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How to lay OSB on the floor

Despite the fact that the quality of oriented strand board is superior to that of chipboard, this construction material is not suitable as a finish flooring:

  • It is necessary to leave a gap of 2. 5 mm between the sheets to avoid squeaking during temperature expansion;
  • seams are sealed with sealant, reduce the aesthetics of the design of the coating.


Therefore, OSB is used more often as a subfloor:

  • Boards have perfect flatness, which allows them to align warped from the long use of tongue and groove board floorboards;
  • the solid surface of OSB is suitable for small format cladding, which can not be laid on a bare board without disturbing the flatness;
  • the boards have a stable geometry and self-supporting capacity, so they can be used to reinforce the subfloor with sparse joist spacing or small floorboards to increase its spatial rigidity and load-bearing capacity.

After laying OSB the surface is even and has a high load-bearing capacity.

It is necessary to know how to attach OSB sheets to the floorboards/layers, to use the offset of joints in adjacent rows.

There are several types of oriented chipboard:

Important! Since the subfloor has a low repairability, it is forbidden to use OSB-2. Boards are additionally treated with antiseptic and waterproofing material.

The main characteristics of oriented strand boards are:

  • density. 630 kg/m³;
  • thermal conductivity. 0,13 W/mK;
  • linear expansion. 0,15% at humidity of 70%;
  • straightness. 0.6 mm/m;
  • perpendicularity of the opposite sides of the sheet. within 3 mm;
  • thickness variation. 0,3. 0,8 mm (sanded, not sanded, respectively).

Advice! Manufacturers produce slabs of different sizes, which should be taken into account when buying to reduce waste cut for a particular size and configuration of the room.

Installation technology

To properly put sheetrock on top of an existing boardwalk, the conditions must be met:

  • Revision of the foundation. rotten beams, boards are replaced, creaks are eliminated, the presence of insulation, vapor barrier membrane over it and waterproofing under it is controlled, the impregnation of antiseptic and fire retardant floorboards is updated;
  • Layout. usually from the long wall, offset joints in adjacent rows at least 30. 40 cm;

Important! When installing parquet, PVC tiles, other small-format cladding heads of self-tapping screws must be putty.

Laying recommendations

Depending on the type of finish flooring, OSB boards don’t orient themselves the same way on a wood floor:

  • For small-format decorative materials it is necessary to provide that the joints of tiles, PVC tiles do not coincide with the joints of OSB boards;
  • when choosing laminate, tongue and groove, decking or parquet board, it is better to lay the rows of OSB across the direction of the long finish or at an angle of 45 degrees for diagonal layout (relevant in rooms with defects in the geometry of the walls).

Advice! OSB is allowed to be covered with a screed of cement-bonded particleboard or selflevelling flooring. However, the surface of oriented strand board should be pre-treated with a waterproofing material to avoid leaks into the lower floor and swelling of the construction material itself.

Repairing the hardwood flooring

The main problem with the boardwalk is a floorboard or a few boards that, with periodic changes in humidity or in the process of drying, have a transverse “hump”. This leads to an increased repair budget:

  • The surface of the floor becomes uneven with a “comb”;
  • OSB is not supported on the floorboards with its entire surface, but only in places of contact with “humps”;

In other words, you have to use OSB 22 mm or thicker. The above problem can be solved by pre-sanding or scraping the substrate:

  • A sanding machine or scraping will smooth out the “waves”;
  • dramatically increase the contact area of the layers of the black floor;
  • you can make do with OSB of a smaller thickness.

However, this is not always possible if the thickness of the existing flooring is small.

Top layer of OSB subfloor

Wood boards are excellent for the top layer of the black floor, as they increase the performance characteristics of the structure:

  • provide an even base for the flooring;
  • increase spatial rigidity and stability of the subfloor;
  • reduce labor and material requirements.

unlike floorboards, self-tapping screws are screwed into OSB boards vertically. In the case of sloping hardware, changes in geometry, warping of the material over time may occur.

The main problems arise with the divergence of opposite walls (trapezoid instead of rectangular room shape). In this case it is necessary to mark out the existing wooden floor in order to undercut only the boards of the first row:

  • A centerline line is drawn along the long wall of the room;
  • depending on the size of the board, parallel to it, marking is made;
  • the edge of the OSB sheet, connected with the wall, is trimmed with a hand saw or a power tool;
  • the second and the next rows are laid on the markings without trimming, taking into account the offset of the transversal joints;
  • the last row is cut in a similar way to give the sheets a trapezoidal shape.

