Truss system roof roof types and device design

Due to the erection of a mansard roof, may significantly increase the usable space of low-rise private houses. However, this is a very laborious process which requires the preliminary calculation, the observance of certain rules and techniques. Properly designed truss system mansard roof is the key to creating comfortable, reliable, functional and durable houses.

The mansard roof allows you to obtain additional comfortable and spacious room attic type

The contents

  • 1 Truss mansard roof system: design features
    • 1.1 Schematic mansard roof
  • 2 Elements of design mansard roof
  • 3 Types of mansard roofs
    • 3.1 Lean-to Dormer roof. Photos of successful projects
    • 3.2 the Gable mansard roof: construction
  • 4 Truss system attic roof. Drawings classic version
    • 4.1 calculation of the mansard roof
  • 5 Windows for mansard roof
  • 6 Methods of installation of mansard roof
    • 6.1 How to build a mansard roof in the traditional way?
  • 7 Technology insulation of mansard roof
    • 7.1 Important rules for insulation of mansard roof
    • 7.2 How to insulate a mansard roof: progress
    • 7.3 Varieties of insulation for the attic roof. What insulation is better?
  • 8 creating a mansard roof with his hands, step by step. Video instructions

Truss system roof roof: design features

Before the construction of the attic needed a good project. Appearance of your future roof should be in harmony with the General appearance of the building. There are several varieties of the design of the truss frame, depending on the type of roof, the pitch of rafters and attic roof. Opt for a specific configuration, you should be aware of any structural elements comprises a frame system. It is the supporting skeleton of the roof, and can withstand not only the weight but also the influence of precipitation.

Truss mansard roof system has its own configuration features that are important to consider in planning and construction

Proper installation of roof system provides the reliability, functionality and durability.

When creating the project mansard roofs should:

  • to perform the correct calculation of the load on the support load-bearing walls and the Foundation, preventing its excess;
  • to choose quality thermal insulation to avoid uneven heating;
  • to choose a good sound insulation due to properly chosen roofing material;
  • to choose a good waterproofing;
  • choose a lightweight lining materials for finishing the attic space.

Scheme mansard roof

The truss system can have a sloping or hanging design. Structures in the hanging rafters are based on mauerlat and ridge run. To distribute the load on the rafters are installed the upper and lower torques. When the slope length of more than 4 m, to prevent sagging in the lower part of the structure of the truss legs propped up with struts and braces. The main advantage of this design is that all its elements are placed in unused areas of the attic, which creates more space.

Correct and precise calculation of the mansard roof allows to obtain a reliable and durable design

The sloping design is used in homes where in the middle of the building is a load bearing wall, which supports the construction of the legs. On the inner support structure is laid groundsel, which plays the role of mauerlat, and he mounted rack that holds the ridge run. This system is used for large areas of the mansard roof of a private house, which you can see in the photo. Here you can use roofing materials with a large weight, such as slate or ceramic tile.

There are projects mansard roofs of private houses, where it is used both roof systems. To release free space frame elements can be offset to one side, where they will be used as the basis for the walls, and Rigel suitable for lining the ceiling. Some architectural styles beams and posts can be used as decorative elements.

For the arrangement of large eaves, mansard roof is done with a focus beyond the supporting walls. Here does not install mauerlat. The system is mounted with the use of beams. Be sure to set the strut, a special rack cut into the beams and rafters are fixed using a reliable anchor connection, and wire twisting.

Diagram of truss system attic roof

Elements of design mansard roof

Truss system under the mansard roof consists of the following structural elements:

  • the mauerlat;
  • the rafters or beams of the uprights;
  • uprights;
  • runs;
  • ridge beam;
  • sheathing;
  • additional beams, regala and runs.

The basis of the whole structure of the roof is mauerlat, which consists of wooden beams of square section, fixed to the external walls of the building. These boards are mounted the other elements of the frame of the mansard roof. The primary purpose of mauerlat is the perception and the uniform distribution of the entire load from the General system of roof-bearing walls of the building.

Rafter leg or rack of beams form a frame of the roof structure. For these items, you must pick boards that can withstand the load of the roofing together with an outer coating. To maintain stands of beams or rafters purlins are used, mounted at an angle. Vertical posts hold the Central part of the truss boards, protecting them from bending. They also provide support for the ridge beam.

