When deciding on a construction material to complete a planned building project, it’s important to know more about what you can expect from each and what will make them the ideal material to use in your case. This is why we have prepared a specialist guide on oak timber, so you can learn about this material type before you order a product and start work.
Read on if you’d like to find out more about oak timber as a material, where it might come from, and the benefits it will guarantee for your installation and your property as a whole. You can also get in touch with us right away if you already know what you need for your construction project in the UK.
About the Oak Tree
Technically speaking, the oak tree is not just a singular type of tree. Instead, it’s a tree or shrub in the genus “Quercus” (which is Latin for “oak”) in the beech family, and there are over 500 species currently in existence. All of these types are native to the Northern Hemisphere, and will mostly be found growing across the Americas, Asia, Europe, and North Africa.
You’re more likely to see a larger number of oak species in the Americas than anywhere else in the world. This location boasts over 200 species of oak tree, with 160 alone growing in Mexico (109 of these grow here endemically, meaning they cannot be found anywhere else). 90 unique species of oak can also be found in the United States. The second greatest centre of oak diversity in the world is China, which grows over 100 species of oak.
The Types of Oak Wood Timber You Will Find
In most cases, you are only likely to find a few different types of timber when looking at oak structures. Construction companies based in Europe will naturally use the strongest wood which is most readily available. In general, this will be European oak, of which two specific species are usually picked. The first is Quercus Robur, which is also commonly known as “English oak”, “common oak”, or “pedunculate oak”. The second is Quercus Petraea, which you might also hear called “sessile oak” or “durmast oak”.
Though the two are classed as two different species, you’re unlikely to see a difference between the two. If left to grow in the best possible conditions, the trees will both usually grow to a height of somewhere between 18 and 30 metres (though this will vary depending on soil and locality). They will also form a clear, straight trunk that may be up to 15 metres in length when the tree is growing in a forest. A European oak tree can also carry lower branches when it grows out in the open, making it a very broad tree under some conditions.
Both Quercus Robur and Quercus Petraea can be found in pure stands (a group of trees that is made up of the same species), and are often the dominant species in mixed forest environments.
All English Heritage Buildings products are precision-manufactured from Quercus Robur and Quercus Petraea trees cultivated on a specially designated site in France. These trees are all grown to be as tall and straight as possible, so that more of the wood can be used in construction and less will be wasted. Three new saplings will also be planted in the place of every tree used in our work.
North American Oak Types
On some occasions, you may also come across the two, very broadly different types of North American oak.
The first of these, which is commonly called the White American oak and can be split into a number of different species, is similar in many ways to European oak. Under the most favourable conditions it will reach a height of 30 metres (and only 15 metres if the conditions are not favourable) and have a straight, clear trunk of between 12 and 15 metres. This oak type is most often found across the eastern half of the United States, and the southern half of Canada, with distribution taking place according to species.
The second species you may find used in some imported oak timber (though not as much as White American oak) is Red American oak. Typically, this tree type will be found in eastern and central parts of the United States, as well as southeastern and south-central parts of Canada. The tree itself resembles other types of oak, but the heartwood (the inner part of the tree trunk) should usually have a reddish hue. It’s also been suggested that Red American oak grown in the south typically grows faster and produces harder, heavier timber with a coarser texture than the same types found in the north.
In recent years, there have also been some small-scale attempts to plant and introduce the Red American oak variety to the UK. When tested, it has been noted that the timber produced from these trees is similar to the timber found in the trees growing naturally in the USA.
Appearances of Oak Wood Timber
The typical colour of European oak wood timber (of any species) is yellowish-brown in its heartwood, with the sapwood (the softer outer layers of recently formed wood between the heartwood and the bark) a lighter colour than this. There may also be a noticeable yellow stain caused by a harmless mould present during drying, but this is not permanent and will not affect oak beams and structures when ready for use.
It is possible that blue-black chemical stains will form on the wood if the timber comes into contact with iron or iron compounds in the presence of moisture. This is because the tannin present in the oak will react with the metal.
The grain of European oak timber will generally be straight, but certain conditions that affect the growth may cause this to vary. In quarter sawn timber, you’re also likely to see the wood’s characteristic ornamental silver grain, due to the broad rays.
Appearances of North American Oak Timber
The colours seen in White American oak species vary more than European oak, from pale yellow-brown to mid-brown in the heartwood. The sapwood, meanwhile, should be almost white in colour and completely distinct from the heartwood.
Like European oak, chemical stains may appear in the wood if the wood comes into contact with iron or iron compounds in the presence of moisture. The timber is also slightly acidic and may promote the corrosion of iron or steel under damp conditions.
The grain of White American oak will most often be straight, with the same characteristic silver grain as European oak, owing to the fact that it also has broad rays. However, the structure and quality of the wood can differ depending on the conditions involved in the tree’s growth. For instance, slow grown northern oak species have been noted to produce a lightweight, mild type of wood. Meanwhile, oak from southern states are typically grown fast and have wide growth rings, producing a harder and tougher timber as a result.
The reddish tinge of Red American oak’s heartwood is the most distinctive feature of this tree. The only other distinguishing feature it has is smaller rays in the grain, causing it to have a less attractive silver grain figure than White American oak or European oak.
