Which roof is better for a wooden house - the opinions of professionals. Roof ridge log and its purpose. Frame with load-bearing gables
The roof is the most important required element any structure, including log houses. Such designs should be certain conditions stability, reliability, heat and waterproofing. Roofing materials are subject to requirements for frost resistance, as well as for chemical and radiation resistance.
Roof structure
The location of the roof makes it an element that survives the elements more than others. It should become a reliable barrier against moisture and withstand the pressure of snowfall.
The roof is an important architectural component, which plays an important role in the appearance log house. Its functionality depends on the characteristics of the roof and the quality load-bearing structure.
The entire roof can be divided into several parts: rafters, lathing, roofing. It has inclined surfaces (ribs and slopes) and horizontal canvases (valley, ridge, gutter). The lower edge of the slope can be equipped with gutters.
roof shape
Various roof structures can be erected over log buildings:
Straight pitched
The simplest and least used option, whose design is based on walls of different heights.
gable
The most suitable variety for a log house, which differs not complex design and relatively light weight. It consists of rafters, Mauerlat, gables, ridge runs. Allows you to equip a full-fledged attic, which can be used for storage or other purposes.
hip
If you rearrange the pediments gable roof sloped towards the center, then you get a hip version. Such a roof allows you to provide a wide inner space, 100% wind and weather resistant.
Half hip
A more labor-intensive variety containing trapezoidal pediments covered with parts of the hips. The attic room has a vast area. The side walls of the structure can play the role of the walls of the room.
Shatrovaya
It has 4 edges combined at one top point. Is ideal option for houses of the correct geometric shape with the same length of the sides. Resistant to shrinkage and climatic manifestations.
Gable
A roof for a house made of timber can have unusual shape, an example of which is the tong option. The complexity of the design requires special building skills, so it is beyond the power of a novice master to create it.
Attic
Most practical option roofs and attic, which is also called a sloping roof. Allows you to save material, allowing you to get an additional square for housing.
Conclusion
The choice of a roof for a log house depends on the experience of the builders, the complexity of the structure and the wishes of the customer. When building a building on your own, it is better to stop at gable version roofs.
They say that the roof of the house is the fifth facade. Any owner country cottage knows well that on how well matched roofing, depends on the overall perception of the structure.
We have already told users of our site about the features of the choice of roofing.
But the roof is only the visible part of a complex system called the roof. The basis of any roof is a reliable and properly designed truss system.
In this material, FORUMHOUSE experts will talk about the main nuances of building a truss system for a wooden and stone house.
From this article you will learn:
- Where does the design of the truss system begin;
- What nuances must be taken into account when installing the truss system of a stone and wooden structure;
- Which structural elements truss system compensate for shrinkage wooden house;
- What features does the truss system of a log house have;
- What is a Mauerlat, and why is it needed in a stone structure;
- What are the requirements for the materials of the wooden truss system;
- What is a truss system built using LSTK technology.
General principles for choosing a truss system for a stone and wooden cottage
Often, novice developers believe that the choice of the design of the truss system can be left "for later", when the walls are already erected. Practice shows that this is fundamentally wrong. Roof even country house- This a complex system, consisting of many elements. The construction of rafters must begin at the design stage of the house.
Company manager "DDM-Stroy" Vera Vavilova, Moscow:
- The rafter system is the basis (skeleton) of the roof of the house. The quality and durability of the roof directly depends on how competently it will be performed. The manufacture of this structure, especially complex, must begin with its design. This is the only way that will allow you to take into account all the nuances and mount it with high quality.
The service life of the roof largely depends on how competently this structure is selected and mounted. It is also necessary to strike a balance between functionality and design refinements.
Director of company " Smart-Build» Pavel Orlov:
- The design of the truss system begins with the choice of the type of roof - mansard or cold attic. For mansard roofs the angle of inclination of the rafters is made from 35 degrees and above. For a cold attic, the base rafter angle is 25 degrees.
The simpler the shape of the roof, the simpler design, the faster it is in production, and the builders are less likely to make a mistake. Therefore, it is cheaper to build and easier to operate a roof that has simple form. Big square roofs, the presence of bay windows, the complex polygonal shape of the building significantly complicate and increase the cost of the construction of the truss system - it requires competent design and calculation.