Thus, structural material OSB is suitable for creating an upper layer of the black floor, as well as for the repair of the finishing coat of tongue and groove board, if the removal of this lining for some reason is not expedient in the room. If you choose oriented strand board reduces the labor intensity of the work, the home craftsman can manage with the existing arsenal of tools.

When to lay OSB boards on the floor

install OSB on the floor under any finishing material. A subfloor of wood sheets can level the subfloor and prolong the life of the flooring by protecting it from wear and tear due to interaction with the floor. Often in this way the floor is prepared for linoleum, laminate, parquet, carpeting. It is not always profitable and relevant to perform levelling screed, so levelling with OSB becomes the only right solution.

  • If there is a good insulation of the base in the room and the inability to fill in the floor concrete.
  • If the house is located in a region with a great minus in winter, which requires additional insulation of cement screed with OSB layer or making an artificial void with sheathing and a layer of insulation.
  • If there are noticeable irregularities (holes, chips) and other defects that can be seen under the decorative coating and will contribute to its rapid deterioration.
  • When it is important to make the floor resistant to mold, rodents, and other negative influences.
  • When levelling a floor with OSB is more profitable financially than other options of preparing the base for laying the finish coat.

OSB can be laid both on concrete and on wooden flooring, on metal framework, other types of durable substrates.

Characteristics of OSB boards

General information about OSB-board

Unique physical and mechanical properties, with comparatively reasonable price, make OSB boards more and more popular in different fields of building. Floors can be excellently levelled and surfaced with low effort, cost and time savings. over, even a person with no experience in the construction industry can deal with the installation of OSB boards on their own.

Before studying the technology of installation of OSB-boards, we must briefly consider their characteristics and compare them with other similar materials.

It should be said that oriented chipboard in some of its technical and operational characteristics are superior to other materials of similar purpose. But owing to their constructional peculiarities they cannot be used as a floor finish most of the time.

Oriented strand boards are made of wood chips, which are placed in several layers in a longitudinal-transverse manner. On the outer layers, the chips are usually placed along the length of the board, and on the inner layers, across. Layers bonded together under pressure by polymer resins.

The scheme visually demonstrates the principle of construction of OSB boards. the intersection of wood chips directions in the outer and inner layers of the material

Due to such manufacturing technology OSB boards have improved physical and mechanical properties in comparison with some other similar building materials.

The main characteristics of oriented strand boards are shown in the table:

Parameter descriptionIndicators
Board thickness, mm 10; 12; 15; 18; 22; 25
Density, kg/m3 630
Thermal conductivity, W/m×K 0.13
Linear expansion at 70% humidity, % 0.15
Deviation from board width and length, mm ± 3,0
Variation in thickness, mm 0,3÷0,8
Boards humidity, % 4,0÷12,0

The characteristic features of OSB boards during their installation and operation can be defined as follows:

  • High moisture resistance. During tests under laboratory conditions, the material was completely immersed in water for 24 hours. resulting in only 18÷25% swelling. And at the same time, the board was not destroyed, and its strength was preserved.
  • Durability and long service life. Oriented strand boards are able to withstand high loads and extreme conditions. Due to the multi-layer structure of the material, the boards retain fasteners well.
  • Ease of installation of large-sized sheet material.
  • The low cost makes such boards affordable, even if the amount allocated for the repair is limited.
  • OSB boards that are produced according to the technological requirements consist of 96% natural materials. Therefore, they can be called conditionally environmentally friendly. If the boards are to be used in residential premises, it is advisable to choose a material marked E1.

Due to their technical characteristics oriented strand boards are very good for underlayment under decorative floor covering.

  • The boards have a perfectly flat surface. Therefore they can easily level wooden floors, arranged with ordinary wooden boards and deformed in the process of long-term use.
  • Each board covers a fairly large area of the floor. The most common sizes are 2240×1220 mm and 2500×1250 mm. which corresponds to 2.98 and 3.125 square meters. When laying them the surface will have a minimum number of joints. That’s why they are perfectly suited for small-format subfloors like laminate, hardwood, parquet, vinyl tile, etc.п.
  • OSB is self-supporting and has stable geometry. Therefore, they can be used as a rough floor covering, fixing them to the frequently installed beams or sparsely left floorboards. Thanks to the same properties it is possible to reinforce an old wooden floor, increasing its load-bearing capacity and rigidity.
  • Since the boards consist of several layers of wood, which itself has soundproofing and thermal insulation qualities, the coverage they are able to shield the room from outside noise to some extent. In addition, an additional layer attached to the wooden floor will help reduce heat leakage from the rooms.
  • OSB boards are not afraid of moisture, so they can be used to create a roughing floor structure on the joists. By lining the beams with them both above and below, it is possible to fill the space formed with one of the thermal insulation materials.

