What Is Solid Wood Flooring? The Complete Guide
What is solid wood flooring? Solid wood flooring is made of boards cut from a single piece of hardwood, usually oak, so every board is real timber all the way through. It is warm, quiet and long-lasting, and it can be sanded back and refinished many times over its life, but because it is natural timber it moves with heat and humidity, so it suits rooms with a steady climate.
Solid wood flooring at a glance
| What it is | Boards cut from one piece of hardwood, with a tongue and groove (or click) joint |
|---|---|
| Common thicknesses | 15mm to 20mm, most often 18mm or 20mm |
| Sanding | Can be sanded and refinished many times |
| Rooms | Living rooms, dining rooms, bedrooms, studies, hallways; not bathrooms, conservatories or damp basements |
| Underfloor heating | Only boards approved for it; engineered wood is usually the better choice |
| Fitting | Secret nailed to joists or a timber subfloor, or glued to a dry, level screed |
| Life | Decades, often generations, with care and refinishing |
How solid wood flooring is made
Each board is sawn from a log, dried in a kiln to the right moisture content, then machined to size with a tongue on one edge and a groove on the other so the boards lock together. Most are finished in the factory with lacquer or oil; some are left unfinished to be sanded and finished on site.
The useful wood is everything above the tongue. Each time the floor is sanded, a little of it is removed, and because a solid board has far more wood above the tongue than the top layer of most engineered boards, it can be refinished more times.
Solid and engineered floors look the same once laid. The difference is underneath: engineered boards have a real wood top layer on a cross-laid core that moves much less. Our engineered wood flooring guide and solid vs engineered wood flooring explain when each is the better choice.
Why solid wood moves, and what that means
Wood takes in moisture from the air when it is humid and gives it out when it is dry. A solid board swells and shrinks across its width as it does so. In practice:
- Small gaps in winter are normal. Central heating dries the air, the boards shrink a little and fine gaps open between them; they close again in the more humid summer months.
- Too much moisture makes boards cup (edges higher than the middle) or, at worst, lift. Damp subfloors, leaks and steam are the usual causes.
- Wider boards move more than narrow ones, so wide solid planks need the most stable conditions.
- A steady room of about 18 to 24°C with normal humidity (roughly 40% to 60%) keeps a solid floor at its best.
This is why solid wood is fitted with an expansion gap at every wall, and why engineered wood is recommended for underfloor heating, kitchens, conservatories and concrete floors.
Your options: species, grade, finish and size
Wood species
- Oak: the UK’s favourite hardwood, strong and hard-wearing, with a clear grain that takes stains and finishes well.
- Walnut: naturally dark and rich, a little softer than oak.
- Ash: pale with a bold grain and good strength.
- Maple: very light, smooth and hard.
Our article on the most durable wood flooring compares species by hardness.
Grade
Grade is about appearance, not strength: prime boards have few small knots and an even colour; select and natural grades allow some knots and colour change; rustic grades show larger knots, filled splits and plenty of character. See wood flooring grades explained.
Finish
- Lacquered: a protective film, from matt to satin; the easiest to clean.
- Oiled: a natural, low-sheen look; worn areas can be re-oiled locally.
- Hand-scraped and brushed: textured surfaces that bring out the grain and hide everyday marks.
- Unfinished: sanded, stained if you like, and sealed after fitting for a flush surface and the exact colour you want. See unfinished hardwood floors.
Colour
From light and natural oak to grey, white-washed, dark and black. All real wood mellows and changes colour with light over time, so expect a new floor to warm up in its first months.
Thickness and width
| Choice | What it means |
|---|---|
| 15mm | Lower floor height; less wood to sand |
| 18mm to 20mm | The standard: strong enough to span joists, plenty of wood above the tongue |
| Narrow boards (about 90mm to 130mm) | Traditional look; move least with the seasons |
| Wide boards (180mm and more) | Show off the grain; need the most stable room conditions |
Where you can use solid wood flooring
| Room | Suitable? | Tips |
|---|---|---|
| Living room, dining room, bedroom, study | Yes, ideal | Felt pads under furniture |
| Hallway | Yes | Lacquered or brushed finish; mats at the door |
| Stairs | Yes | See solid wood flooring on stairs; matching stair nosings |
| Kitchen | Possible with care | Steam and spills make engineered wood or luxury vinyl the more practical choice |
| Conservatory | Not recommended | Big swings in heat and humidity; choose engineered wood |
| Bathroom, basement | No | Choose luxury vinyl |
Solid wood and underfloor heating
Solid wood is not usually the right floor for underfloor heating: the heat dries the boards, which shrink and gap. Some narrower solid boards are approved for it, and then the heating must be brought up slowly and the floor kept below 27°C at the surface. If you have, or plan, underfloor heating, choose a board approved for it or go for engineered wood for underfloor heating, which gives the same real wood surface.
How solid wood flooring is fitted
| Method | How it works | Subfloor |
|---|---|---|
| Secret nailing | Nails are fired at an angle through the tongue so they are hidden by the next board | Timber joists, floorboards or plywood |
| Full bond gluing | Boards are bedded in a flexible wood floor adhesive | Dry, level screed or concrete (moisture-tested) |
| Floating | Click solid boards over an underlay, only where the product allows it | Level, dry subfloors; see floating hardwood over concrete |
Before you start
- Measure and order: add 5% to 10% for cutting waste; our measuring guide shows how.
