Create A Level Surface On A Wooden Subfloor

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-08-25 07:54

• Alignment types
• Plywood selection
• Benefits
• Base requirements
• Alignment with grooves
• Scheme
• Leveling technology
• Grinding
• Checking the result

Any subfloor for subsequent flooring must be carefully leveled. For this, there are many options, among which you should pay attention to the laying of plywood. But here it is necessary to take maximum measures to obtain the ideal basis for work. Otherwise, you may encounter negative manifestations - creaking, destruction of the coating, deformation, and so on. In addition, the use of plywood does not take away large finances, and the installation process takes a shorter time compared to other options.

Alignment types

Plywood flooring can vary. When it comes to a wooden base, then most often it will be enough to screw the sheets of material to the old base.

In this case, the foundation itself should be prepared and given the maximum horizontal level. The same applies to the parquet board, which will not be superfluous to dismantle at all for installation.

A certain size of plywood for repair is also selected. It usually should not be less than 1 cm. Some use logs in their work, after the device of which plywood sheets are laid. Subsequently, it is possible to produce flooring of various floor coverings - tiles, linoleum, laminate, etc.

Plywood selection

Depending on the purchased flooring, you should also choose the option of plywood for laying on the sub floor. For linoleum and carpet, a small sheet thickness will be enough. True, it is unlikely that it will be possible to align significant defects.

Approximately 10 mm thicker should be plywood, arranged under the laminate or parquet. In residential premises, material grades such as FC or FSF are mainly used. In the first case, it does not contain any harmful substances (for example, phenol) that can adversely affect the health of a person and others during operation. According to the level of moisture resistance, it belongs to the average indicator, but it is able to withstand even significant external mechanical influences.

FSF plywood is based on phenol-formaldehyde resins. This immediately indicates the toxicity of the material. At the same time, the indicators of water resistance are significantly higher, as well as the level of wear during use.

In hardware stores, plywood is presented in varieties, of which there are 4 in total:

1. 1st grade. It is one of the best quality materials that does not have any defects other than minor cracks and surface deformation. Sometimes they are not even noticeable. Of course, everyone will recommend it for leveling the sub-floor, but the cost will be very high.

   

2. 2nd grade. Of the defects, you can even find glue, wood inserts, as well as dents.
3. 3rd grade. In addition to traces of wormholes, knots of minor parameters are visible on the surface.
4. 4th grade. Few people use it because of its very poor quality. In the process of processing and creating materials, all the negative qualities and defects that are inherent in plywood appear. This variety cannot be used at all.

Ideal for arranging the floor and creating a flat surface - the second grade. It has all the advantages and qualities that are necessary in work and during operation.

It should be noted that plywood can be sanded on one side, on both sides, or even not sanded at all. Each of these options is also immediately reflected in cost and scope.

Benefits

With the help of plywood, you can create a flat floor surface as quickly as possible, which is subsequently used for flooring or for processing. But the advantages should include other features of each sheet used in the work:

• Despite the considerable size of plywood sheets, they are very easy to transport.

  

• The finished base is not only durable but also reliable in use.
• Everyone can independently install plywood on the base of the floor.
• Of all the possible odors of materials, only the aroma of wood can be noted. But if you perform flooring, then there will be a complete absence of any extraneous odors.
• The plywood floor can be laid even in rooms with high humidity levels.
• During the installation process, sheets of material are very easy to cut, adjust to the required dimensions, and also cover with any kind of protective equipment. At the same time, practically no construction waste remains.

• The sheets seem to be very rigid, but they can be bent to the required parameter.

  

When installing a plywood floor, it additionally acquires thermal insulation qualities. Heat escapes from the room to a lesser extent. In addition to the rough version of plywood on a wooden base, it is also used as a topcoat. It all depends on the level of grinding and the selected grade.

Base requirements

Any base for subsequent leveling must be carefully prepared for the job. The room itself must have an acceptable level of humidity. For this, all the necessary measurements are made. Most often, this also applies to concrete floors.

To check the moisture level of the concrete floor, put a piece of polyethylene film on it for three days. At the same time, its edges must be carefully pressed against the base. After the specified period, the film is checked. If there is condensation on the inside, the humidity level is high.

To reduce the level of humidity in the room and the base, cover it with special agents, as well as antiseptics. Subsequently, this will contribute to the fight against mold or the appearance of fungi. For rough alignment, the cheapest option is grade 4 plywood.

Particular attention is paid to the wooden base of the floor. All skirting boards around the perimeter of the room must be removed. You may encounter floor squeaks and squeaks.

To do this, you should initially find out where this all comes from. Most often it is a poor fixation of wooden boards. Nails loosen over time. Getting rid of such a problem is very simple - duplicating the nails over a section of the wooden floor, as well as additional scrolling them with self-tapping screws. For each lag, the boards must be fixed. The usual length of self-tapping screws in this case is 50-100 mm. The main thing is that they do not reach the floor slabs, if any.

If there are irregularities on the wooden floor, they are constrained by a plane. This will allow you to subsequently get rid of the appearance of bumps on the plywood sheets.

Alignment with grooves

You can encounter significant indentations in the work. This is due to the constant presence of massive objects in a given place or constant load. For this, an algorithm of actions is provided, which includes the following points:

• We define the troughs using a long level.