In the table below, for the sake of clarity of information, the comparative estimated characteristics of various board materials made from wood raw materials and having approximately the same purpose are given.

Name of evaluated parameters Rating on a five-point scale Final average score2,863.003,283.57
Fibreboard Particle board Glulam plywood OSB
Durability 2 3 4 4
Resistance to external atmospheric influences 1 2 3 3
Dimensional stability 2 3 3 3
Weight 2 2 3 3
Machinability 3 4 4 5
Technological efficiency of surface coloring 5 3 3 2
Probability of material defects (splitting, notches, knots) 5 4 3 5

Variety of OSB boards

There are several varieties of oriented strand boards available in construction stores today. They differ in characteristics and therefore in purpose. When choosing a material for a specific area of construction or repair this factor must be taken into account.

  • OSB-1. this material has very low indicators of moisture resistance and durability, it is not of high quality. Therefore, such boards are most often used only for auxiliary works.
  • OSB-2 is a board of considerably higher quality, but its moisture resistance characteristics are still not outstanding. They are intended, as a rule, for use in dry rooms in those structures where contact with moisture is completely excluded.
  • OSB-3 are universal products, which can be used for boarding surfaces both in dry premises and rooms with high humidity. They are used for cladding walls, laying on wooden floors when leveling them, arrangement of floors with lagging.
  • OSB-4 is 15-25 mm thick and is most often used for bearing structures in premises with any level of humidity or even outdoors. They can also be used for flooring as a subfloor.

Boards can have different linear dimensions, but most often there are the dimensions already mentioned above. Nevertheless, you should pay attention to this parameter when purchasing the material. This reduces waste when cutting.

OSB. classification and choice of the class

OSB (oriented chipboard) is a material that is successfully used in construction and furniture manufacturing. Externally similar to chipboard, but the new material has a significant difference. In the manufacture of OSB large chips are used, laid down in layers.

The odd-numbered layers are placed along the length of the board, while the even-numbered layers are placed crosswise. The minimum number of layers is three. This intersection of chips and woodchips provides the material with high fracture strength. Those who today are concerned about the construction of the house, or its repair, wonder whether OSB board can be laid on the floor?

OSB floor

The role of OSB in frame building and insulation of standard houses is very important. OSB is used especially often for forming and leveling floor surfaces. OSB boards are characterized by high mechanical strength and resistance to moisture, good thermal and acoustic insulation. The chosen solution has the advantage of being easy to install.

Slabs are ideal for the construction and leveling of floors, perfectly able to withstand the load of furniture, equipment, human movement. When leveling small defects in the floor, it is enough to use OSB boards with a thickness of 10 mm. If you want to make a floor on joists, thickness of used OSB must be not less than 1525 mm.

Installation of OSB boards on concrete floor (cement screed)

The work should be carried out according to the following scheme. The concrete base must be absolutely clean and dust free in order to ensure good adhesion to the mounting adhesive. It is recommended to cover the surfacing of OSB boards with a special adhesive primer Soppka.

Then it is necessary to lay the OSB boards on the surface and, if necessary, perform trimming with an electric jigsaw or circular saw. On the underside of the OSB is applied parquet glue and glued sheets to the concrete substrate. When laying, it is mandatory to leave 35 mm joints between the boards. On the perimeter of the room, between the OSB and the wall, the joint must be 12 mm. It is recommended to fill up the joints between the boards with a special putty for joints SOPPKA Smart ELASTIK OSB. Time of full drying is 24 hours.

Mounting OSB boards on the boardwalk

Laying OSB on the old wooden floor helps to level the surface and prepare it for the finish coating. To begin with, you need to determine the location of irregularities in the boardwalk with the help of a level. Boards that are staggered or too high above the general level, tighten to the joists with dowels, sinking them into the material.

Spread OSB on the floor with an offset of joints of every following row. There should not be any cross joints. Be sure to leave a gap between the boards of 35 mm, the perimeter of the walls 12 mm. Drill holes in the boards every 2030 cm and fasten the OSB to the floor with self-tapping screws. Make the floor even more durable by installing a similar second layer of OSB. Joints of the upper and lower layers should be laid with an offset of 2030 cm.

Laying OSB on the joists on a concrete base

If there is a concrete base (eg, floor slabs), the device beams and lining them can create a flat floor without using wet screed. And also put insulation, water and noise insulation materials in the structure. Beams (wooden planks) are fixed on the concrete floor with dowels or anchors. Calculation of the distance between the beams is based on the thickness of the OSB boards. The thicker the boards, the less often joists can be installed, and vice versa.

