Table of contents:
- The history of the attic
- Attic floor - design features
- Attic characteristics
- Mansard roof of a country house - types of construction
- Insulation, sound insulation and ventilation of the attic
- Residential attic in a country house
Video: Attic In A Country House
2023 Author: Douglas Hoggarth | [email protected]. Last modified: 2023-11-26 20:16
- The history of the attic
- Attic floor - design features
- Attic characteristics
- Mansard roof of a country house - types of construction
- Insulation, sound insulation and ventilation of the attic
- Residential attic in a country house
Over time, the size of any country house becomes small, because the number of households is growing. And his owner is faced with a dilemma - to attach a new wing to the house or, perhaps, to demolish the building and build a new one, of a larger area. Meanwhile, there is an optimal and cost-effective solution - an attic, which transforms a boring attic into a fully-fledged residential and comfortable space without any major remodeling of the house.
The history of the attic
The idea of increasing the building's living space by changing the shape of the roof originated in the 16th century with Pierre Lescaut, a French sculptor and architect. However, the attic owes its popularity and name to the 17th century architect - Frenchman François Mansard, who designs castle and palace complexes for the noble and richest landowners in France. Almost all buildings designed by Mansar have attics. Residential premises instead of an attic, previously used only as a warehouse of unnecessary things, quickly became in demand among owners of apartment buildings, since they made it possible to bypass the requirements of building height standards. In those days, it was forbidden to erect buildings with a height of more than 20 m, while measurements of the height were carried out from ground level to the cornice, respectively, the attic did not fall under the height restriction,because it was located above the cornice. In addition, buildings in Paris were subject to a special floor tax, i.e. for each floor a certain amount had to be paid to the city treasury. And the attic made it possible to avoid paying tax - its premises were not considered a floor, they belonged to the attic. In the 17th-17th centuries in France, all rooms under the roof of a broken shape were called Mansar.
Francois Mansart. Maison-Laffite Palace near Paris. 1642 - 1650. Main facade
In Russia, the first multi-storey buildings with attics appeared in the 18th century - under the influence of Parisian architecture, such buildings were erected in St. Petersburg. True, these mansards differed from the French ones in that they practically did not have windows - one or two massive dormers or lucarnes did not allow fully illuminating the attic during the day. For a long time, there were no attics in Moscow at all, and only twenty years ago a steady interest of developers appeared in them.
In the 19th century in Russian cities, a fashion arose for houses with a kind of attic - a mezzanine, which, as a rule, was built over the central part of the facade of the building. Most often, the mezzanine did not perform any functional tasks and was just a decorative element.
Apartments in European mansard floors of the 17th-18th centuries were rented out at a low price, because it was cold in them in winter, and streams of moisture flowed through the roofing at the slightest precipitation. Today, thanks to modern insulation and roofing materials, as well as the high content of carbon dioxide in the atmosphere in the lower tiers of high-rise buildings due to the dense traffic of cars in large cities, attics have become very popular among wealthy citizens.
Attic floor - design features
The geometric shape of the attic floor can be very different - broken or triangular, have symmetrical sides and not symmetrical, be located both over the entire width of the building, and only on one side of it. The structure of the classic broken shape of the attic roof is as follows: the lower and wider part is sloped up to 70 o, the upper narrow parts are more gentle and are located at an angle of 15-30 o. The attic floor can be located both within the boundaries of the outer walls of the building, and protrude beyond them, while additional supports, such as walls, columns or suspensions, are required.
Taking into account the increased load on the supporting structures of the building, the creation of an attic requires the use of extremely light materials. As a rule, structural materials for creating the frame of the attic floor are made of metal and wood, while wooden structures must be subject to mandatory processing with fire-fighting compounds. From the outside, the walls and ceiling of the attic are sheathed with a roof covering, therefore, its frame must be adapted to the geometric shape of the building's roof.
Considering that there is a roof immediately outside the perimeter of the attic room, work on its creation is accompanied by specific problems, namely, condensation of moisture on the ceiling and insulation under it, high heat loss, insufficient sound insulation and ventilation. Options for solving these problems will be proposed below in the text of the article.
The era of industrial construction of standard houses with flat roofs depersonalized the cities of Russia and, at the same time, did not solve its main task of providing the country's citizens with comfortable housing. Meanwhile, most of the monumental reinforced concrete high-rise buildings of the Soviet period allow them to be upgraded in the form of attic rooms, thereby not only providing additional living space at the level of modern standards, but also significantly ennobling the boring and, sometimes, frankly squalid outlines of the buildings of Soviet neighborhoods.
In private housing construction, the attic floor is more interesting from the point of view of increasing living space, the cost of creating which is much less than for the construction of a two-story building.
