With the help of the attic, you can quite easily increase the living space of the house. This structure is built in the attic and can be used for living, but only on condition that the mansard roof truss system is properly designed. We will consider the manufacturing technology of such a design in our article. After all, it is this issue that should be given most of your attention when designing.
A little about the features
Attic is a room that is located directly under the roof of the house. The facade of this structure is fully or partially formed by two roof surfaces. This is a completely full-fledged floor, it can contain both one and several rooms, it all depends on what parameters the system has.
Attic. This word came to us from distant France, in 1630 an architect came up with such a simple way to ennoble the attic. Not surprising,that the architect's name was Francois Mansart. It is from the surname that the construction takes its name.
The main feature of the truss system is that the design has an original and unlike anything appearance. But since the room above is residential, it is necessary to lay several layers of vapor and moisture insulation, insulation material under the roof. It is also worth noting that the load on the walls and foundation increases when installing the mansard roof truss system on the house. Therefore, it is wiser to use lightweight materials in construction.
Pros and cons of attics
You can highlight the positive qualities of the attic:
- Infrastructure is used from the building on which the construction is carried out.
- Significantly increases the area of the house.
- The building takes on an original and attractive look.
- Heat loss is reduced, and the energy costs of the entire building during the cold season are significantly reduced.
But there are two big drawbacks:
- The ceilings are sloping, but if you do the layout correctly, it will not be very noticeable.
- Roof windows are expensive. When installing such windows, it turns out to give an attractive look to the house, but if you decide to save money, you can refuse them.
Quite often such structures are used in the construction of individual houses. We need to give some numbers. Heat loss through the roof of the building is reduced by almost 10%, and in severe cold conditions this is extremely important. In addition, construction costslofts are much lower than the cost of building a full-fledged floor.
Pitched mansard roof
Shed mansard roof is the simplest roofing option. There is only one slope, which is installed on the multi-level walls of the house. This is how the angle of the slope is formed. It is worth noting that it is recommended to make a slope of no more than 45 degrees. But it needs to be over 35 degrees. If you make a small slope, then snow will accumulate on the roof in winter, and this can increase the load on the house, so you will have to install additional supports in the attic.
But if you make too much slope, then it will not add convenience to using the floor. The design of the truss system in this case is very simple. It is worth noting that additional supports will not be required if the distance between opposite walls is less than 4.5 meters. The roof looks very original despite the fact that it has a very simple design. As a rule, a window is made from the side of a high wall. With it, you can well illuminate the entire space of the room.
Gable roof
This option can also be called simple, because of this it has become widespread. The main thing is to ensure that the height of the roof makes it possible to equip a living room under it. The rafter structure is very similar to the gable roof system. It can be either symmetrical or asymmetrical. It all depends on where the ridge of the truss system of the attic floor is located.
Gables are usually straight and simple, the inside of the room has the shape of a square or a trapezoid. The height of the walls in the attic floor is about one and a half meters, then there is a cone-shaped sloping ceiling. But this design has one drawback - a lot of free space is lost. In other words, with roof slopes you cut off a very large proportion of free space. But given that before installing the attic you had nothing in the attic, then this shortcoming, frankly, is doubtful. The drawings in the article show the design drawings of a gable roof.
Polylines
If you look closely, it turns out that a sloping roof with a mansard truss system is one of the types of gable structures. But one slope in her has at least two parts, which are located at different angles with respect to the ceilings. With this design, you will get a spacious attic room, which in terms of area will not be inferior to a full-fledged floor. Ceilings in height will be the same around the entire perimeter - about 2.2 m. The area of the attic floor will be less than that of the first floor by about 15%. And this is relatively little.
In the manufacture of such a structure, it is necessary to construct a very complex truss system. A sloping mansard roof needs careful calculations. A novice master is unlikely to cope with such a task. But, despite this, a broken roof is common in the construction of houses. After all, alwaysyou can find a specialist who manufactures roofing systems.
Mansard hip roof
This roofing is the most complex, as a very "cunning" truss system is used. When planning, it is necessary to make all the calculations very finely. The roof surface has a fairly large area, so you have to spend money on waterproofing, vapor barrier, insulation. At the attic, of course, a very large part of the area is cut off. But still, it will turn out to be very spacious due to the large size of the attic roof truss system.
A huge plus of such a roof is its high resistance to winds and snow. Overhangs can be made large, they will protect the walls of the house from the negative effects of precipitation. The appearance of such attics is very attractive. But it is worth noting that during the construction of four-pitched truss systems, it is necessary to strengthen the inclined beams. After all, it is they who are affected by the maximum load.
