Solid floorboards: a technical compendium of selection and installation

A solid wood floorboard is a floor made from a single piece of natural wood, prized for its durability, its capacity for repeated renovation and its timeless look. Correctly installed and properly cared for, it can serve for several decades while retaining its practical and aesthetic qualities.

The solid wood floorboard is the choice for those who value durability and the natural look of wood. Unlike an engineered floor, solid floorboards are made from a single piece of wood, which allows repeated sanding and gives them a timeless character.

• A solid wood floorboard is an element made from a single piece of wood (European oak, ash, strand-woven bamboo, teak) with a thickness of 15–22 mm, allowing repeated renovation – the number of sanding cycles depends on the board’s thickness and how it is used.

• Durability depends on technical parameters: wood moisture content (7–9%), grading class, installation method (full-surface adhesive bonding) and the choice of finish.

• With underfloor heating, a limited thickness (14–18 mm), control of the surface temperature (max 27–29°C) and a suitable wood species are required.

• A lifespan of 20–80 years with proper use makes solid boards cost-effective over the life of a building, despite the higher initial outlay.

What is a solid wood floorboard in technical terms?

Solid boards are flooring elements made from a single piece of wood through their full thickness, with no glued layers or veneers. A typical oak board measures 20 mm × 140 mm with lengths of 600–2200 mm.

Technical parameters:

• Density: European oak 680–750 kg/m³, strand-woven bamboo above 1000 kg/m³

• Janka hardness: oak 1290–1360, ash 1320–1440, strand-woven bamboo over 3000

• Volumetric shrinkage coefficient: 10–12% with changes in moisture

• Profiling: tongue-and-groove system on the long and short edges, or square-edged boards

With engineered boards, such as the Kaczkan Baltic Seaside engineered oak floor, the wear layer is usually 3–4 mm, which limits the number of renovations. Solid floors offer the full thickness of premium material.

Wood species used in solid boards

The choice of species affects the floor’s stability, its resistance to mechanical damage and the aesthetics of the interior.

European oak – the market standard, with a hardness of 6,5–7 on the Brinell scale. Oak stands out for its dimensional stability (radial shrinkage 5,2%, tangential 10,2%) and is available in Select, Natur and Rustic grades. Solid oak boards are an excellent choice for showpiece rooms.

Ash – an alternative with greater elasticity and an expressive grain pattern. Well suited to modern schemes in industrial and Scandinavian styles.

Strand-woven bamboo – a material of extreme density, exceeding 1000 kg/m³. Resistant to moisture and intensive use, strand-woven bamboo products differ from horizontal and vertical bamboo in their production method.

Exotic species (teak, merbau) – their natural oiliness gives high moisture resistance, but they require compatible oils or lacquers.

Softwood species (pine, spruce) – a Janka hardness of 380–510 makes them prone to scratches and dents. Recommended for bedrooms or a holiday home.

Construction, dimensions and profiling of the solid wood floorboard

The dimensions available from manufacturers allow the board to be matched to the character of the interior and the technical capabilities of the substrate.

Thicknesses:

• 15 mm – the entry level, 3–4 sanding cycles

• 18–20 mm – the standard, 5–7 renovation cycles

• 22 mm – maximum durability

Widths:

• 80–100 mm – classic, more thermally stable

• 120–160 mm – the modern standard

• 180–220 mm – wide boards requiring a substrate with deviations below 2 mm/2 m

Lengths: from 400 mm (short boards) to 2200 mm (showpiece elements). Mixed-length boards (mix length) keep installation waste below 5%.

Profiling: bevelling on 2 or 4 edges (micro-bevel 0,5–1 mm) masks slight differences in height. Relief cuts on the underside (transverse, every 30–50 cm) increase flexibility by 15–20%.

The solid wood floorboard and underfloor heating

Using solid boards over underfloor heating was once a contentious subject, but by 2026 trade practice has clarified the rules.

