Flooring and door installation guides

• Room / Floor preparation
• Floor nailing applications
• Floor gluing applications
• Floating floor applications
• Finishing your flooring
• Fitting Hardwood Doors

Room / Floor Preparation

When installing any hardwood flooring or doors it is important that the conditions within the property are suitable.

• The building must be weather tight
• The heating system must be tested, in working order and switched on if it is the heating season
• Wet trades such as screeding, plastering and any other which may contribute to the moisture in the room must have been completed for at least 2 weeks
• Any concrete screed must have a moisture content of no more than 4%
• The relative humidity of the room should be between 40 and 60%
• The room temperature must be between 16 and 23 degrees celcius
• Any timber sub-floor should be sound and dry

We strongly recommend that the installation of hardwood flooring and/or doors should be one of the final works at your property to avoid any subsequent damage or dirtying of the products whilst other works are being carried out.

Floor nailing applications

Load bearing flooring (i.e. 18mm thick or thicker) can be secret or face nailed to existing / new joists and or battens providing they are dry and sound. Each flooring product on this website has a section detailing whether it is suitable to be fitted onto joists / battens, please look out for this.

Most joists or battens are usually set at 400mm centres or less, a structural engineer can always confirm these details.

These products can also be fitted onto chipboard or existing timber flooring by nailing through to the joists beneath.

Secret nailing involves nailing at a 45-degree angle through the tongue of the flooring, usually this is done using a portanailer gun or similar device. If you are nailing by hand it is recommended pilot holes are drilled before nailing.

A suitable expansion gap should be left around the perimeter of the floor area and under doorframes. On a standard size room, i.e. up to 70 square metres, this is recommended as 15mm.  For larger rooms, please call us for further advice.

Floor gluing applications

This section refers to the gluing of flooring directly to the sub-floor, not gluing the boards for use as a floating floor (see floating floor applications).

Gluing solid floor boarding to sub-floors will always have an element of risk, as when the wood naturally shrinks and expands there is the potential of the glue bond breaking. We have developed the following guidelines to help reduce this risk.

We recommend using Lecol MS250+ adhesive when gluing wooden flooring to sub-floors.

It is essential when gluing to concrete that the concrete sub-floor is in a suitable condition.

• Concrete must be dry - maximum 4% moisture content. If there is significant moisture in the concrete, i.e. the concrete is too fresh or does not have an adequate damp proof membrane (DPM), then gluing is not advisable unless Lecol PU280 DPM is used.
• Concrete must be flat - a deviance of more than +/- 3mm over a 3 metre area is not acceptable and must be levelled using a floor levelling compound.
• Concrete must be of a sound consistency. A good test for this is to score an area of your sub-floor with a screwdriver, if the concrete flakes / cracks this is not acceptable. In this situation the concrete needs to be sanded down to remove the loose material, a new screed is required or plywood can be laid across the sub-floor.

Concrete must be vacuumed to remove any surface dust.

A suitable expansion gap should be left around the perimeter of the floor area and under doorframes. On a standard size room, i.e. up to 70 square metres, this is recommended as 15mm.  For larger rooms, please call us for further advice.

Floating floor applications

A floating floor is when the wooden floorboards are fixed together and not fixed to the sub-floor.

We do not recommend solid hardwood flooring to be laid as a floating floor, due to the risk of movement.

Both Kahrs and Dennebos engineered flooring can be laid as a floating floor on any load-bearing sub-floor that meets our guidelines:

• Concrete
• 18mm+ flooring grade chipboard
• 18mm+ plywood
• Existing timber flooring

Finishing your flooring

Unfinished Flooring

If your flooring is an 'unfinished' product it requires a finish (usually either an oil or a lacquer). Finishing an unfinished floor is a crucial part of its installation, and if you are unsure how to make your floor perfect, always consult a professional tradesman. As a guideline we have the following recommendations:

• The floor must be thoroughly cleaned to remove any dust and dirt using either a vacuum and/or a damp (not wet) cloth
• If necessary the floor can be given a light sand to help remove any undulations / marks in the floor’s surface or if the grain has risen as a result of the cleaning of the floor
• Apply the first coat of oil, or primer if you are lacquering the floor. This may raise the grain of the timber and therefore may require a very light sand with a '00' grade sand paper
• Once this coat has dried, apply any subsequent coats recommended by the finish manufacturers, adhering to their guidelines

Pre-oil / wax oiled floors

We recommend pre-oiled or pre-wax oiled floors are given an extra coat of oil once they have been laid. This tends to help lower the maintenance needed and restores any lustre lost during fitting:

• The floor must be thoroughly cleaned to remove any dust and dirt using either a vacuum and/or a damp (not wet) cloth
• If necessary the floor can be given a light sand to help remove any undulations / marks in the floor’s surface or if the grain has risen as a result of the cleaning of the floor
• Apply the extra coat of oil and allow to dry

Fitting Hardwood Doors

Please ensure the initial guidelines given in the 'Room / Floor Preparation' section are followed.

• These doors are not designed for reducing in size other than for 'industry normal' hanging and fitting tolerances (up to 5mm equally reduced maximum on all sides).
• We strongly recommend that the engineered doors within our ranges are not cut down in width or height beyond these tolerances, nor have glass apertures formed.
• Timber is a hygroscopic material, and if exposed to high humidity or dampness, will absorb moisture which could result in swelling and/or distortion. The doors must only be hung internally, in warm dry conditions, when the ambient temperature of their immediate service surroundings have been established and are stable.
• We recommend 3 no. 75mm brass / chrome butt hinges and brass / chrome screws per door, and that the use of steel ironmongery is avoided, as Oak reacts and stains when in contact with ferrous metals, especially in high humidity and damp situations.
• The doors which are detailed as unfinished are ready to be stained / varnished and this work should be done as soon as possible to reduce the risk of moisture ingress. For internal doors we recommend Osmo Polyx / Wood Wax oils or Danish oils.  Water-based finishes are not recommended.

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