Usually when we installing or layering an engineered floor many aspects must be considered. This includes assessing the house design, environment in which the engineered floor is to be laid and the desired look of the finished floor. These aspects are covered and also aspects relating to selection of products, widths of boards, and finish systems applied.

Engineered flooring are manufactured in Australia and Asia. Most of it is manufactured in Asia with face veneer or lamella from both Australian and species from other countries. Product construction can differ significantly from one product to the other product. There are a range of manufacturing methods that are too diverse to explain in detail.

However, what is similar among all engineered flooring is the veneer or lamella of solid timber on the exposed face of the board. Veneers are typically up to about 2mm thick. Lamella is thicker than Veneer, it’s 2.5mm to 6mm in thickness. In constructing this decorative sheet it can be peeled, sliced or sawn.

A solid piece of timber is considered to be hygroscopic. Because, once it has been properly dried out it will still absorb moisture from the air during times of high humidity and during times of low humidity it will lose moisture to the air. With these variations in moisture content the timber will swell with high humidity and shrink with low humidity. Another feature of timber is that swelling or shrinkage only happens in the width of the board and not to any appreciable degree to its length. This feature is used to advantage in many engineered floors by cross laminating with the grain direction in each layer alternating at 90 degrees. Using this procedure the natural width movement of each layer is controlled and a floorboard is created that is more stable in width movement resulting from moisture content changes. Though the cross laminating does significantly minimise the width movement that often results in gapping at board edges with solid timber flooring in dry climate, it does introduce a less amount of lengthwise movement in the board with changing moisture content. Such movement is accommodated with expansion allowance at installation.

Another advantage inherent with engineered flooring is better use of resources in that the thin high quality face veneer or lamella is often adhered to plywood or other timber species that are of a more plentiful resource. This process therefore provides a high quality board with a solid timber exposed face, with reduced in-service width movement.

Engineered flooring is typically supplied as pre-finished. The surface visible to sight in the floor is generally a UV cured coating system. It may have additives to make the coating harder. Once board blanks are produced and exposed surface coated they are machined to provide the tongue and groove or glueless joint system to the edges and ends of the boards. A small number of manufacturers supply boards for site sanding and coating. Numerous quality checks are done throughout the procedure and the product is finally packed for shipment.

The customer’s choice

Aspects relating to what customers want is of paramount importance and should not be considered simple. They are depending not only on the expertise of those who have manufactured the product. Also advice on the variety of products available in market, difference between installation procedures. Its important to advise customers ongoing care and maintenance. Each of these characteristics can influence the owners’ satisfaction with their floor. Owners are very conscious and have much more access to information than earlier days. However they are unlikely to have the same depth of knowledge as those dealing with engineered flooring on a day to day basis. It is important to give priority to customer likings, however this should not be to the detriment of the performance of the floor or its final output. Where customer choices cannot be accommodated then the customers should be informed. Colour variation between showroom samples or production batches and the product provided and provision of expansion joints are two areas which affect appearance and may necessitate specific discussion with the customer. With engineered flooring the combination of colour and figure in the boards, , will perform its own natural beauty.

• Engineered flooring product types & installation methods-:Engineered flooring is manufactured with a decorative layer of solid timber bonded over layers of other timber or other materials beneath which not only provides some additional stability but also maintains all the appearance and characteristics associated with solid timber flooring. Engineered floors can differ markedly in their construction, may be laid as floating floors, glued to a subfloor as an overlay or in some cases fixed as a structural floor.
• Constructions -: Board construction differs significantly between products and a number of product types currently in the market will be considered. For some years product types that have been in the market are generally two; the first type holds a face lamella, core block layer and stabilization layer and the second containing a face lamella over a plywood base.
• Direct adhesive fix and floating installation -: Engineered floors are having 2 main methods of laying. Most floors are direct adhesive fixed to the subfloor which may be concrete or sheet flooring such as particleboard or plywood. A direct adhesive fix floor provides a solid feel under foot and with some products is considered to be more suited to higher humidity environments. Floating floors as the name suggests indicates that there is no fixing of the flooring to the subfloor. The boards are fixed to each other and they rest on an underlay. Correct sub-floor preparation along with careful underlay selection, will ensure a solid foot feel and sound. Note also that a very limited number of products have been tested for installation and direct fixing to floor joists or battens over concrete slabs.
• T&G and glue less installation There are two profile types available in the market. The first method is the ‘tongue and groove’ or T&G profile. It is found in traditional solid timber flooring. The second method is interlocking or glue less joint systems. The T&G profile is used for direct adhesive fix applications where adhesive is used to bond the lower surface of the boards to the subfloor. This profile is also used for floating installation and in this application adhesive is applied to specific locations within the T&G joint. T&G is only designed for direct adhesive fixing.

