Engineered, bamboo, and laminate flooring can all be installed over a structural subfloor using an underlayment. The boards in floating flooring are attached to each other but not to the subfloor. Another feature shared by all of these goods is the presence of cellulose fibre, which has the virtue of being hygroscopic. A hygroscopic material absorbs moisture from the air and swells when the relative humidity is high, but releases moisture to the air when the relative humidity is low. As a result, each of these goods used in floating floors is susceptible to seasonal swelling and shrinking, and because they are not attached to their subfloors, seasonal movement impacts can be higher than some owners or contractors anticipate.
Movement in Solid Timber
First, we must analyse solid timber flooring and how it shrinks and swells in response to changing relative humidity. Board expansion happens under high humidity circumstances and board shrinking under low humidity conditions. Although temperature and humidity fluctuate throughout the day and night, a floor's response is typically sluggish, and we frequently notice slight variations month to month. However, during protracted wet periods or persistent hot and dry weather, things can change, and a floor may react substantially over the course of a week. For a floor to function to its full potential, every site and expected in-service environment must be analysed, including floating floors, engineered, bamboo, and laminate.
MOVEMENT OF FLOATED ENGINEERED FLOORS
Engineered flooring varies from solid timber flooring in that it is often a multi-layered timber product. The reason for this form of construction is to limit the amount of width movement in a board when the moisture content of
The flooring changes. As a result, when wet, an engineered floor expands less than a solid timber floor, and when dry, it shrinks less than solid timber flooring. Movement is primarily in width, but there is also some lengthwise movement, which distinguishes it from solid timber flooring.
MOVEMENT ON FLOATED BAMBOO FLOORS
Bamboo is technically a grass, not a timber. The most common type of bamboo flooring is strand woven bamboo, which is manufactured by cutting the bamboo into long strands, coating the strands with adhesive, and curing the adhesive under pressure and heat to form a beam. The beam is then separated into boards. The fibres generally align, and as a result, the majority of the movement caused by humidity changes occurs in the width of the board, but there is also some longitudinal movement. Floated floors typically experience greater seasonal fluctuation in board width (shrinkage and swelling) than engineered and laminate floated floors.
DESIGN LIMITATIONS AND PRODUCT MOVEMENT
These floating floor products have design restrictions, and if the humidity remains either too low or too high for an extended period of time, the product's performance may be less than optimal. It should be noted that floated floors are less resistant to adverse weather conditions than solid timber floors. To meet more extreme conditions, it may be easier to modify the moisture content of solid wood floors prior to installation. It is also critical that while installing floating floors, the manufacturers' recommendations are reviewed and followed.They frequently specify an optimal humidity range for their products, and if conditions remain outside of this range for an extended period of time, both the performance and appearance of the floor can suffer.
The ideal performance ranges stated by each manufacturer are unique to each product. One manufacturer may state that their product performs best in situations ranging from 35% to 60% relative humidity, whilst another may state that their product is better suited to 40% to 70% relative humidity. Most residences in major cities have internal relative humidities ranging from 50% to 60%, however keep in mind that the internal climate might occasionally dip outside of this range, causing floors to be damaged.
In addition to seasonal variations, the internal climate associated with building design, as well as the effects of heating and cooling systems, must be considered. The conditions we choose to live in are also optimal for floating flooring. Window coverings can help to prevent heat gain in the space as well as direct heating of the flooring from sunshine. Evaporative coolers can be useful in hot, dry weather because they provide moisture to the air when it is low. Refrigerative air conditioning can also help in hot, humid situations by lowering humidity levels. Wood-fired heaters can generate severe drying effects due to higher temperatures and low humidity, so caution should be exercised with any systems generating dry heat.
For these reasons, the installation environment, as well as building design and heating and cooling systems, must be analysed in order to lay an appropriate product and account for projected seasonal movement in the floor during installation. Similarly, owners might be cautioned on areas that they should be wary about.
THE NEED FOR CONTROL AND EXPANSION JOINTS
We should now evaluate the expansion allowance and control joints. If a floor is in a controlled environment with minimal humidity fluctuations, it will move little (seasonal shrinking or swelling). Some floors are like this; however, it is difficult to forecast how much seasonal movement a floor will experience because, as previously said, this is determined by external weather conditions, building design, and both the heating and cooling systems installed, as well as how they are used.
Expansion allowance and control joints are thus not considered owner options. The manufacturer's installation instructions specify what is required in this regard.
