# European oak

> European oak is the timber of two closely related species, Quercus robur and Q. petraea, and it is among the important parquet woods in forest-science guidance. It is a medium-hard, fairly dense wood whose tannins give it durability but also make it react with iron and respond strongly to fuming. How it behaves on a floor depends mainly on how it is sawn, dried and acclimatised.

Source page: https://www.misterendgrain.com/species/european-oak/
Updated: 2026-11-03

| Fact | Value |
|---|---|
| Scientific name | Quercus robur (pedunculate or English oak) and Quercus petraea (sessile oak) [3] |
| Janka hardness | 1,120 lbf (4,980 N), Q. robur [1] |
| Density | 675 kg/m³ (42 lbs/ft³) average dried weight, Q. robur [1] |
| Density, second source | Specific gravity 0.74 at 12 % moisture content, mature wood of both species [3] |
| Origin | Europe and parts of western Asia (Q. robur) [4] |
| Shrinkage, green to dry | Radial 4.7 %, tangential 8.4 %, volumetric 13.0 % (Q. robur) [1] |
| Conservation status | IUCN: least concern; not listed in the CITES Appendices [1] |

European oak is the timber of two closely related species, *Quercus robur* (pedunculate or English oak) and *Quercus petraea* (sessile oak), which CIRAD's oak datasheet treats together [3]. On the Janka scale The Wood Database gives English oak 1,120 lbf (4,980 N) [1], which makes it a medium-hard floor timber rather than an especially hard one. Its character as a flooring wood comes less from hardness than from its tannins, its moderate-to-high shrinkage and how carefully it has been dried.

## What is European oak, and where does it grow?

Both species are native to Europe. EUFORGEN describes pedunculate oak as native to Europe and parts of western Asia, and as a tree of fertile, well-watered soils in lowland forests [4]. Sessile oak is described as native to most of Europe and often found in upland areas on well-drained soils [5]. The Wood Database gives the range of English oak as most of Europe, to Asia Minor and North Africa [1].

The two species are close: EUFORGEN reports that natural hybrids occur frequently where they overlap [5], and forest-science guidance from waldwissen.net says the timbers cannot be reliably separated by their wood features alone, although sessile oak tends towards a milder wood [6]. Local trade names include *chêne* (France), *Eiche* (Germany), *quercia* (Italy) and *roble* (Spain) [3].

## How hard and how dense is European oak?

The Wood Database lists an average dried weight of 675 kg/m³ and a specific gravity of 0.53 (basic) and 0.67 (at 12 % moisture content) for English oak [1]. CIRAD gives a higher specific gravity of 0.74 at 12 % moisture content for mature wood of both species, and notes that properties can vary significantly with origin and growing conditions [3]. Both sources are given here because they differ.

For hardness, The Wood Database figure is 1,120 lbf (4,980 N) [1]. CIRAD instead reports the Monnin scale, with an average of 4.2 [3]. If you are comparing species, American white oak is listed by The Wood Database at 1,350 lbf (5,990 N) [2]. Our guide to [Janka hardness](https://www.misterendgrain.com/guides/janka-hardness-explained/) explains how to read these numbers and why they say little about how a floor looks after years of wear.

## How does European oak move with humidity?

All timber changes size as it gains or loses moisture below its fibre saturation point. The USDA Forest Products Laboratory notes that wood shrinks most along the growth rings (tangentially), about half as much across them (radially), and only slightly along the grain, and that the result can include gaps in flooring [8]. The same chapter advises using tangential values to estimate the width change of plain-sawn boards and radial values for quarter-sawn boards [8].

Two published sets of figures for European oak differ slightly:

| Source | Radial | Tangential | Other |
|---|---|---|---|
| The Wood Database (*Q. robur*) | 4.7 % | 8.4 % | volumetric 13.0 %, T/R ratio 1.8 [1] |
| CIRAD (both species) | 4.5 % | 9.7 % | T/R ratio 2.2, fibre saturation point 31 % [3] |

Waldwissen.net adds that the tangential-to-radial ratio of oak is less favourable than that of beech, ash, spruce or pine, and that narrower annual rings give better shrinkage behaviour [6]. CIRAD rates oak as slow to dry, with a high risk of distortion and checking, so the quality of kiln drying matters [3]. In practice that means conditioning boards to the room before fitting, which we cover in [moisture and acclimatisation](https://www.misterendgrain.com/guides/moisture-and-acclimatisation/). Our page on [engineered wood](https://www.misterendgrain.com/flooring/engineered-wood/) covers how layered construction changes this.

## What does European oak look like?

The Wood Database describes the heartwood as light to medium brown, often with an olive cast, and the sapwood as nearly white to light brown and not sharply separated from the heartwood. Quarter-sawn faces show prominent ray fleck; the grain is straight with a coarse, uneven texture, and may be irregular or interlocked [1]. CIRAD, by contrast, describes the sapwood as clearly demarcated and the colour as light brown to straw, darkening with light, with texture ranging from fine to coarse depending on origin [3]. Treat the sapwood contrast as something that varies by log and supplier.

## Why do tannins matter for oak floors?

CIRAD links oak's natural durability to water-soluble tannins, and warns that tannins can cause smudges if the wood is not well dried, is machined in an unprotected area, or has no protective finish. It also advises care with gluing, because the wood is dense, slightly acid, rich in tannins and prone to staining [3]. Waldwissen.net notes that fresh oak contains on average 6 % tannin in the wood, and that iron reacting with these compounds produces blue-grey to black discolouration [6]. The Wood Database makes the same point about wet oak and iron [1]. Keep steel wool, damp fixings and spilt water away from bare oak, and see our guide to [floor finishes](https://www.misterendgrain.com/guides/wood-floor-finishes/) for how coatings change that risk.

