Engineered Wood Flooring, Kahrs Flooring

Engineered Wood Floor Laying

Engineered Wood Flooring Installation Guide Image

This in-depth article will explain in writing and demonstrate with images and video the method of engineered wood floor laying. So, whether you are a visual learner or prefer written instruction, whether you are a complete novice or a seasoned DIY-er, you should find all of the information you need right here for the wood flooring installation method.

How To Install Engineered Flooring?

There are two main installation methods that you need to consider in the first instance. Whether you are going to install as a floating floor or glued-down. we will outline both methods in detail below and answer the question how are wood floors installed fully.

In certain situations, perhaps if the sub-floor is particularly uneven or there is a specific need to keep your floor, when installed, below a max height, then it will be necessary to glue-down your engineered wood floor. This method is more labour intensive and also requires adhesive, so it’s a more expensive and time-consuming option and should only considered if absolutely necessary.

In most situations, it is possible to lay the engineered hardwood in a floating installation which essentially means using the click-joint on the planks to lock the boards together, with an engineered wood flooring underlay on top of the sub-floor to provide protection against damp as well as both sound and thermal insulation, and then lay the engineered flooring atop the underlay without the need for any adhesive at all. This installation method is quicker, easier and less expensive as well as making it easier to lift any boards in the future if spot repairs are required.

Engineered Wood Floor Laying (Floating): Video Guides

Normal Installation

The Last Row


Quick Tips

Engineered Hardwood Floating Installation

Conditions for Installation


Kährs wooden floors are only intended to be installed in a controlled indoor environment. Wood is a hygroscopic material, which means that wood adapts to its ambient humidity. This causes wooden floors to swell when it gets damp and shrink when it gets dry. It is the relative humidity (RH) that controls how wood-based floor materials are affected. It’s important to understand when considering how to lay engineered wood flooring that excessive variations in temperature and humidity can cause permanent damage to the floor. The room and material temperature at the time of engineered wood floor laying should have a temperature of 15-23 ° C. The humidity in the room should be between 30-60% RH.

Humidity, Temperature and Acclimation levels for engineered wood flooring installation.

Note that moisture levels in new build premises often remain relatively high by the time wood floors are installed. In these cases, it is important that the correct RF is ensured before installation can take place. The wooden floor should be installed when all other work is completed, e.g. painting, wallpapering, tiling and when the construction site has the right RF. This is to avoid damage, dirt damage and unnecessary moisture related damage on
the floor.

Acclimation of the Floor Bundles

Before installation, engineered wood floors must be acclimated in the space where the floor is to be installed, for at least 24 hours. Faster temperature rise is obtained if the floor bundles are not laid in a single pile but are divided into several smaller ones. However, do not open the packaging of the floor bundles until the installation is to begin.

Fixtures & Fittings

When laying engineered wood flooring, furnishings, kitchen islands, wardrobes, walls, etc. must never be attached to the wooden floor. Attachment to the subfloor can take place if holes are drilled through the wooden floor to accommodate, for example, support legs or fastening including distance. The same movement joint that applies to the entire floor surface must then also be around the support legs/attachment. The floor must never be pressed down and locked. Kitchen fittings are attached to the wall to relieve the weight on the floor. The interior rests in the front edge against the floor with support legs. Alternatively, the kitchen fittings can be mounted on four legs. The wooden floor can be laid under the white goods, with the required drip protection on top. For kitchen fittings with worktops in heavy materials such as stone, stone composite, concrete or other mineral-based materials, the wooden floor must not be installed under the heavier fittings, as this risk locking the floor. If you still want wooden floors under the interior, the wooden floor must be divided and installed as a separate surface with expansion space to the rest of the floor. An alternative to wooden floors under kitchen fittings is a chipboard with a corresponding thickness. Another alternative is to drill holes in the wooden floor so that the support legs rest against the subfloor, do not forget the movement joint around the support legs. If a wood-burning stove is placed on the floor, for example, a chipboard should be laid on a surface that is slightly smaller than what the “spark protection” is. Do not forget the expansion space. The chipboard also takes up the weight from the wood stove. The floor is then installed around the chipboard!

Requirements for Sub-Floors

One of the key requirements with engineered wood floor laying, is to understand that the subfloor must be dry, level, clean and firm. Remove fitted carpets and linoleum carpets. Never leave sawdust or other organic residues on concrete subfloors. This is because the moisture coming from below remains under the vapor barrier and can give rise to unwanted organic growth.

Sub-Floor Levels for Hardwood Flooring Installation

Check that the subfloor is flat and level over measured lengths of 2m and 0.25m. If any unevenness exceeds 3mm over 2m and 1.2mm over 0.25m, the floor must be levelled first. Kährs also accepts a measured length of 1m. The tolerance in this case is 2mm.

