On a properly designed pitched roof there is always a place for the auditory window. It is small in size and can have a completely different device. Why is there a dormer window on the roof and what kinds of this design exist? With its help you can ventilate the attic space, get out on the roof for technical work. For most roofs, the dormer window is the only source of daylight. However, performing important practical functions, this design can serve as an ornament of the house.
Functionality of the dormer window
Ventilation rooms today are taken to pay great attention, especially when it comes to attic. The roofing structure of most pitched roofs is made of well-dried wood. It can serve for decades if all conditions are created for this. The main enemy of rafters is damp, but where does it come from under the sealed roof? Do not forget the laws of physics: from the rooms through the attic ceiling comes warm air and a cold roof formed condensate. It falls on all elements of the rafter system, and only the dormer windows in the attic will allow for a timely airing of the room.
Eliminates the installation of the dormer and mold, which is actively developing in darkened rooms. Microorganisms also adversely affect the condition of the rafter system, speeding up the destruction of wood. On roofs with dormer windows, a large enough mold does not exist, especially if the attic is kept clean and tidy.
A tent roof with a dormer window is more sheltered from a strong wind. Masses of air moving at high speed create a vacuum over the roof, as a result of which the roof tries to "lift up" because of the difference in pressure. In this situation, you can not do without a valve, which would relieve the excess pressure in the under-roof space. His role is played by a dormer window on the roof. Thus, a short digression into the laws of physics and biology made it possible to understand why a dormer window is needed and why it is impossible to build a good house without them.
Types of dormer windows
In some countries, documentation has been developed that describes the arrangement of dormer windows and possible finishes. In other states rely on the competence of roofers and designers.
The variety of solutions allows us today to distinguish the following main types of auditory windows:
- rectangular with pitched roof;
- is lucrative.
In most cases, the design of the dormer window is chosen which will optimally fit into the roofing type.
Two types of dormer windows deserve special attention: attic and lucarne. If the traditional design of the dormer on the roof implies a separate exterior structure, a kind of house on the house, then the roof window is part of the roof. It is able to withstand high snow loads, is leakproof and can have a variety of shapes. The presence of integrated valves allows you to equalize the pressure on a windy day, and for ventilating, special opening mechanisms have been developed.
Lucerne appeared in Western Europe in the Middle Ages and is a vertical frame, located in the same plane as the facade of the house, and closed at the top and sides. During the Late Gothic period and the beginning of the Renaissance, the houses with the lyric were built everywhere, their owners asked the architects to richly decorate this element with stucco, carved platbands. As a result, lakarna stressed the status of the owner of the house, the presence of his taste. Widely spread this element in France, England, Germany, Austria, Italy and Russia. Windows-lucarne decorated the palaces until the beginning of the twentieth century, being an indispensable element of Baroque architecture.
Features of the design of dormer windows
A special feature of the mounting of the dormer windows is their location between the beams of the rafter structure. This is done in order not to reduce the strength of the system, capable of withstanding high loads. The skeleton of the dormer window is built in parallel with the construction of the truss system. Strengthened rafter legs and beams jumper, it is not allowed to tie into the structure. The fronton frames are carefully verified and a ridge bar is installed. To facilitate the design, it is covered with moisture-proof plywood. Only when the structure is ready, the roofing material is made.
The main feature of the design of the dormer window is the number of skates. Most often their number is limited by the construction budget and the architectural features of the roof. The monochromatic dormer window has a flat roof with a tilt angle of at lea
st 15 degrees. This is the simplest design, since the abutment to the roof is not difficult. The overhang of the roof directly above the window should be large, especially if it is not glazed.
The dome roof window has become most common, its roof can be either a strict or semi-circular shape. Its design is more complicated, since it is necessary to properly link the slopes of the main and window roofs. Demand, as well as material to protect the ridge, will be required. If the device of the dormer window of this type is executed correctly, the water flows are distributed more efficiently, and the frame is not poured, which allows it not to glass, but to close the louver.
Skylights are supplied by manufacturers in a finished form. This is explained by the fact that their design should be as strong as possible, and all mechanisms - effective and reliable. Much attention is paid to the salary, which ensures the tightness of the abutment of the attic window to the roofing material. The dimensions of the dormer window of this type can be any, that allows to provide the attic with natural light in accordance with the requirements of SNIP.
The most complex construction is lacquered, as it carries not only practical but also aesthetic function. It has its own facade, roof and decorative elements. The window-lucarne shape can be rectangular, triangular, arched. The roof is a one-pitch, two-slope, hip or semicircular. A beautiful, but difficult arch makes special demands primarily for the roofing materials used. It is used on buildings with a roof of flexible or natural tile, slate or flat metal. Windows-lucarne can be glazed or closed shutters.
Features of the choice of design and arrangement of dormer windows
The dormer window should not be located on the front side of the roof, in this case it will provide minimal illumination of the under-roof space.
The vertical arrangement of the dormer windows gives sophistication to the entire house, but it is not relevant for small roofs.
If two windows are installed-lykarny or more, then you need to keep between them a distance of at least 80 cm. In the opposite case, between the dormer windows on the roof will accumulate snow. As a result, the load on the roof will exceed the estimated load, which will negatively affect the service life of the rafter system. Snow will adhere to the finishing materials of the dormer windows in those places where it is not designed. It is possible to melt the water and damage the attic or heat insulation material.
One of the main issues that the owners of attic houses are interested in is the area of the dormer windows. To ensure normal natural daylight can only be provided that the total area of windows will be 12-16% of the floor area of the attic floor. The best option would be lushroom with one large window, but if several dormer windows are planned, then their total width should not exceed half the width of the room in which they will be installed.
In a residential building, the height of the dormer windows should not exceed 80-90 cm, and their optimal height is recommended in the range from 120 to 150 cm. It is easy to take care of such a window, and the amount of light in the room will meet the standards.
Advantages and disadvantages of dormer windows
A rooftop window located on the roof gives the building a more cozy and aesthetically pleasing appearance. To look after a window it is simple, and if necessary they can be used to get on a roof for installation of the equipment, antennas or for planned repair. If there are no shortcomings in the design, the dormer windows will provide the under-roof space with natural light. This is especially important for residential attics and maintained technical premises.
Among the main drawbacks of dormer windows and lyucarnes are the following:
- increasing the likelihood of leakage in the roof at the junction;
- the formation of snow bags and the increasing load on the rafter system;
- pass less light than the dormer windows of the same area, while the area of the illuminated floor surface is smaller due to a more obtuse angle of light;
- increase the cost of roofing.
Despite the shortcomings, the absence of a dormer window will be a more serious problem than its existence.
The dormer window must necessarily become part of the tent roof project, this will avoid unforeseen expenses, both during the construction process and during the operation of the building. To choose the design of the dormer window it is necessary to treat with special care and take into account, residential or uninhabited will be an attic space. When creating a frame, it is necessary to strengthen the truss system in the area of the dormer window. All this will help to get the maximum benefit from having such a complex construction on the roof of the house.