Diagram of the device of the ridge mansard roof

To ensure the rigidity of the future roof structure on the long roof truss systems are installed ridge beam. The crate is an additional wooden structure that is attached to the truss system and is the basis for a future roof.

Types of mansard roofs

Today there are several options of mansard roofs, which have a different design of the truss frame:

  • single;
  • gable;
  • polylines consist of two or more rays with different angles of inclination;
  • a gambrel has two triangular ramp with the short sides of the roof and two trapezoidal slope with long;
  • poluvalmovaya have two short front hip over the front part of the roof;
  • the dome is characterized by round or polygonal shape;
  • vaulted have a sectional arc shape.

An example of successful implementation of complicated mansard roof design

Shed roof is the most simple in execution. He is frequently approached when it is necessary to make the attic into a small country house. The most popular among other types of mansard roofs of private houses photos clearly confirm this, is the gable roof. Its design and construction is straightforward. Especially if we are talking about a gable roof.

When choosing a sloping roof, it is possible to obtain a large, functional and comfortable attic room with no additional work associated with the construction of the walls. Today, many prudent owners of private houses prefer truss system gable roof under the corrugated sheet, a construction which does not require numerous technological and technical tricks and unnecessarily high consumption of resources for construction materials.

The most difficult to install are hipped, arched and domed mansard roofs. Their device requires a professional approach. Data mansard roof, photos of private homes clearly show, have unusual and highly aesthetic design. They are characterized by a large number of pitched breaks that are device ends. Diagram of the truss system demonstrate the peculiarity and uniqueness of this design. The unsatisfactory state of each of the valleys (internal angles) can be a potential danger to the integrity of the entire roof.

Hipped mansard roof of a complex configuration requires a specific miscalculations of the load on the Foundation and walls of the building

Lean-to Dormer roof. Photos of successful projects

The most simple, reliable and cheap option is a lean-to roof mansard. The result is an unconventionally designed building. This type of roof is used for industrial and commercial buildings. Also, often used for single storey small houses. Here you can use all roofing materials.

Design involves the creation of a high mansard roof Windows. In this construction, missing strong point, which simplifies its installation. Mauerlat fixed on the walls with different levels, due to which is formed the bevel. It is based of the beam.

An example of a successful project shed Dormer roof

The angle of the slope must be in the range of 35-45 deg. The less the slope, the more snow will accumulate on the surface of the roof that will require additional supports and strengthen the girders. Besides, it will greatly reduce the roof space. Design able to withstand strong winds with proper orientation of the roof slope, which is necessary to improve the stability of the structure.

A useful tip! If between opposing bearing walls at a distance of not more than 4.5 m, it is possible to mount the supporting elements, and just put on the wall of long wooden beams. This further reduces the cost of construction of the roof.

This type of roofing involves the use of simple elements to create a ventilation of roof spaces. Enough to sew two perforated soffit overhang, or mount the ventilation grille.

Shed roof is more resistant to weathering, but during the construction it is necessary to consider the wind direction in the region

However, it is not necessary to choose a single slope roof for narrow buildings where it is impractical to arrange the attic floor that way.

Gable Dormer roof: construction

The gable roof is the most common and rational solution that allows you to get a comfortable attic. Pictures of houses with a mansard roof this configuration confirm the relevance of the design.

The gable roof is one of the most popular design options in the construction of the attic floor

Design and construction of a gable mansard roof with his hands does not cause any difficulties. It is formed by two inclined planes (ramps), which intersect in the region of the ridge at a certain angle. Through proper selection of the optimal angle can create a reliable protection of the building from heavy rainfall, strong winds, excessive snow pressure during heavy snowfalls.

There are varieties of configuration of the truss system gable roof roofs:

  • a symmetrical gable roof is a classic option that gives you the opportunity to evenly distribute the load-bearing walls and support the roof. The disadvantage of this design is the presence of sharp corners, which take free space of the attic;
  • the asymmetric roof is a custom design where the ridge can be displaced to one side. If one angle is more than 45 deg., get a very spacious attic room. However, the calculations should take into account uneven distribution of load on mauerlat and load-bearing walls.
  • sloping mansard roof has a surface of rays, a bend in the middle, forming faces, resembling two rectangles.