• Self-tapping screws are screwed in in established places at a distance of 20 cm from each other. They will be a kind of beacons. For accurate calculations of the head level, the level is applied.

  

• Plywood sheets will be laid on these screws. But even in this case, bending of the sheets in the recesses is possible.
• To get rid of the negative, the void under the sheets is filled with small sawdust, which is mixed with PVA glue. Plywood is coated with PVA glue and from the seamy side. Complete drying of the glue usually takes 5-7 days. This period must be maintained before further work.

In general, to determine the height differences on the basis of the floor, you should use not only a water level, but also a laser level. This will provide the most accurate results possible.

Scheme

There are 4 main schemes, guided by which you can lay plywood on the floor with your own hands:

• Without lag device. No additional boards are applied. This option can be called very simple in terms of installation. A distance of 20 mm should be kept from each wall. The distance between the plywood sheets should be about 5 mm. It is possible to level the floor without logs in two layers of plywood. In this case, installation should be done according to the brick laying principle, that is, in a checkerboard pattern. Since the plywood is laid on the bumps of the curved floorboards, the fastening is carried out to the highest points and evenly over the entire plane.

  

• Installation of mini-lag. Plywood devices for leveling are allowed in the case when the height differences are up to 80 mm. The installation process is quite complicated and includes fixing the slats, as well as wooden boards. With their help, a single network of supports for future sheets is made. In this case, it is very important to make accurate calculations so that the task is completed with maximum efficiency. Each element has its own height and size, which is also calculated during the preparation process.

  

• Fixing longitudinal logs with transverse boards. From each wall, the logs are attached to the base at a distance of 30 mm. In the future, it remains only to lay the plywood to level the floor.

• Turned supports as lathing. A separate support is cut from the boards or plywood sheet, the thickness of which will depend on the differences in the floor height. As a result, you will also get a single grid, along which plywood is laid on the floor.

  

Each of these requires attention and patience during the preparatory activities, as well as during the installation of sheets of material. But in the end, you get a really flat surface on which you can make flooring.

It should be noted, however, that drilling should be carried out in two stages. To begin with, a hole is made for the fastener itself, and then for the screw cap. As a result, the hat should completely sink into the plywood sheet and not have protrusions. The nearest edge of the plywood sheet must be at least 20 mm apart.

If the plywood sheet is sanded on one side, the non-sanded side must be facing up so that the subsequent leveling layer can have better adhesion. For a simple masking of the caps of the screws, the polished side turns upwards, which is subsequently sealed with a sealant and painted.

Leveling technology

Installing plywood on a sub-floor includes three sequential main steps:

• Fitting sheets.
• Installation of lag. This step can be skipped if the process is dispensed with.
• Fixing to the floor.

Plywood is sawn to the size of the room. This takes into account the seams from the walls in the room, as well as the distance between all sheets from each other. Otherwise, you may encounter deformation of the plywood after installation, which is also facilitated by changes in the level of humidity and temperature indicators. Even after cutting, each element should be carefully inspected. If defects are found in the form of delamination or chips, then it is better not to use them at all in work.

Next, the sheets are laid out on the floor area and it will not be superfluous to number each of them in order not to be confused. It should be noted that in the presence of a lag, all joints of plywood sheets should be located in these areas.

Wooden blocks, plywood boards can act as lags. The width is taken at least 30-40 mm. Fastening to the base is done with self-tapping screws or with glue. A special filler is used to fill the space between the lags. You can additionally arrange a layer of heat and sound insulation.

When all of the above is done, you can level the floor with plywood. For fixing the sheets, one of the above schemes is selected. It will not be superfluous to treat each element of plywood with an antiseptic. The fixing is usually done with self-tapping screws with plastic dowels. Precisely in order to prevent the plywood sheet from cracking, holes are pre-drilled.

In some cases, plywood glue is used. The most important thing is that it is based on pine resin. Dowel screws are used to tie the sheets to the base. The glue is applied not only to the base, but also to the inside of the plywood sheet. After laying on the surface, they are immediately screwed on with self-tapping screws. As soon as the laying of all sheets on the floor area of the room is completed, it is necessary to start working with the seams. They are treated with putty, plaster or acrylic sealant. It remains only to glue the top with mounting tape.

Grinding

There may be burrs and cuts on the plywood surface. To get rid of them, grinding is done. This event also allows you to get rid of possible insignificant and invisible areas with elevation differences. For grinding, not only a sander is used, which can be rented, but also ordinary sandpaper.

This step leaves dust. It should be removed at the end of sanding.

Checking the result

After completing the work, you should inspect the entire plane in the room. If quality alignment is carried out with plywood sheets, then everything should look like this:

1. The sheets do not touch the walls in the room, but there are left gaps between the sheets themselves.
2. Using the rule, the horizontal is determined. The check is carried out in several places throughout the entire area, constantly changing the direction of measurement. Minor deviation is allowed within 0.2 percent.

Using a wooden block, the surface is tapped. The resulting sound should be firm and consistent in each area. If you encounter a dull sound, then most likely the plywood has peeled off from the base. According to building codes, delamination from the base of a plywood sheet in an area of less than 20% of the entire sheet area is permissible. If this figure is large, then you will have to replace it with a new one.

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