Engineered flooring coating system and gloss levels

Usually most engineered flooring prefinished in the factory, a very high standard of fi nish is achievable. In many products the coating to the exposed upper surface includes of a multi-stage system including sealers, fillers and final coats with additives. Aluminium oxide is an additive used to offer a tough wear resistant surface. Coloured stains may also be used in the coating system to add different colours or tones to the boards. The coating is done in a controlled environment with UV curing that provides a fully cured finish at the end of the process. Products are available in different gloss levels. From a satin or low sheen finish to a full gloss level. It should however be noted that not all suppliers may provide both in the range of products they sell. From some suppliers product is available unfinished so that it can be sanded and coated on site. Sanding and coating on site can be beneficial in permitting the final appearance to be achieved at the end of the project when floor installation is required beforehand. It also provides for coating choice. Although a high standard of fi nish is achievable, site sanded and finished floors generally contain some imperfections and where such imperfections have a limited effect on the appearance of the floor, the imperfections are considered acceptable. Provided below is a photo of an engineered floor that was sanded back to bare timber and coated. The appearance is quite acceptable even though at an oblique angle in refl ected light the surface is not as smooth as the original pre-finished boards.

Locality, dwelling environment and product choice

As we discussed previously it is mainly the relative humidity that influences the moisture content of flooring and different products will be more suited to some localities and internal environments than others. Usually the moisture content that timber will approach under set conditions of relative humidity and temperature. For an example, if the conditions above a floor were maintained at a temperature of 20°C and the relative humidity maintained at 55%, then in time the flooring moisture content would settle to about 10%. At this temperature a rise in relative humidity to say 65% would result in board moisture content rising over a period of time to about 12%, conversely a lowering in relative humidity to a very low 35% would cause the moisture content to reduce to about 7%. Within a dwelling there are many things that affects the relative humidity and a comfortable living environment is not as extreme as the conditions outside the dwelling. In cold weathers the internal environment is moderated by heating when cold wet conditions cause high humidity outside and in summer months when conditions can be hot and humid, refrigerate air-conditioning is often used which moderates the high external humidity. In places experiencing hot dry summers, evaporative coolers add moisture to the air thereby also moderating the conditions. Furnishing such as curtains and rugs also tend to moderate the internal environment by not only reducing heat gain in the floor but also absorbing and emitting moisture depending on the humidity, similar to the floor. Generally, in the conditions that we feel most comfortable, the engineered floor will also perform the best. Care is necessary not to create conditions within the dwelling that we would feel particularly uncomfortable in. More extreme use of heating and cooling systems, unfurnished dwellings and permitting hot humid conditions for extended periods inside the dwelling can all have a detrimental effect on engineered floors. Changes in the construction of engineered products have been outlined above and associated with these there will be differences in the performance of products in particular environments. Most engineered products are well suited to drier conditions with manufacturers and suppliers often indicating suitability down to about 35% relative humidity. For the main populated coastal cities humidities may drop below this for only short periods in very dry conditions such as during bush fi re days but the period over which this occurs is not generally suffi cient to affect the floor.