The design of the truss system
When making a mansard roof, make the truss system from hanging or sloping components. In the case of an inclined version, it is necessary to install the rafters so that they form a triangle, in which the sides are equal. Support must be done directly on the Mauerlat. It is fixed around the entire perimeter of the walls of the first floor. In this case, one of the reference points is the connection of two bars near the ridge.
When hanging type rafters are installed, no additional beams for supports are provided. Installation of all structures is carried out directly on the walls of the house. The use of puffs is allowed. At the same time, rafters work both in compression and in bending. When building an attic, it is necessary to create a high-quality truss system. This is a primary task that needs to be solved correctly. First you need to correctly calculate and take into account all the nuances of construction. Let's decide what the main elements are in the system.
The main components of the truss system
There are quite a lot of these elements. Calling some main or most important language does not turn, they all affect the operation of the structure. So let's list all the ingredients:
- Mauerlat is a board or beam, with the help of which the roofing system is fixed on the end part of the wall of the house. It is on this beam that the rafter legs are fastened. Mauerlat performs the function of a support, transfers the maximum load from the roofing system to the wall of the structure.
- Racks are any vertical beams that support rafter legs. A series of beams that are laid in a horizontal plane, and form the floor of the floor, they are also called ceilings. It is worth noting that they serve as a ceiling for the first floor of the house. It is not difficult to install the attic roof rafter system with your own hands, but follow the recommendations that we give in the article.
- Wooden beams arrangedhorizontally and performing additional reinforcement are called a crossbar. They are also supporting components for rafters. Sometimes they are called puffs.
- "Rafter legs" are sometimes referred to simply as rafters. With their help, the roof frame is made, the final shape is given.
- Moisture-proof material, crate and coating are attached to the rafters from above. Sheathing is a large number of sheets of plywood or beams that are fixed directly to the rafters. Roofing material is fixed on these elements.
- A board is installed under the puff or crossbar to help distribute the load. It's called a pendant.
- The board with which the roof overhang is formed, fixed on the bottom of the rafter legs, is called a filly.
As you can see, the design of the attic truss system is not very complicated. But let's move on to the most important stage - calculation and design.
Calculating the parameters of the attic floor
And now about how the calculation of the mansard roof of the house is performed. The calculation of the rafter system must also be performed at the preparation stage. In order to avoid mistakes in the manufacture of the attic floor, it is necessary to carry out preliminary calculations. They depend on what type of rafter system and roof is used. If you wish, you can use special programs, but if there are none, do all the calculations yourself.
You need to correctly identifythe area of the final roof structure, the width of the floors, the dimensions of the attic floor. The calculation must be carried out based on the following parameters:
- The width and length of a residential building.
- The amount of precipitation falling in summer and winter. With these parameters you will be able to determine the desired angle of the roof.
- Width of joints between slab components.
Let's look at an example that shows the practical calculation of attic elements. Let's say the house has a width of 3 m and a length of 12 m. If there is quite a lot of precipitation in your area, then it is necessary to slope the roof by about 40 degrees. The calculation must be made according to the formula:
Нк=L x tgA.
Hk is the required height of the building, L is half the width of the building. And the last parameter is the tangent of the angle of the roof. After doing the calculation, we get a height of 1.26 m. This means that the roof should have a maximum height of no more than this value. Very often, when building a mansard roof, owners choose broken truss systems for manufacturing. Mansard roofs of this design look attractive and allow for less loss of usable area.
Step by step rafter installation guide
Now let's look at how to make a mansard roof truss system. Several steps can be distinguished:
- First, it is necessary to lay waterproofing material on the end of the walls. An ordinary roofing material is ideal for this purpose. If there is no desire to use it, then processing with bituminous mastic is allowedor by similar means. If you use roofing material, then it is necessary that its width be the same as the end part of the building. If necessary, trim excess material.
- Then it is necessary to lay the board on the roofing material. It is she who will serve you as a Mauerlat. It must be aligned along the inner edge of the end of the wall. In this board, you need to drill holes that are necessary for fastening. Holes are also drilled in the wall, anchor bolts are installed in them. With the help of such fasteners, a Mauerlat is installed around the perimeter of the house. The same actions must be carried out in the manufacture of the truss system of the mansard gable roof.
- Next, you need to fix the board on the wall with anchors measuring 130 x 10 mm. Be sure to use an additional wide washer, in this case you will provide a large area for pressing the material. The anchor nut is tightened with a wrench. Just be careful not to overtighten, otherwise the wood may burst.
- Make floor beams. They are made of three bars, the size of which is 200 x 50 mm. They are connected to each other with self-tapping screws.