The most cost-effective truss system is for a simple gable roof with a slope of at least 25 - 30 degrees.
The main factors that affect the complexity of manufacturing and the final price of the structure:
- Type of finishing roofing. The choice of one or another coating determines the composition of the roofing cake, the type of lathing and the load on truss system. The most popular roofs are metal tiles, soft roof, TsCH (cement-sand tiles), ceramic or seam roofing;
- The angle of the roof. It determines the loads, and this is the main factor in the design of the structure;
- Will the structural elements (decor element) be visible or will it be completely hidden behind the ceiling lining;
- Large overhangs at the roof significantly increase the cost of the truss system.
If the construction of the last floor of the house provides for large unsupported spans, then this entails an increase in the cost and complexity of the structure. In this case, depending on the distances, the truss system is performed using trusses.
- The presence in the project of large chimneys, skylights and other passage elements significantly affects both the complexity of manufacturing the structure and its price.
The design of the truss system (especially complex) should be handled by a person with relevant experience. This design is always calculated for a specific building. A common approach - "I will make a rafter, like a neighbor's" leads to disastrous construction results. The rafter does not withstand loads, which ultimately leads to costly alterations.
The design begins with the collection of expected loads on the roof.
1. Constant values, including the total weight of the roofing, thermal insulation material and fasteners;
2. Temporary values. These are the loads that are exerted on the roof climatic conditions especially snow and wind.
Designers lay the calculated step of the rafters in accordance with the expected load. Let's see how true this is.
Pavel Orlov:
- In my opinion, it is better to choose the pitch of the rafters for mansard, well-insulated roofs, based on the size of the insulation - so that the distance between the rafters is 1 cm less than the width of the insulation. This will make it easier to install.
The main load on which the calculation of the truss system is made is snow. Usually, all such structures are designed with a margin, but if there is any doubt (it is supposed to mount a heavy roofing - natural tiles etc.), you can slightly reduce the pitch of the rafters.
Although the snow load is not constant, the rafter must be calculated taking into account the totality of all loads acting on it. The calculation must be carried out not “back to back”, but with some margin in case of heavy precipitation (prolonged snowfall) or increased wind load.
The "work" of the truss system is significantly influenced by the choice of material for the walls of the house.
Features of the truss system in a wooden and stone house
The main difference between the rafters of a stone house and a wooden one is that stone walls have a structure that is not subject to shrinkage and deformation.
Pavel Orlov:
– The rafters of a stone house do not need deformation elements, since stone house practically does not shrink. main feature truss system of a stone house is the need for reliable fastening of the Mauerlat. IN wooden houses the role of the Mauerlat is performed by the wall.
Mauerlat is a roofing element (paired boards 50x150, timber 100x150 or 150x150 in size), which is laid around the entire perimeter of the upper wall of the house. The lower part of the rafters rests on the Mauerlat. Thus, the Mauerlat redistributes the point load transmitted from the rafters to the entire area of the upper part of the wall.
Also, when designing the rafter system of a stone house, it is necessary to take into account the thickness of the walls.
Pavel Orlov:
- The design requires the calculation of the permissible lateral load of the rafters on the wall with a fixed mauerlat.
A thin and high wall withstands less side load. This requires application for the supporting structure of the rafters additional elements- retaining racks and runs.
At wooden houses there are also some nuances that must be taken into account in the manufacture of the truss system.
Vera Vavilova:
- The main feature is that the walls, which are the basis for the rafters, shrink and change their geometry when the weather, temperature and humidity change outside and inside the house.
The main element that compensates for the shrinkage of the walls relative to the rafters is a sliding support (it is also called a sliding support). A sliding support is necessary in order to compensate for the distortions of the truss structure resulting from shrinkage of the wood. natural humidity.
The sliding support is a composite fastener, which includes a bent plate and a corner with a guide.
When the house shrinks, the rafter slides along the guide, thus compensating for all distortions general design rafter system of the house. The sliding part of the support is attached to the rafter beam so that there is a gap between it and the rafter. And the corner with the guide is screwed to the beam.