However with higher humidity conditions greater care is essential. Frequently during the building phase when the dwelling is not being lived in internal conditions tend to more closely reflect external conditions. Floor installation as the final thing of the building process necessary, if the building is during a humid time of the year. Other humid localities include the tropics, buildings within a few hundred meters of the coast, areas with large expanses of grass around them such as farmland, gullies with tall surrounding trees and where the dwelling is often shaded and often near a watercourse and elevated hinterland and ranges where conditions are often cooler and more cloudy and misty.

Regarding this some products are only suggested for internal environments up to about 65% relative humidity for floating floor applications and 70% for direct adhesive fix applications. Similarly, although small periods more than these values will not affect the engineered floor, even in localities such as Brisbane, and more so in the northern tropical locations, relative humidity in a naturally ventilated dwelling will frequently and consistently exceed 70%. Higher humidity is experienced in houses in bushy gullies

In higher humidity locations choice of product is very important. There are engineered floors to suit humid dwelling atmospheres. But some specific species and constructions will not provide adequate performance. It is vital to check both the manufacturer’s installation recommendations and warranty circumstances that the product being considered is designed for the dwelling environment. The beachside environment provides a higher humidity environment and some wet trades were also present after the floor had been installed. Less of protection of the prefinished product also resulted in damage to the flooring.

Therefore it is emphasized that each site and dwelling environment needs to be correctly assessed.

Building site conditions-:

With regard to the exterior of the building or dwelling, all gutters, downpipes and drainage systems need to be in place and operational prior to laying the floor. Likewise, ground work needs to be sufficiently finished to ensure water drains away from the building and that no ponding of water occurs either adjacent to slabs and footings or beneath the building. Before the product is being delivered to site the building should be weather tight with all windows and doors in place. Wet trades including plastering, tiling, painting and plumbing should be finished and the building or dwelling then given time to dry from higher levels of moisture released from these trades.

Storage and handling-:

All products should be handled with extreme care. Unopened cartons must be stored in dry conditions and elevated at least 100 mm off ground floor slabs. Conditions within the dwelling should look like as closely as possible the in-service conditions of the completed building or dwelling. If the normal in-service conditions of a building is that it is air-conditioned or heated at the time of the year when the floor is being installed then if possible these conditions should be replicated prior to floor installation and then maintained. Temperatures in the 20s and relative humidity of 40% to 60% are indicative of moderately dry conditions that are best suited to floor installation with many of the products available. The focus should be on comfortable indoor conditions.

Acclimatisation-:

Before laying the engineered floor some consideration required to be given to acclimatising the product. Although the word acclimatise is used, it often has a different meaning to that used with solid timber flooring and therefore individual manufacturer details need to be considered. In some instances manufacturer recommendations state that no acclimatisation is necessary, others indicate that acclimatisation by the processes used with solid timber flooring should be undertaken while others state that storage for 7 to 10 days in the installation environment is all that is necessary to acclimatise or accustom the product to the installation environment. In general, the intention of these guidelines is to bring the temperature of the new flooring close to that of the indoor environment. This means that the panels are not subjected to temperature shock and distortion on opening

Choosing the subfloors

Floating and direct adhesive fix applications a wide range of subfloors can be put over provided the subfloor is in an appropriate condition to accept the flooring as outlined below. In the case of direct adhesive fix applications the structural integrity of the subfloor must be adequate to withstand forces associated with board expansion.

In most cases subfloors are going to be concrete slabs or sheet floors of plywood or particleboard. Underlay, which could be acoustic, can provide an intermediate layer. Other subfloors suitable to some product manufacturers also include existing timber floors, Masonite, resilient flooring and ceramic tiles. Some of products can be fixed direct to joists or battens. For the specifics concerning to the preferred installation method, the product supplier’s installation recommendations need to be viewed and then recommendations adhered to.

According with the Building Code of Australia, engineered flooring is not to be installed in wet areas such as the bathroom, toilet and laundry. Kitchen and food preparation areas are not deemed to be wet areas.

