Floor installation methods

The type of framework the wooden floor is going to be based on usually depends upon the character of the facility, wooden floor type and client’s needs. When equipping the framework and wooden floor decking, one has to follow decking instructions. We are going to review the most frequently used wooden floor frameworks, their advantages and disadvantages.

1. Gluing wooden floor to concrete surfacing.
2. Gluing wooden floor to comfort improving floor boarding.
3. Wooden floor laying using OSB or veneer for concrete levelling.
4. Wooden floor laying on lags.
5. “Floating method” of wooden floor decking.

1. Gluing wooden floor to concrete surfacing.

It is a simple, economic and reliable way of laying, when wooden floor is glued to a well-leveled concrete surfacing. This method can be used in new flats, detached houses and other buildings where surface leveling or rising is not obligatory.

The framework has the following advantages:

• It is much cheaper and faster in comparison to all other glue-to-surfacing wooden floor frameworks. In many cases (for instance, when decking factory covered floor) you may need only glue.
• It raises the floor height minimally. When decking wooden floor, the level of the surfacing is likely to become higher as much as the wooden floor, thus, reducing the living space minimally. If You know in advance how thick the wooden floor is going to be, it can easily be leveled with other floor covering, e.g. tile.
• The framework is simple. Everybody knows: the more sophisticated framework is, the bigger the chance is to make a mistake during the equipping stages, so the whole framework can become defective. Wooden floor glued to concrete surfacing is one of the simplest and most reliable floor decking structures which does not require special skills.
• Such floor is easier to rescue in case of any accidents. For example, should a flood happen, timber floor can be saved by collecting water within a short period of time (multilayered wooden floor in most cases is impossible to save as it often delaminates after water influence). After the floor has dried out it will be necessary to polish, putty and varnish the floor over or to cover it with oils, though there will be no need to disassemble the floor. After the floor built on other frameworks has been flooded, there are fewer chances to preserve them and one will have to disassemble the whole frameworks.
• The framework is ideal for heated floors.

Notice that:

• The concrete surfacing a wooden floor is going to be glued to should be totally smooth, firm, physically “healthy”, clean and a little rough. The requirements to the surfacing evenness are the following: on a 2 meters stretch an acceptable deviation and waviness are 3 mm. Small irregularities near walls and doorways can be levelled with special machines.
• To level slightly uneven concrete surfacing one can use levelling compounds, though it may reduce the framework’s reliability. It happens due to the fact that self levelling compounds are often used in disregard to producer’s requirements, compounds may be too thin or too thick, and once a wooden floor has been laid the compounds may break off the concrete. Another frequently met problem is incompatibility of self levelling compounds and wooden floor glue, due to which the glue may not adhere or react well, or adhere to the surfacing partly. Besides, concrete floor levelling using self levelling compounds raises the floor cost. Taking all these reasons into consideration the most often recommended method to level slightly uneven concrete surfacing is using OSB panels or veneer.

2. Gluing wooden floor to comfort improving floor boards.

In order to make wooden floor covering much better and comfortable, special underlays can be glued between floor and concrete surfacing (e.g. cork rubber flooring DamTec Standart).

The framework has the following advantages:

• Comfort. Cork and rubber mat and other mats for improving comfort have good acoustic characteristics, they absorb and silence footsteps and make the floor soft. The acoustic characteristics depend upon flooring’s structure and thickness, for example, DamTec Standart flooring is 3 mm thick and absorbs 20 dB.
• Elasticity. When the microclimate in the room changes, wooden floor expands or contracts, so waves or gaps may appear. Comfort improving mats are special for their elasticity - that is why they partly absorb wooden floor movement and reduce surfacing and glue tension.
• Wooden floor mats are usually good heat conductors, thus such framework is suitable for heated floor. Each mat’s suitability for heated surfacing should be written in the flooring equipping instruction or in the technical specifications.
• Floorings can be of different thickness and may help to equalize different surfaces or floor in different rooms.