The joists create a space between the OSB and the concrete slab. It can be put to good use, filled with insulating material. For example, in the floors of the first floors you can lay thermal insulator: mineral wool, polystyrene foam, EPPS If there is a wet basement under the floor the floor design is often supplemented with a vapor barrier films or membranes. OSB must be laid across the joists. Joints between neighboring boards (in width) must run exactly in the middle of the beam. It is also recommended to leave expansion joints (35 mm between OSB plates, 12 mm between OSB and the wall, which can be easily sealed with SOPPKA Smart Elastik in the future). OSB boards are fixed to the joists with self-tapping screws or nails (spiral, ring nails). Fixing element pitch: along the perimeter of boards 15 mm, on the intermediate (additional) supports 30 mm.

Installation of OSB flooring on the joists

This technology is appropriate only if there is a pile or foundation. Beams should be mounted on the foundation. The pitch of the beams must match the thickness of used OSB (the bigger is the pitch, the thicker is the thickness). Then run the rough surfacing of the floor. To do this, along the joists there should be nailed retaining strips, on which OSB will be laid and fixed. It is recommended to put a layer of vapor barrier on top of OSB, and then you need to cover the insulation with another layer of OSB. Fastening is carried out the same way as when installing OSB on joists on the existing concrete base. After that the process of works is considered to be finished.

Preparation of OSB for finish coating

Durable, hard and even surface makes OSB a universal base for all modern types of finish flooring. Here are some popular solutions:

In this case OSB will serve as a finishing floor, which needs only a decorative finish with paints. OSB does not require any additional preparation, it is enough to clean it from dust and apply 23 layers of varnish (paint), specially designed for OSB.

OSB Subfloor Installation Video

Roll-fed materials Linoleum and carpet.

When laying roll materials, care should be taken to ensure that the joints between the OSB boards are flush with the rest of the surface. It is advisable to remove all irregularities with sandpaper. Seal the joints between the boards with SOPPKA Smart ELASTIK.Smart joint.

To hold the tiles on the OSB base, it is necessary to ensure its immobility. To do this, the beams are placed more often than required by the thickness of the boards. It is also recommended to reduce the pitch between the fasteners. Glue the tiles to the OSB, using a special adhesive that is appropriate for the wooden surface and the tiles used. It is recommended to pre-treat the surface of the board with SOPPKA for better bond with tiles.

This coating is quite rigid, so there is no need to prepare the OSB for laying laminate flooring. Minor irregularities that may occur at the joints of the boards are smoothed out by the subfloor.

Surface finish after laying OSB

As the appearance of the material is rather decorative it is not rare, when the owners make the finishing floor of OSB. However, if you intend to further decorate with other materials, the boards need an auxiliary treatment.

  • Tiles on OSB board on the floor is installed most often in kitchens, bathrooms, baths (about “What to lay on the floor in the kitchen and how to do it properly”). In this case, it is important to ensure absolute immobility of the base. To do this, the beams are placed with minimal pitch, and the OSB boards are chosen with grooves for a more secure hold. Before you put the tiles on the OSB boards, it is necessary to apply glue, designed for fixing wood and ceramics to the surface of the wood.
  • When installing a carpet all joints between OSB plates should be smoothed as much as possible, otherwise irregularities will stand out clearly on the surface. Under the carpet is best suited thin sheets of OSB, the joints of which should be filled with sealant. In this case, the carpet will be laid correctly. Indentation should be left only at the walls.
  • Installation of laminate flooring does not require any preconditioning. Since this material itself is quite hard and durable, all the faults will be ironed out during its installation. Fix the laminate flooring with glue.

OSB as a subfloor should be painted or varnished, which will increase the lifetime of the floor and improve its appearance. The surface must be thoroughly cleaned before lacquering.

How To Install OSB Subfloor

Laying of OSB on a wooden floor

The wooden base is cleaned of debris, areas with biological damage (fungus, mold) are removed, and if necessary, the material is treated with bactericidal impregnation. The installation process is carried out as follows:

  • With the help of the rule determine the location of floor defects (swells, depressions);
  • Boards with a large backlash, tighten to the logs with extra screws, with their heads sunk into the layer of material;
  • Protrusions, swells, layers of paint material are removed by a grinder, and are placed on the floor. It is necessary to monitor the offset of joints relative to each other. Between the two boards leave a gap of 3 mm, between the board and the wall 12 mm.
  • Boards are fixed with screws on the perimeter with a spacing of 20-30 cm. To do this, it is necessary to pre-drill a hole with a diameter corresponding to the thickness of the screw and make its countersinking. Recommended screw length of at least 45 mm.
  • In the case where it is necessary to obtain a particularly durable floor, the installation of a second layer of boards is carried out. At the same time the butt joints should not overlap. An offset of 20-30 cm is recommended.

