When arranging wooden plank floors, there is usually a number of additional beams (lag) from a bar between the supporting base and the flooring. Logs simplify installation, as well as improve the performance of floor coverings, which are called “floors on logs”.
Advantages of the floor on the logs
Modern plank floors consist of a number of wooden products laid in a certain sequence. One of these elements are floor logs - rectangular wooden beams or profiles made of other materials that serve as supports for the overlying subfloor or finish floor.
Why do we need lags
What are logs used in the construction of residential, public, cultural, entertainment and commercial buildings and structures?
With the help of these elements, it is possible to regulate the span between the supports of the plank sheathing, and therefore its strength, rigidity, permissible deflections (parameters regulated by Building Codes and Rules - SNiP), depending on the thickness of the boards used for flooring, as well as leveling floor horizontal.
The resulting free space between the lags is usually used for:
- insulation, filling voids with loose (expanded clay, ash, perlite, vermiculite), slab (mineral wadding, extruded polystyrene foam, polyethylene foam, propylene) or self-foaming (polyurethane) heaters, which at the same time can serve as a soundproofing layer in the floors of private or multi-apartment buildings;
- laying a variety of cable and pipe engineering communications and systems, including for the installation of underfloor heating of water or electric type.
Among other things, logs in construction isolate the floorboard from direct exposure to moisture during installation. floors on a soil or reinforced concrete base, significantly slowing down the processes of rot, mold, damage fungus.
Kinds
Most often, floor logs are made of wood, in particular, from bars of rectangular or square section. However, sometimes you can find a floor on logs in an apartment made of plastic or rolled metal (including pipes) profiles.
In order to get an answer to the question, what are logs in construction, you need to understand that almost all wooden plank floors, whether then the subfloor for linoleum, parquet, laminate or finishing flooring is a floor like a deck board on tongues, stacked on lags.
The most common are still wooden logs. Sometimes they can be made from a pair of narrow boards knocked together, installed on the ribs, as well as from hewn logs of a small section, which is typical for log cabins.
The size of the lag and the calculation of their number
Usually, the ratio of the height and width of the timber for the log is taken as two to one (2: 1).
The length of the lag should correspond to the size of the room intended for their installation.
The actual dimensions of the lag section depend on their pitch, support spans, if they are installed on top of load-bearing wooden, steel or reinforced concrete beams. These values can be easily calculated using SP 64.13330.2017 - Updated version of SNiP II-25-80.
When calculating, it must be taken into account that their height must be at least two thicknesses of boards, plywood, chipboard punched to them. That is, with a 3-cm thickness of the flooring, the height of the log should not be less than 6 centimeters. The same parameter cannot be less than the thickness of the heat (noise) insulation used + 2 centimeters or the diameter of the pipes, cables, and other life support systems laid between them at home.
The span or distance between the floor lags is determined by the thickness of the subsequent coating. For example, when using a 2 cm board, 10-12 mm plywood or chipboard slabs, this distance, according to the conditions of flexibility (fluctuation) and bending strength, should not exceed 30 centimeters.
The number of required lags is determined depending on the distance between the walls parallel to the installation. Its measured value must be divided by the step (distance between them) lag, thereby calculating how many of them will be needed to lay the floor.
How to process wood
Before laying the logs, they, like all wooden products, will need special processing.
The two most important enemies of wood are biological damage and open fire (fires). In order to avoid or at least reduce the likelihood of encountering these hazards, wooden elements are impregnated or coated before use:
- antiseptics that provide biological protection against mold, decay, fungal infection, infection by wood-eating insects;
- flame retardants - compounds that prevent fire, enabling wooden structures to withstand high temperatures for a long time.
Biological protection can be attributed to - impregnation with formalin, crude oil processing products such as creosote. Flame retardants are available in the form of colorful coatings or coatings. When exposed to high temperature, they create a foamed heat-insulating cocoon that prevents direct exposure to open fire on the joist structure.