The slipper must be installed strictly perpendicular to the rafters, with a cut in the timber for the installation of its base. In order to shrink wooden structures to ensure the maximum travel of the slide, when it is installed, it is installed in the most extreme position.
The degree of shrinkage of a wooden house (and hence the amount of movement acting on the rafters) depends on the material used in the construction of the walls. Natural moisture lumber shrinks more, dry profiled lumber shrinks less, and glued lumber shrinks minimally, etc.
The walls of a house made of dry timber can shrink by 6% of their total height. If we are talking about the walls of a house built from a bar of natural moisture, then shrinkage can be even greater. Our article details what are the pros and cons .
Roof construction on log house
In addition to timber, wooden houses are built from the so-called log manual felling. Practice shows that the truss system of such a house has its own characteristics.
Dmitry Filippov, company specialist "Traditional Carpentry Technologies":
– In log houses based on a log house, a male-legged roofing system is used plus a “sliding” one. rafter part.
Roof in the house from a log, the device.
The roof for a log house has its own design features. Slegs - horizontal logs cut into a log pediment (the top of them is a ridge) - sit down together with a log house. After that, a lining from a board (aka a ceiling) is laid on the logs (lay down). Next, the rafters are mounted (in gable roofs ah, they are attached to each other on the ridge with sliding mounts). Then a roofing pie is formed - vapor barrier, insulation, waterproofing, counter-lattice, crate, roofing material is laid on top.
Dmitry Filippov:
- Thus, the rafter part with roofing cake are not tied to the frame, but as if “lying” on it, which allows the roof to retain its shape and integrity when the frame shrinks.
From our article you will learn about the types of structure and roof shapes of log houses.
Materials going to the rafters
In addition to taking into account the features of wooden and stone houses, when designing a truss system, it is necessary to understand the requirements for lumber.
Vera Vavilova:
- Pine and spruce will do. These are inexpensive and meet the basic strength characteristics rafters of a tree species.
It is important to follow and make sure that the lumber meets grade 0-2 according to GOST 8486. Rafter elements should not contain large falling knots, rot, wane and cracks. These defects weaken the bearing capacity of the truss system.
Pavel Orlov:
- Apply to the truss system edged wood conifers humidity up to 20%. All lumber used must be treated with certified bio-fire retardant impregnations.
If you put freshly sawn, raw wood on the rafters, then in the process of drying, the already mounted rafters will lead. This will cause deformation of the roof and roofing.
To avoid this, it is better to make rafters from calibrated chamber-drying lumber.
Another option for materials used to make rafters can be trusses and glued beams.
The use of these materials is determined by the project, based on the size of the spans and the expected load on the structure.
Vera Vavilova:
In this case, the elements of the truss system are manufactured at the factory and brought to the site in the form of parts ready for assembly.
This eliminates the so-called "human factor". It also saves time, because such a design is assembled faster than the one that is done on the site with the inevitable sawing and fitting of parts on the spot.
Factory truss systems are made strictly according to the project and specifications. Thanks to this, it is achieved high quality the foundations of the future roof, because the wood has already been treated with antiseptic agents, and the entire truss system is assembled according to the principle of the designer.
Another material used in the construction of truss systems of a stone or wooden house can be light steel thin-walled structures (LSTK). Such a rafter does not need to be treated with antiseptic agents, it has no big weight, long service life and high fire resistance. Consider the main features of the truss system built using this technology.
Deputy commercial director companies "Polymetal-M" Andrey Usachyov:
– The roof truss system, made according to the LSTK technology, includes galvanized rack-mount and guide profiles. If it is necessary to install a warm roof, a thermal profile is used (a profile with perforation along the entire length), which will remove the cold bridge and avoid heat loss.
The thickness and cross section of the profile used in the construction depends on the load that is expected on the truss system.
Each element of the system has strictly specified dimensions according to the project.
This greatly reduces assembly time and also avoids waste at the construction site.
Each profile is marked in accordance with the drawings and assembly instructions.
Andrey Usachyov:
– Thanks to the marking, assembly is simplified. Each profile is marked with a bulge (extrusion). Because the metal frame is fastened together with self-tapping screws, then thanks to the extrusion it is clear where the connection should be. Puklevka increases the rigidity of the assembled node, reducing the force acting on the cut, on the self-tapping screw.