The same chemistry underlies ammonia fuming. A peer-reviewed study fumed heartwood samples of *Quercus robur*, maple, spruce and larch for up to 16 days; oak reacted intensively in a very short time, had the highest initial tannin content, and lost the most tannin during fuming [7]. The authors also note that fuming is frequently used on furniture and flooring [7].

## Where is European oak used in floors?

CIRAD lists flooring among the end uses of oak, alongside cabinetwork, cooperage, joinery and stairs [3]. Waldwissen.net calls oak one of the most important parquet woods and well suited to parquet and plank floors [6]. Oak is cut into several formats, including [herringbone](https://www.misterendgrain.com/flooring/herringbone/) and other patterns, wide boards and end-grain blocks.

End grain shows oak differently: the [Cube collection from OscarOno Paris](https://www.oscarono.fr/collections/cube) sets square blocks of European oak side by side in an open, even grid, built as 10 mm birch plywood with a 6 mm oak top layer and offered in Natural, Smoke and Black (shou sugi ban) finishes [10]. Our page on [end-grain flooring](https://www.misterendgrain.com/flooring/end-grain/) explains how that format differs from plank construction.

## How does it compare with American oak?

American white oak is a different group of species with similar looks. AHEC states that structural testing carried out in Europe found American white oak to have greater inherent fibre strength than European oak [9]; strength is a separate property from surface hardness. For floors, the practical differences are in colour, grain character and supply rather than in a clear gap in performance. Read more on [American white oak](https://www.misterendgrain.com/species/american-white-oak/) and [American red oak](https://www.misterendgrain.com/species/american-red-oak/).

For other European timbers often set beside oak, see our profiles of [sweet chestnut](https://www.misterendgrain.com/species/sweet-chestnut/) and [bog oak](https://www.misterendgrain.com/species/bog-oak/), the subfossil oak recovered from bogs and riverbeds.

## Is European oak sustainable?

The Wood Database reports an IUCN rating of least concern for English oak and no listing in the CITES Appendices [1]; CIRAD likewise records that oak is not listed in the CITES Appendices (2023) [3]. EUFORGEN gives no formal Red List category but says fragmented, marginal or small populations could be at risk, that genetic resources in Europe are generally not endangered, and that introducing exotic genotypes into plantations is a threat to genetic diversity [4] [5]. Ask your supplier for chain-of-custody documentation if certification matters to your project.

## Frequently asked questions

### How hard is European oak?

The Wood Database lists English oak (Quercus robur) at 1,120 lbf (4,980 N) on the Janka scale [1]. CIRAD reports hardness on the Monnin scale instead, with an average of 4.2 for oak [3], so the two figures cannot be compared directly.

### Is European oak the same as English oak?

English oak is the common name of Quercus robur, one of the two species sold as European oak. The other is sessile oak, Quercus petraea [3]. The two hybridise frequently where they grow together [5].

### Why does oak turn black where it touches iron?

Oak contains tannins, which react with iron. Forest research from waldwissen.net describes blue-grey to black discolouration from this reaction [6], and The Wood Database notes that wet oak is especially prone to staining from iron [1].

### Can European oak be fumed?

Yes. In a peer-reviewed study, heartwood samples of Quercus robur reacted intensively with ammonia gas and darkened markedly, and oak had the highest tannin content of the four species tested [7].

### Is European oak endangered?

The Wood Database reports an IUCN rating of least concern for English oak and no CITES listing [1]. EUFORGEN notes that fragmented and marginal populations can be at risk, although the genetic resources are generally not endangered in Europe [4].

## Sources

1. [English Oak](https://www.wood-database.com/english-oak/), The Wood Database, accessed 2026-11-03
2. [White Oak](https://www.wood-database.com/white-oak/), The Wood Database, accessed 2026-11-03
3. [Oak (Quercus petraea, Quercus robur), Tropix datasheet 2023, copy hosted by ecochoice.co.uk](https://ecochoice.co.uk/wp-content/uploads/2024/01/OAK-2023.pdf), CIRAD (Tropix-web), accessed 2026-11-03
4. [Quercus robur](https://www.euforgen.org/species/quercus-robur/), EUFORGEN (European Forest Genetic Resources Programme), accessed 2026-11-03
5. [Quercus petraea](https://www.euforgen.org/species/quercus-petraea/), EUFORGEN (European Forest Genetic Resources Programme), accessed 2026-11-03
6. [Nutzung der Eiche](https://www.waldwissen.net/de/waldwirtschaft/holz-und-markt/verarbeitung-und-technik/nutzung-der-eiche), waldwissen.net, accessed 2026-11-03
7. [Wood color changes by ammonia fuming](https://bioresources.cnr.ncsu.edu/BioRes_07/BioRes_07_3_3767_Miklecic_SJ_Wood_Color_Change_NH3_Fuming_2762.pdf), BioResources 7(3), 3767-3778 (Miklečić, Španić, Jirouš-Rajković, 2012), accessed 2026-11-03
8. [Chapter 4: Moisture relations and physical properties of wood, Wood Handbook (FPL-GTR-282)](https://research.fs.usda.gov/download/treesearch/62243.pdf), USDA Forest Products Laboratory, accessed 2026-11-03
9. [A Guide to Sustainable American Hardwoods (2nd edition, 2024)](https://www.americanhardwood.org/sites/default/files/publications/download/2024-05/AHEC_Species_Guide_2024_2ndEdition_English.pdf), American Hardwood Export Council, accessed 2026-11-03
10. [Cube collection](https://www.oscarono.fr/collections/cube), OscarOno Paris, accessed 2026-11-03