Notice that:

• Comfort mats are not subject to level surfacing, as they do not level unevenness but simply duplicate them. Concrete surfacing evenness should comply with the gluing-to-concrete surfacing requirements.
• When choosing the right mat, one has to pay attention to the fact that it should be designed for gluing to surfacing, and it would allow wooden floor gluing, i.e. the flooring should bear loads from up and down.
• The flooring will raise wooden floor cost: mats’ price starts from 6.5 Eur/m2, You will also need twice as much glue.

3. Wooden floor laying using OSB (oriented strand board) or veneer for concrete levelling.

OSB or veneer is often used to level rooms’ surfacing in old buildings, where linoleum, old wooden covering or other floorings of low quality have been removed. OSB or veneer are also often used to combine height inequalities between the rooms.

The framework is special for the following advantages:

• OSB or veneer can level concrete surfacing with deviation or waviness not exceeding 1 cm.
• This levelling method is cheaper, simpler and very often more reliable in comparison to self levelling compounds method.
• The framework allows raising the floor height, this can be useful if one wants to level the floor between rooms, wooden floor and tile, by the doorways, etc.
• If uneven concrete floor was levelled with the help of levelling compounds, but You are not sure of its quality, You may lay additional OSB on the surfacing. The OSB is to be glued, fastened with bolts, at least some of them to be screwed into concrete through the layer of levelling compound. Should the levelling compound break off, the bolts will hold the OSB fastened to the surfacing.

Notice that:

• OSB or veneer thickness should not be less than the floor it is covered with. It is very important when laying parquetry made of unstable wood, as when it is expanding or contracting, the OSB or veneer may become deformed.
• When laying wooden floor using OSB or veneer, the room loses its height.
• The framework is not technologically sophisticated, though one has to keep to several rules when equipping: before laying the OSB or veneer is cut into 1-1,5 m2 pieces, then they are glued and fastened to the surfacing with bolts (bolt consumption is about 10 pcs/m2), leaving 10 mm gaps between pieces. The OSB should be fastened with bolts very carefully in order not to damage water (or other) pipes in the subfloor. Before cutting and after fixation the OSB is smoothed with a belt sander and coarser sandpaper to clean isoparaffin layer and to guarantee adhesion between concrete surfacing and wooden floor. If the upper side of OSB was not smoothed, it has to be primed before gluing the parquetry. To avoid future problems, one has to follow the recommendations on glue and bolts consumptions when flooring OSB or veneer. Wrongly attached OSB or veneer can unstick and start creaking in certain spots.
• It is necessary to use water-resistant OSB or veneer when equipping wooden floor. Though OSB and veneer are not subject to be used for hydro isolating needs and if are laid on the damp surfacing, they will gradually absorb moisture which will later get into wooden floor. The liquid will also get faster into wooden floor through the gaps left between OSB or veneer pieces. To avoid this, before flooring OSB or veneer, the concrete surfacing should be dried or covered with a special hydro isolating layer.
• Wooden floor laid onto OSB or veneer is hard to preserve in case of flood. Should a flood happen, wooden floor will absorb the moisture and begin to bend and cast, due to this OSB or veneer are likely to rise and it is almost impossible to preserve wooden floor in such case.
• OSB or veneer increase heat resistance very much, that is why such framework is not recommended for heated floor.

4. Wooden floor laying on lags.

This method is used in old buildings, in the old town, in cases when very uneven concrete surfacing is technologically impossible to level with the help of OSB or veneer.

The framework’s advantages are the following:

• It allows levelling considerable unevenness or surfacing deviation or equalizing large-scale height differences between rooms. Often such unevenness can be smoothed by pouring with a levelling concrete layer, though it will be more expensive and take longer time. This method can be used if there are non-hidden pipes, bars, etc.
• Lag framework can be equipped straight on the Ferro concrete floor without using levelling concrete layer. This will allow to finish wooden floor decking quicker as it will be possible to avoid waiting for the levelling surface to dry (i.e. You can save at least 6-8 weeks). In certain cases (e.g. in wooden dwellings) when equipping wooden floor the lag framework can be used instead of Ferro concrete floor.
• Lag framework allows You to install heat and sound isolation between lags, if it is not present in the subfloor or if there is a need to make additional isolation.