Technical requirements:

• Maximum surface temperature: 27–29°C

• Wood moisture content: 7–9%

• Screed moisture: below 2% CM (cement) or 0,5% CM (anhydrite)

• Recommended board thickness: 14–18 mm

• Evenness of heating: deviations below 1°C/m²

Denser wood conducts heat more effectively than a light material such as pine. Manufacturers use underside relief cuts and polyurethane adhesives with low moisture emission. It is worth entrusting the installation to an experienced parquet fitter working to a screed heat-up protocol.

Finishing and impregnating the solid board

The finish determines abrasion resistance and gives a natural floor its unique character.

Lacquering:

• Water-borne polyurethane and polyurethane-acrylic lacquers

• 3–7 factory coats (0,1–0,15 mm thick)

• Taber abrasion resistance below 200 mg/1000 cycles

Oiling and hardwax oils:

• Open vapour diffusion, a matt look and natural feel

• Oil renewal every 12–24 months in heavily used zones

Structural treatments: brushing and hand-scraping increase resistance to micro-scratches.

Installing the solid wood floorboard – technical requirements

A natural solid wood floor is most often installed by full-surface adhesive bonding to the substrate.

Substrate requirements:

• Cement screed: strength min. C20/C25, residual moisture below 2% CM

• Anhydrite: moisture below 0,5% CM

• Flatness: tolerance of 2–3 mm over a 2 m straightedge

Choice of adhesive:

• Polyurethane, silane or MS hybrid adhesives

• Avoid adhesives with a high water content

Acclimatisation: store the boards in the destination room for 3–7 days at 18–22°C and 40–60% relative humidity (this may vary by manufacturer).
A perimeter expansion gap of 8–15 mm depends on the width of the board.

Use, care and renovation of solid boards

The lifespan of a solid floor is measured in decades – provided the right climatic conditions are maintained.

Optimal conditions:

• Temperature: 18–24°C

• Air humidity: 40–60%

• Use of humidifiers during the heating season

Surface protection:

• Teflon felt pads under furniture (a 70% reduction in dents)

• Entrance mats

• Pads under furniture legs of min. 4 cm²

We invite you to explore the high-quality products available in our shop – choose a solution that will serve for generations.

FAQ – the most common questions about solid wood floorboards

Installing the solid wood floorboard – technical requirements

A natural solid wood floor is most often installed by full-surface adhesive bonding to the substrate.

Substrate requirements:

• Cement screed: strength min. C20/C25, residual moisture below 2% CM

• Anhydrite: moisture below 0,5% CM

• Flatness: tolerance of 2–3 mm over a 2 m straightedge

Choice of adhesive:

• Polyurethane, silane or MS hybrid adhesives

• Avoid adhesives with a high water content

Acclimatisation: store the boards in the destination room for 3–7 days at 18–22°C and 40–60% relative humidity (this may vary by manufacturer).
A perimeter expansion gap of 8–15 mm depends on the width of the board.

Use, care and renovation of solid boards

The lifespan of a solid floor is measured in decades – provided the right climatic conditions are maintained.

Optimal conditions:

• Temperature: 18–24°C

• Air humidity: 40–60%

• Use of humidifiers during the heating season

Surface protection:

• Teflon felt pads under furniture (a 70% reduction in dents)

• Entrance mats

• Pads under furniture legs of min. 4 cm²

We invite you to explore the high-quality products available in our shop – choose a solution that will serve for generations.

FAQ – the most common questions about solid wood floorboards

Will a solid wood floorboard work in a small flat in a block?

In flats of 40–60 m², solid boards are feasible provided humidity remains stable throughout the year. Widths of 120–150 mm in oak or ash are recommended. The quality of the screed, correct expansion gaps and acoustic insulation between storeys are all important.

Is a solid wood board suitable for a bathroom or kitchen?

In bathrooms with sharp swings in humidity, tiles or vinyl are the better option. In the kitchen, solid floors require hard-wearing lacquers and protection of the sink area.

Can solid boards be combined with other flooring materials?

Combining them with tiles, stone or vinyl requires the layer heights to be levelled. Transition profiles and flexible sealants are used at the junctions, allowing the wood to move naturally. In areas exposed to water, careful sealing is essential.