Metal joists must be carefully cleaned with steel brushes, treated with corrosion converters and coated with rust-preventing compounds. This can be a thin-film coating based on minium, chromium oxide, as well as coal or bituminous paint.
Log protection materials must be environmentally friendly, not harmful to the health of people and pets, and have the appropriate certificates.
Mounting tools
Any tool is suitable for arranging the floor along the lags, used for work with wooden structures and their installation on all types of surfaces - soil, wood, reinforced concrete, metal sheets and panels. These include:
- pencils;
- roulette (rangefinder);
- meter steel ruler;
- square;
- bubble and water levels;
- construction knife;
- plane;
- hacksaws (for wood and metal);
- clamps;
- hammer;
- drill;
- perforator;
- grinder with cutting discs;
- set of wrenches
- screwdrivers;
- screwdriver
Sometimes, diamond grinding wheels may be required to level uneven reinforced concrete surfaces of the base.
Consumables and accessories
When installing a lag, a certain amount of consumables and devices may be required, which include:
- mounting, fastening devices, fixtures, including those with the possibility of adjusting and leveling the horizontal;
- nails of various lengths and diameters;
- bolts;
- hairpins;
- dowels - screwed and driven;
- self-tapping screws;
- anchor bolts.
The same list may also include paper for drawing sketches, adhesive tape for temporarily fixing the lag during their installation.
Preparing for installation
Installing a log under wooden floors requires quite careful preparation. It should usually include:
- drawing on paper a draft plan for installing a lag on an appropriate scale;
- calculation and selection of cross-sectional area, length, their required number;
- procurement (purchase or order for cutting boards of appropriate thickness) of wooden elements and delivery of future logs to the facility at the place of use;
- preliminary layout and clarification of all final dimensions, as well as the number of fasteners with the addition of shortages that have appeared.
Other works include wet cleaning, removal of construction waste, dedusting the surface in the room intended for installation.
Mounting Features
When installing and leveling wooden and other logs, you can use various linings made of thin plywood, linoleum, fibreboard, wooden wedges hammered towards each other.
All locations of the linings, together with them themselves, must be carefully treated in an appropriate way from the effects of fire and decay. The mounts themselves are rigid and reliable, not allowing distortions during installation and subsequent long-term operation. To avoid deformations and warpage from resizing with temperature and humidity changes, the logs should not reach the walls by 2-4 centimeters.
If the logs are laid directly on the ground or reinforced concrete slabs, in order to avoid capillary rise water, under their lower face it is necessary to put tapes cut from any modern rolled bitumen-polymer material.
With the presence of experience in working with wood and the availability of appropriate tools, it is not at all difficult to do the floor on the logs in the apartment with your own hands.
Gain lag
The easiest way to reinforce wooden beams, of which logs are a special case, is that in the zones of maximum moment (mid-spans) and cutting forces (supporting parts) on the logs on both sides are attached pads that increase the cross section of the beam in the most dangerous places.
Areas with traces of decay, damage by fungus, wood-eating insects are subject to cutting and replacement using standard cuttings recommended for connecting elements of wooden structures.
Metal logs can be reinforced with strips attached to the profile with bolted joints. Welding of any type is not recommended, as this can lead to buckling of the stressed zones of the metal as a result of its unforeseen annealing.
Also, to increase the bearing capacity (strengthening) of a wooden floor, you can reduce the installation step by placing new ones with a similar section between existing ones.
When strengthening the lag, it must be taken into account whether the overlap is able to withstand additional loads and whether they will have a devastating effect on it.
Therefore, before starting work on strengthening, it is recommended to make an additional calculation of the load on the floors, taking into account the changed circumstances.
Conclusion
Floors on wooden logs were invented hundreds of years ago. But, nevertheless, they still remain one of the most popular ways of arranging wooden floors in modern buildings. These floors are relatively warm, environmentally friendly and are not too expensive, both in production and in operation.
Wooden floors on the logs give special comfort and convenience of living together from children to the elderly.