Notice that:

• This framework is technologically more sophisticated in comparison to the above-mentioned surfacing equipping methods, and needs more professional and skilled implementation. The most frequently used lags for surfacing equipping in Lithuania are those made of pinewood or fir-tree with minimal width and height of 5 cm. Lags are to be laid every 60 cm min. and fastened to concrete with bolts, sound-isolating flooring is to be installed under the lags. When equipping sound and heat isolation, stone cotton or other means are laid between the lags. OSB or veneer with 22 mm minimal thickness is to be fastened to lags using bolts. If the OSB or veneer that has been laid is too thin, it can bend between-the-lags. OSB or veneer to be laid onto lags is cut into 1-1.5 m2 pieces leaving 10 mm gaps. The pieces are fixed moving them in such a way so that the gaps would not make lines. Laid OSB is smoothed and grounded according to the gluing instructions.
• In most cases, it is impossible to effectively renovate surfacing made of low quality lags. That is why a complete framework's replacement is required.
• Lag framework reduces the height of the room very much, especially if it is made using levelling layer. That is why this method is often unacceptable in standard flats where ceiling height does not exceed 2.7 m.
• Lag framework is not suitable for heated surfacing at all.

5. “Floating method” of wooden floor decking.

“Floating method” is used for multi-(three-) layered parquet boards which are not to be attached to the surfacing, but joined between themselves using mechanic latch or gluing slots and tongues.

The framework has the following advantages:

• It is the simplest floor framework – polyethylene, cork, rubber or other mat is laid onto concrete surfacing, which is in turn covered with parquetry. This flooring method does not require special professional skills and can be performed by the floor owner himself.
• It is the fastest way of flooring. If the flat is not big, of standard size and planning, wooden floor decking can be completed within one day.
• It is the cheapest method of flooring which does not require skilled experts and expensive equipment. When flooring parquetry without glue the cost of the parquetry will include the price of the flooring only.
• “Floating method” flooring does not require high quality surfacing and can be done on a cracked or crumbling concrete.
• “Floating” floor does not cause floor tension. That is why it can always be laid onto concrete surfacing levelled with levelling compounds.
• Minimal renovation expenditures. Some planks being spoilt are easy to disassemble and to be changed with new ones. If the floor has been worn out, it can easily be smoothed and re-varnished or covered with oils. If one wants to alter the floor, this type is the easiest of all wooden frameworks to disassemble.

Notice that:

• When using “floating method” the evenness of the surfacing is quite essential. The requirements to the surfacing evenness are the following: on a 2 metre stretch an acceptable deviation and waviness is 3 mm. If the floor is decked on the surfacing which does not meet the requirements mentioned, it may swing, creak and later cast or break in weak places.
• Floor decked by “floating method” can not be pressed to the surfacing. The “floating floor” principle implies the idea that the flooring is simply put onto prepared surfacing without being fixed to it, i.e. simply lies (“floats”). If freely floating flooring is pressed or glued in some places, “floating” floor loses operating characteristics. Due to this, depending on many factors in the house (e.g. how relative air humidity and temperature will change, motion intensity) the general floor appearance can be spoiled, waves on the floor and foot clip-clopping may occur. Because of this solid stationary furniture (e.g. bookcases) should be separated by compensatory spaces. Some producers even require cutting openings in the floating floor for bed legs and leaving compensatory intervals between legs and parquetry.
• A very frequent “floating” floor problem is “laminate effect” – i.e. unpleasant sound, tapping caused by footsteps. The cause of the sound is the emptiness between the surfacing and the floor. The appearance of this sound depends on the flooring between the subfloor and wooden floor. Special flooring pieces should be placed under parquetry; they are specially designed for using under "floating" floor. These flooring pieces are of high density; they do not cast under footsteps and keep their sound isolating characteristics for a long time. To achieve better results parquetry can be laid on special flooring designed for comfort (e.g. made of cork or rubber) which absorb footsteps very well. From one side, the flooring should be covered with polyethylene film to prevent getting wooden floor humid from beneath. If the flooring is not covered with film, hydro isolating film should be placed on a surfacing before starting flooring.
• “Floating” floor is more difficult to re-smooth, comparing to glued-to-surfacing floor. This type is not fixed to the surfacing and can bend, ripple and vibrate while being smoothed with heavy equipment, for this reason smoothing will be much more difficult and expensive.