Basic Fitting Guide For Pre-Finished and Unfinished

Installer and Owner Responsibility

Solid wood floors are a natural product. Allow for a grading tolerance of 5–10% when estimating quantities.
Complete all wet work — plastering, cement work and decorating — and let everything dry fully before you bring the flooring on site.
Do not install solid hardwood below ground level or in bathrooms.
Cut out boards with obvious defects. Use stain, putty or filler stick for minor corrections — this is standard practice.
For unfinished flooring, spot or trowel fill before sanding. We recommend Junckers Prefill mixed with sanding flour.
For pre-oiled flooring, hand sand with 120-grit or finer and apply a light finishing coat of oil with a cloth after installation.
For flooring finished with a stained lacquer (wenge, walnut, white etc.), apply two coats of clear lacquer immediately after installation.
Store the flooring in the installation area for approximately one week to acclimatise. Time varies by product and species.
Manufacturers allow a ±2% dimension tolerance.
We recommend secret nailing to a plywood subfloor as best practice.
Once you install the boards, you and the owner accept the product.

Check the subfloor is in good condition. Repair any bouncy, squeaky or uneven areas before you start.
18mm plywood, solid wood or battens hold portanails better than MDF or chipboard.
Run the flooring the length of the room where possible. If laying over existing floorboards, install at right angles to them. Otherwise, fit plywood first so you can change direction.
A solid perpendicular subfloor makes the finished floor stiffer and less prone to joint separation.

We recommend Timbermate Excel as a vapour and acoustic barrier between the subfloor and the finish floor.
It controls dust and moisture from below, dampens squeaks and reduces noise transfer.
Builders paper or roofing felt also works well — staple it directly to the floor.
Lay polythene sheeting over any exposed soil beneath the subfloor to reduce vapour transmission.

Find the centre point between the two walls at each end of the room.
Snap a chalk line between the two points — this is your baseline.
You do not have to start laying from the baseline. Wherever you start, keep your boards parallel to it.

Fitting from the wall is the easiest method for most rooms.

Remove skirting boards. Cut door linings and architrave using a scrap piece of flooring as a guide.
If you leave skirting in place, use scotia or quadrant to cover the expansion gap around all edges.
Set a chalk line parallel to the longest outside wall, leaving at least 13–20mm expansion gap. Use spacers to hold it.
In large rooms, starting from the centre means the floor expands outward from the middle rather than pushing against one wall.
Use long lengths for the first rows. Hand-nail the first two rows — the portanailer needs more room to operate.
Place the first row along the chalk line. Pre-drill holes before hand nailing.
Nail through the tongues with finishing nails and punch them flush. Coloured putty or filler hides nail holes if needed.
Always work from at least 3 cartons simultaneously. Rack the floor out ahead of you in a balanced pattern.
Minor width variation is normal during acclimatisation. UK flooring typically gains 1–2% moisture, adding 1–2mm to the width.
If you find small width tolerances from milling or acclimatisation, sort boards into groups of equal width.

Fix subsequent rows with a portanailer.
Hand-nail the last two or three rows — the portanailer will not fit near the wall.
Fix skirting boards or scotia to cover the expansion gap. Always fix to the wall, never to the floor.

Keep these rules in mind throughout the installation.

Space secret nails at 6–8 inch (240–320mm) intervals. Use narrower spacing for wider boards or planks.
Boards over 150mm wide also need face nailing, or screwing and plugging.
We recommend a portanailer for all nailing work.
Wood flooring expands mainly across its width (across the grain). Length movement is minimal. The wider the board, the more it expands and contracts.
Always stagger end joints by mixing strip lengths. Never align joints in the same area.
You can lay T&G flooring straight over joists, but 12mm or 18mm ply gives a much better platform.
End-matched T&G boards (T&G all round) do not need to finish on a joist. The surrounding lengths lock them stable.
Wider boards may need additional support. Space joists or battens at 250–350mm centres.

Higher grades typically mean longer lengths and less colour variation.
Traditional grades show more and larger knots and surface features — even in pre-finished flooring.
Always add 5% for grading tolerance and cutting waste before you order.
Most hardwood flooring comes in random lengths: approximately 300mm–1,400mm. Check the manufacturer’s specification.
Unfinished flooring comes in strapped bundles. Pre-finished comes in cardboard cartons.
If you find a warped piece, force it into position with a wedge. Nail part A first, then tap part B until the board sits flush.

Always use a moisture meter before installation.
The moisture content of the new flooring must be within 2–3% of the subfloor.
On concrete: tape a 400mm square of polythene to the floor. After 24 hours, bubbles or condensation under it indicate high moisture.
An acceptable moisture level on a concrete floor is below 5%.

Concrete moisture does not measure directly against timber. Follow these guidelines carefully.

BS 8021:1987 sets a maximum of 75% relative humidity or 5% moisture content (use a humidity box to measure). We recommend 35–40% RH or 2–3% moisture content as the ideal target.
Concrete slabs dry slowly — allow roughly 1 day per 1mm of slab depth (1 month per inch).
If the slab is too wet, apply a surface DPM: polythene sheeting under 18mm ply, or a paint-on type where you bond the flooring directly. Check that adhesive and DPM are compatible.
You can bond solid hardwood directly to dry concrete using a specialist adhesive such as Rewmar, applied by trowel.
Alternatively, use battens (250–350mm centres) or 18mm plywood sheets as a secret-nailing platform.
Another method: cut 12mm plywood into 50–75mm strips at 250–350mm centres and secret-nail using a portanailer with a special shoe adapter and 1½-inch portanails.
All concrete slabs must incorporate a DPM. Confirm the slab is completely dry before you lay any flooring.

Record all moisture and humidity readings before and during installation. Keep them for any future manufacturer or warranty enquiry.
These instructions are a guide only. Always consult the manufacturer’s fitting details for your specific product.
Maintain environmental humidity at 35–55% during and after installation. Use humidifiers or dehumidifiers to limit seasonal movement.
Always refer to BS 8201, the British Standard for fitting hardwood floors.