Overlappings in cottage construction

Overlapping is one of the most important knots in individual construction. From their correct calculation and the choice of a constructive solution, the reliability and longevity of the structure as a whole largely depends. There are overlapping attic and inter-floor. In the interfloor floors there is no thermal insulation, as inside the room the temperature on all floors is almost the same. However, to suppress noise, it is necessary to use sound insulation between the floors. In attic floors, it is necessary to use thermal insulation, in order to avoid the penetration of cold air from the attic and the loss of heat from warm living quarters.

Wooden floors

The most common in the cottage construction are arranged floors on wooden beams. This is due to the simplicity of the device, the lack of the need for additional equipment and the attraction of special equipment, as well as with relatively low financial costs.

Advantages of wooden floors:

• cheapness;
• Low consumption of timber;
• Effective sound and heat insulation;
• Simplicity of manufacture;
• Relatively light weight.

Beams or logs are used as beams. If the walls of the cottages are laid out of aerated concrete blocks or foam concrete, in the level of overlapping along the bearing walls , a reinforced concrete armored pavement is necessary.

The reinforced belt will be the support zone for the beams, and it is necessary to fasten them to the armopoy by means of anchor plates. The maximum width of spans of wooden floors is not more than six meters. The cross-section of the beams used depends on the width of the spans, the distance between the beams themselves and the load per unit area of the floor. The load per unit of floor area depends on the type of insulation used.

For example, if mineral wool is used, the load from 1m2 overlap will be about 1000 kPa. And when using, for example, claydite, the load will increase threefold. There are special tables showing the dependence of the minimum cross-section of the beams on the length of the span, the distance between the beams, the thickness of the insulation or the backfill. Tables can be found in the reference books for builders, and they should be used when designing and calculating overlaps.

Wooden interfloor overlappings are with the upper and recessed downslope. These two types differ primarily in terms of heat-insulating capacity and thickness. In overlappings with recessed downhole, the thermal conductivity is higher, therefore, they are colder. Wooden beams can be replaced with boards, in such cases, to avoid buckling, they are strengthened with wooden spacers. Consumption of timber with the construction of boards is reduced by about a third.

Wooden attic and interfloor overlappings, as well as elements of the roof truss system, are necessarily protected by fire, bioprotective antiseptics.

The main recommendations for the installation of inter-floor wooden floors.

• The distance between the ceiling beams should be about 1.0 meters, the beams are fastened by the rolling boards, 2.5 cm thick, on which sound and heat insulation is laid (usually mats from mineral wool).
• From the bottom the beams are hemmed with fiberboard or plasterboard.
• To lower the resonance properties of the wood, a double layer of building felt or parchment should be placed on top of the boards.
• The rough floor can be arranged from slag concrete, a few centimeters thick, or use a floorboard.

When designing a floor or attic floor for a cottage or apartment building, apart from the low cost and simplicity of the device, their fire resistance must be taken into account. Building standards stipulate that the wooden floors with plastered bottom surface and backfill should have a fire resistance limit of 45 minutes, plastered on both sides - 15 minutes.

Overlapping of metal beams

Another common type of overlap is from metal beams. As beams use metal I-bars, they are fixed at a distance of 1.2 meters from each other.

Due to the high thermal conductivity of the metal, the beams should be laid on paronite pads with a thickness of 3-5 mm. To protect the metal on the beams, it is necessary to apply a layer of anti-corrosion coating. The gap between the beam and the wall is sealed with a porous sealant and protected with waterproofing. This will ensure the vapor tightness of the beam-wall interface unit, prevent condensation of moisture and corrosion of the supported part of the beam. In the rest the device of overlap from metal beams differs nothing from wooden.