- Connect all the boards, you need to evenly lay them on the spans between the opposite walls of your house. The distance between the floor beams should be about 40 cm. To fix the log on the Mauerlat, metal corners are required. They must be perforated. It is advisable to use self-tapping screws with a length of 90 mm. Only they are able to provide a quality connection. The article provides truss schemesmansard roof systems, be guided by them during installation.
- Now the installation of the truss structure begins directly. It is necessary to install boards on temporary jibs with support. They will form the future perimeter of the entire attic floor. Boards must be level. Otherwise, you will get a crooked roof.
- Now you need to make jibs. First, the first one is mounted, it is fixed on the previously installed boards and lag callouts. Metal plates and self-tapping screws are used as fasteners. Then, on the first jib, you need to make a template. It is on it that the remaining elements are made in the required quantity.
- The remaining jibs must be installed in the places intended for them. Fixing elements is carried out in the same way as in the previous step. The device of the mansard roof truss system is simple, but all the elements must be made, focusing on a pre-prepared plan.
- Then, vapor barrier material is covered over the mounted jibs. It must be fixed with 50 x 50 mm bars.
- On top of these bars it is necessary to make a counter-lattice. It is on it that you will subsequently mount the roofing material. The counter-lattice is made of boards, fixed to the previously nailed crate.
- Now you can form a skate. To prevent the boards from bending on the ceiling, you need to install temporary supports. With such elements, the work is much easier. It is necessary to lay several bars on the boards, along which you will move freely duringinstallation.
- Now you can install the ridge beam at the required height.
- In advance, you need to cut the rafters and install them with one side on the already assembled roof structure with jibs, and the other on the ridge beam. At opposite ends of the roof, the rafters must be butted together directly above the ridge beam.
- Similarly, as in steps 9 and 10, it is necessary to lay a layer of vapor barrier, nail the crate. But all this is done on the installed rafter legs. Remember that they must be securely fastened. Only after fixing is the vapor barrier performed.
- Similarly, it is necessary to make a counter-lattice on the truss system of the attic house.
- Making the front part of the attic roof. It is necessary to install a wood extension at right angles to the joists. The length should be about 50 cm. Fixing is done using metal corners and self-tapping screws to the Mauerlat and lags.
- The stem must be the same length. Therefore, if necessary, the boards can be sawn to the desired size.
- Racks are being installed. They need to be fixed from below to the installed outriggers using self-tapping screws. From above, they are fixed on metal plates. If there is a roof window in the project, then it must be formed at this stage.
- Then it is necessary to install bars on the roof overhang that connect the individual elements of the crate.
- Finish the roof. It can be slate, metal tile, profiled sheet and other materials.
We reduce the load onfoundation
If you understand that the foundation of the house cannot withstand the increased load, then additional supports must be installed. In this case, the attic floor will be able to have less impact on the walls and foundation. The article provides drawings of truss systems for mansard roofs. It is the floor beams that need to rest against the foundation.
Work can be done in this way:
- First, a separate foundation must be poured along the perimeter of the house, it must be reinforced. The depth should be about 70 centimeters. It must be provided in advance with holes for mounting additional supports.
- It is necessary to install supports around the entire perimeter of the house - these are wooden bars.
- Arrange the floors between the house and the attic, after that you can create a roof truss system.
- Then it is necessary to sheathe the roof with the selected material.
- From the inside, sheathing is made with a vapor barrier.
- Insulation material is being laid between the rafters.
- Do the interior decoration of the attic floor.
This is a short guide on how to implement load reduction on an existing foundation. In this case, of course, it will be necessary to carry out the manufacture of an additional base. You can pour not a strip foundation, but a simple columnar one. In this case, you can reduce the cost of manufacturing additional supports.
Basic mounting rules
Before starting the construction of the attic,it is necessary to study all the rules that must be observed without fail. Otherwise, you end up with a rather flimsy and unreliable design.
Try to stick to these rules:
- The attic roof should be well insulated. Of course, if this is not a temporary house or a small house in the country, which is used exclusively in the summer.
- Before starting work, you need to create a drawing of the entire truss system, carefully carry out the calculations. All this can be done both electronically and in handwritten form.
- Wooden components must be treated with antiseptics, as well as compounds that protect against fire.
- Rafter legs must have a section of over 100 x 100 mm.
- Be sure to make high-quality waterproofing of the roof. Only in this case you will receive reliable protection from snow and rain.
To understand what kind of roof you need, you need to pay attention to all aspects of the work. Read the examples and drawings in advance. Of course, you can make any adjustments to the project. But be aware that changes are allowed if they do not affect the strength of the entire structure. Now you know all the subtleties that are necessary when making a truss system of a gable mansard roof with your own hands. Only by following all the recommendations, you can make a quality roof.