Consider the benefits of an attic:
- its lightweight design allows the construction of old buildings above the load-bearing walls;
- often an unclaimed and cluttered attic becomes a full-fledged living space, thereby increasing the living space of the building as a whole;
- significant improvement in the appearance of the building;
- the ability to display the attic on one or two storey levels;
- minimization of heat loss of the building through the roof area, which can significantly reduce its energy consumption in the cold season;
- work on the creation of an attic room above the load-bearing walls of the existing building does not require the involvement of heavy construction equipment, there is no need to resettle the residents of the house.
Negative characteristics of the attic:
- the rafter system of a sloping roof does not allow full use of the entire attic room;
- there are angles of inclination of walls and, less often, ceilings, which reduce the height of the room and create certain discomfort for households;
- in the window openings of the attic, it is permissible to install only roof windows of a special design, the price of which is higher than ordinary windows;
- complex and painstaking work on insulation and waterproofing is required, any miscalculation will lead to condensation deposits and the formation of icicles on the outside of the roof in the cold season.
Despite the inherent drawbacks of this room, the attic allows you to get a full-fledged two-story house from a one-story private house without the need to demolish the old and build a new cottage.
Mansard roof of a country house - types of construction
The rafter systems of mansard roofs can be gable gable, gable half-hip, hip, hip, four-slope hip and half-hip, multi-gable, mansard hip and half-hip, hip with a broken slope, conical gable and pyramidal. Due to the fact that most types of rafter systems allow you to get only a small room under the roof, under the attic, half-hip and hip attic, as well as hip with a broken slope are most often used. It should be noted that obtaining an attic room with a minimum sufficient area, the smallest width between the external load-bearing walls of a country house should be from 4 800 mm. The attic (cranked) wall with a Mauerlat on top of it, or a Mauerlat, launched along the top of the bearing walls of the last floor, serves as a support for the attic roof.
A wall built on a reinforcing belt (crown) above the outer walls of the last floor of the building is called an attic or attic. Its construction allows you to increase the height, and hence the area, of the attic room. The attic wall allows you to transfer the load of the attic roof to the ceilings of the upper part of the walls of the lower floor, the roof rafter system rests on it.
For the construction of the attic, the same materials are usually used that were used to create the load-bearing walls, with reinforcement with additional columns and crowns made of reinforced concrete. Also, the attic wall can be made of a wooden bar as a full-fledged structural element of the roof - in this case, it is sheathed on the outside with a ventilated facade, which protects the wooden attic from destruction under the influence of atmospheric phenomena.
If the attic space, formed, among other things, by the attic wall, is intended exclusively for any household needs, then it will be sufficient to bring the attic to a height of 700 mm. For the construction of a residential attic room, its output to a slightly greater height is required - from 800 to 1 100 mm. At a height of 1,100 mm, a window sill is usually located in the attic, allowing households to look out the window in a sitting position, while a wall of this height will be sufficient to place a desk or bed close to it. If you bring the attic wall to a height of one and a half meters, then it will be possible to place next to it a TV on a pedestal, a floor rack for books or a table with chairs, while already half a meter away from it, residents will be able to move without tilting their heads. However, the frame construction of the walls between the dormers will seriously complicate the construction of an attic with an attic height of 1,500 mm - it would be wiser to raise its walls to 2,000 mm, i.e. to the level of the lintels of window openings, thereby acquiring a room of sufficient height and without any internal obstacles in the form of roof structural elements.
The masonry of the attic wall without additional reinforcement is made of solid bricks to a height of not more than 700 mm, while the thickness of the masonry should be half the height of the construction. When climbing to a great height, reinforcement of the attic with reinforced concrete posts is required, with anchoring to the ceiling (reinforcing belt) and reinforcing bandaging in the seams of the brickwork at several levels on both sides of each post. The step of their installation is 2,000-3,500 mm, which will make it possible to place every second or third leg of the rafters in close proximity to them. In the corners, three reinforced concrete columns are placed close to the "L" -shaped, reinforcement with brickwork of the wall is performed in the seams of each row of masonry. If, however, lay a reinforced concrete Mauerlat with a minimum cross-section (250 cm 2), with the fixing of anchor rods ("S" -shaped, at least two per column) of reinforced concrete columns in it, then you can do without tying them with brickwork. The exact calculation of the attic wall with reinforced concrete columns in relation to a specific building should be entrusted to the designers.