In the case of construction of mansard roof with a non-standard configuration of the truss system is to resort to the services of specialists

Truss system roof roof. Drawings classic version

When the question arises, how to make a mansard roof houses with their own hands, should choose the most simple in execution and practical for further use option. Therefore, private homes are the preference for sloping roofs.

This design allows you to not only create a significant area attic room, but with overhangs that drop pretty low, to protect the upper part of the building walls and foundations from rain. Besides, this is a good solution for creating original exterior of a private home.

Related article:

The attic insulation from the inside, if the roof is already covered: materials and technologies

How to choose a suitable material. How to avoid common errors. Phased carrying out work with your own hands.



The angle of sloping of the roof depends on the region, climatic conditions and the choice of roofing material. Classic sloping mansard roof, where the drawing clearly shows, is the ratio of the slope of the upper slopes to the floor plane in a 30 deg. and the bottom is 60 degrees. The angle of the side surfaces can range from 45 to 80 degrees.

The classical scheme of the device roof system attic roof

A useful tip! For regions characterized by strong winds, it is better to arrange a flat roof. Because, the larger the slope, the greater the windage it creates.

Based on these data, the parameters of the house, and what is the ceiling height in the attic room should not be less than 2 m, it is possible to calculate all parameters. In the classic version you can not take into account the load on the lateral surface from rain, as they will stay at the top of the roof.

The calculation of the mansard roof

On specialized sites, you can find a drawing of a broken mansard roof with his hands for a small house. It can be taken as a basis for future calculations including the calculation of the mansard roof, loads of the elements of truss construction and of construction materials.

For the calculation of the mansard roof, you can take advantage of years of experience of experts, who have repeatedly built classic sloping ceilings and can tell you what material you want to use. It depends on many parameters of the truss frame. The calculation of the required amount of lumber to create the roof system is to determine the height and width of spans, and consequently the number of wooden bars, which are multiplied by their height.

Accurate planning and estimation of construction plans — a pledge of reliability and durability as the roof and the whole building

The width of the insulation depends on the step between the rafters, which should be 3 cm less than the width of the insulating material to reduce waste and simplify its installation. Boards for the rafters also are selected based on the thickness of the insulating material. In the case of using stone wool insulation, with thickness 200-250 mm and create the required air gap of 20-30 mm, the minimum Board width is 230 mm. the thickness of the rafters must be 50 mm. more

For beams and struts, you should choose the beam parameters 100×100 mm, which will allow you to create a solid and reliable design even for areas in difficult weather conditions.

To calculate the amount of insulation and roofing materials use a mathematical formula to determine areas of geometrical figures, which make up a particular type of mansard roof.

Today on the Internet you can perform an online calculation of the mansard roof. For starters the type of a mansard roof, the scheme of roof system, thermal insulation and roofing material and enter the requested geometrical parameters. For more accurate result you should use the services of a specialist that not only calculates all the loads and sizes of building elements, but also will tell you what material you should choose.

For the calculation of the mansard roof and the number of required materials you can use the online calculator on the Internet

Windows for mansard roof

Loft differs from the usual areas the fact that her wall is a truss frame, which consists of certain roof surfaces, which is clearly shown in the drawings of the mansard roofs. This affects the design of the window for this room, which is good to pass the natural light, and at the same time to keep the load in the form of strong winds or heavy rainfall. This is due to the fact that the influence of weather conditions on a sloping part of the roof is much stronger than on the massive load-bearing elements of the building.

Important! According to SNiP, the window area shall be not less than 10% of the total floor area.

The window in the mansard roof photos clearly show, it can be placed in the plane of the roof, inclined or vertically, or be at the end of the attic. Vertical Windows in the roof plane may be exposed on it (Dormer), or recessed in the room.

In the Assembly and arrangement of the roof, you should pay special attention to the insulation of Windows to avoid the formation of “Islands of cold”

The most popular and easiest to install is the tilt window in the roof. It is able to pass the maximum amount of natural daylight. After installation the roof surface is not changed, and remains smooth. However, this option requires the creation of a proper waterproofing of an adjunction. Here it is necessary to use special models with reinforced glass and reinforced plastic frame.

