Know your wood – Red Oak

Each issue, we take a look at a particular wood species or wood product. This time it’s the turn of American red oak – a sustainable and strong wood that machines well, steam bends and takes colour beautifully.

The tree

Rather than a single species, American red oak refers instead to a cluster of sub-species that grow throughout hardwood forests, almost exclusively, in North America. Red oaks are tall trees, with sizes varying according to species, averaging about 18 metres to 21 metres in height, with a diameter of one metre. Although the wood can be warm in tone, it is not in fact red – the name comes instead from the trees’ vibrant leaves in the autumn.

Red oaks are widely distributed throughout most of the eastern hardwood forests of the United States, where they are the dominant species. The quantity of red oak in American forests is expanding so that, after harvesting is considered, its volume is increasing by 28.7 million m3 per year. It takes just 1.04 seconds to grow 1m3 of red oak, making it a highly sustainable material.

Image © Studio Woodgate. Robust but delicate: the edges of the wood taper to a subtle 2mm radius.

The timber

Red oak is a straight grained, often coarse textured wood that varies in shade from light brown to pink/red brown. It usually has a reddish cast, although sometimes approaches white oak in colour.

Its end grain shows clear growth rings which features pores that are open. This porosity is such that some red oak, when cut from end-grain to end-grain, can be blown through like a straw. This structure is also the reason red oak absorbs oils, stains and colour well.

The downside to this porosity is that water can more easily penetrate the wood, meaning red oak that has a classification of ‘slightly durable’ (class 4 in British Standard EN350) is better suited to use class 1 interior environments.

The quality of red oak depends greatly on growth conditions. Northern red oak, with its comparatively slow rate of growth, compares favourably with northern white oak, while southern red oak is generally of faster growth, and consequently coarser and more open in texture.

Working with red oak

Red oak is very strong and machines easily. The wood is hardwearing, and it is also flexible, making it excellent for steam bending. As it is stable when dry, and easy to finish and stain, it is ideal for furniture and flooring. It can be fumed with ammonia to make it darker, scorched to blacken it and reveal its texture, oiled or stained to emphasise or change its colour, or even injected with dye using compressed air.

Inspiring specifiers to make sustainable choices

Image © Benchmark. Each Migo chair, designed by Pascal Hien, is built from a single plank of red oak.

Although widely used in North America for furniture, flooring, joinery and cabinets, red oak has been underused in Europe, suffering from preconceptions mostly to do with its name and colour.

The American Hardwood Export Council (AHEC) has played a proactive role in recent years showcasing the beauty, performance and sustainability of this particular species.

Some of this work has been done through creative projects, in partnership with British craft powerhouse Benchmark. Collaborations such as ‘Legacy’ and ‘Discovered’ for the London Design Festival aim to prompt architects, designers and manufacturers to question prevailing material choices and raise awareness of this readily available species.

Designer Pascal Hein chose red oak for his Discovered piece, Migo Chair, for its strength. He worked on a design with a highly economical construction: each chair is made from a single plank of red oak (ensuring consistency of grain), and its parts are held together with dovetails.

Designed by Terence Woodgate for Alex Beard CBE, Chief Executive of The Royal Opera House, as part of AHEC’s Legacy project, Duo is a pair of sofas that look deceptively delicate. The light rectangular arms have a curved chamfer detail, while the backrest is subtly tapered from bottom to top. The seats are upholstered in tan leather, complementing the red oak frame.

“An expanding resource in North America, red oak regenerates naturally and in vast volumes. Despite its warm tones, unique grain and ability to be milled and steam bent to distraction, European designers and brands still tend to favour other oaks over this interesting and prolific timber, that can provide an affordable option and a solution to increased oak availability.”

David Venables, Director, AHEC Europe

An awesome display

The Vortex entrance to the Bloomberg Headquarters by Foster + Partners.

Bloomberg’s London headquarters, designed by Foster + Partners, has been a major showcase for American red oak in the UK – using over 40,000m2 throughout the building. The dramatic entrance space, the Vortex, comprises three curved timber shells covered with six thousand panels of red oak that were assembled together, in specific order, like a jigsaw. Four different shades of veneer were used to create a variety of tone and warmth across the surface. Core to the interior aesthetic of the project, red oak was used for panels, flooring and in the walls, in the form of glulam.

This article is taken from issue 4 of Designing Timber magazine,