In the FORUMHOUSE topic you can find out what begins. Also here you will find all the information about. Read how to build with your own hands, it is told.
Watch our video about roofing in Russian wooden architecture.
A wooden frame made of timber or logs is a traditional building for Russia, which is used both for housing and for utility rooms. The process of assembling such a building takes place according to long-known and constantly improving technologies, so the house turns out to be cozy, warm and comfortable for living. special attention the device of the truss frame deserves, because many qualities of the roof and features of functioning depend on its strength and reliability gable roof. It is important to know how to install the rafters on the log house so that they can withstand all the necessary loads and serve correctly for many years.
It is customary to call the rafter system the roof frame, a unique set of supporting elements that give it shape, slope and sufficient bearing capacity. Such a roof foundation is made of dry and durable wood that has been treated with antiseptic preparations, or a metal profile. This frame evenly distributes all the loads falling on it between the bearing walls. The following types of rafters are used on log cabins:
- Hanging. Such rafters have only one point of support - Mauerlat, they rest against each other with the free end of the rafter leg, thus forming a kind of triangular arch. This design for a gable roof it is used when the log house inside does not have load-bearing walls on which it would be possible to install racks. This truss system experiences a sufficient load on expansion, which is why it includes various kinds of puffs designed to compensate for such stress. Hanging rafters are distinguished by their massiveness and some complexity of installation.
- Layered. This type of rafters has two points of support - the same Mauerlat and ridge run supporting uprights. This design is used provided that inside the log house there is at least one bearing wall or a series of columns onto which the skate can be unloaded. Laminated rafters are only under deflection load, so it is easier to install them.
The log house is made from the well-known natural building material - wood, which has unique properties. At the end of the assembly of the structure, the moisture content of the tree begins to level out, so the truss system usually shrinks over about 4 years of operation.
Important! Most significant changes dimensions of the object occur in the first year, so it is recommended to fix the rafters only after this time has passed.
Mounting methods
Fastening rafters to a log house made of wood is a technologically rather complicated process, from correct execution which directly affects the strength, durability and integrity of the roof. When working, it should be borne in mind that the wood tends to settle during the drying process, so the geometry of the entire building changes. Besides, given material subject to thermal expansion, so it is not necessary to fasten the rafters to the log house too rigidly in order to avoid deformation. Rafter legs to the log house can be fastened with two types of fasteners:
- Movable. Such rafter fasteners are called special metal fasteners, which allow the structure to be given a certain degree of freedom in movement and resizing. With the help of them, the rafter legs do not receive a load on the deflection, and can also respond to the slightest temperature fluctuations, adjusting to the geometry of the log house. These products allow you to attach truss frame until the end of the shrinkage of the building without the risk of deformation.
- Stationary. Fixed-type fasteners do not leave a margin of mobility when installing rafters, however, they guarantee the strength and rigidity of the structure to a greater extent. The role of such fasteners are nails, wooden dowels, self-tapping screws, metal staples, lining, and so on.
Important! A log house made of wood has one extremely unique ability - it can, as the people say, “breathe”. This means that the log house itself can regulate the humidity in the room, which is why its dimensions do not have a clear fixation.
Movable fasteners that can adapt to the shrinkage of walls and changes in the size of the material as a result of reaction to thermal effects - best option fastening to the frame of the rafters.
Assembly methods
After shrinkage wooden frame finally passed, they begin to establish the truss system and the construction of the roof. This process difficult and painstaking, especially if you work alone. There are 2 ways correct installation Mauerlat frame:
- Installation of finished roof trusses. This process consists in assembling the necessary truss trusses simply "on the ground" with their further lifting to Right place assembled installations. To lift such massive and heavy structures, special equipment is needed such as a crane, aerial platform, a tractor, and the like. This is usually how layered rafters are installed, weighing less than other structures.
- Assembly of farms "on top". In the presence of a large weight and dimensions of the structure of the truss system, along with the absence special equipment, farms are assembled right on the spot. The disadvantage of this technology is the complexity and inconvenience of such work.