Strength of Oak Timber
The strength of any piece of timber is determined by its grade and the general strength of the tree species it was cut from. Because of this, high timber grades from generally weaker species may result in a timber piece that’s just as strong as a lower graded piece from a stronger species.
Both the most popularly used types of European oak have well-known and high strength properties. The wood itself is considered slightly weaker than European beech. This means that it can readily be used for both interior and exterior construction, including cladding, joinery, decking, flooring, and furniture.
White and Red American oak are both noted to have particularly high strength, comparing very well with the strength of European oak.
Density of Oak Timber
The density of oak timber is an important factor to take into consideration if you’re planning on using the wood to make furniture or carry out a similar woodworking project. Woods with lower density are considered inferior in strength, stiffness properties, and manufacturing characteristics.
Timber with a density range of 400 to 800kg per m3 is preferred. European oak timber will normally have a density range of around 720kg/m3, though this may vary by as much as 20%. White American oak timber will normally have a density of around 770kg/m3, while Red American oak should have a density of around 790kg/m3.
Despite its high density and strength, Red American oak is generally considered more suitable for flooring and furniture than oak frame structures such as porches, garages, or garden rooms. This is because it lacks the durability required.
Oak Timber Drying
It has been noted that oak timber of all types and species dries very slowly, with a tendency to split and check (a drying defect in which tensile stresses cause the wood to separate and form narrow cracks). This is especially likely to happen in the early stages of drying.
There is also a considerable risk of honeycombing if the drying is forced, especially if the wood pieces are thicker or more solid. This is when irreversible radial and circular cracks appear in the wood, resembling a honeycomb texture. Honeycombing is considered one of the worst defects in timber because it cannot be detected by looking at the face of the timber.
There are two common ways of drying oak timber: air drying and kiln drying. When air drying timber, the stock should be piled in a space that’s exposed to both the sun and prevailing winds, and stickers should be used to create gaps that allow for airflow between the pieces. The thickness of the stickers should be reduced for piles in early spring and onwards, until winter.
When kiln drying oak timber, warm air is pumped over the wood in order to reduce the moisture content through fast evaporation. This is typically done if the wood is to be used internally, as the moisture content in the timber needs to be lower when it is prepared for use in interiors.
Grades of Oak Timber Frames
There are many different standards and rules for oak grading, depending on a range of factors. These include how the timber is dried and what the timber is going to be used for.
English Heritage Buildings uses grades that are more specific to the green oak market. In the UK, these would be considered TH1, TH2, THA, and THB. TH1 and TH2 are considered the grades for smaller beams, unless its cross-sectional area is equal to or greater than 20,000mm2 and its thickness is equal to or greater than 100mm. If this is the case, the timber will be reassigned to the THA or THB grade.
As most of the supply chain is European, you may also find that our oak beams are categorised under the grades QPA and QP1. These are the standard continental categorisations for the highest quality oak and second highest quality oak.
The Benefits of Using Oak Wood Timber
Oak timber has remained a popular construction material throughout the centuries, and there are many reasons for this. The first, and perhaps the most important, of these reasons, is that it is reliably solid and strong, with many types of the timber offering excellent durability. This allows it to withstand the elements with few worries about prolonged damage or the need for repairs.
As it is so durable and needs very little repair work, oak timber will also need very little overall maintenance or cleaning. You may consider painting or varnishing the wood once you have had buildings, extensions, or structures installed on your property, but leaving it exposed should allow the wood frames to naturally darken. This offers its own stunning aesthetic appeal, and is bound to bring a timeless look to any home or business.
The versatility of the wood as a material also means that it can be crafted and used in a variety of project types. Whether you are intending to add a classically charming finish to a modern red brick home, or need a material to match the appeal of an older property, oak will suit your purpose and blend in seamlessly with the rest of the architectural design.
Oak timber is also often cheaper than other building materials and allows for a faster build than materials such as brick or cement, as it will not have a drying time after the wood has been prepared for construction. It will also require a smaller installation team to ensure the work is done, which may save you both time and money in terms of hiring third party labour.
The versatility of the wood as a material also means that it can be crafted and used in a variety of project types. Whether you are intending to add a classically charming finish to a modern red brick home, or need a material to match the appeal of an older property, oak will suit your purpose and blend in seamlessly with the rest of the architectural design.
Oak timber is also often cheaper than other building materials and allows for a faster build than materials such as brick or cement, as it will not have a drying time after the wood has been prepared for construction. It will also require a smaller installation team to ensure the work is done, which may save you both time and money in terms of hiring third party labour.
Looking to Build Using Oak Timber?
If you have been considering your options and have decided on a solid oak garage, garden room, porch, or pergola for your property, English Heritage Buildings will be ready and fully prepared to provide you with the high-quality building solution that offers everything you need to make it a reality.
We will be glad to help you design a fully bespoke product for our expert craftsmen to make into an easily assembled kit. This kit will then be delivered to you anywhere in the UK once the work has been signed off, putting you in charge of your own schedule for installation as soon as the frames arrive at your door.
Contact us today and one of our friendly team members will be waiting to discuss the specifications for your perfect oak timber product.