- Check for damp: new screed and plaster must be fully dry; concrete must be moisture-tested and protected with a damp proof membrane where needed.
- Acclimatise: leave the unopened packs in the room for a few days (at least 72 hours, or as the instructions say) at normal living conditions.
- Check the joists: boards laid across joists must be thick enough for the spacing; 18mm or 20mm boards are usual.
While you fit
- Leave an expansion gap of around 10 to 15mm at every wall and fixed object, covered by skirting or scotia beading.
- Lay boards at right angles to the joists and mix boards from several packs.
- Stagger the end joints well apart from row to row.
Solid wood is best laid by an experienced fitter. For the steps, see how to lay solid wood flooring and our flooring installation guides.
Caring for solid wood flooring
- Sweep or vacuum to remove grit, and put mats at every outside door.
- Clean with a well-wrung microfibre mop and a pH-neutral wood floor cleaner; never a steam mop or a wet floor.
- Felt pads under chairs and table legs; lift furniture rather than drag it.
- Keep the room at a steady temperature and humidity; a humidifier helps in very dry winters.
- Oiled floors need an occasional coat of maintenance oil; lacquered floors can be re-coated when they look tired.
- When the whole floor is worn, it can be sanded back to fresh wood and refinished, even stained a new colour. That is the great advantage of solid wood.
Solid wood compared with other floors
| Solid wood | Engineered wood | Laminate | Luxury vinyl | |
|---|---|---|---|---|
| Surface | Real wood | Real wood | Printed design | Printed design |
| Real wood all through | Yes | Top layer only | No | No |
| Can be sanded | Many times | Depends on the wear layer | No | No |
| Stability | Moves with humidity | Very stable | Stable | Very stable |
| Underfloor heating | Only approved boards | Most boards | Most boards | Most products |
| Wet rooms | No | No | No | Yes |
More detail: engineered vs hardwood flooring and types of wood flooring.
Pros and cons of solid wood flooring
| Pros | Cons |
|---|---|
| Real timber all the way through | Moves with heat and humidity; gaps in dry winters |
| Can be sanded and refinished many times; lasts generations | Not for bathrooms or conservatories, and limited with underfloor heating |
| Warm, quiet and solid underfoot | Usually fitted by a professional, by nailing or gluing |
| Ages beautifully and suits period homes | Can dent and scratch, like any real wood |
How to choose your solid wood floor
- Check the room is right for solid wood: steady temperature and humidity, no underfloor heating (unless the board is approved), and a suitable subfloor.
- Choose the species and grade for the look you want.
- Choose the thickness and width: 18mm or 20mm; narrower boards for stability, wider for drama.
- Choose the finish for how you live: lacquer for easy cleaning, oil for a natural look and local repairs.
- Plan the fitting and the adhesive, trims and nosings you need (see our accessories guide).
- Order free samples and look at them in the room in daylight and lamplight before you decide.
Browse all our solid wood flooring, or request a callback for help choosing.
Frequently asked questions
Almost always, yes. "Hardwood" means wood from broadleaf trees such as oak, walnut, ash and maple, and solid wood floors are made from hardwoods. People also say "hardwood flooring" for engineered wood, which has a hardwood top layer, so check whether a floor is solid all the way through.
Central heating dries the air, so the boards give out moisture and shrink slightly across their width, opening fine gaps. They close again as humidity rises in spring and summer. Keeping the room at a steady temperature, and using a humidifier in very dry weather, keeps the gaps small.
Usually several times over its life, often four or more, depending on how much wood there is above the tongue and how much each sanding removes. That is why a well-kept solid floor can last for generations.
Glued solid floors do not use one. Nailed floors do not need a standard underlay, though a thin acoustic or building paper layer is sometimes laid beneath them. Floating click solid boards, where the product allows floating, need an underlay suited to wood floors.
Yes, if the concrete is dry, level and moisture-tested. The usual method is to glue the boards to the screed with a flexible wood floor adhesive, with a suitable damp proof treatment where needed. Over concrete with underfloor heating, engineered wood is the safer choice.
Yes. Treads are cut and fixed to each step, usually with a matching stair nosing on the front edge. See solid wood flooring on stairs.
Yes. Sanding takes the floor back to bare wood, which can then be stained, treated and finished in a new colour. It is one of the biggest advantages of solid wood over laminate and vinyl.
Solid boards with a click joint instead of a plain tongue and groove, so they lock together and can sometimes float over an underlay where the product allows it. See click solid wood flooring.
It is possible for an experienced DIYer, but solid wood is usually best laid by a professional: nailing and gluing need the right tools, and the subfloor, moisture and expansion gaps must be right for the floor to last.
It is real wood, so it can scratch and dent, especially softer species and glossy finishes. Oak with a matt lacquer, a brushed surface or a rustic grade hides marks best, and a worn floor can always be sanded and refinished.
Leave the unopened packs in the room for a few days, at least 72 hours or as the instructions say, at normal living temperature and humidity, after any new plaster or screed has fully dried.
A solid wood floor nailed or glued down feels and sounds solid. Noise problems usually come from a floor that is not properly fixed or from movement in old joists; fixing those first, and felt pads under furniture, keep it quiet.
