Installation of Solid flooring

Note these are only guidelines for installation. However we highly recommend you read them and adhere to the advice contained herein.

Site conditions

Storage conditions are extremely important, as the flooring can soak up any moisture that is present if stored situations of high levels of moisture and humidity. Always check the moisture content of the place of storage prior to installation.

The correct site conditions required before a delivery of the solid wood flooring are: -

• The building must be weather proof - warm and dry i.e. normal living conditions.
• New build or renovations must be thoroughly dried out and heated before installation.
• All masonry, plaster and concrete floor slabs must be thoroughly dry.
• Relative humidity of the air to be 35% - 50%
• Temperature to be 15 - 25oC

Once the above site conditions are correct and can be maintained the flooring can be delivered to the site of installation. The packs of flooring should then be laid horizontally on the floor in the centre the room with the packaging in tact for a minimum of 48 hours, ideally longer if possible before installation.

Preparation before installation

The aforementioned site conditions should be maintained

If the room cannot achieve these levels consistently, we can only suggest you install a humidifier at your own discretion. All walls and sub-floors must be checked for humidity, if they fall below the required criteria, you must not install the flooring.
We will not accept any claims due to movement if the correct moisture reading has not been recorded prior to installation. Moisture is the biggest factor of movement in solid flooring and if the above instructions are strictly not adhered to, the flooring will take on the moisture and subsequently cause the flooring to expand rapidly.

Basic rules to double check

1. Room temperature 15ºC - 25ºC
2. Sub-floor 2% moisture content - and recorded
3. Ideally a relative humidity level in room 35%-60% at time of laying - and recorded.
4. All windows and doors to be fitted/watertight.
5. All wet trades should be finished.
6. All heating/air conditioning systems commissioned and operating (in the case of under floor heating see the appropriate section)
7. Sub-floor to be level as indicated below.

Sub-floors

Concrete - The concrete sub-floor must be extremely dry and if the floor has been recently screeded, it is very important you wait until the correct humidity level has been reached, check using a hydrometer. The correct moisture content level should not exceed 2%, which equates to a maximum relative humidity in the concrete of 35% to 60%. The concrete slab must contain an effective damp proof membrane. In reality it is difficult to achieve 35% RH in the slab and in these cases a D.P.M. must be used over the slab.

The sub-floor must also be extremely level, to within 3mm on a 3M straight edge according to British Standards. Any variation greater must be re-addressed and re-levelled, by screeding / self-levelling compound.

Both the self-levelling compound and D.P.M. systems are available from specialist manufactures or the supplier of your floor

Installation

A note of caution whilst fitting

Timber is a natural material with naturally varying characteristics i.e. Colour, Texture and Grain pattern. These variations are what give timber its aesthetic appeal they do however mean that it is entirely possible that up to 5% of the product may not be useable for its intended purpose.

It is the sole responsibility of the installer not to install any material thought to be defective. No claim shall be entertained for any materials installed, which have visible defects or damage prior to installation of the boards. We will also not be responsible for damages due to installation, transportation or storage.

Methods of installation

We strongly advise solid timber floors should either be nailed or glued directly to the sub-floor.

Glue directly to sub-floor - Glue usage is usually 1kg adhesive to m2. The adhesive is spread over the sub-floor and the boards are stuck directly to the sub-floor.

All manufacturers’ glues vary and it is the discretion of the end user to see the manufacturer’s guidelines when sticking down the sub-floor. Glue guns and glue beads vary, so it is important that detailed instructions should be in accordance with specific manufacturer’s instructions.

Secret nailing to battens - Timber battens should be kiln dried at the maximum moisture content of 14%. They should be placed at intervals of no more than 300mm apart.

One method is to lay the first row of boards 15mm from the longest, straightest wall. The boards must follow the line of the wall. If the wall is not straight, you must use the first board(s) to scribe the shape and create your own straight line.

Another method is to find the centre line down the middle of the room for aesthetic appearance this could be along the length of the room and working away from the centre with the leading

tongues of the flooring towards the walls. The use of a loose tongue to form a connection between the two central boards can be made with a strip of 6mm plywood. Measure and off set slightly from the centre line, if required, so that the final boards nearest to the wall are large enough to still allow suitable fixing.

Secret nailing can be best achieved with a portable nailer at 45% through the tongue. It is important no adjacent end or butt joints are within 150mm (or 2 times the width which ever the greater) of each other when laying on battens or joists. Ensure expansion gaps are maintained on all perimeters to allow for expansion. See expansion gaps.

Expansion gaps and expected movement in timber floors

Perimeter Expansion Gaps
By whatever method you have used to install the floor, it is imperative all floors must have expansion gaps of at least 15mm around the entire perimeter of the floor.

For Solid floors in particular, we suggest the expansion gap is modified by additional provision for rooms over 3m wide. Adding an extra 3mm per metre each side for every metre over 3m that is fitted. This is only necessary in the width as solid will not expand or contract to any notable degree in the length.

Expansion Breaks
For large areas, expansion breaks are advisable to allow the natural movement of a timber floor which occurs in most buildings due to the humidity changes between winter and summer.

• If the flooring is engineered and floated we recommend introducing an expansion break if the room exceeds 12m in the length of the room, and at 8m in the width of the room.
• If the flooring is engineered and fully stuck down then there is little or no limit.
• If the flooring is solid and it is in a modern well insulated property then the flooring could go up to 6m in the width without the need for intermediate expansion.
• If the flooring is solid and the building is of an older style with poor insulation, particular care is needed as bigger changes in humidity between the seasons of summer and winter can occur. Intermediate expansion should be introduced above 3m in width.

An intermediate expansion can be by either of two methods:

1. In between boards at about 800mm centres across the width should be made these can be in the form of 2mm packers. Visible lines will be noticeable every 800mm but this has to be explained to the end user as a necessary precaution.
2. Between every board by the use of 0.3mm packers.

Expansion gaps should be made at the junctions of doorways to create a break between rooms. This not only prevents large area expansion problems, but also relieves uneven stresses which can be caused by the differential movement in different rooms.

Use temporary wedges to ensure this expansion gap is maintained not forgetting to apply this also to any fixed object for example fire surrounds pillars especially including radiator pipes.

Without this precaution the floor will move and have nowhere to go. This will cause extreme levels of pushing upwards and outwards, thus lifting the flooring up. Also, walls may be affected and all manner of problems will occur.

All solid floors will move a certain amount even under correct installation. It is normal to expect

during certain times of the year, as different levels of humidity occur, that the width joint between boards will open and close. Note of course that wider boards will cause wider gaps and narrower boards will cause more but smaller gaps.

In warmer weather windows tend to be open and humidity will increase thus causing the flooring to absorb the increased moisture, this will cause the flooring joints to become tighter and close up. In winter months, the heating will raise the temperature to be comfortable, this will dry out the floor thus making the boards shrink slightly, and consequently the joints between the boards will increase. The cycle will repeat over the years, but if fitted correctly, will only expand and contract within the allowed tolerances.