Engineered flooring -:Subfloor construction, flatness and cleanliness

Subfloors need to be sound and structurally agreed with related Australian construction standards. Any determined issue with an existing subfloor or overlaid product such as squeaks in an existing timber or sheet subfloor or tile fixing integrity that may affect the performance or appearance of the installed engineered floor need to be adjusted earlier to floor installation.

All subfloors need to be sufficiently fl at to accept the flooring system (floated or direct adhesive fi x). For floating floors this generally does not exceed 3 mm beneath a 1 m long straight edge. For direct adhesive fi x applications 3 mm beneath a 3 m long straight edge applies.

Excessive variation in the sub-floor may lead to excessive deflection of a floating floor panel with foot traffic. Such movement may also lead to excessive noise, therefore proper preparation is critical in order to achieve a solid and quiet floor underfoot.

Individual flooring products having specific recommendations or as recommended by adhesive manufacturers may be tighter than this and in such cases will apply. Sometimes concrete subfloors are not sufficiently flat. In such cases we need to level the subfloor using levelling compounds, grinding etc. When there is a timber subfloors, packing of joists and sanding of sheet subfloors may be essential.

The surface on which the flooring is to be adhesive fixed must be free from all contaminants that could stop or reduce the efficiency of the adhesive. In certain the surface required to free from any waxes, grease, paint, sealers and other similar substances. Concrete slabs may be required Sanding or grinding to provide a suitable surface.

For floors direct adhesive fixed to concrete subfloors the following additional provisions apply:

Any intermediate layer between the flooring and the subfloor (e.g. ceramic tiles over a slab) needs to be removed or if permitted to be laid over by the engineered flooring manufacturer, it needs to be tested to ensure it is adequately adhered to the subfloor. If adhesive fixing to an intermediate layer the flatness provisions outlined above apply

On a concrete slab we apply levelling compounds according to the manufacturer recommendations. Also care is needed to ensure sealers used in conjunction with the product are completely covered by the levelling compound. Sealers prevent adhesion. The levelling compound also needs sufficient tensile strength to accommodate the expansion forces from the adhered flooring. Levelling compounds with low tensile strength are not sufficient for adhesive fixed floors. The levelling compound in the photo can be gouged with a steel ruler

Concrete slab subfloors protection from moisture-:

Regardless of whether the floor is floated or direct adhesive fixed, phases need to be taken to prevent possible moisture uptake into the flooring from the concrete subfloor. Moisture absorption from beneath the floor can effect in larger levels of expansion. It is resulting in buckling, adhesive bond failure and a cupped or crowned appearance.

It is important to guarantee that slabs have under slab moisture retarding barriers that comply with AS 2870 - Residential Slabs and Footings. These barriers distinct the concrete from possible sources of moisture that may delay or could stop the concrete from drying sufficiently. Provided they are installed correctly, water vapour transmission through them is minimal. It has been shown that such barriers form close contact with the slab avoiding moisture movement between the barrier and slab. Puncturing, gaps or inground piers can result in localised areas of higher moisture and slab edge dampness also needs to be considered

At the time of engineered floor installation the installer will usually not be aware of what the actual water-cement ratio was , how well the ground moisture vapour barrier was installed or how well the concrete was placed. The presence of beams also requires to be considered. The weather, including wind, temperature and humidity variations, also infl uences drying. Due to that, regardless of how old is the slab, its moisture levels need more assessment before laying an adhesive fixed, engineered floor.

Slab moisture can be assessed with concrete moisture meters as well as in-slab relative humidity tests. Such measures along with assessments of the risks outlined above are necessary for all slabs. When moisture meters are used new slabs may give readings with a concrete capacitance moisture meter of about 6% a few days after placement. Within 3 months the readings may be down to about 4% and after two years readings may settle to about 1.5%. Once a slab is known to be reducing in moisture content like this and at least 3 months old, other means of protecting against possible slab moisture can be employed if considered necessary. Some engineered flooring manufacturers will leave the onus on the installer while others recommend an applied moisture retarding barrier or similar as an added safeguard.Concrete moisture meters used to asses moisture as well as in-slab relative humidity tests.

