20mm Engineered Wood Flooring
20mm is the thickest engineered wood board on the market and the specification for buyers who want the most substantial floor money can buy. It carries a 6mm real oak wear layer, double the 3mm found on a standard premium board, which gives it the greatest refinishing potential of any engineered floor. A 20mm floor is a genuine forever floor: laid once, sanded and re-finished many times over, it can outlast the room around it.
20mm is offered selectively across GF by Grosvenor Flooring, our own-brand oak range with online checkout and free samples and V4 Wood Flooring, most often in wide-board plank collections. Browse the 20mm collection below or order up to 5 free GF samples.
What 20mm Engineered Wood Means
Two numbers describe any engineered board and it is easy to confuse them. The first is the total thickness of the board, in this case 20mm. The second is the thickness of the real oak wear layer bonded to the top, which on a 20mm board is typically 6mm. So you may see a 20mm floor written as 20/6, meaning a 20mm board with a 6mm oak wear layer over a stable multi-ply core. The wear layer is the number that matters most, because it governs how many times the floor can be sanded and re-finished over its life. A 6mm layer allows four or more sandings, roughly double a standard 14mm board, which is what earns a 20mm floor the forever-floor reputation.
14mm vs 15mm vs 20mm
Thickness is mostly about the wear layer and the feel of the board underfoot, not the durability of the surface day to day. The table below sets out the common profiles so you can see where 20mm sits.
| Total thickness | Typical oak wear layer | Feel and use |
|---|---|---|
| 9mm to 11mm | 2mm to 3mm | Slim boards and click formats; fewer sandings, tighter budgets |
| 14mm to 15mm | 3mm | The standard premium spec: substantial board, sand two to three times |
| 20mm | 6mm | The thickest, most substantial board: four or more sandings, a forever floor |
Most projects are well served by 14mm or 15mm. Step up to 20mm when you want the maximum refinishing life, the heaviest board feel underfoot or a floor you intend never to replace. Our engineered wood flooring thickness guide covers the full picture.
Is 20mm Solid or Engineered?
Engineered. A 20mm engineered board is a 6mm real oak wear layer bonded to a stable multi-ply core, not a solid piece of oak. Because the wear layer is so thick, a 20mm engineered floor gives you almost everything a solid board would, the same deep sanding potential and the same weight underfoot, but with the stability of an engineered core. That stability is why 20mm engineered works over underfloor heating and in centrally heated homes where a solid 20mm board would move too much across its width.
Fitting a 20mm Floor
20mm sits on a multi-ply core and can be floated, glued or secret-nailed over a properly prepared subfloor. Because it is the thickest profile, it is worth checking door and threshold clearances early: with a thin underlay the finished height is around 21mm to 22mm, so internal doors may need trimming. It is fully compatible with both wet and electric underfloor heating up to a maximum surface temperature of 27C, though a thicker board conducts heat a little more slowly than a thinner one. Acclimatise the boards in the room for at least 48 hours before installation and follow the supplied fitting instructions.
The 20mm Ranges We Stock
20mm is a selective specification rather than a full range. It appears most often in V4’s wide-board plank collections such as V4 Alpine and V4 Tundra and in selected GF plank ranges. GF is available to buy online with full pricing and free samples; V4 is sold on a Request a Price basis.
Where to Use 20mm
20mm suits any dry room and is most often specified in whole-house projects and higher-end refurbishments, across lounges, dining rooms and hallways. As with all engineered wood it is not suitable for bathrooms or wet rooms.
Key Takeaways
- 20mm is the thickest engineered wood board: a real oak board with a 6mm wear layer on a stable multi-ply core, often written as 20/6.
- The 6mm wear layer can be sanded and re-finished four or more times, roughly double a 14mm board, making 20mm a true forever floor.
- 20mm is not solid wood: it is a 6mm oak surface on a multi-ply core, which is what lets it work over underfloor heating where a solid 20mm board would move.
- It works over underfloor heating up to 27C, but check door clearances early because the finished height is around 21mm to 22mm.
- 20mm is a selective specification, most often found in V4 wide-board plank collections and selected GF plank ranges; choose it over 14mm when you want the maximum refinishing life and the heaviest board feel.
Explore Related Categories
- Other thicknesses: 9mm, 10mm, 11mm, 14mm or 15mm.
- By format: plank, herringbone or parquet.
- By colour: natural, light, grey or dark.
- Brands: GF own-brand or V4 Wood Flooring.
How to Buy or Get a Quote
For GF: every 20mm floor is available to buy online with full pricing, free samples and UK delivery, backed by a 25-year residential guarantee. You can see the collection on full-size display at our 24/7 Altrincham Smart Showroom or preview a floor in your room with our free AI room visualiser and supply and fit is available across the North West. For V4: sold on a Request a Price basis. Get in touch via our enquiry form, WhatsApp or phone and we will come back the same working day with a tailored, competitive price.
Frequently Asked Questions
What does 20mm engineered wood flooring mean?
20mm is the total thickness of the board. On a 20mm engineered floor the top layer is real oak, typically 6mm thick, bonded to a stable multi-ply core, so you may see it written as 20/6. The 6mm oak wear layer is the number that matters most, because it sets how many times the floor can be sanded and re-finished and 6mm is the thickest available.
Is 20mm engineered wood worth it over 14mm?
It depends on your priorities. 20mm gives you a 6mm wear layer, roughly double the sandings of a 14mm board and a heavier feel underfoot. For most homes 14mm is more than enough. Choose 20mm when you want the maximum refinishing life and a floor you never intend to replace.
How many times can a 20mm floor be sanded?
A 20mm board with a 6mm wear layer can typically be sanded and re-finished four or more times. That is roughly double a standard 14mm board and is the main reason a 20mm floor is described as a forever floor.
Is 20mm engineered wood the same as solid oak?
No. A 20mm engineered board has a 6mm real oak wear layer on a stable multi-ply core. A 20mm solid board is a single piece of oak, which moves more with heat and humidity and is not recommended over underfloor heating. Engineered gives you the same deep sanding potential and weight with far better stability.
Will a 20mm floor fit under my doors?
Check early. 20mm is the thickest profile, so with a thin underlay the finished height is around 21mm to 22mm. Internal doors and thresholds may need trimming to clear it. Measure against your own doors before ordering so there are no surprises on fitting day.
Which ranges come in 20mm?
20mm is a selective specification rather than a full range. It appears most often in V4's wide-board plank collections such as Alpine and Tundra, sold on a Request a Price basis and in selected GF plank ranges, available to buy online with free samples. Both can be supplied and fitted across the North West.
