Installing a lag for the floor

Lags can be stacked both on an earthen base, and on wooden or reinforced concrete floors of buildings.

  Installing a lag for the floor

Lags are carefully dried wooden bars serving as the basis for a clean floor covering.

If the overlappings are wooden, then most often their beams do not differ with excellent flatness, and when laying the lag directly on them it is very difficult to achieve a flat horizontal surface. In this case, the logs should be attached to the sides of the beams.

The main advantage of this method is that it is not necessary to use linings to adjust the height of the lag. Fastening is performed using incomplete screws, while their length should be no less than 2.5 times longer than the width of the log, and the diameter not less than 6 mm.

Tip: in order to avoid splitting wood, it is recommended to drill a hole 2.5 mm in diameter less than the diameter of the screw in the log and the beam before fastening.

If the beams are located at a large distance from each other, then it is necessary to lay the second syllable lag perpendicular to the first, but at a closer distance. Another way to remedy this situation is to use thicker boards for a clean finish.

When laying the lag on concrete floors, you need to take into account that in such a situation, the entire floor structure will look a little different:

  1. When laying the floor on concrete, you need to take care of waterproofing, otherwise the floors will constantly damp.
  2. Next is the heat and sound insulation layers.
  3. Then be sure to make a dry or cement screed.
  4. And only after that the lags are stacked, on which the fair covering spreads.

For lag one should not take boards shorter than two meters. If the selected length is still not enough, then the parts are joined together end-to-end.

Important: when connecting the lag between themselves, it is necessary to ensure that the joints in the adjacent rows are displaced at least two feet in relation to each other.

Lags are laid on the floor screed. If this is not possible, then the base surface should have at least waterproofing.

Before laying the lag concrete floors must be waterproofed so that the wood does not pull in moisture

But on the soft insulation flooring lag categorically not recommended, in this case they will float, which will lead to the gradual destruction of the finishing. If the heat and noise insulation allows the laying of cloths of a certain width, the lags on the base are arranged so that the insulating material is located strictly between them.

Tip: if lags cannot be placed under the width of the roll insulation, then the distance between the lags should be selected so that the last cells can be filled with the scrap with a minimum of material waste.

Laying the log on the ground foundation

If the floor on logs is located directly on the ground, then first it is necessary to remove all the turf, sprinkle about 50 mm of gravel over the surface, carefully tamp it and pour a 5 cm layer of lean concrete. Next, we proceed as with a concrete base, that is, we put waterproofing, insulation and screed.

Tip: when laying the floor on an earthen base, the insulating layer and screed can be replaced with polystyrene concrete.

Slightly above, we touched on such a thing as “distance between lags.” I think many will be interested in how to correctly calculate this value, because to achieve an optimal load distribution, the lags must be laid at the maximum equal distance from each other. Usually the distance between them ranges from 350-400 cm.

Assume that the room in which the lag for the floor is being installed is 8.5 meters long. The door is in one of the short walls, and the window opposite it is in the far wall. Lags will be located perpendicular to the long side, and the finishing board with a right angle to the lags. This is done to ensure that the final coating is located parallel to the light rays entering the room from the window.

Let the width of the bars prepared by us under the logs be 0.09 m. Usually, the first and last logs are necessarily 30 mm from the walls. Take the lag number for y, then their total width will be 0.09 * y. The averaged distance between the lags is 0.375 m and such distances will be y-1, then the total distance between all the bars will be 0.375 * (y-1). Knowing the recommended distance to the walls, 0.03 * 5 = 0.15, we obtain the equation:

deciding which determines what we need 18.96 lag. Since their number should be an integer, rounded to the nearest value. That is, for this room we need 19 lag. Now we find the sum of all distances between the lags:

and since such distances are 19-1 = 18, we get the exact width between the lags

6.73 / 18 = 0.374, not 0.375, as we assumed at first.

  1. The surface on which the floor is planned to be laid on logs should be thoroughly cleaned and well primed.
  2. All wooden parts must be dried and treated with an antiseptic, for example, bitumen.
  3. Noise insulation can be made of slag or sand, as well as fiberboard.
  4. Install logs should be on the window, with a gap between them and the walls of no more than 30-40 mm.
  5. After laying, the surface plane of the lag is checked with the rule (long level) located across the beams. If there are no gaps between it and the beams, then the installation was made correctly. If they are still there, then the surface can be leveled by removing or, conversely, pouring sand under the lag.

After laying the surface of the lag is checked by the rule (long level)

New technologies have touched and such an old method, as the device of a floor on logs. In modern beams, ready-made threaded holes have already been made, adding reliability to the joints.