Those homeowners who are pretty puzzled by the design of the attic wall and those who want to arrange an attic using a simpler technology, without increasing the additional load on the load-bearing walls with brickwork on top of it, can place the Mauerlat under the rafter legs directly on the harness at the top of the load-bearing walls. In this case, you will need a wooden bar with a square section and a thickness of about 140-160 mm. It is allowed to establish pieces of timber under each of the rafter legs, but it will be more thorough to install it along the entire perimeter of the harness belt. Fastening of a wooden bar-Mauerlat is made to anchors with a diameter of 120 mm or more placed in advance in a monolithic reinforced concrete strapping, "S" -shaped bent on one side (inserted into a reinforced concrete strapping) and with a threaded thread on the other. The largest step of fastening anchors in the strapping belt is 1 200 mm,but it is better to use a smaller step. The length of the anchors should be sufficient to be completely immersed in the reinforced concrete strapping with the installation under the reinforcement in its lower part and go through the Mauerlat beam so that it is possible to tightly fasten them with nuts and washers. Through holes are drilled in the Mauerlat beam, through which, after the harness has hardened with the anchors fixed in it, their racks are threaded. During the fastening of the Mauerlat, the nut of each next anchor should not be tightened to the end - it is necessary to tighten them gradually, having previously "baited" a beam on them along the entire perimeter of the installation, otherwise in some sections of the perimeter its fragments from the full tightening of the nuts will shift and the drilled holes will not coincide with the position of the anchors. Between the wooden Mauerlat and the reinforced concrete strapping of the bearing walls, it is necessary to lay a moisture-proof material - at least a roofing material.
Upon completion of the installation of the Mauerlat for the attic, work begins on the installation of the rafter system - the general procedure for their implementation is given here.
Important: The connections of all elements of the rafter system, without exception, as well as the attachment of the rafter legs to the Mauerlat, are made only by anchor connections. There should not be any connections to a nail or screw!
Insulation, sound insulation and ventilation of the attic
Compared to work on the insulation of residential premises of a house or apartment, it is technically difficult to insulate an attic - the area of the surfaces enclosing it, which border only on the external environment, is much higher than the area of any other room in the house. The mansard roof is a complex structure, replete with valleys, abutments and ridges, dormer and dormer windows. In addition, the joints of the timber elements of the truss system are subject to seasonal displacement as they dry out and become wet.
The insulation of the attic enclosing structures is carried out in accordance with the requirements of SNiP 23-02-2003 "Thermal protection of buildings", with the help of which it is possible to find out the heat transfer resistance of the attic room required for a given area. To insulate the attic, slabs of mineral wool or glass wool of the P-75 and P-125 brands are used - the first brand is for horizontal unloaded surfaces, the second is suitable for both horizontal and vertical unloaded surfaces due to its greater rigidity. In addition to mineral wool slabs, you will need a hydro and vapor barrier film.
There are five design solutions for warming the enclosing structures of the attic room: sheathing of the inner side of the rafters; insulation between the rafters; laying under the rafters; over the rafters; a combination of several ways.
Sheathing of the rafters from the inside of the attic. For the implementation of such insulation and the simultaneous sheathing of the walls of the room, sheets of fiberboard (fiberboard) will be needed. The procedure for work on such insulation is described here. It should be noted that this is the most budget-friendly option for insulation, because mineral wool insulation is not used at the same time and at the end of the work, a minimum of finishing the inner surfaces of the attic is required.
Installation of insulation between the rafters. This method of insulating attics and other rooms is the most popular among performers of work due to its simplicity. You will find a description of the installation work in this article. In addition to the information it contains, there are several recommendations:
- the insulation must have a stable shape, the grade is not lower than P-75, because the rigidity of smaller grades of mineral wool will be insufficient;
- polyurethane foam plates for attic insulation are not suitable due to the impossibility of achieving a snug fit to the rafter legs. Attempts to blow out the cracks with polyurethane foam will not improve the situation;
- when laying several layers of insulation on top of each other, it is necessary to shift the joints of each new layer by half the length of the joint of the previous one. Otherwise, a cold bridge is formed at the joint;
- each joint between the mineral wool slabs must be sealed as best as possible, trying to prevent the formation of a gap;
- if you need to achieve a significant thickness of insulation, and there are only a few types of thinner mineral wool available, then use the thickest types. In other words, in order to get a layer of insulation with a thickness of, for example, 500 mm, it would be correct to use two plates of 250 mm, and not five of 100 mm. The more layers of insulation will be laid in the same area, the more there will be gaps and air "pockets" between them, which will significantly increase heat loss through this area;
- Do not ignore the installation recommendations provided by the manufacturer of this brand of insulation.
The main disadvantage of laying the heat-insulating layer between the rafters is the impossibility of forming a continuous carpet of insulation, which creates a constant threat of the formation of open cracks.