The square window opening is chosen in proportion to the angle of the roof. The window width should be selected so that element fit into the distance between the rafters without disturbing the integrity of the design. If the window is much wider, then you have to install a reinforced beam that will connect the cut rafters to install Windows. In this case, if a narrow window is not enough, it is better to install two adjacent narrow element that will ensure the integrity of the truss frame.

For the installation of Windows, a Dormer requires a complexity of the geometry of the roof, and it required the installation of lateral and upper ends and their subsequent thorough waterproofing. Also complicated by the laying of roofing.

Installation and insulation of Dormer Windows should be carried out according to the instructions, to avoid condensation and the appearance of indoor humidity

Vertical window, recessed into the room, it is advisable to arrange only when through it will be an exit to the balcony. In other cases it’s an unnecessary significant financial costs (the complexity of the geometry of the roof) with a minimum effect (lack of natural light).

The simplest, most practical and cheapest option is to install Windows in the gable of the roof. This is especially true for holiday houses with a mansard roof.

The methods of installation of mansard roof

The device roof system attic roof can be done in two ways. The first option involves the collection of roof frame on the ground with a subsequent rise in its finished form the top of the house and thorough fixation. The method is effective for small structures.

The farm is most convenient to collect on the ground and then lift them out and fix

How to make a mansard roof with the collection of part of the truss system on the ground? Previously at the top of a vertically exposed and fix extreme designs which will be subsequently Gables. Temporarily secure it with the help of long boards nailed to the wall. In mauerlat recesses are created at a given step, which will be mounted on the assembled structure. To ensure correct geometry and create stiffness of the structure, its elements can be mounted struts. When will be finished the installation of the side members, and the whole system will gain the necessary rigidity, the strut can be removed. Video installation of the truss system gable roof the roof will clearly show all the features of this embodiment.

The second option is more traditional. It involves the device mansard roof on the place with the observance of strict sequence of actions. This method is most convenient and efficient for construction of large truss system. Because for lifting the assembled structure up to require the involvement of specialized equipment.

How to build a mansard roof in the traditional way?

Some of the subtleties in the technology of construction of the mansard roofs of private houses depend directly on its type. However, the sequence of steps are similar for all types of mansard roofs.

Wooden roof trusses are attached with metal gear gvozdevyh plates

Before you make a mansard roof, to be installed in the longitudinal direction on the bearing walls mauerlat, and attach it to the walls or nets with pins or wire. Roof truss mansard roof of the wooden house can be mounted on the upper rim, which will play the role of mauerlat.

The construction of mansard roofs start with the installation of beams to overlap. They are fixed on mauerlat. Then the beams are attached to building legs. In the center of the beams should mark the location of the mounting supports and the ridge element.

Compliance with the same distance must be mounted in a rack of boards, fixing them with parts. The first pair of racks fastened bongs wooden bars. Formed U-shaped design should be mounted to the rafters. They can be installed on mauerlat or with cutting groove on the beam overlapping.

Next, you should proceed to installing the ridge rafters, which are connected by metal straps or bolts with washers. To create the necessary rigidity to the Central portion of the side rafters and a rack to attach the struts, and torque to mount the beam. In the same way you install other farms with a distance of 60-100 cm they are Fastened to each other with the runs.

Rafters can be connected with mobile construction press

With staples, you commit all nodes of a mansard design, and is given her final strength. After that it is necessary to mount the sheathing, which may be solid or sparse, depending on the option of roofing.

If you use shingles, asbestos-cement flat sheets or rolled material, you should perform continuous sheathing. It is installed in two layers. The lower deck consists of bars with a thickness of 20 cm, stacked in increments of 30 cm of the Upper deck, consisting of boards with a size of 20×50 cm, nailed towards the bottom layer at an angle of 30-45 degrees.

For clay tiles, asbestocementnye slate, metal, steel, metal coating is used, a sparse type of sheathing. This is done by mounting the bars, the cross-section of 5×5 cm and a step in the 20-30 cm, from the eaves up perpendicular to the rafters. In the eaves you need to install a flooring of wooden planks with a width of about 70 cm Then it should fix the bars along the ridge and ribs, which are connected back to back. Clearly this process can be seen in the photo of the truss system gable roof under metal roofing.