Changing the height of the adjustable log is carried out by turning the special bolts

In addition, such logs can be adjusted by rotating special bolts that allow you to quickly and effortlessly change their height. After the adjustment is completed, the excess part of the bolts is simply cut off.

As experience shows, wood is almost an ideal material for flooring.

Properly laid wooden floor has a long life, it is beautiful, environmentally friendly and does not require complex care. Consider the main advantages of this foundation:

  • ease of leveling the floor surface;
  • increased thermal insulation properties;
  • quick and easy installation;
  • profitability;
  • good sound insulation;
  • the possibility of the location under him communication facilities.

If coniferous woods are used when laying the floor, the result will be not only a beautiful and durable coating, but also a wonderful well-being microclimate in the house. So,

What is needed for laying wooden floor on logs

  • perforator;
  • ax;
  • level;
  • saw or jigsaw;
  • hammer nail;
  • drill and screwdriver;
  • wrench 13-14;
  • lags 50x50mm;
  • floor board;
  • insulation;
  • hardware (anchor bolts 10mm, screws – 35, 50, 75mm, nails – 50 and 70 mm).

Lags are placed on the previously calculated distance from each other on the soundproofing material. When laying it is necessary to apply a level, achieving a flat surface. Lags are attached to the concrete base with anchor bolts, to all others – with the help of dowels.

Tip: calculate the length of the anchor bolt, adding 6 cm to the height of the lag.

Thermal insulation, for example, polystyrene foam, izospan or basalt fiber, is laid in the gaps formed by neighboring lags. It is more convenient to use rolled insulation. Claydite can also be used as a heat insulating layer.

Insulation is placed on top of the waterproofing between the lags.

The arrangement of the wooden floor along the lags starts from the corner of the room. The first row of boards has a tongue against the wall, leaving a small gap between the wall and the boards up to 10 mm, which is necessary to compensate for the deformation of the tree as a result of environmental changes.

The next row is placed offset by about two lags relative to the previous one. A snug fit of the boards to each other is achieved by lightly tapping with a hammer on a piece of wood attached to the end of the adjacent board.

The boards are stacked so that each subsequent row is shifted by about two lags.

When attaching the boards along the walls, it is allowed to place the screws on top, since their heads are still masked by the plinth, but in all subsequent rows the cover should be fixed only behind the bottom wall of the groove, driving the heads of the screws inside the board.

After laying all the boards, you can begin to close the expansion joints using a plinth. In addition, it will protect the walls from pollution.

  1. It is possible to start the flooring of wooden floors only after complete leveling of the lag.
  2. Boards are attached to each lag, without exception.
  3. The size of the boards should be chosen so that the joints are in the middle of the lag and are located perpendicular to the long side of the board.
  4. To prevent the boards from cracking, the holes for fasteners must be drilled out in advance. For the self-tapping screw we use a thin drill bit, and for its cap a thicker one.
  5. Instead of a plinth to mask the gaps between the walls and the floor, you can position the fillet – special profiled strips.
  6. Holes for pipes must be drilled with a diameter of 8-10 mm larger than the diameter of the pipe.

Tip: for greater reliability, before attaching the boards with nails, it is better to pull together with building brackets with a stapler.

The foundation of the floor in old houses almost never differs smoothness and evenness. The differences in its height can reach 20 cm and it is very difficult to adjust such a surface. And the use of concrete screed is not always permissible, since not all the beams in the old housing are able to withstand a large load. This is where the use of regulated lag will help. Let us consider in detail the process of their installation:

  1. Bolts are screwed into special holes in logs, with at least five holes needed for every two meters of beams.
  2. We decompose the lags taking into account the previously calculated distance between them.
  3. In the ceiling drilling holes for dowels-nails, be sure to bring the drill to the holes for rack bolts.
  4. Align the logs on the level and hammer in the dowel-nails, cut off the protruding parts of the bolts-racks.
  5. We lay the wooden floor on the logs, that is, the finish coating.

But laying the floor on the logs is far from the end of the floor device. Next, you need to get rid of roughness and high-altitude differences. For this it is convenient to use a small grinding or scraper machine. We begin to grate with a large sandpaper that quickly removes all irregularities, and then polish the surface with a fine-grained sandpaper.

Next, proceed to the protection of the floor in order to increase its durability and service life. For the floor there are three main types of coatings:

  • oil impregnation;
  • parquet lacquer;
  • wax mastic.

To begin with, it is necessary to determine the places where the floor staggers and flexes. Now it is necessary to remove the loose nails and screw the screws into their place. According to the old nails, you can easily determine the location of the log under the fair base, these places should be strengthened with additional screws so that the cap completely entered the tree. After eliminating the squeak, all these places are puttied, and the floor covering is completely renewed.