As previously stated, the boards in floating floors must be attached to one another rather than the subfloor. This results in a flooring panel known as a raft (a raft floats on water, and these floors 'float' on an underlay). As a result, the raft's movement must be accommodated, which can be significant as seasonal fluctuations cause movement in both width and length. As a result, we must analyse the rafts rather than the boards.
Compartmentalisation is a phrase used to describe the process of laying the floor into a series of smaller rafts that are connected together by expansion or control joints and trims. The reason for this is that if we don't, the movement of one raft region may interfere with the movement of another. Understanding this is critical, and it is illustrated diagrammatically by showing how each raft shrinks and swells in both directions from its centre.
Seasonal weather variations cause each individual raft to increase in breadth and length. If the floor is not sufficiently separated into independent rafts, movement in one section of flooring can affect the adjacent area, resulting in buckling, separation at board joints, and flooring migrating out from beneath skirtings. Where seasonal movement is higher, more room for raft movement is required, which can be achieved by using broader skirting boards or creating smaller rafts.
If a floating floor is installed in a rectangular room, there is just one floor area. However, we must also consider the raft's size; if it is too large, an intermediate expansion allowance must be allowed. This is another expansion trim that is put partially over the floor. Manufacturer instructions provide the maximum floor widths and lengths. Heavy objects, such as kitchen benches, cannot be installed on top of floating floors because they hold the floor in place and cause all expansion and shrinkage to occur at the fixed point of the bench rather than the centre of the raft.
FLOATED FLOORS UNDER EXPANSION PRESSURE.
When floating floors expand during lengthy periods of high humidity, which is frequently associated with wet weather, unevenness throughout the floor and squeaking at board joints can occur. Similarly, if the expansion allowance is used up, was insufficient when the floor was constructed, or the floor was not properly compartmentalised, pieces of the floor may lift and buckle. Under harsh conditions, the flooring may change shape. Engineered flooring may develop a crowned look, with the centres of the boards higher than the borders, and breaks in the face lamella (or veneer).Raised board edges and end joints in engineered, bamboo, and laminate flooring can also form (known as peaking) if a floor experiences excessive expansion pressure.
High Shrinkage on Floating Floors.
High degrees of shrinkage can occur as a result of a variety of reasons, the most common of which are an excessively dry internal environment or a raft that is too large or inadequately compartmentalised. As a result, flooring might pull away from beneath skirting and scotia, causing board joints to separate within the floor.Severe dry conditions with engineered flooring can also cause surface checking (split appearance) of the face lamella, as well as some cupping or delamination at the board edges. Also, be aware that excessive direct sun exposure on engineered floors can cause checking, as well as increased degrees of shrinkage on bamboo and laminate flooring.
Buckling of a Floated Bamboo Floor
Intense sunshine causes checking in engineered floors.
Providing for floor movement during installation.
As the saying goes, prevention is frequently better than cure. The first step is to ensure that the floor is properly built, particularly taking into account the possibility of lengthy wet or dry conditions that may occur in the future, as well as establishing adequate expansion and control joints. According to anecdotal evidence, flooring become more stable after a few years of usage, and when a new floor experiences expansion pressure owing to more extreme wet weather, some owners have acquired small dehumidifiers to drain moisture from the air and lower the pressure in the floor. Similarly, refrigerative air conditioning will remove moisture from the air but is less effective than a dehumidifier.Under extremely dry conditions, comparable but opposite methods can be employed to supply moisture to the air, such as portable evaporative coolers or pots of water atop wood-fired heaters.
Under extremely dry situations, comparable but opposite methods can be utilised, such as portable evaporative coolers to impart moisture to the air or pots of water atop wood-fired heaters.
Knowing the conditions within the home is also an effective management tool for owners, and temperature/relative humidity metres are now reasonably priced and a worthy investment. Owners who took these proactive methods during times of harsh weather reduced or eliminated potential floor concerns.
For floors that have witnessed significant expansion or shrinking, it is important to understand that the weather has frequently had a role. Such conditions do not occur every year, and when they do, they are usually for only a few weeks or fewer. The basic line is that if a floated floor has the proper expansion capacity and is compartmentalised effectively, potential difficulties are greatly reduced. However, if difficulties arise in correctly installed floors, they can frequently be resolved by cutting the floor or adding additional expansion trim.
At times some immediate work to relieve the effects may be required, but care needs to be exercised in the timing and extent of such, with it often best not to complete remedial work until the extreme conditions are over and weather conditions are closer to the average ‘more normal’ conditions that the floor was performing in. At that time final tidying up can be undertaken.
