The roof overhang is not the most important part of the roof, but it can be used for a wide range of different tasks. Provided that the calculation is correctly done, the cornice will be beneficial to emphasize the levels and planes of the slopes, as well as perform a number of useful functions. In modern homes, much attention is paid to such elements at the project stage. How to make the eaves overhang of the roof so that it is as practical and aesthetically attractive as possible? To do this, you first need to determine its configuration, then the parameters and possibilities for decorative design.
What tasks does the cornice perform?
The proportions of the cornice can change the visual image of the house, increasing or decreasing its expressiveness. Do not discard the stylistic accents characteristic of a particular region. Architectural traditions are being revived today in the private residential sector, where owners seek to emphasize the particular style of a particular area. As for the tools for achieving this or that image, both the size and the shape of the eaves overhang will be of importance. The photo of the roof presented above, for example, demonstrates the advantages of a massive overhang in relation to a small house. Visually, the structure becomes lower and wider, which adds to the perception of the structure a feeling of reliability and quality factor.
Functional tasks will mainly be expressed through structural capabilities. In the part of the cornice, it is possible to lay communications, arrange conclusions for ventilation and the chimney, and mount other engineering and technological channels. The width of the overhang will also affect the microclimatic properties of the house. The fact is that a long protrusion of the cornice obscures the window, absorbing thermal energy. If we are talking about a metal roof, then the accumulation will occur very quickly, passively warming up the entire roof covering. This effect can be used in different ways in winter and summer.
Roof cornice device
The overhang as such is a structural unit in which the ramp and horizontal overlap converge. The latter can only be a cornice stripe that extends from the point of attachment of the Mauerlat to the outer wall. The configurations of the pairing of the parts of the rafter system may differ, therefore, there can be no single principle for determining the elements of this node. One way or another, in any design an important role will be played by the roofing cake forming an overhang. This is the part of the ramp that goes beyond the level of the outer wall horizontally to the side, and in some cases it can fall much lower than the level of the attic floor horizontally.
Now it’s worth moving on to the materials of eaves overhangs. The roof structure is determined by the combination of the base of the slope with wooden (or thin metal) beams, crate and outer coating. The outer layer can be represented by a soft roof, corrugated board, tiles, etc. In essence, this combination will provide an external protective frame for the cornice. The cornice itself is formed due to the lower bar, which will connect the outer wall and the ramp. It is also often made of wood, but plastic is also found.
Varieties of eaves overhang
There are several options for the execution of the roof cornice, which differ in design and functionality. The most common is the usual closed cornice, which provides for a slope, average in slope and length of departure, and a horizontal bar forming a spotlight. A simpler design does without a bar. Also, an overhang is directed along the inclined, but there is no cover from the underside - an open construction is obtained, which has significant pros and cons. Firstly, this is a typical eaves overhang with a metal deck. The coating is rather flimsy and poorly functional, so with such a slope there is no point in arranging cornice closed boxes. Secondly, this solution requires a higher degree of isolation at the point of convergence of the Mauerlat and the roof.
Brick structures represent a special group of eaves overhangs. Instead of a wooden plank, the lower part of the overhang in this case will be covered by brick (or masonry). This option is used infrequently, but with its help you can create original facade designs.
Features of eaves on a soft roof
This type of roofing is one of the most problematic in the sense that the material is heavy and gives a significant load to the slope. Accordingly, you should focus on strengthening the structure from below and from the side. The optimal device of the eaves overhang for a soft roof may include a binder from the crate with the use of wooden blocks and metal fasteners. The power base will be provided with anchor joints along the entire length of the lathing, as well as metal corners and mounting plates, which will act as additional clamps.
Features of a flat roof cornice
In this case, the design is simplified, since there is no need to create an inclined slope angle with the corresponding decorations from the bottom. That is, support and casing from below will be, but implementing it horizontally is much easier. In the simplest version, the eaves overhang of a flat roof can be designed as a combination of a direct slope and overlap. Roughly speaking, the attic floor will take off to the side beyond the borders of the outer wall. At the upper level there will also be a roofing cake on a slope. Then it remains only to close both structures on the side with plastic or wooden sheathing. The result is a fairly functional box of the correct form.
Parameters of the eaves overhang of the roof
As before, and in our time, the optimal way to calculate the width of the cornice is the angle of the overhang. It may be different depending on the slope of the ramp. On average, Russian houses are designed with roofs, the slope of which varies from 30 to 45 degrees. Which flight will be optimal? There is a special regulation that defines the size range of the eaves of the roof over a width of 10 to 70 cm. Further, everything will depend on the type of roofing material. So, the shortest cornices are used on metal roofs - from 10 cm. Galvanized steel sheets allow you to arrange overhangs with a minimum length of 15 cm. And wavy asbestos-concrete panels are made with a width of 25 cm.
Mounting a cornice
The installation of this element for the most part comes down to the back lining with wooden planks, plastic panels or siding. The main thing is not to use metal in this part, since the condensate discharge through spotlights creates favorable conditions for corrosion. How to mount a roof eaves overhang? When the contours of the ramp and Mauerlat have been determined and their designs are ready, you can proceed with the installation of the supporting crate for filing. It is advisable to use a small-format beam. The supporting parts are fixed with screws to the wall or Mauerlat - as the design allows. A number of small planks with indentations of about 20-30 cm are fastened along the lines of the load-bearing planks. At the final stage, over the entire area from the back of the cornice, sheathing is performed - with plastic or wooden lining.
Cornice ventilation system
Even at the stage of development of the cornice scheme, it will not be superfluous to determine the method of implementing the ventilation system. Air circulation in the under-roof space is necessary to combat dampness, which is harmful to the wooden rafter system. The simplest method of ventilation in the eaves overhang is to initially use perforated plastic panels for cladding. They are specially designed as spotlights under the eaves for the organization of the duct. If wooden planks are used, then first you need to leave room for gaps. Sometimes, for such purposes, they simply withstand the space between the planking planks of several millimeters. Actually, it is enough that the overhang box is not completely tight.
Conclusion
Eaves - a significant and crucial part of the roof, but very delicate in execution. Much in the implementation of this element will depend on neighboring materials of construction. For example, the eaves overhang of a soft roof cannot be installed without taking into account the characteristics of the coating, which often limit the masters in choosing technical solutions. For such a roof, it is better to turn to special additional spotlights that can cope with the loads from a heavy roof and provide the necessary space for a possible installation of communications in the duct.
If the ramp is covered with light corrugated board, then you can completely do without capital support with the formation of the skin. It is enough to take care of the mechanical protection of the unit and ensuring free air circulation in the butt joints. But, on the other hand, the absence of an installation box in itself eliminates a number of structural possibilities, also associated with the installation of gutter elements and snow retainers. For this reason, counting on the long-term operation of the roof, it is worth considering the role of the cornice from the point of view of various aspects of application.