To nails when attaching the rafters do not split the rafter foot and the filly must comply with the requirements of the building regulations

Technology insulation of mansard roof

The warming of the mansard roof of a private home allows you to not only insulate the attic and create a proper thermal insulation of the entire roofing system that lasts for years.

In a schema of insulating a mansard roof is a complex of activities, which include creation of heat, hydro – and vapor barrier. On top of this roof fit roofing material, which protects the entire structure from adverse environmental factors. To protect the insulation from the negative impact of condensate, which reduces its insulating properties, it is necessary to protect him from the roofing material. This can be used one of the sheet materials:

  • waterproofing film, which is attached from the outer side to the rafters. She must not touch the insulation material, so cut off from his crate or kontraktami;
  • the diffusion membrane is attached to the insulation and protects it from any moisture.

A useful tip! Waterproofing material should be laid with slight SAG, eliminating the possibility to pull it.

The insulation and the insulation of the mansard roof should be carried out, adhering to the conventional technology of laying the roofing

The waterproofing layer must be expanded across the rafters. We must start from the bottom. The first row is lowered into the gutter. Each next roll must overlap in the 10-12 cm should reach the ridge. There is material on the upper edge with two sides trimmed and secured. Along the ridge you should roll strip, which runs down from two sides of the roof to the gutters, which provides a uniform abstraction of the water.

The vapor barrier in the form of a membrane is a reliable protection of the insulation from the penetration of his thick steam from the room. The material is also laid overlapping each other and fastened to joists with staples. All joints and places of contiguity should be carefully glued with special double-sided vapour-barrier adhesive tape.

A useful tip! On the vapor barrier film has a strong line from which you want to start the next layer. Following in her canvases held together with tape.

Insulation of mansard roofs from the inside using foam polystyrene, which is applied to the surface in liquid form, filling in all the cracks

Important rules for insulation of mansard roof

When the question arises, what insulation is best for mansard roofs, there is no single answer. However, due to the fact that the mansard roof is characteristic of a large angle, do not use soft materials that will cake and slide from the surface.

Roll insulation must be laid from the bottom up. To do this, use a staple gun and string. Unrolling the roll of material is pressed against the slats. With lace, straps, draw a letter Z. this technology is attached to each layer of insulation.

It is better to prefer plates with the density of 30-50 kg per cu. m. In this case, the pitch of rafters will have to adjust the size of the heater, which is 10-15 mm must be less than the width of the insulating plate. This is required to ensure that the material could be breaking without the formation of cracks and good to stay between the beams. If the width is smaller or larger, you will need to cut the material. To create a clean cut is not always possible, and besides, still a large number of residues. Plate positioning should be so that the stitches of the previous row overlap subsequent.

Diagram of the device of a roofing pie

The heater is placed so as to provide the minimum number of thermal bridges. Additionally, the excess material can be placed on the stuffed space strips of the required width. On top of the insulation layer is laid a vapor barrier and is crate for future finishing. The option of overlap where even the rafters, virtually eliminates the formation of cold bridges. Despite the fact that it will take a little more insulating material to the attic will eventually get warmer, which will give the opportunity to reduce the cost of heating the room.

Important! Cold bridges contribute to the formation of moisture in the roofing pie. This can lead to rotting of the rafters, swelling of the insulating material, corrosion of metal structural elements, the occurrence of unpleasant odors indoors.

How to insulate a mansard roof: progress

There are two methods of roof insulation: inside or outside. When you use the first option you can push the interior decoration of a certain period. The second option involves a full complex of works, which allows to achieve a quick completion.

The process of insulating the roof from the outside foamed polystyrene

How to insulate a mansard roof outside? It is necessary to prepare the surface of the rafters, clearing away the protruding elements that can damage the layer of hydro – and vapor barrier. With the inside room across the rafters it is necessary to fill the crate, which will house the heater. Instead of crates, you can attach a galvanized wire or cord.

Of the roof this purlin is mounted the insulating layer in accordance with the above rules. The thickness of the insulation mansard roof should be more than 100 mm. on Top of the insulating material is deposited super-diffused membrane. Next, you need to fill a crate on which to lay the roof covering.

