Technical

What is engineered wood flooring?

Engineered wood flooring is real hard wood as well but instead of being produced from one single piece of timber like solid floors, engineered floors consist of a core and a hardwood wear layer. The core usually consist of 3 to 12 thin layers plywood – which are glued to each running in the opposite direction to the next and pressed with huge force creating a firm and very durable substrate. The wear layer is securely bonded to the core and it is usually 2-6mm thick depending on the overall thickness of the flooring. By design engineered hardwood becomes less susceptible to the effects of moisture and temperature fluctuations therefore making it a more ideal option in general.

Benefits of engineered floors:

– More versatile and stable than solid wood floors, by being more resistant to moisture and humidity they are much less likely to be expanding, warping, cupping or gapping.
– Suitable for installation over under floor heating, unlike the majority of solid wooden floors.
– Allow for easier methods of installation.
– Can be sanded and refinished as many times as solid wood.

Wood Flooring Grades:

Prime Grade (also called AB):

It is the highest grade of flooring available. Typically, prime grade has few, if any knots, and these are of minimal size. There will be a relatively small amount of colour variation making the visual of the floor consistent. Prime grade floors are also the most expensive because only a small percentage of the timber planks qualify for this grade. It is important to remember that wood flooring is a product of nature and no two pieces are alike

Nature Grade (also called Classic or ABC):

This grade has a natural appearance displaying the full characteristics of the wood and it is often selected because of these natural features and the character they bring to a room. Colour variations are allowed as well as small surface knots and other characteristics that naturally occur in the wood.

Rustic Grade (ABCD):

Rustic grade allows even more of the natural character that develops in a wood than found in the Nature grade. The floor can display a variety of knot sizes, colours and shapes, heavy grain markings and figuring. Due to the abundance of raw material, for most species we sell, this wood flooring type will offers the best price, although provides the same quality, stability and wear property as of the cleaner grades.

Oil vs Lacquer

The main difference between lacquer and oil is that lacquer forms a protective barrier over the surface of the floor whereas oil penetrates the fibres of the wood grain therefore creating a more natural form of protection and appearance.

Hard Wax Oil is a mixture of oil and wax. The oil component ingress into the timber, fills in the pores until it completely saturates the timber. By doing so, oil makes the surface of the wood impervious to any other liquid, protecting it from spills and allowing the wood to be cleaned without staining. The wax component provides a thin protective layer on the surface that helps to prevent small scratches and scuff marks. Probably the greatest advantage of Hard Wax Oil is that it allows to touch up small areas. This also means that oiled floors do not really require sanding. A simple application of a maintenance oil, every year or two, nourishes the wood and brings the lustre back. What is more important – the method is easy,it dries out quick(3-4hours) and could be applied by cloth or mop.

Lacquer protects the floor in a slightly different way than oil. It forms a protective barrier/film over the surface of the wood. The advantages of this finish are that it is slightly more durable than oil and requires little on-going maintenance other than general cleaning. Nevertheless, over the number of years, the flooring may start to show signs of wear due to scratching. At this stage apply a coat of Bona Freshen up or Bona Polish Gloss (for gloss sheen). It revives scratched and dull surface giving a newly finished look and continuing protection against wear. However, lacquer has some disadvantages – touching up a small area will leave a visible difference in sheen and Bona Freshen up can be applied a limited amount of times, before it has to be sanded down and refinished.

Maintenance

Lacquered Flooring

Keep your floor swept or hovered as any debris or dust acts as a sanding paper damaging the surface.

For weekly cleaning we recommend using Bona Cleaner. It efficiently removes engrained dirt and keeps the floor nourished.

Over a period of time your floor may start to look tired or dull, at this stage apply a coat of Bona Freshen up or Bona Polish Gloss (for gloss sheen) after a clean with Bona Cleaner. It revives scratched and dull surface giving a newly finished look and continuing protection against wear.

For high traffic / commercial areas

Immediately after installation, it is recommended to clean the floor with Bona Cleaner and apply a coat of Bona Polish Gloss for gloss sheen (if needed).

You can reapply Bona Freshen up after cleaning with Bona cleaner when your floor looks tired or dull.

Over time residues of the Bona Polish Gloss or Bona Freshen up will build up on your floor, remove the residues with Bona Remover and re-apply a fresh coat of Bona Freshen up for a fresh start.

*Please note that you should NOT wait until the floor is worn down to raw wood before you re-lacquer. In high traffic it is advisable to re-coat before this happens, as you will only need to gently sand the existing lacquer and NOT remove all of it before additional coats of lacquer are applied.

Regular maintenance will prolong the life of the finish on your floor.

Preventive maintenance:

Place high-quality floor mats and area rugs near outside entrances to prevent dirt, sand and other unwanted substances from being tracked directly onto the flooring. Also, if you have wood flooring in your kitchen, a throw rug with a soft or felt backing should be placed in front of the sink area to catch spills and splashes.
Attach felt floor protectors on moveable furniture, including chairs, tables, sofas, etc. that sit directly on the floor.
Keep pet nails trimmed and filed in order to minimise excessive wear.

Oiled Floor

Keep your floor swept or hovered as any debris or dust acts as a sanding paper damaging the surface.

Wipe up spills and spots immediately with a damp cloth. (Oiled floors, because of their more porous nature, should not be cleaned using excessive amounts of water)

For weekly cleaning we recommend using Osmo Wash & Care. It efficiently removes the engrained dirt and keeps the floor nourished. When used regularly it creates a highly effective, easy-to-use and anti-sliding surface.

Periodic cleaning can be carried out using a liquid wax cleaner such as Osmo Liquid Wax for refreshing and revitalising the flooring. This can also be used to try and remove more stubborn stains and marks. Deep scratches in the timber can be coloured in using a stain.

Oiled floors will need to have a coating of maintenance oil applied to them after a period of time. The frequency with which this is necessary will depend on the amount of wear on the floor and on your own preferences. High-traffic areas such as hallways may need more frequent applications. Generally, the floor will need re-oiling every 12 to 24 months. We recommend using Osmo Maintenance Oil. It comes in Matt, Semi-matt or Satin finishes. The timely use of Osmo Maintenance Oil can prevent the time consuming sanding or renovation work.

The method for applying maintenance oil:

Apply a thin coat of oil either by hand with a soft cloth or using an applicator. Do not apply it directly to the boards. If using a cloth, put the product on the cloth and rub it into the timber. If using an applicator, put the product in a plastic bucket or box, wet the applicator and distribute smoothly on the floor. It should dry within a few hours but will continue to harden over the next 3 to 5 days. The floor can be walked upon as soon as it is dry, but avoid too much water coming in contact with the floor for the next 7 days.

Re-oiling or resurfacing

Resurfacing the floor after a number of years you may wish to have the hard wax oiled surface sanded down and re-finished. You could then choose to re-oil the floor or have it stained first or even re-finished in lacquer. Hitt Oak offers sanding and re-finishing service.

Preventive maintenance:

Place high-quality floor mats and area rugs near outside entrances to prevent dirt, sand and other unwanted substances from being tracked directly onto the flooring. Also, if you have wood flooring in your kitchen, a throw rug with a soft or felt backing should be placed in front of the sink area to catch spills and splashes.
Attach felt floor protectors on moveable furniture, including chairs, tables, sofas, etc. that sit directly on the floor.
Keep pet nails trimmed and filed in order to minimise excessive wear.

Under Floor Heating

All of our engineered floors are suitable to be installed with under floor heating, but there are some factors that you should take into account before you go ahead with the installation.

Under floor heating systems must be carefully installed in order to avoid warping the wood floor. The system should be designed to spread the heat uniformly over the entire floor and the control settings should be set up to avoid sudden changes in temperature. Wooden floors are unfortunately prone to warping, but a properly designed and installed under floor heating system is able to prevent this potential problem.

You must ensure that the system can be properly controlled to ensure the maximum temperature at the surface of the timber floor (at any point) will not exceed 27°C.

* For water systems this is easily achieved by adjusting the regulator to a maximum water temperature that is commensurate with a floor temperature of 27°C.

* For electric systems you will also need to set up the system so it is impossible for the floor temperature to exceed 27°C. The best way of doing it is with an infrared heat monitor.

* Please note that room temperature settings are NOT floor temperature settings.

The temperature of the floor only needs to exceed 27°C for a short period of time to damage your floor.

Wood is an insulator, which means that it slows down the transmission of heat produced by the under floor heating system the system’s efficiency. However, wood is less insulating than other flooring types such as carpet. The heat transmission characteristics of the wood can also be beneficial in that wood holds onto heat for a long time after the under floor heating system is turned off, which means that the room will be kept warmer for longer by the under floor heating system. The floor will feel pleasantly warm but not hot underfoot.

On Site Conditions

Subfloor preparation:

This includes smoothing compounds, primers and surface DPM’s. Sites need to be clear of obstruction and surfaces must be dust free. Sticking to dust means the integrity of the floor is reliant on the bond of the dust to the substrate! Products generally perform by curing and/or drying. The limiting parameter for curing of products is temperature. Epoxy DPMs, rapid set smoothing compound, resin based primers etc. all work far better at 15 to 20degC than at 10degC. The rates of cure are significantly reduced as temperatures drop. In fact, below 5degC many systems will fail to cure successfully so it is important to get a subfloor temperature of at least 5degC. Along with temperature is humidity, or in main contractor terms dampness in the air. If the air is damp (condensation on the windows, raining outside and no windows etc.) then products that are required to dry out to perform cannot dry at anywhere near the rate claimed and some can take days and days. Humidity can also be high in buildings in summertime, particularly on new build projects where a lot of wet trades are working. So get heat in the building (not fuel burning space heaters as they add moisture to the air) and also decent ventilation. Consider using underfloor heating systems to both keep the building and the subfloor warm. Use dehumidifiers, particularly overnight as the air temperature drops and condensation can be more prevalent. So, warm and dry.

Adhesives and floor coverings:

Manufactures are moving more and more to solvent free, water based products when it comes to adhesives. Therefore the same issues for subfloor materials also apply to adhesives and floor coverings. Humid and/or cold conditions means that adhesives will not give up their water easily so may not develop the required tack and grab. Also, the bond strength build up will be significantly slower. Historically, the use of solvents within adhesives has helped in this respect (solvents can evaporate at a much lower temperatures than water), but things are changing, for the environment, for the manufacturer and the installer’s health and safety. So again warm and dry.

Timber flooring

As most people know, wood is hygroscopic. In other words, it likes water. Timber ‘swells’ in the damp and shrinks as it dries. We know this from our shed doors being a pain to open in the winter but barely filling the frame in the summer. It is exactly the same with flooring manufactured from timber. The most problematic is solid timber of large dimensions. Engineered timber can be more forgiving due to it’s unique structure. So, the message has to be, get your conditions right then products will perform as specified. Failure to do so may result in flooring failures. The key in all cases is warm and dry.

Wood Flooring Installation Guide

It is the responsibility of the owner/installer, whether professional or not, to determine that all onsite conditions are stable and suitable for the installation of the agreed flooring. The wood flooring must also be thoroughly checked prior to installation. No complaints regarding the appearance of the product will be accepted by the company once the wood has been installed.

Where to install wood

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Wood flooring can be used internally in most rooms except those, which are likely to get excessively wet. If you considering wood flooring in conservatories we would only recommend engineered flooring and only when the conservatory shares the same conditions as those found in the house.

Delivery, storage and acclimatisation of wood

Please do not arrange delivery to site until all wet works (i.e. subfloors, plastering, painting, cement work and tiling) are completely finished and dry. Conventional heating systems should have been run for a minimum of two weeks and under floor heating for a minimum of three weeks.

It is essential that wood flooring is allowed to acclimatise and is stored correctly once delivered to site. We recommend the flooring to be placed in the room where it is to be fitted or in one with a similar environment.

Solid wood should be left for a minimum of 10 days to acclimatise and engineered for a minimum of 48 hours. The room temperature should be at normal living conditions (minimum of 15ºc and maximum 25ºc and a relative humidity of 45-65%).

The flooring should be unwrapped and lattice stacked, separated by battens, to allow air to circulate around it. The product should not be stored next to a radiator or on any direct heat source.

General notes

Engineered Flooring – A product of the modern age. With the aesthetic characteristics of a solid board, it provides more versatile fitting options. Top layer of 4/5mm oak glued to 11/15mm of crossover glued birch. The construction increases the stability of the planks and reduces the natural tendency of wood flooring to expand, contract, warp and cup due to the changing room temperature or moisture in the air. Suitable with an under floor heating.

Solid Flooring – A classic floor. It is cut from a single piece of timber and of structural thickness.

Traditionalists will be unanimous in their appreciation of solid flooring. We would not recommend with under floor heating.

Brushing – The surface of the planks are roller brushed to remove some of the softer growth. This results in a textured surface that gently highlights the natural grain structure of the wood.

Hardwax Oils – All prefinished boards are oiled with products, giving deep protection, because they are oil based and the natural wax sits on the surface to protect against daily wear

and tear.

Smoking – Smoking oak boards with ammonia is a traditional method for enriching and darkening the floor’s appearance. The tannin acid within the oak reacts with the ammonia to create a truly unique finish. Not every oak board contains the same quantity of tannin therefore the colour and appearance can vary significantly.

Cutting and wastage – For a standard area, a rough guide of 6% is recommended. For small, and complicated areas or if a greater deal of consistency is required we would recommend 10%.

Tolerances – Due to the nature of wood some variation in the size and thickness of the wood will occur.

Considerations prior to installation/Planning the room

Wood floors should be installed at the final stage, prior to decoration. Generally speaking, the boards should be laid lengthways towards the main incoming light source and, where possible, down the length of the room.

The wood flooring must be thoroughly checked to ensure the correct finish and quantity has been received.

When fitting a floor subject to significant variation whether it be board length, colour, and/or natural features, the board selection has a significant influence on the overall look of the room. The fitter must be sensitive to this and distribute variation evenly (this is particularly imperative with the smoked floors) to achieve a natural looking floor. In addition it is the installer’s responsibility to ensure the suitable placement of distinctly featured boards. We would recommend dry laying the floor prior to installation. Any boards deemed too conspicuous can be used as cuts or installed in less obvious areas.

We would also recommend the client and installer agree a starting point for installation as the first row of flooring sets the line for the entire floor.

Prior to laying the boards it may be necessary for the installer to under-cut the bottom of kitchen plinths, doorways etc to enable the boards to fit underneath.

Skirting Boards and Expansion Gaps:

To accommodate the natural expansion and contraction movement of wood 15mm expansion joints are required around the entire perimeter of the area to be fitted. This includes doorways and fireplaces. A 15mm gap is sufficient for a maximum flooring width of 6.0 linear metres between walls. For floors in excess of 6 metres wide, additional expansion of approximately 1mm per metre width will need to be integrated evenly across the floor.

Whenever possible the skirting boards are best fitted after installation of the wood as they can conceal the expansion gap around the perimeters. If this is not possible the expansion gaps can be concealed with hardwood beading.

Site Preparation

Careful site preparation is essential to avoid potential problems with wooden floors after installation.

Moisture and Humidity:

All wood is hygroscopic (it will react to the moisture around and in contact with it) and as a result will expand or contract accordingly. A damp atmosphere will cause the wood to expand and dry conditions will cause the wood to shrink. Shrinkage will create gaps between boards, which is characteristic of wood floors. Excessive variation in humidity can lead to boards distorting in shape and possibly lifting.

All wet works (i.e. subfloors, plastering, painting, cement work and tiling) must be completely finished and dry. Conventional heating systems should have been run for a minimum of two weeks and under-floor heating for a minimum of three weeks.

All possibilities of damp e.g. wall, drains, damp proof courses, plumbing, washing machines etc. must be thoroughly checked and repaired if leaking. The suitability of the environment of particular room/s for a wood floor can only be assessed by the use of good quality testing equipment for measuring moisture content, relative humidity and temperature. Do not use existing or previously laid floors as a guide to the suitability of laying a new floor. Failure to carry out the correct checks and take preventative action at this stage leads to the vast majority of wood flooring problems.

Subfloor preparation

All construction dampness must be completely dry and the house should be at the temperature and humidity expected during occupation.

The condition of the subfloor is integral to the stability and performance of the finished floor. All substrates should be structurally sound, flat, free of any debris, old adhesives, clean and dry. The normal tolerances are +/- 3mm over a 2.0 metre straight edge.

Uneven floors should be levelled.

Prior to installing the wood floor, check and record the relative humidity (rh) level of the substrate. If above 85% wood floors must not be fitted and specialist advice is recommended.

Concrete subfloors at ground/basement levels must contain a damp proof membrane (DPM). If one does not exist or has been damaged then a new DPM must be fitted prior to installing the wood floor.

Installing onto Sand and Cement/Concrete/anhydrite screed

We would recommend prior to installing the wood floor that at least one coat of primer is applied.

Solid Boards and Parquet can be fully bonded onto suitably prepared screeds with Sika T-52 Wood Adhesive. Please follow the manufacturer’s installation guidelines.

Engineered boards can be installed using the floating system. We would recommend the pre-laying of a suitable underlay to provide a cushion between the floor and the subfloor. Float the floor on top of the underlay gluing the tongue and grooves.

Existing Timber Floor:

Joists, tongue and groove floorboards, plywood/chipboard and floating floors

A final moisture check should be carried out and recorded immediately prior to installation. The wood to be installed should be within +/- 2% moisture of the surface onto which it is to be fitted.

Only Solid boards can be fixed over sound and secure joists. When laying solid boards directly onto existing joists the gap between joists should not exceed 450mm.

All wood flooring can be fitted onto floating floors, which must be sound, flat, firm and free of any deflection. If under floor heating is present only engineered boards can be installed.

Existing wood floors must be dry, level and firmly fixed. Loose boards not secured may cause the new floor to squeak. Take care if using nails and screws not to damage pipes or electrical cables beneath.

If the floor is on or below ground level the installer should ensure there is no moisture build up beneath the boards, there is adequate ventilation beneath and between the joists, and air bricks are present and not blocked.

Suspended ground floors must have sufficient cross ventilation to prevent condensation occurring on the underside of the flooring. It is advisable to lay a suitable membrane over the joists to help protect the undersides of the new boards from moisture.

Under floor heating

Only engineered boards are suitable with under floor heating.

Please ensure your under floor heating supplier is aware that a wooden floor is to be installed over their system. The under floor heating must be installed according to the manufacturer’s guidelines and run as per their guidelines for at least three weeks prior to wood installation.

The heating should be turned off prior to installation. Over water systems we would recommend gluing with Sika Bond T-52 Wood Adhesive. Over electric mat systems, where the electric mat is not the main source of heating, the engineered boards can be floated (see previous sections)

For re-starting the heating post installation we would recommend starting with a low temperature, gradually building up so as not to shock the wood. We would not recommend covering the floors with rugs or protective sheeting as this may compromise the timber, glue and/or finish. The surface temperature of the new timber floor must not exceed 27ºc (81ºf). Significant damage may occur to the flooring if this is not adhered to.

Sealing and finishing

Lacquer��protects the floor in a slightly different way than oil. It forms a protective barrier/film over the surface of the wood. The advantages of this finish are that it is slightly more durable than oil and requires little on-going maintenance other than general cleaning. Nevertheless, over the number of years, the flooring may start to show signs of wear due to scratching. At this stage apply a coat of Bona Freshen up or Bona Polish Gloss (for gloss sheen). It revives scratched and dull surface giving a newly finished look and continuing protection against wear. However, lacquer has some disadvantages – touching up a small area will leave a visible difference in sheen and Bona Freshen up can be applied a limited amount of times, before it has to be sanded down and refinished.

Our unfinished parquet and panels require finishing on site. Once installed they may require filling with a suitable product. Apply according to manufacturer’s guidelines. Once the filler is dry, additional sanding will be necessary. The level of sanding required will depend on the product and sub-floor. After sanding we would recommend 2 coats of original Hard-wax Oil for a natural finish.