There are some of the limitations of concrete moisture meters. They measure moisture near the top of the slab and once a floor is laid moisture levels usually increase toward the top of the slab. In-slab relative humidity measurement is a method of slab moisture assessment that is increasing in popularity throughout the world and is considered to provide a more accurate assessment of the potential for slab moisture to affect a floor. The test takes into account that moisture in a slab increases toward the top surface of the slab once an engineered floor is laid. In-slab relative humidity remains relatively high in all slabs and information from overseas suggests that in-slab relative humidity’s of about 80% are at a level where timber based flooring products can be considered. In slab relative humidity requires holes to be drilled in the slab, the holes plugged and readings with a hygrometer taken some time later. Again other means of protecting against possible slab moisture may also be part of engineered flooring manufacturer recommendations and should be followed.

Therefore before laying a direct adhesive fix floor the level of moisture in a slab needs to be assessed and when down to suitable levels an applied moisture vapour barrier, if recommended by the flooring product manufacturer, is to be used. If the floor is being laid on battens a 0.2 mm polyethylene plastic over a slab should be used.

With floating floors an underlay and moisture retarding layer is a standard recommendation of engineered flooring manufacturers. Most of engineered flooring products have specific underlays that have to be used and contain an integral moisture retarding layer. Engineering flooring product supplier recommendations concerning the desired system are to be followed and underlay or applied moisture vapour barrier products are to be applied in accordance with manufacturer recommendations.

Timber and sheet subfloors – Protection from moisture

Engineered flooring can be laid over particleboard or plywood subfloors on joists and often on solid timber flooring on joists as either a floating floor or an adhesive fixed floor. It is essential to guarantee possible moisture in either the sheet or timber subfloor and the subfloor space beneath does not affect the flooring being laid

Other subfloors and those needful acoustic rating

Engineered flooring may also be installed over subfloors not specifically outlined above, but as these are less common the flooring product manufacturer needful regarding the product and installation system to be used.

A degree of acoustic isolation is achieved with either floating installation on underlay or with some adhesive fixed systems. Always requirements specific underlays and installation practices need to be employed to achieve the required sound isolation. Features relating to the thickness of concrete subfloors play a significant role and thinner timber floors generally result in less sound transmission than thicker flooring. Underlay performance relates more to the design of the underlay rather than the thickness. Timber flooring systems including acoustic underlays often provide about 10 to 20 dB attenuation. Hereafter with such applications advice from the flooring product manufacturer and others will likely be necessary.

Heated slabs-:

As engineered flooring differs considerably in its construction between manufacturers not all products are suitable for installing over heated subfloors. Therefore if installing a floor over a heated subfloor it is necessary not only to choose the correct product but also to follow the specific manufacturer installation instructions.

Choosing the subfloors

With floating floors the underlay provides a cushioning effect between the engineered floor and the subfloor over which it is placed. Also it allows the floor to also accommodate the minor acceptable tolerances in the flatness of the subfloor. Most of underlays provide the role of a moisture vapour retarder and have this built into them with a plastic layer to prevent moisture vapour from affecting the flooring. Though, this is not provided with all underlays and moisture vapour transmission may need to be considered separately, such as by placing a 0.2 mm polyethylene plastic sheet over the subfloor first. In such occurrences the plastic sheeting is typically overlapped by about 200mm and the joints taped.

The noise transmission through a floor also influence by the underlay. But also the noise emitted from the floor when walked on. Underlays come in a variety of materials depending on the properties that the manufacturer desires to achieve. Underlay products include expanded foams, polyesters, cork and rubber. In commercial applications where heavier loading may occur, a more dense product may be use.

Engineered flooring can differ significantly between manufacturers and therefore the subfloors over which the product can be laid and the environmental conditions most suited to the individual products will also differ.