We hope that our article will help you decide on the type of floors and independently cope with the flooring of a wooden floor.

Everything you wanted to know about floor lags and floor technology for lags

Despite the relatively short operating time of multi-layered wooden structures, their light weight, environmental priorities, cost-effectiveness act on the owners convincingly. If in the field of building walls with natural organic matter, foam concrete, brick, gas silicate blocks can still be argued, then lumber is still leading in the field of flooring. Basically, for the device of multi-layer wooden structures, logs for the floor are used, made of durable polymer compounds or of wood.

What attracts owners to the floor with peculiar air cushions formed by laying polymer or wooden bars? The list of benefits includes important items such as:

  • excellent thermal insulation characteristics;
  • affordability of sawn timber;
  • the formation of a minimum load on the foundation, on beams or concrete floor slabs;
  • the ability to raise the plane of the floor to any level;
  • reducing the cost of building materials;
  • the speed of the construction of the wooden floor construction, not leading to the expectation of the screed;
  • availability of convenient for installation communications technological space;
  • ensuring an optimal microclimate inside buildings or rooms;
  • the ability to perform the laying of wooden floors on the logs yourself.

The device of floors on logs – quickly, economically, reliably

In addition, a well-executed device for the floor of the lags will eliminate the rather costly alignment process, since it fully performs its function. The presence of ventilation cavities in the floor construction will extend the operating time used for the arrangement of lumber, which are still recommended to be treated with antiseptics, means of aging wood and fires. Economical owners can use bitumen instead of antiseptic.

Constructive and technical features

Floors with logs can be laid on the earthen foundation and on the floor, built of wooden beams or reinforced concrete slabs. Regardless of the type of foundation, identical materials are used for the floor construction.

What can lags be made of?

Lags are transverse floor joists, over which a topcoat is laid. It is extremely rare to use metal and reinforced concrete beams as lags, most often wooden bars or progressive products made of polymer. Wooden bars are chosen mainly because of their cheapness, polymer because of the speed of construction and ease of installation.

Lags – cross beams, most often of wood or polymer

Note. Instead of a bar, which for some reason could not be purchased, there can be used boards matched to each other according to the dimensions of the cross section of the bar. Acceptable sectional dimensions are allowed. In such cases, the installation of a log for the floor, made of stitched boards, is made on the edge.

To this day, builders of chopped houses use equal logs hemmed from three sides with a similar diameter instead of a bar. In austerity mode, logs may well replace the timber. The only condition: they must lie before laying for about a year in a dry room.

The right choice of section

The cross section of the bars selected for the device of the floor along the logs resembles a rectangle with a height of multiple of 2, a width of multiple of 1.5 (aspect ratio in the section of 2 × 1.5). If the floor is arranged on wooden floor beams, then the size of the span between the elements on which they will rest will affect the size of the cross-section of the bars.

The cross section of the logs depends on the thickness and strength of the floor covering.

Pay attention to those who are planning the arrangement of the floor construction with an insulating layer. A ventilation gap of at least 2 cm (preferably 3-4 cm) should remain between the lower surface of the finishing coating and the insulation laid between the bars-lags. So, the timber needs to be bought taking into account the size of the ventilation gap. If the floor structure will be supported on the ground, it will be necessary to take into account the thickness of the reeling, laid on the cranial bar attached to the logs.

It is recommended for flooring logs to purchase a timber with a “margin” in the dimensions of the section. When constructing the floor above the earthen base, in order not to use a too expensive large section beam, the span is reduced by installing brick columns. The intermediate distance between the supports is 1.2 m. They are made of red brick M100, silicate is applicable only if the aquifer level is less than two meters.

Floor plan for logs with emphasis on brick columns

Competent laying of the floor on the logs with brick columns implies the equality of the distances between the rows of supports and between the elements of the timber. Before the construction of brick pillars pour the foundation of 40 × 40 cm under each of them. The foundation can also be poured in the form of a tape under a number of brick pillars. In each row of the support column there are two bricks, the height of the support depends on the level of the elements on which the beam will be supported (the bottom trim, the grillage of concrete).

The height of the brick column determines the height of the element on which the timber will be supported.

Installation step log

The step between the lags is an important parameter on the basis of which calculations of the consumption of materials are made. You can draw a plan of rooms and accurately calculate how much timber and brick with cement will be needed if the floor is not laid on the floor. This is the magnitude between the axes of elements parallel to each other. The step size is influenced by the power of the final coating and its strength characteristics. That is, when laying a coating that can withstand a large load, it is permissible to increase the distance between floor lags.