It is worth considering that experienced craftsmen quite rarely they use the method of installing ready-made truss trusses, because these designs do not allow achieving high accuracy in fitting elements, although they save time significantly.
The rafter system on a log house, albeit a fairly common option on the territory of Russia, but the installation of rafters should always be approached with all responsibility, because the reliability of the gable roof and the entire building as a whole depends on it.
In this article, we will talk about the design features of the roof of houses built of wood, or rather log houses and houses made of timber. What unites them is that they are subject to shrinkage after assembly.
Here on all pictures will be shown , simply because log walls I have a hard time drawing on the computer. In general, everything that will be said applies to equally and to timber houses and to log.
So everything wooden buildings depending on the features of the construction of the roof of houses can be divided into two types:
With frame gables;
With gables made of timber or log.
I Option:
If the roof is made with frame gables, then in principle it is no different from the roofs of brick houses, which we considered in previous articles.
Let's say we have a box at home, shown in Fig. 1:
Picture 1
We can build either a gable roof with layered rafters, with the latter resting on the floor beams (see Fig. 2):
Figure 2
Or on such a house, we can make a roof with hanging rafters, with the latter also resting on the floor beams, as shown in Fig. 3 or as described in detail
Figure 3
We see that here there is no ridge beam resting on the middle load-bearing partition. The upper ends of the rafters rest on each other through the ridge board. The role of puffs is performed by floor beams.
We can also use both of these schemes, only to lean the lower end of the rafters not on the floor beams, but on the Mauerlat. Rather, on the upper crown of the box (log), because in wooden houses, it is he who is the Mauerlat. IN this case when using hanging rafters, you will need to add puffs. Similar roofs have been previously described in articles And .
So, we have four schemes. I think we have already talked enough about the sequence of erecting gable roofs and the necessary calculations in previous articles. Which scheme to choose is up to you. From the point of view of reliability and simplicity of construction, I would prefer the very first option - layered rafters supported by floor beams (see Fig. 2), of course, provided that we have an average load-bearing partition.
II Option:
Now let's talk about the features of the roof of houses with gables made of timber or logs. Their main feature is that the pediment is subject to shrinkage, i.e. over time, its height changes (decreases), and the angle of inclination of the slopes also changes accordingly (also decreases). What can this lead to? Let's look at Figure 4:
Figure 4
We took the same box at home and made pediments out of timber. They put a ridge beam on them to install layered rafters. Of course, with such a length, it is obvious that the skate will not survive. Someone here might come up with the idea to put vertical racks under it, resting them on the middle partition.
But let's just say, this idea is very bad. The height of these racks will not change over time, because. wood shrinkage along the fibers is only 0.1-0.3%. The height of the gables can be reduced to 8-10%. Those. with a pediment height of 1.5 meters, it can sit down by 12-15 cm. Imagine what will happen to the roof.
In this regard, if we want to make pediments from a bar (log), the middle partition must be assembled to the very top and settle along with the pediments. For example, Figure 5 shows several houses where the ridge beam will lower evenly when the house shrinks:
Figure 5
On last photo we see that the ridge beam on the balcony is supported by a vertical post. But this rack is installed through a special screw shrinkage compensator of the log house.
Now a little about fixing the lower ends of the rafters on houses with gables made of logs or timber.
If we imagine the process of shrinkage of the pediment and, accordingly, the lowering of the upper end of the rafter, it becomes obvious that the lower end of the rafter will be displaced relative to the wall, i.e. like sliding down. But how in this case to fix the rafters to ensure its mobility. The methods of attaching the rafters to the Mauerlat, which we considered earlier, are not suitable here. And the scheme with the support of the rafters on the floor beams in this case is not applicable at all.
How this connection is made is shown in Figure 6:
Figure 6
A shallow cut is made on a beam or log (the stop is not cut down) and a special sliding support is installed. There are two things to keep in mind. The "slider" should stand perpendicular to the rafter, and during installation it should be cocked to the lowest position (as shown in the photo above) to ensure the maximum possible travel of the rafter when the gable shrinks.
Also, the connection of the rafters to each other at the top on the ridge has its own characteristics. They should be able to slightly change the angle of inclination during shrinkage. The two most simple ways How to ensure this is shown in Figure 7:
Figure 7
So let's sum it up. In roofs with gables made of logs or timber, the rafters must be able to move during shrinkage and nothing should interfere with this. No puffs and additional intermediate racks are placed on such rafters. Connections are also made movable.