Engineered floor installation required Equipment-:

The equipment necessary to lay the engineered floor will differ a little depending on whether the flooring is to be floated or direct adhesive fixed and with floating floors whether it is T&G profile or glue less joint system. Though boards need to be cut and drop saws, circular saws and jig saws are frequently used. General carpentry tools including such as tape measure, pencil, string line, hammer and carpenter’s square are essential. Specific to floor installation are tapping blocks, pull bars and means to assess subfloor moisture. Adhesives of several types may be needed with T&G floating fl oors generally using a cross linked PVA and direct adhesive fixed floors generally using a polyurethane flooring adhesive. Likewise, cleaning cloths and products for dealing with excess adhesive are also required. With direct adhesive fix applications subfloor levelling equipment, applied moisture retarders and sanding and grinding equipment or levelling compounds may also be required. Correct glue trowels are also needed and are specific to the adhesive manufacturer. Systems which include a moisture vapour retarder and adhesive generally need to be from the same manufacturer to maintain warranty of these products.

Safety

Safety is a priority and therefore correct use of power tools and use of products associated with the floor installation essential to be in accordance with the manufacturer’s procedures, safety instructions and application instructions as applicable for the equipment and products used. The work area also needs to be kept clean always.

Floating floor installation-:

Mainly two products types may be floated over an underlay. It’s the T&G profile and the glueless joint system. Before the floor installation aspects relating to the product chosen, on-site storage and acclimatisation, the in-service environment, subfloor condition, underlay to be used, safety aspects and equipment needed to complete the installation should all have been considered and be in accordance with the manufacturer recommendation.

Some general facts with floating floor installation are as follows:

All floors are installed on underlay. Which usually has a pre-attached moisture retarding barrier and manufacturers generally need the inclusion of a moisture retarding barrier.

Floating floors are not to be fixed to the subfloor for any reason. It desires to be guaranteed that the floor is free to move in all directions. That is, the floor is not to abut any vertical surfaces which include doorways, other adjoining floor surfaces, pipe work, benches or staircases. Likewise the kitchen benches are not to be placed on the floor, but the floor is to be cut around them.

Manufacturer recommended expansion allowance to all vertical surfaces is to be provided noting that in more humid environments greater expansion can be expected and therefore expansion allowance toward the upper end of the manufacturer range is prudent. Similarly wider or longer floors should be provided with more than the minimum

highly guaranteed that intermediate expansion joints are provided where recommended and that appropriate expansion joints at doorways are also should be provided. Subfloor expansion joints and construction joints running parallel to the direction of laying should be mimicked in the engineered floor above. Construction joints in slabs need to be sealed from vapour transmission.

Between manufacturers the installation process differs a little but is generally as follows:

The underlay is rolled out onto the subfloor with integral moisture retarding barrier facing the subfloor as relevant. Joints in the underlay are butted together and taped to provide a continuous layer.

The first row of boards is laid with the groove side facing the starting wall. It is important to ensure the suggested expansion allowance has been provided. To maintain the correct allowance expansion gap blocks or wedges can be used . If the wall undulates then this row of boards will need to be scribed and cut so that the expansion allowance is even down the length of the wall. Also, consideration may need to be given that on the opposite wall the floor will not finish with a very narrow board. This can be another reason for cutting back the first row of boards.

T&G profile installation:

• Where the flooring has a T&G installation some manufacturers specify that the first few rows should be initially ‘dry fitted’, therefore it is then possible to check whether the floor is straight.
• Once this is done the rows are disassembled and then boards glued together from the initial starting position. Boards consecutively glued together in a staggered pattern. An unbroken bead of adhesive is applied in all T&G joints according to the product manufacturer’s directions. This is essential to provide the required bond strength and a degree of moisture resistance. The location of the bead or beads is important, it can differ between manufacturers and may differ over the fi rst few rows of boards to the main body of the floor
• It will take nearly an hour to adhesive drying, often about an hour. Should not be walked of the floor before proceeding with the installation of the remainder of the floor
• To gently tighten all joints, During the installation both a tapping block, with groove fitting over the board tongue, and pull bar are used. Clamps may also be used.
• Also during the installation all hints of adhesive to the board surface must be cleaned off. A cotton cloth and regular changing of rinse water is required to avoid glue haze on the board surface.
• It is likely that the final row of boards will need to be cut lengthwise, again ensuring an even expansion gap to the recommend size is provided to the external wall. Wedges are also to be placed in the expansion gap to hold the final row of boards tight as the adhesive sets. When dry, the wedges are removed • It is also important throughout the installation to consider the overall floor area and where intermediate expansion joints and joints at doorways may need to be provided, with appropriate trims being used to permit floor expansion movement.

Glueless joint system installation:

• When flooring has a glueless joint system the process is similar to the T&G installation outlined above except that no adhesive is required. The choice of starting wall, possible need to cut the first row of boards lengthwise to provide an even expansion gap and staggering of joints etc. is all the same
• Some manufacturers advise laying three rows of boards. The first row laid by rotating the end joints together and subsequent two rows rotating the edge joints together and then using the provided blocks to gently tap end joints together. Once three rows are installed this flooring section can be slid on the underlay to achieve the final correct positioning and expansion allowance gaps. The fitting of the main body of the floor and possibly cutting of the final board are similarly executed.

Direct adhesive fix installation-:

• A T&G profile that permits a sliding fit and allowing small movements at board joints is used for direct adhesive fi x applications.
• Aspects relating to the product chosen, on-site storage and acclimatisation, the in-service environment, subfloor condition, underlay to be used, safety aspects and equipment needed to complete the installation should all have been considered and be in accordance with the manufacturer recommendations, prior to the point of floor installation.

Some general points with direct adhesive fixed flooring installation are as follows:-:

• Flooring manufacturers will often mention a particular adhesive be used with their product. Therefore it is important that such recommendations are followed as the properties of polyurethane adhesives differ between manufacturers. Floors on slabs a moisture vapour retarder compatible with the adhesive will be specified. On plywood and particleboard subfloors no moisture vapour retarder is usually necessary as these subfloors should be within a suitable moisture range prior to floor installation. However, installers must still check the subfloor moisture conditions
• It’s important to use polyurethane adhesive in accordance with the flooring and adhesive manufacturers’ guidelines and particularly in terms of the trowel size, spread rate, open times, curing times and weather conditions that could affect bonding. Surface preparation and testing is particularly important.
• Floors are generally laid to a chalk line about 450 mm out from either end of the starting wall. The exact distance being a multiple of the board widths plus the expansion allowance to the wall as recommended by the flooring manufacturer. However, consideration also needs to be given to walls that may undulate and rooms that are not square which may influence the positioning of the string line and necessitate cutting of the first row of boards lengthwise to suit. The required expansion allowance at walls needs to be maintained.
• The first rows of boards should be installed, seated in the adhesive with the groove edge lined up to the string line and the tongue edge facing the starting wall (longer and straighter boards being preferred for this row of boards). Note also that some manufacturers require board end T&G joints to be adhesive fixed with a PVA adhesive.
• When laying it is usual to engage the end T&G joint with the side T&G’s of the boards as close as possible. The side T&G’s are then engaged with a minimal amount of sliding movement. This ensures minimal displacement of the adhesive and possibility of pull back from memory effects.
• Laying from the first row of boards will initially commence toward the starting wall. This row of boards can be held in position with a sacrificial row of boards nailed to the subfloor on the groove side of the boards. The board to the starting wall, if not otherwise trimmed, will likely need the tongue removed to provide adequate expansion allowance.
• Laying can then continue away from the starting wall with the same method as outlined above. It should be noted that working on the flooring just laid should be avoided as it can create numerous drummy spots when the floor is completed. If unavoidable in some areas a kneeling board to distribute the weight should be used.
• During installation the transfer of adhesive can be checked by removing smaller floor boards after laying and checking the back of the board. If adhesive skins and transfer is inadequate the bonding will be compromised. Some recommendations require the floor to be weighted to achieve even transfer. Weather conditions affect the open time and care is necessary not to spread the adhesive too far ahead of the work area.
• Any adhesive on the board surface needs to be cleaned off during the laying with the cleaner recommended by the adhesive manufacturer and cleaning cloths need to be frequently changed to prevent an adhesive haze to the board surface
• During laying, joints should be continually checked to ensure that they are tight, that the floor is aligned and that board lengths are chosen to achieve a staggered appearance with a minimum of 100mm but preferably with board ends 300mm to 500mm apart.
• Heavy foot traffic should be avoided for at least 24 hours and it should be noted that at this time the adhesive will not have fully cured. Even so it is permitted to lift heavier items of furniture or benches back into place after this time.
• The final row of boards will likely need to be cut lengthwise, again ensuring an even expansion gap to the recommended size is provided to the external wall. Wedges are also to be placed in the expansion gap to hold the final row of boards tight as the adhesive cures. When dry the wedges are removed.
• It is also important throughout the installation to consider the overall floor area and where intermediate expansion joints, and joints at doorways, may need to be provided with appropriate trims being used to permit floor expansion movement.

Engineered floor installation completion process-:

After the engineered floor laid, and to complete the installation, skirtings of sufficient size to cover expansion allowance provided at walls etc. need to be fitted and fixed to the walls. Where floors are laid with the skirting in place a fillet mold is usually used to cover the expansion allowance. In some gaps elastomeric filler can be used. When prefinished floating floors are used they should be thoroughly cleaned using the appropriate cleaning products. Any scuffing or negligible scratches should be fixed before we do handover. At times minor imperfections may also be present in the Floor and these can usually be filled with an proper colour matched filler or a hot wax repair. If the floor has been damaged and unable to be repaired up to an acceptable condition, the individual board or area of flooring may need to be changed. Likewise the above applies to adhesive fixed fl oors and those that are sanded and coated on site. However, depending on the individual installation, a period up to 10 days would be required for the adhesive to cure and for a sanding and coating process to be undertaken. It is important to note that both during the installation process of an adhesive fixed floor and then any following sanding and coating, no one should walk on the floor except the contractors. Similarly, actions such as just opening a door can introduce unwanted dust onto a freshly coated surface. Minor imperfections with site sanded and f nished floors often occur but do not necessarily require remedial work.

Engineered timber floors are easy to maintain but like all floor surfaces they do require regular cleaning and few precautionary practices to maintain their appearance and preserve their service life. Regularly floors should be dry mopped with a static mop, soft bristle broom or by vacuum cleaning, provided that a brush or felt head is used and any wheels can rotate freely. You have to make sure with such cleaning that nothing hard rubs on the floor as it may mark it. These practices not only pick up any lint and dust but also grit that can be harmful to the floor surface. Likewise, if pets are to be inside it is necessary to make sure that nails are trimmed and paws dirt free, thereby not introducing excessive grit. Any spill needs to be wiped up as soon as it occurs. Failure to do so can dull or discolour the finish and if left for a long period can damage the flooring. Rugs and floor mats are also effective in trapping grit at doorways, both inside and out, and reducing wear in high traffic areas. Under the effect of UV light both the coatings and timber colour can change and this can cause colour differences under rugs. For this reason it is prudent to not use rugs for the first six months or so. Otherwise, moving rugs on a more frequent basis and at times furniture over this initial period and ensuring curtains and window covering filter sunlight, can assist in reducing these effects. Rugs should also not be rubber backed or have similar impervious backing. Such products affect the floor finish and they can also prevent the floor’s natural exchange of moisture vapour through the board surface. Legs of moveable furniture such as dining room chairs need to have protective felt pads to prevent scratches from occurring. When moving heavy objects such as furniture or appliances they need to be lifted into position to prevent bruising or scratching of the floor. Foot ware with high point loads such as stiletto heels will also damage timber floor surfaces and therefore management of this is necessary. In addition to the above there are a number practices not appropriate for engineered floors and these are as follows: Do not use cleaning methods or products not designed for timber floors such as scouring pads or cleaners that may contain abrasives, soaps, waxes, ammonia or silicon. Specific timber floor cleaning products are available and should be used. Do not use steam mops or any form of scrubbing machine.