Check the relative humidity (RF) of the subfloor, if this is above 90%, a vapor barrier of polyethylene foil is not sufficient, but further action is required before installation can begin. On the following subfloors, regardless of age, it is mandatory to have an approved age-resistant vapor barrier, e.g. polyethylene foil. This should always be installed as close to the floor surface as possible. It is important that it is installed according to the supplier’s instructions.

  • Concrete floor that lies directly on the ground
    (slab on the ground)
  • Over a hot or humid room
    (e.g. boiler room or laundry room)
  • Flooring over crawl space foundations
  • Lightweight concrete floors
  • Over floor heating systems

An underlay should be installed on top of the vapor barrier to reduce the impact sound and increase walking comfort. Our range of engineered wood flooring underlay features combination underlays that act as both vapor barrier and underlay in one.

Planning for Engineered Wood Floor Laying

Measure the width of the room and calculate how wide the last row of boards will be. If it is less than 30mm wide, you should also saw the first row of boards, so that the first and last rows of boards are about the same width. Do not forget to count on the movement joint! When installing floors from our range of engineered wood flooring click jointed, it is easier if the installation is started at the long side that has the most doors. If there are doors on the short sides of the room, it is also easiest to start a new row of boards from that side. The boards can be laid both from the left and right and backwards. If the floor width and length exceed the specified maximum dimensions, the floor must be divided by an expansion joint.

Be careful with the planning so that the maximum floor width and floor length do not exceeds the maximum width and length of your floor, see table below:-

Wood Flooring Installation Max. Width and Length Guide

Floor Type / Thickness Joint Max. Width Max. Length
15mm Click Hardwood Kahrs Woodloc 5S 25m 50m
13-15mm Click Hardwood Kahrs Woodloc 5G 15m 25m
7 - 9mm HDF Core Kahrs Woodloc 5G 15m 25m
10-15mm Click Hardwood Kahrs Woodloc 2G 12m 18m
14-20mm T&G Hardwood Tongue & Groove 12m 18m

Installing Engineered Wood Flooring on Underfloor Heating

Approved vapor barrier is mandatory in the construction when installing on underfloor heating, e.g. the combination product Kährs Tuplex. The vapor barrier should be placed as close to the floor as possible. Regardless of the choice of floor heating system, it must be ensured that the surface remains flat and stable, even over time, to avoid e.g. noise and flex. When installing on underfloor heating in grooved subfloors (e.g. chipboard or EPS) with heat distribution plates, the wooden floor must be installed perpendicular to the loops of the underfloor heating. If this is not possible, it is necessary to first cover the subfloor with a board material. If the heating coils are embedded in the substrate, no extra consideration needs to be given to the installation direction. The surface temperature of the floor must never exceed 27 ° C. This applies both during installation, at start-up of the heating system, and after the installation is completed.

Choice of Installation Direction

We recommend engineered wood floor laying in the longitudinal direction of the room, as the board moves less in length than in width. In the case of long narrow spaces, such as hallways, the floor must be laid in the longitudinal direction to ensure that the floor lies flat against the ground.

Movement Joints in Engineered Wood Floors

Expansion Joints When Laying Engineered Wood FlooringNatural seasonal variations cause a certain amount of movement (expansion and contraction) in wood floors. So its important to realise with engineered wood floor laying that the floors must never be installed close to adjacent walls or other fixed building parts. A movement joint according to the table below must therefore be left around all sides of the continuous floor surface. Remember that the width of the expansion joint is the sum of the movement joints of the two connecting surfaces!

The size of the movement joint in mm is calculated using the formula: 1.5 mm x meter floor width. The size of the movement joint should never be less than 10mm. The floor must be able to expand at, for example, thresholds, door frames, heat pipes, columns, stairs, tiled floors and other parquet floors. It is important to ensure that even the climate-induced shrinkage in winter is covered by the skirting.

Door Openings

Door Openings

When installing through doorways or narrow passages, e.g. vaults, the floor must be divided by an expansion joint, which is then covered by a threshold or moulding. The threshold can also be removed, then refitted, when the floor has been installed with an expansion joint under the thresholds position. If the threshold is too high, the door can be trimmed accordingly.

End Joints

End Joints

A proper staggering, according to the table below, of the end joints in adjacent rows, must be present to keep the floor flat during climate variations. Even small areas must be installed staggered, i.e. all floor areas must have end joints in every row. In long narrow areas, such as halls, it is particularly important

Wood Flooring Installation End Joint Displacement Table

Floor Type / Thickness Type of Joint End Joint Displacement
15mm Click Hardwood Kahrs Woodloc 5S > 500mm
13-15mm Click Hardwood Kahrs Woodloc 5G > 500mm
7 - 9mm HDF Core Kahrs Woodloc 5G > 500mm
10-15mm Click Hardwood Kahrs Woodloc 2G > 500mm
14-20mm T&G Hardwood Tongue & Groove > 500mm

Gluing Joints

Adhesive should not normally be used on boards with Woodloc® joints. However, in connection with doorjambs or radiators, installation is sometimes easier if 1/3 of the locking edge is planed off and adhesive is applied to the horizontal underlip (see illustration). This means that board can be tapped into place.

