# Calculation of lag for the floor: material, parameters, installation

A wooden house and a bathhouse are the dream of many citizens. Each of those who had to build a wooden frame with their own hands, knows the purpose of log and beams well. These are the supporting structures of the building, therefore, it is necessary to select the material for them, as well as their number very carefully. Lags for the floor are recommended to be made from dry first-class material treated with antiseptic and flame retardant compounds. The most common way to install them is to install on beams embedded in walls during construction.

The lag for the floor is done, taking into account the basic parameters, the logs must be 1.5-2 times higher than the height of the flooring, otherwise the nails will not be able to firmly hold the boards floor.

They are installed taking into account the fact that between them is usually placed insulation material. This may be expanded clay, polystyrene foam, but most often mineral wool is used, pressed into plates 50-60 cm wide. Lags are mounted at the same distance from each other. They spread wooden floor, which, with proper installation will last for several decades. Lags are made of bars, beams, boards. They serve for the redistribution of loads from the floor, and also serve as a fixer that unites all components and parts into a complete system.

## Advantages of using lag

Paul on lags has a certain degree of functionality. In the space between them you can lay pipes, wires, insulation materials.

Bars are relatively inexpensive. Installing them is available to everyone.

These floor supports are capable of withstanding a load of 5 tons per square meter.

Figure 1. The scheme of fastening wooden beams.

When repairing the floor, it is often enough to repair the lag. Reshape the floor when this is not required.

The design does not have a large mass. The load on the floor is much less than with a cement screed.

The space filled with mineral wool will keep the heat in the house and protect it from excessive noise.

Bars allow you to bring the floor plane to any height.

The structures laid on the place do not require additional work. You can immediately lay the floor covering.

Floor flaws in the logs:

1. The room loses a few centimeters of height.
2. High labor intensity. It is required to carefully mark and align all elements of the structure.

## The calculation of some parameters of the lag

The calculation of the lag for the floor is made, taking into account the basic parameters. Lags for the floor must be 1.5-2 times higher than the height of the flooring, otherwise the nail will not be able to firmly hold the floorboards. If the thickness of the floorboard is 50 mm, then the height of the bars should be about 100 mm. If the draft floor is made of plywood or another sheet material having a thickness of 20 mm, the bars may be significantly lower, 30-40 mm.

Material for the manufacture of wooden logs should be selected softwood. Humidity blanks should not exceed 20%. Section of bars is chosen rectangular. They can be cut from a board 50-60 mm thick. Placed finished products across the light coming from the windows. The installation step is from 40 to 70 cm. Knowing the installation step and the size of the room, it is easy to calculate the required number of elements. Before installation, all wooden elements are treated twice with an antiseptic composition. Antiseptic can be replaced by ordinary hot bitumen.

Figure 2. Adjusting bushings. Apply to level floors on logs.

In practice, very often the height of the lag is chosen taking into account the thickness of the insulation layer. As insulation for the floor is usually used mineral wool, produced by plates, the thickness of which is 50 mm. The same height should be lags for the floor. If it is decided to lay the insulation with a double layer, then the bars are needed with a height of 100 mm. The distance between them depends on the thickness of the subfloor material. The thinner the rough flooring, the more often lags are installed. When the thickness of the plywood, which can be used as a substrate for finishing flooring, in 12 mm the size of the gap between the bars is 30 cm.

Most often, the subfloor is made of a grooved board. Boards should be spruce, pine or fir. For the finishing floor they are not suitable, because the wood is very soft, there are even traces of thin heels on it. From above it is necessary to lay laminate or other topcoat. The thickness of the boards with a normal step lag of 50 cm is recommended not less than 35 mm. In most cases, the calculation of the pitch of the bars is made taking into account the thickness of the floor material:

Figure 3. Fasteners. It is used for fastening wooden structures.

Board thickness (mm) - lag pitch (mm):

• 20 - 300;
• 24 - 400;
• 30 - 500;
• 35 - 600;
• 40 - 700;
• 45 - 800;
• 50 - 1000.

For the manufacture of these parts not only wood is used, but also reinforced concrete, various polymers and metals. Reinforced concrete products are highly durable. They can be used in the construction of houses outside the city. The remaining materials can be used for repairing floors.

If the base of the floor is wooden beams, logs can be installed by attaching them from the side with screws (Fig. 1). The size of the fasteners must exceed the thickness of the bar 2.5 times with a diameter of 6 mm. The positive point of this method is that when adjusting the height of individual lags, no additional adjustment pads are required.

In construction, special wooden or plastic products are sometimes used, having openings into which small adjusting plugs from plastic are inserted. They contribute to the rapid leveling of the surface formed by the lags. Such products are mounted very quickly and do not require the use of linings (Fig. 2).

## Tips for installing the lag

Figure 4. Layout of floor installation on logs.

It is recommended to start laying them from opposite walls, departing by 20-30 cm. Horizontalness is controlled by level. Between them, stretch the nylon thread or fishing line. All other lags are set for it.

Before installing the wooden elements, it is necessary to protect against various microorganisms and wood-borne pests by treating the material with a disinfectant and then with a water-repellent compound.

In rooms with low ceilings, it is better to use other methods of floor installation. When performing the calculation, we must not forget that the bars reduce the size of the room in height by 10 cm or more.

Floorboards or sheets of rough flooring should be attached to each lag.

The ends of the structural elements should not touch the walls of the building. There must be a gap of at least 5 cm between them.

Instead of a certain section of a wooden bar, boards can be used, pairwise connected to each other and reaching the size of the desired bar across. Several large sizes are not forbidden. Boards are installed on the edge.

Table for calculating the distance between lags.

Lags can be fixed to the concrete base with special galvanized metal angles, which are fixed on the base with dowels and self-tapping screws. Instead of corners, often used U-shaped devices (Fig. 3).

If necessary, the bars of which lags are made, are joined with each other to achieve the desired length. Under the junction must be a solid support. This support often serves as a brick pillar. Under its construction you need to dig a hole about 10 cm deep. It is covered with sand and poured with water. Above the sand pillow is covered with a layer of polyethylene. A cement-sand mortar is placed on it and a column of red brick is laid out.

You can lay out the columns in rows and fix the logs on them (Fig. 4). The size of the columns is 25x25 cm. The calculation of the number of bricks is not difficult.

The floor construction on the logs allows you to immediately mount the rough and finishing flooring.

Lags can be made from various materials. Most often, their manufacture is a wooden bar or board. And there are a lot of materials for finishing. Their choice depends only on the preferences of the owners and the contents of their wallet. To make the calculation of materials for the manufacture of lag for the floor will help paper-based room plan with exactly the specified size. All calculations are best done before the start of the main installation.

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