OSB: composition and characteristics

OSB or OSB is oriented strand board. In transliteration OSB is often called OSB, but it is not quite correct, as it contradicts the transcription, but is used everywhere.

The boards are a composite of coarse wood chips and polymer binders. Formed of several layers arranged perpendicular to each other. This design resists torsional deformation of the sheets and makes them resistant to tear and delamination.

According to the production technology OSB is identical to chipboard with the difference that the first uses a finely chopped chips up to 4 mm thick and up to 25 cm in length, while the production of the second uses fine sawdust. Thermosetting resins (urea-formaldehyde, melamine, etc.) are added to the raw material as binders.). Typical plate sizes:

  • OSB-1 is a thin board, used for production of packaging, furniture parts, construction of temporary facilities, etc.п.
  • OSB-2 is a standard sheet, which can be used in dry and ventilated rooms. Usage. for inner roughing works (flooring, alignment of walls, ceiling, forming of utility boxes, etc.).д.).
  • OSB-3 is a moisture-resistant material with m paraffin additives. It has an increased resistance to high humidity, it is recommended for use both indoors and for exterior finishing works.

Withstands high humidity both indoors and outdoors. When used in rooms such as baths, saunas, etc. is recommended to use laminated or decking waterproofing materials.

Definitely can not say which one is better or worse. Everything depends on the purpose. Levelling the base for laminate, linoleum, ceramic tile and other types of finishing materials by OSB-3 sheets. Their advantages are that they perfectly withstand serious loads (furniture, equipment), even when installed on the joists, resistant to temperature and humidity extremes, easy to handle, and installation under force even an inexperienced beginner.

In addition to the above advantages, OSB. a heat insulating material with a small sound-absorbing effect. That’s why so often the manufacturers of vinyl and carpet strongly recommend laying on the concrete floor first a warm substrate of hardwood materials, which is closed with a finish.

The thickness of the plates used depends on the method of installation. For concrete flat base with a difference of not more than 2-4 mm for every 2 meters of area it is reasonable to use 10-12 mm OSB. When laying the floor with your own hands on the joists justified installation of OSB with a cross-section of 18 mm or more. Experts recommend laying sheets of 10-12 mm in 2 layers with overlapping joints. It turns out a kind of multi-layer “substrate”, which guarantees increased strength and durability of the base.

The OSB installation technology is considered below.

Choosing the thickness of OSB plates when installing on the floor

Manufacturers offer the material in standard sizes, but there are restrictions. So, the size range in length is 244-280 cm, and in width from 60 to 250 cm. In terms of installation of the floor, the thickness of the board, which varies from 6 to 24 mm. the most important parameter that affects the reliability and durability of coverage. The greater the thickness, the greater the load that can withstand the OSB. But, with an increase in this indicator, the height of the room will also decrease, so it is important to balance the strength and elevation of the floor. In addition to the above, with an increase in this size of the board, the cost of repair increases.

Many years of experience and calculations show that for installation as a roughing floor on the grating, you need to choose the thickest sheets that are available in production. 22-24 mm.

When attaching directly to screed or concrete, it all depends on the condition of the cement surface. If, it is without significant irregularities and defects, then 10 mm of panels is enough, and otherwise, the acceptable thickness of the boards increases to 18 millimeters.

When the OSV surface is conceived as a front surface. will need 22 millimeter sheets. Because they will be better insulated and deform slightly under load, allowing the paint finish to remain monolithic and durable. This information is shown more clearly in the table below.

Installing the Subfloor

Conditions for work performance Recommended minimum thickness of OSB sheets in millimeters
OSB subfloor (with decorative material on top, e.g. laminate) Covering (simply varnished or painted)
Trusses made of timber or lagging 22 24
Board surface with sanding finish 18 22
Wavy Boardwalk 22 24
Old concrete screed with significant defects 18 22
22 Surface poured with self-levelling compound, factory concrete slab with a level surface 10 22

The structural data of the material is also important. OSB-3 quality board is used, no less. The joints can be either straight or tongue and groove. In the latter variant the joints will be further strengthened.

Learn more about the varieties, characteristics and applications of oriented chipboard in a separate article: OSB types, characteristics, applications.



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