Before laying thin materials, logs will have to be installed frequently (0.3-0.4 m for laying boards up to 24 mm thick). For 50 mm boards, the distance between the axes of the lag can be 1 m. Basically, 40 millimeter boards are used for home improvement, logs are laid with a 70 cm distance between the axes. Reducing the pitch between the elements, as well as increasing the cross section, will increase the structural strength costs. Only the owner to decide what is more important to him.

Laying the floor on the logs with their own hands should remember that the margin of the element at the end of the wall should not exceed the step size between the logs. Usually they recede from the wall by 20-30 cm.

Geometric guidelines for styling

Orientation in space – a significant component of the correct floor device. Those wishing to learn how to put lags on the floor correctly, you should follow the following building rules.

  • Flooring in rest rooms and living rooms is carried out along the direction of the flow of natural light. Lags are located “in the cross” in the direction of the boards.
  • In vestibules, hallways and other rooms with intensive traffic, boards are laid according to the direction of movement, logs, of course, in the direction perpendicular to the direction of the floor covering elements.

Lags are laid “in the cross” floor boards

Note. If the reinforcement of the floor structure is made by installing two interlayers from the timber, the upper layer is laid “in the cross” to the previous one.

Mounting methods

Previously, logs were fastened to a concrete slab or beams simply with nails. Not the best and not the long-term method was replaced by fixing with galvanized metal corners. The instruction on “how to fix lags to the floor” reads:

  • Fixation of the corners is made with screws.
  • One of the planes of the corner is attached to the timber.
  • The depth of penetration of the screw into the timber is 3-5 cm.
  • The corner is fastened to the bottom trim bar similarly.
  • To the brick support or concrete grillage, which must be covered with a layer of waterproofing, fastening is done with dowels.

Instead of a corner, a U-shaped fastener can be used.

U-shaped fixture used for fixing timber

It often happens that the standard length of the timber is not enough. Elements can be joined in two ways:

  • right next to each other;
  • by cuttings, called “the floor of the tree.”

Attention. Joining places should be strengthened by stitching nails to one, and better to two sides of the timber, pieces of lumber 1 m long.

Ways to join the timber “in the floor logs”

When installing a bar in the gap between the points of junction of the bar should be at least 50 cm.

The sequence of work on the device of the floor on the ground

Practical democratic floor cake on wooden lags can be arranged before the construction of bearing walls, for example, a frame house, or during the period of interior decoration. It is recommended to carry out the finishing of the floor after all plastering and painting operations.

When constructing a multilayer cake above the ground, the works are performed with the following sequence:

  • Vibrator or the end of a simple log soil compacted.
  • The compacted rubble is covered with a layer of 5 cm; it will perform the function of an incompressible base.
  • Pour in the formwork, specially made for each support or for a number of supports, cement.
  • Construct supports of brick (between the base for the supports and the brick should be a layer of waterproofing).
  • Above the support have another layer of waterproofing and sound insulation strip.
  • Install and fix the logs.
  • Then stack the cranial bar and arrange the boardwalk of cheap lumber.
  • After the re-run, another layer of waterproofing is again located.
  • Insulation is placed between the lags.
  • The upper plane of the entire installed beam is leveled by cutting off the excess, the presence of deviations is revealed by the level.
  • Be sure to leave the ventilation gap between the floor boards and the insulating layer.
  • At the end, the floorboards are laid with a distance of 2 cm from all the walls around the perimeter. This gap is necessary to compensate for the advances of wood occurring under the influence of moisture and temperature. After the scraping and processing of the finishing composition (on the implementation of these works, you need to read the relevant articles), this gap is closed with a plinth.

The scheme of the floor with lags on the ground

Alignment of a bar before laying of a covering

When constructing the floor above the ceiling, the process is shortened, since the logs are attached directly to the timber or to the reinforced concrete slab.

Device lag with adjustment

A convenient innovative scheme is the installation of adjustable plastic lags that can withstand about 5 tons of load per m 2. There are lugs designed for adjusting the level of the floor in the logs designed for the operational floor device. Lags are rigidly attached to the rough concrete surface with dowels, to wood with self-tapping screws. Excess lengths are simply cut.

Adjustable lags for flooring

Video example of the work

It is not too easy to construct a multi-layered floor cake on wooden lags, but it is he who significantly reduces the budget for construction or repair. In addition to minimizing the consumption of materials, the pace of finishing production is also increasing. Thorough adherence to the technology of arrangement of this floor construction scheme and compliance with the recommendations guarantees long-term operation and aesthetic appeal.


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