Installation of insulation under the rafters. This method of insulation is attractive for rooms with high ceiling heights, because Between the required layer of insulation and the roof, an air cavity of a serious size is needed - at least 0.15 m 2 per meter - natural ventilation of which will not be enough, forced ventilation will be required. The formation of a layer of thermal insulation in this way when insulating private buildings is extremely rare, it is used mainly for insulating industrial buildings.
Insulation layer over the rafters. If you are interested in the answer to the question "how exactly are attic in Europe insulated?", Then this method will be the answer. Forming a continuous rockwool carpet directly above the rafter system and below the roof covering has the following advantages:
- a continuous thermal circuit is achieved, without any gaps and breaks;
- perfect sound insulation of the attic space, in comparison with any other method of laying insulation, provided the thickness of its layer is the same;
- inside the attic, not a centimeter of area is left for insulation, i.e. its premises will be especially spacious.
To place a mineral wool carpet on top of the rafters, it is required to fill a rail on them almost close to each other - it is necessary to obtain a durable flooring that is resistant to mechanical stress, since you have to walk on it while laying the insulation. A special vapor barrier film containing diffuse membranes is laid on the formed slatted flooring; at the joints, the film is overlapped and glued. Mineral wool slabs are laid on the finished film coating, then a waterproofing film is laid and lathing is made under natural tiles, which is the most popular roofing material in Europe.
Disadvantages of this method of attic insulation: the execution of work requires the involvement of specialists, especially with a complex roof topography; the need for dry weather, as the old roof covering will be completely dismantled.
Combined insulation methods. Using two different methods of laying insulation, you can achieve significant cost savings and create a sufficiently high level of thermal protection of the attic.
The simultaneous laying of mineral wool above the rafters and between them allows the use of a less dense insulation as the main (lower) layer; above the rafters, a more rigid material is installed, such as fiberboard (fiberboard) or basalt plates. In this case, the upper insulation layer must completely overlap the rafters, otherwise cold bridges will remain. As the top layer, the installation of rolled mineral wool of low rigidity is allowed, but in this case it will be necessary to create a power frame over the rafter legs, which will withstand the loads from the weight of the roofing, winds and snow masses.
The combination of layers of insulation between and under the rafters will provide high thermal insulation of the attic enclosing structures due to the complete thermal insulation of the rafters. With this method of installing the insulation, it will be more convenient to place the vapor barrier film between the layers of mineral wool, because it will be possible to avoid damage during future electrical work and interior decoration. It is possible to exclude moisture condensation on the film between the layers of insulation if the inner layer of mineral wool, i.e. laid between the rafters, will have thermal resistance, which is only 20% of the value of the same parameter of the main (located under the rafters) layer of insulation.
The most difficult and expensive will be the combination of layers of insulation under the rafters, between them and above them. Its advantage over other methods of laying mineral wool lies in the complete solution of any possible problems, such as freezing of the insulation, cold bridges and condensation deposits, allowing the owners to find housing 100% insulated at home.
An important point in the construction of attic insulation will be the solution to the issue of providing roof ventilation, while it must be constant and sufficient. A constructive solution to this problem is based on the arrangement of ventilation holes in the ridge, eaves, ridges, in the areas of abutments and valleys. It is equally important to ensure that these ventilation openings are adequately protected from the effects of precipitation.
Residential attic in a country house
In addition to solving an important issue with the insulation of the attic, it is required to equip it with windows for sufficient illumination in the daytime, arrange a comfortable staircase, and take care of heating.
The total area of the attic window glazing should be at least 10% of the area of the enclosing structures. At the same time, the design of dormers and the technology of their installation are somewhat different from the usual glazing of houses - for more details about attic windows and how to install them, see here.
The traditional way to enter the attic has always been a staircase, most often attached and without railings - this method of lifting households into the attic is in no way suitable due to its low convenience. You will need to raise a marching or spiral staircase to the new living space, as an option - both, a metal marching staircase outside, along the wall of the house, and install a spiral staircase inside it. The convenience of summing up both the internal and external stairs is obvious - it will be easier to lift the overall household appliances and pieces of furniture along the external staircase, and move along the internal spiral staircase in the cold season.
Heating a new dwelling, in the presence of an existing heating system, is solved by installing heating devices and connecting them to the circuit, while the old heating system may need to be reconstructed. If the country house is located in the wilderness, where the central electricity and gas supply is promised to be supplied sometime in the boundless future, then you will have to heat the attic with wood or coal stoves - a number of articles that discuss the characteristics of such stoves can be studied in this section.
With regard to the layout and purposes of using the attic space, this is already at the discretion of the owners of the house. The main thing is that the new living space is a joy to them.
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