the thickness of the wall on which it rests. As a rule, the thickness of the Mauerlat beam tends to be chosen equal to or close to the thickness of the wall.
It is necessary to lay the Mauerlat flush with the outer part of the wall, firmly connecting them together. To connect the Mauerlat with the wall, anchor bolts or wire are laid (poured into the armored belt) even at the stage of wall construction. If wire is used as a fastener, then after laying the timber, it is tightly tied around with this wire and remains firmly fixed in this form. In the event that anchor bolts were immured into the wall, through holes are pre-drilled in the Mauerlat, with which the beam is mounted on the bolts and tightened from above with nuts with wide washers.
It is also important not to forget to lay a layer of waterproofing material in the form of a gasket between the wall and the Mauerlat. As a waterproofing, as a rule, roofing felt or similar materials are used. More information about fixing the Mauerat is described in this video
After the base has been prepared, they begin to assemble the gable roof truss system. Installation of rafters can be done in several ways: install rafters immediately on the roof or perform some structural elements on the ground, and then lift them to the installation site using special equipment. Correctly setting the rafters on a gable roof with your own hands without the help of a partner is quite problematic, so it’s better to use help so as not to make a mistake and nullify all efforts.
To make it easier to fasten the bars, it is worth marking the attachment points on each wall and connecting the opposite walls with beams (beds), on which racks will be installed to support the rafters. A ridge beam is installed on the racks, which is a guide for installing the rafter system. In order to connect the rafters as accurately as possible, so that the entire skeleton of the rafters is the same, use templates. So you can avoid failures and distortions in the roof.
After installing the ridge beam, they proceed to the most critical part - the installation of rafters (already fastened together or separately). It is important to constantly monitor the level and evenness of the installation. The rafters are fastened together, as a rule, on nails or with the help of iron staples. Common schemes for placing rafters on a gable roof and attaching them to each other are shown in the figure below.
After completing the roof frame, it is required to install auxiliary fasteners to improve the rigidity of the roof. To do this, install struts and medium skates.
We invite you to watch a video that clearly shows the installation of rafters with your own hands for a gable roof.
The lathing of a gable roof in the simplest case is the installation of transverse boards on rafters for laying roofing material on it. But, as a rule, modern roofing is a more complex cake of various layers.
After installing the crate, the roof is covered with a layer of waterproofing, the layers of which are mounted overlapping each other, and the joints are fastened with adhesive tape.
The next step is to fix the counter-lattice - strips fixed at an angle of 90 degrees to the main crate. This is necessary to provide a ventilated gap in the roof pie to get rid of moisture.
At the final stage of the installation of a gable roof, the roofing is laid, the choice of which, as mentioned at the beginning of the article, depends on several factors, including the financial component
External work on the installation of the roof ends with the arrangement of gables, if they are not part of the walls. After that, they move on to interior finishing work and, if necessary. We will talk in detail about roof insulation in the following articles.
It is worth noting that building a gable roof with your own hands is not so difficult, the main thing is to make the calculations correctly and follow the instructions step by step so as not to miss important points during installation.
A brief video instruction on the installation of a gable roof is presented in the video:
