How to install engineered oak floorboards

A helpful guide

We recommend that the installation of engineered oak flooring is carried out by a professionally trained wood floor fitter, or a competent D.I.Y. person with suitable experience. Each professional or experienced fitter will have their own installation techniques, and each property and installation will require a different approach to the next.

Depending on the local environment and the property, each floor will enjoy its own characteristics once fitted. Whilst we can’t cover every aspect, here are some useful general guidelines:

Suitability of Engineered Oak Flooring

Engineered wood flooring is more versatile than solid flooring, and can be used in most rooms in your home.  It can withstand moderate changes in temperature and humidity, so, in addition to everyday living spaces, it can also be used in kitchens, conservatories and rooms with large amounts of glazing.

Suitable for:

  • Most domestic applications such as living rooms, dining rooms, hallways, bedrooms, landings, conservatories, children’s play areas and home offices.
  • Most commercial applications such as offices, reception areas, meeting rooms and board rooms.  
  • Underfloor heating (please see separate guidelines)

Unsuitable for:

  • Rooms that have excessive fluctuations in moisture, humidity or temperature such as bathrooms, utility rooms, cellars, basements, wet rooms or saunas.

Site Conditions

The building must be weather-tight, the heating system working, and all ‘wet’ trades (plastering, painting etc.) must be completed and fully dry. All guttering and rainwater goods must be properly fitted and fully functional. All windows and doors must be glazed, sealed and fully functional.

At the time of delivery, installation, and thereafter, room temperature would ideally be between 18oC to 20oC, and relative humidity between 45% to 55%.

The delivery of your floorboards to site should ideally be within a week of the floor being installed.

Storage on site of pre-packed standard profile flooring

Once you have received delivery of pre-packed engineered floorboards, the packs should be taken indoors immediately and stacked in the room where they are to be installed to acclimatise. Packs should be stacked flat horizontally (not on edge) in the centre of the room. The boards should not be removed from their packs, however, the ends of the packs can be opened to assist airflow.  To assist airflow further, spacers can be placed between the packs. Use wooden spacers which are long enough to span the full width of a pack.

Use at least three spacers per running metre so that the weight is evenly distributed. Ensure the spacers are of identical thickness, and that packs are not in direct contact with the sub-floor. Leave to acclimatise in the room for at least 3-4 days prior to installation.

Sub-floors (i.e. the existing floor over which the flooring is being fitted)

Sub-floors must be flat, dry and clean.  If you have an uneven sub-floor, your oak flooring will not sit on top correctly.  The entire sub-floor must be flat.  Any unevenness of more than 3mm needs to be addressed.  On a concrete sub-floor, ridges and dips can be smoothed out using a self-levelling compound.  On a wooden sub-floor, you can line the surface with 18mm plywood board or thicker.

Wooden sub-floors such as timber joists, battens, ply or floorboards should have a moisture content of no more than 14%. This can be measured with a moisture meter.

Concrete sub-floors should have a moisture content no higher than 3%. This can be measured with a hygrometer.

Expansion provision

Hardwood flooring is kiln dried to a moisture content of 9% to 11% prior to despatch. As local conditions vary in each property, the moisture content of wooden flooring will fluctuate depending on the heat and humidity. Floorboards, therefore, contract and expand during their life (however we are generally unaware of this happening).

It is essential that an expansion gap of at least 15mm is left around the perimeter of the room, and around any obstructions such as columns, radiator pipes, door casings, hearths etc. and in doorways between rooms. In rooms larger than 10m x 8m, and in rooms which are subject to regular fluctuations, it may be necessary to provide larger expansion gaps. Your fitter will be able to advise further. Expansion gaps can be covered with a variety of solid skirting or trims. It is essential that the natural movement of the boards isn’t impeded.

Installation of pre-packed engineered flooring

Take the boards out of the packs immediately before installation; draw from at least 3 packs to ensure a good colour/grade mix which is to your liking and repeat this process as the floor is laid. Decide on which direction to run the planks (usually with the light-fall from windows or along the length of the longest wall.) Use wedges to maintain expansion gaps during installation and remove them after completing the floor installation. Try to stagger joints in adjoining rows. The first and last rows may require cutting down.

Fitting methods

Engineered oak flooring can be mechanically fixed to the sub-floor with nails or glue, or it can be floated over an underlay.

Secret Nailing

It is good practice to apply a polythene damp proof membrane (DPM) over concrete sub-floors which are to have battens or joists fitted for secret nailing. Any joints in polythene DPM must be overlapped by 200 mm and be taped with polythene adhesive tape. The DPM should be taken up the walls by 25mm or more (this will be hidden behind skirting). Insulation can be placed between joists or battens. For old concrete sub-floors, we recommend that a liquid DPM is applied prior to the polythene DPM.

For existing wooden sub-floors make sure that any existing nail or screw heads are flush with the surface of the joists or battens. For uneven wooden sub-floors fit 18mm plywood or thicker over the joists or battens to provide a level surface.

Secret nail to wooden sub-floors (joists, battens, ply or floorboards) at an angle of 45o through the shoulder of the tongue using lost-head nails. Be sure to punch the nail head below the surface of the tongue. Nail length should be twice the thickness of the floorboard or a little longer. Professional fitters will use specialist nailing devices. The first and last rows should also be face nailed near to the edges (face nails will be covered by skirting boards).

Joists or battens should be fixed at no more than 400mm centres. If nailing to existing floorboards, fit the new boards at 90′ or 45 to them, nailing every 300mm. If nailing to ply, nail every 200mm. Use wedges to maintain the expansion gaps during installation.

Stick Down

It is good practice to apply a liquid damp proof membrane (DPM) over concrete sub-floors which are to have floorboards stuck down to them.

Use a permanently elastic Polymer glue system. Only spread as much glue as you can cover within the curing time of the glue, and always follow the glue manufacturer’s instructions. Use wedges to maintain the expansion gaps during installation.

Make sure the joints are tight, and don’t glue them!

Floating Floor

It is good practice to apply a liquid damp proof membrane (DPM) over concrete sub-floors which are to have floorboards floated over them.

Engineered oak flooring can be floated over a suitable underlay. In this type of installation, the new wood floor is not fixed to the sub-floor, it is held in position by its own weight (i.e. it is said to be floating). Apply a small amount of PVA wood glue to the joints. As with ‘stick down’, make sure that the boards fit tightly together. Immediately wipe away any adhesive that seeps from the joint with a damp cloth. Use installation clamps to ensure a tight fit of the first three rows, and leave clamped together for one hour before proceeding with the remainder of the floor. Use wedges to maintain the expansion gaps during installation. The last row should be installed with with an installation bar. Don’t walk on the floor until the glue has cured.

A few more thoughts

Oak flooring is a natural product. Each board is unique, and, depending on grade, may have knots, sapwood and colour variation which are not preferred by customers. Unwanted natural defects can be cut out during installation and the resultant cut boards can be used at the end of rows.

We would recommend that an additional 10% of the floor area is purchased to allow for boards which are rejected due to their appearance, and wastage resulting from the removal of unwanted natural defects.