Gluing to the Subfloor

In cases where you want to glue the wooden floor to the subfloor, it is important that the requirements for subfloors are met and that the right glue for the purpose is used. Note, that there may be different regulations around what applies to gluing down to the subfloor in different countries. Consult your glue supplier so that you get the right glue and spatula which is suitable for gluing wooden floors. It is often the properties of the subfloor that determine which glue you should use. Follow the glue supplier’s instructions carefully. Before gluing can begin, it is important to ensure the quality and moisture of the subfloor, the type of glue and the amount of applied glue per m2.

Pattern Misalignments

Minor pattern misalignments that occur during manufacturing of for example Dutch pattern are permitted. When laying engineered wood flooring boards with a Dutch pattern, the transverse strip must fit in the center of the longitudinal strip on the adjoining row of boards. In the case of large areas, the installation can advantageously start from the middle of a new board row and then be laid out towards the edges, in order to minimize the effect of a possible pattern misalignment over large areas.


At Kens Yard we specialise in Kahrs Engineered Wood Flooring. They are the oldest wood flooring manufacturer in operation in the world today and generally considered to produce some of the highest quality wood flooring in the market. Kahrs purposefully manufacture boards that are slightly convex lengthwise to make the floor easy to install.

Start & Stop Boards

Packages may contain start and stop boards. These boards have no joints on one short side and are used as the first and last board in a row.

Engineered Wood Floor Laying: Visual Guides

Kahrs Woodloc 5S Installation 10-Step Visual Guide


Temperature and relative humidity in the room

The temperature in the room where the floor is installed should be between 15-23 C °. The humidity (RH) should always be between 30-60% to avoid unwanted climate-related damage and movements  in the wooden floor, e.g. cracks, gaps, noise, cupping etc. In summer you may therefore need to dehumidify the air, while in winter it may instead be necessary to increase the humidity in the air. At a too high or too low relative humidity, permanent shape changes of the wooden floor can occur. It is important that even in empty and uninhabited spaces, ensure that the temperature and humidity are correct. This is especially important when installing in connection with e.g. new constructions or major renovations. When laying engineered wood floors in so-called module production, it is important that the above criteria are ensured both immediately after installation, as during storage and assembly of the modules. It is not only wooden floors that thrive best, but also us humans get a better indoor air with a relative humidity inside this interval.


Note that the dimensions of the skirting must never control the size of the movement joints. In the case of large floor areas, therefore, the skirting must be chosen on the basis of the required size of the movement joints and not the other way around. One solution for a situation that requires a large skirting board: In new buildings, a simple way of permitting additional floor movement is to “stop” wall panels immediately above the floor surface. If the wall panel is 13 mm plasterboard, for example, this provides an additional 13 mm movement allowance. This allows a thinner skirting board to be used than would otherwise be necessary. To get nice endings and connections, there are skirting and mouldings of various kinds to use (see our Flooring Accessories).

Installation of skirting

The skirting must not be pressed down against the wooden floor, as the floor can then be locked. Skirting are suitably fastened with nails, screws or with Kährs clip system for concealed attachment to the wall.

Treatment of natural oiled wooden floor

When installing a natural oiled wooden floor, a first oiling must be done immediately after finishing, use Kährs Satin Oil for wood floors and follow the instructions on the packaging. This is important for the floor to better maintain its protective coating for a long time. It is then very important that the maintenance is carried out according to the instructions for your particular floor. For more detailed information on care and maintenance, see the brochure Maintenance guide which can be downloaded at

Protective covering

If further work is to be carried out in the room where the floor has been installed, the floor must be protected with a moisture permeable material (e.g. paper). Make sure it does not discolor the floor. Note that some commonly used types of papers do not allow moisture to pass through and have a wax coating that may be transferred to the wood floor. This causes undesirable gloss variations. Kährs Protection Paper is intended for use on all floors, both lacquered and oiled surfaces. White goods generally do not have large enough “wheels” to avoid damage if they are pulled over the floor. In these cases, a harder board material is usually needed as protection to avoid damage to the parquet surface. Under wheeled furniture, such as office chairs, permanent protection against point load is needed, for example a transparent plastic mat or the like, which is commonly used for this purpose.


Never tape to the floor surface, skirting or moldings, but only to the protective cover. Many tapes adhere so tightly to the floor surface that the varnish releases when the tape is removed. The longer the tape is allowed to be attached, the greater the risk that it adheres harder to the varnish.

Color change

Wood is a natural material that gradually matures to its natural color, this change occurs fastest at first. To avoid an uneven color change, carpets should not be laid on the floor during the first months after installation of the parquet floor.