said that the roof of the house - this is the fifth facade.Any owner of a country cottage is well aware that on how well matched roofing depends on the overall perception of the house.
We already told users about the features of our site selection of roofing.
But the roof - this is only the visible part of a complex system called the roof.The basis of any roof is secure and properly designed truss system.
In this article, experts talk about the main FORUMHOUSE nuances erection truss system of wooden and stone houses.
In this article you will learn:
- How to start the construction of roof system.
- What nuances to consider when installing the truss system of the stone and wooden house.
- Which features truss system compensate shrinkage of the wooden house.
- What features have chopped roof system at home.
- What mauerlat, and what it is in a stone house.
- What are the requirements to materials wooden truss system.
- What truss system, based on technology LSTC.
General principles for selection of trus
Often novice developers believe that the choice of the construction of roof system can be left "for later", when it will be built the wall.Practice shows that it is fundamentally wrong.The roof of the house - is a complex system composed of many elements.Construction of the roof system should start at the stage of designing the house.
management company «DDM Story» Faith Vavilov:
- truss system - is the foundation (the skeleton) roof of the house.On how skillfully it is performed directly depends on the quality and durability of the roof.Production of roof system, particularly difficult, must begin with its design.This is the only path that will take into account all the nuances and accurately mount truss system.
On how skillfully chosen and installed truss system, depends largely on the life of the roof.It is also necessary to strike a balance between functionality and design refinements.
head of the company « Smart Story» Pavel Orlov:
- Design roof system starts with selecting the type of roof - loft or cold attic.Typically, for roof trusses roof angle is between 35 degrees and above.For cold attic base value angle rafters is 25 degrees.
The simpler the shape of the roof, the easier Truss, the faster it is to manufacture and builders less likely to make a mistake.Therefore cheaper to build and easier to operate the roof having a simple form.A large area of the roof, the bay windows, a complex polygonal shape of the building considerably complicate and increase the cost structure truss system.This truss system requires competent planning and calculation.
most cost-effective truss system - from simple gable roof with a slope of at least 25 - 30 degrees.
main factors that affect the complexity of manufacturing and the final price truss system:
- Type finish roofing.The choice of coating determines the composition roofing pie, lath type and the load on the truss system.The most popular roofing - it's metal, soft roof, CHR (cement-sand tiles), ceramic, or folded roof.
- Roof pitch.It defines the load, and is a major factor in the design of roof system.
- Will visible elements of the truss system (truss system as an element of decor), or it is completely hidden in the headlining.
- Large overhangs at the roof significantly increase the cost of roof system.
- If the construction of the last floor of the house has large unsupported spans, this entails a rise in the cost and complexity of truss system.In this case, depending on the distances, truss system operate using trusses.
- presence in the project of large chimneys, skylights and other migratory elements significantly affects both the complexity of the manufacture of roof system and on its price.
Designing truss system (especially difficult) is to deal with a person who has relevant experience.Truss system is calculated for a specific house.A common approach - "do stropilku as a neighbor," often leads to disastrous results.Rafter system can not withstand, which ultimately leads to costly rework.
Design roof system begins with the collection of the estimated load on the roof.
These loads include:
1. constant, including the cumulative weight of the roofing, insulation material and fastener elements.
2. Time value.This load, which have a roof on the climatic conditions, especially snow and wind.
Typically, designers lay a settlement step rafters in accordance with the intended load.Is this true?
- In my opinion, a step for roof rafters, well-insulated roof is better to choose based on the size of insulation - so that the distance between the rafters is obtained at the 1 cm smaller than the width of a heater.This will simplify its installation.
main load over which the calculation of roof system - snow.Usually all truss designed with a margin, but if there is any doubt (for example, to mount the heavy roof covering - natural tile), you can slightly reduce the pitch of rafters.
Although the snow load is intermittent, the truss system should be calculated taking into account the totality of the loads acting on it.The calculation of roof system must be conducted not "butt", but with some margin, for example, in case of heavy rainfall (prolonged snowfall) or high wind load.
In addition, the "job" roof system is significantly affected by the choice of material for the walls of the house.
Features truss system in the wooden and stone house
main difference truss system of the stone houses from wood - that the stone walls are not subject to shrinkage and deformation.
- Rafters stone house need not be deformation elements as stone house sits almost.The main feature of the stone house roof system - is the need to secure reliable mauerlat.The wooden houses mauerlat role performs the wall.
mauerlat - an element of roofing (50h150 paired board, timber size of 100x150 or 150x150), which is placed around the perimeter of the top wall of the house.On the lower part rests mauerlat rafters.Thus mauerlat redistributes point load transmitted from the trusses to the entire upper area of the wall.
also in the design of the stone house roof system must take into account the thickness of the walls.
- Any design truss system requires the calculation of allowable lateral load on the trusses wall with fixed mauerlat.
thin and high wall stands a smaller lateral load.This requires the use of additional trusses support structure elements - retaining struts and girders.
have wooden houses and there are nuances that need to be taken into account in the manufacture of roof system.
- The main feature of the roof system of a wooden house - that the walls, which are the basis for the trusses, shrink and change its geometry at change of weather, temperature and humidity inside and outside the home.
main element that compensates for the shrinkage of the wall with respect to the rafters - a sliding support (it is called skolzyachka).Sliding support is needed in order to compensate for the distortions of truss construction, resulting shrinkage of the wood of natural humidity.
sliding support - a composite fasteners, which includes a bent plate and the area with a guide.
shrinkage house rafter slides along the guide thus offset all the distortions of the general construction rafter of the house.Moving part of the support it is attached to the rafters so that between it and the rafter gap remained.A corner with rail is screwed to the beam.
Skolzyachka must be installed exactly perpendicular to the rafters, with gashes in the tool bar for the installation of its base.In order to shrinkage of wooden structures to provide maximum stroke skolzyachki at its installation it is set to the most extreme position.
degree of shrinkage of the wooden house (and hence the magnitude of shifts acting on the rafters) depends on the material used in the construction of walls.For example, a bar of natural humidity gives greater shrinkage, dry profiled shrinks less, and glulam gives minimal shrinkage.
walls of the house, built of dry timber may shrink by 6% of their total height. When it comes to the walls of the house, built of timber of natural humidity, the shrinkage can be more. about what the pros and cons have dry profiled timber and conventional, gives details in this article .
Besides timber, wooden houses erected the so-called handmade log cabin.Practice shows that the truss system of the house has its own characteristics.
Dmitry Filippov, specialist company «Traditional carpentry techniques» :
- The log houses based on the log-applied Samtsova slegovaya system device plus roof "sliding" part of the truss.
feature of this design that came down - horizontal logs vrublennye log in pediment (top of them - a fad) - sit together with the framework.Next on the slug is placed knocked out of the board (aka ceiling).Then they assembled the rafters (in gable roofs are fastened to each other on the ridge sliding mounts).Then formed a roofing pie - steam, heat insulation, waterproofing, kontrobreshёtka, sheathing, roofing material is laid on top.
- Thus, with the roof truss of the pie is not tied to the frame, as it were, "lie" on it, which allows the roof shrinkage log to keep its shape and integrity.
On peculiarities of the choice of material for the construction of a wooden house gives details in this article .
materials reaching the rafters
addition to accounting features wooden and stone houses, in the construction of roof system is necessary to understand the requirements for lumber.
- For the manufacture of roof system is suitable houses pine and spruce.It is inexpensive and meet the basic strength characteristics rafters wood.
important to trace and make sure that the timber truss system posted 0-2 grade according to GOST 8486. Elements of the rafters must not contain large loose knots, rot, cracks and wane.These defects weaken the carrying capacity of truss system.
- On the truss system, usually used edged softwood humidity up to 20%.All used timber to be processed by certified ognebiozaschitnymi impregnation.
If you put on freshly sawn rafters, wet wood, the drying process is already mounted rafters will lead.This will cause deformation of the roof and roofing.
To avoid this, elements of roof system is best done from the calibrated timber drying chamber.
Another embodiment of the materials used for the manufacture of roof system can be a farm and laminated beams.
use of these materials is determined by the project, on the basis of the value spans and the expected load on the structure truss system.
- In this case, elements of roof system is made in a factory and brought to the site in the form of parts ready for assembly.
This eliminates the so-called "human factor".Also saves time becausethis truss system is going faster than the one made in the area with the inevitable sawing and fitting the parts in place.
Factory truss system made strictly on the design and technical specifications.Due to this, a high quality of future base of the roof, sincewood already processed antiseptic agents, and the whole truss system is going on the principle designer.
Another material used in the construction of roof systems, stone or wooden house may be light steel thin-walled structures (LSTC).This truss system does not need to handle antiseptic means, it has a light weight, long life and high fire resistance.Consider the main features of the roof system, built on this technology.
Deputy Commercial Director «Polymetal-M» Andrey Usachev:
- The roof truss system, made by technology LSTC, are galvanized rack and guide profiles.If necessary, the device applies thermo warm roof (profile with perforations along the entire length), which will remove the bridge to avoid the cold and heat.
thickness and cross-section used in the design of the profile depends on the load that is expected on the truss system.
Each system component has strictly defined on the project size.
This significantly reduces the time of assembly truss system, and avoids waste on site.
Each profile marked in accordance with the drawings and assembly instructions.
- Through labeling, simplified assembly truss system.In addition, each profile applied puklёvka (pads).Sincemetal frame fastened together with screws, thanks to clear pads where there should be a connection.In addition, it increases the rigidity of the assembled puklёvka node, reducing the force acting on the slice on the screw.
How to start the construction of the roof?The answer to this question FORUMHOUSE users can learn in this topic.This includes information on the truss system.On how to build roof trusses with their hands, then it tells.
detailed photo report on the recast of the wooden house roof system is presented here.Can the incorrect installation of truss system collapsed stone wall at home?The answer can find here.
Roofing in Russian wooden architecture, what is it?It is shown in this video.On the truss system features wooden and stone houses is told here and here.