The roof of a log house is no less important than the foundation and walls. Modeling and bringing to life the construction of the roof of a log house is not an easy task and beyond the power of home-grown craftsmen, excluding small country houses with a simple shed type. The popular types of truss systems that make a log object individual are described below. Owner's choice.
There are several types roof structures depending on the device, material and purpose:
- Straight pitched;
- gable;
- hip;
- Half hip;
- Tent;
- Forceps and multi-forceps;
- attic;
- Combined.
More on each below.
Straight pitched roof
To put it bluntly, such an option is devoid of wisdom. Yes, and the appearance leaves much to be desired. It is mainly used in outbuildings, garages. Relies on walls of different heights. Even an amateur can build such an option. Cheap and angry.
The most practical option for a log building. Not too heavy and simple design.
Depending on the dimensions of the object, such roofs of log houses are built using reinforcement along the rafters, mauerlat, ridge runs and gables, assembled on the ground and raised up in finished form. Under such a roof, you can arrange a full-fledged attic for storing items or organize an area for other non-residential purposes.
Usually, sliding supports are used in the rafter system - the beam is not attached tightly to the corresponding mates, but using a special device that allows the massive house not to deform the roof during shrinkage. Otherwise, such a system is called - a sliding roof of a log house. The measure is invaluable when building a facility from scratch.
Having presented the gables of a simple gable roof at an angle to its center, the owner receives this option. Present dormer windows. The advantages of this type are a wide space inside, absolute resistance to bad weather, strong winds and seismic activity of the soil.
The construction of the roof of a log house of this type is difficult to perform and should be left to professionals. As for the appearance - such a roof, combined with a beautiful roofing material it looks great and gives the impression of a fortress, which it really is.
Half hip roof
An even more labor-intensive option. Interesting for its appearance- the pediments are made in the form of trapeziums and are covered with parts of the hips. The attic in this case is extensive and the side parts of the roof can become the walls of the room.
Perfect alignment of edges at one point. Strongly recommended for buildings that have the right geometric shapes with equal side lengths.
The advantages of other pitched options are resistance to shrinkage and external manifestations of the climate. This is one of the varieties of the hip roof, that is, it will require professional knowledge during the device.
Gable and multi-gable roofing
In a timber or log house, the roof, as conceived by the designer and designer, can become a work of art. This feature was obtained by gable options used on objects that are complex shapes - polygons, bay windows, ledges, turrets.
Covering them with one plane is too problematic, and sometimes impossible. The design of the rafters does not lend itself to forces home master, which does not have basic knowledge about the specifics of construction.
mansard roof
Most practical design roofing and attic space. Otherwise, such options are called - a log house with a sloping roof. The practicality lies in saving material - solid whips - for building a house, with the possibility of obtaining additional living space.
Combined roofs
Different styles used in the construction of a log house should be covered with special roofs that combine all of the above types. So that this does not look like a dissonance, such a truss system is determined even at the design and computer modeling stage.
It will not be possible to independently make such a roof, in principle, damage and waste of material. People who choose this type of roof anticipate spending or increasing their budget in advance.
How to make a roof on a log house yourself
If for some reason the owners cannot use the services of professionals, and have chosen a simple version of the system, then trying to do the work on their own is still worth it - you cannot leave a log house without a roof for a long time. So, a simple gable system:
- For rafters, a beam with a cross section of at least 150 mm is used. Accompanying elements can be more modest parameters, bearing - never.
- The upper crown is removed and a Mauerlat is installed in its place - a strapping lower bar.
- Finished rafter legs, cut at an angle for connection, are mounted on sliding supports and among themselves, if a ridge run is not used. Go beyond the crowns, they should be 20 - 25 cm.
- The pediments are assembled on the ground and raised into place in the form of shields.
- The crate is stuffed for the insulation tab, heat and waterproofing is installed.
- Roof line. It is offered to owners of private housing in numerous options - soft, ceramic, metal. It all depends on the purpose, choice and purchasing power of the client.