Now with the inside room must be anchored to glue vapor barrier layer. Then you can begin to interior decoration. This option is insulation of the roof is considered the most simple in execution. Insulation boards are easy to fit on the previously created crate.

Do not neglect the vapor barrier layer, which helps protect wooden elements of the roof and insulation

Technology insulation mansard roof with their hands from the inside is performed in two stages. The first required step as follows:

  • Rolled and fixed on the rafters of the waterproofing layer.
  • Stuffed crate.
  • Mounted roofing material.

After performing the obligatory list of works to postpone the warming of the mansard roof for an indefinite time, which can be due to lack of financial ability at the present time.

The second stage is less convenient to implement. The warming of the mansard roof will be performed from the inside. Here it is necessary to create a building envelope that will hold the insulation and prevent its lifting more than is possible. For this between the joists stuffed the strap in increments of 40-50 cm. They will not only keep the insulation, but would create the required air gap.

Next is the installation of thermal insulation layer in compliance with all rules. Him stuffed crate. Next, you need to arrange and stick vapor barrier membrane. After that you can start finishing works. It is possible to mount the crate, but you can do without it.

A layer of insulation for the attic space shall be not less than 100 mm

Types of insulation for the attic roof. What insulation is better?

Today there are several options for roof insulation of the roof:

  • mineral wool;
  • polystyrene;
  • polyurethane foam;
  • foam;
  • glass wool;
  • isvert;
  • ecowool.

The most popular material is mineral wool, namely basalt. This relatively inexpensive material is produced comfortable sufficient thickness and rigidity. It retains heat well, is non-flammable and does not rot. However, she is afraid of water. Therefore, in order to ensure the preservation of all technical and operational purposes and must be carefully protected from all sides.

Mineral wool is one of the most popular materials for the insulation of roofs and building walls

The foam has good operational characteristics, which give it the ability to create a good insulation. The price of the material is relatively low. It is easily installed between rafters breaking due to its elasticity and due to the fact that you can purchase a plate of the required size. All joints should be sealed with foam.

A useful tip! During combustion, it is able to produce harmful substances, so it is better to give preference to self-extinguishing grades, are used where special additives.

The material is not afraid of water. It does not hold pairs that is the main drawback of the foam. In this regard, it is necessary to create good ventilation in the attic, which will lead to additional financial costs.

The best characteristics of extruded polystyrene, the thickness of which in two times less than that of mineral wool and a half than foam. The material is equipped with a locking system that prevents the formation of cracks. On EPPS is not formed fungus and mold, its not like rodents and insects. However, it does not pass steam, which requires a good ventilation system. Another disadvantage is the high material cost.

Special attention should be given to insulation and heat insulation of window openings to prevent mold and mildew inside the building

Recently, a new type of insulation – foamed polystyrene. It is applied to the surface in liquid form, filling in all the cracks. Thus by reacting with oxygen, increases several times in size, forming a monolithic coating.

A useful tip! The use of foamed polystyrene will help to improve the situation in the absence of a layer of waterproofing during installation of roofing.

Another insulating material of new generation is cellulose that has good features. However, its use requires the observance of special technology. Loosened wool is fed under pressure into the closed cavity, filling all voids and forming a solid coherent layer of insulation. For the organization of the closed cavity to the bottom and top rafters nailed sheet material in the form of plywood, fiberboard or gypsum fiber Board.

One of the criteria for the selection of insulation are territorial especially the climate and the type of heating in the house

A distinctive advantage of this material is its ability to hold vapor. Here the humidity is regulated in a natural way that does not require vapor barrier. However, between the insulation and the roof must be established a ventilation gap, where the movement of air masses.

Today, among the possible projects of houses with a mansard roof, you can choose the most suitable and attractive option, and to make it a reality for your own private residence. To make the house visually beautiful and aesthetically pleasing, you need to take seriously the question of the selection of the mansard roof, which should be in harmony with the design of the building. Correctly arranged in a truss roof system is able to perfectly perform all of its operating and protective functions that create a warm, cozy and comfortable room.

Insulation of the attic floor with ecowool

Creation of mansard roof with his hands, step by step. Video instructions

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