Cross laminated wood, cross laminated wood or CLT (cross laminated wood) has become a building material that inspires architects around the world. Its properties make it possible to build large wooden buildings even skyscrapers soon. The magazine Architect Magazine considers it one of the materials that will mark this century.
This advance has not only to do with the properties of the material, but also with the role that it can play in our environment. Every time cities get bigger, more populated and demand more energy and materials, and polluting them produces them.
On the one hand, cross-laminated wood can help reduce the negative impact on the environment that construction has, perhaps the most polluting activity.
On the other hand, it offers an alternative to building in height in relation to concrete and steel, an area where they had exclusivity. It is important that structural wood has a presence in this sense, since it is at a time when today only many cities are able to grow.
Many architects and engineers emphasize that what is really complex in this area, especially when it comes to wooden skyscrapers, is not the building itself. It’s to fight against stereotypes and prejudices of citizens and investors.
What is cross laminated wood or cross laminated panels (CLT)?
They are basically prefabricated panels as a result of the advancement of engineering and architecture in the field of wooden construction. It consists of using several layers of wood that are joined in alternate directions, glued and on which pressure is applied. The result is large pieces of wood with nail excellent construction performance.
When gluing the wood in this way, movements are reduced typical of the material. Thanks to the construction with CLT more than meets the current demands of building materials
Although a wide variety of wood can be used to manufacture counter-laminated panels, the most common are Pine, the fir, larch and cedar. Others, like oak or chestnut, are not frequent, but cases can be found.
Characteristics of cross laminated wood
- They can be found in different thicknesses and with different numbers of layers. They must have an odd number and at least 3. They are most often found with 3, 5 or 7 layers. Thicknesses range from 80 millimeters to over 200 millimeters. Larger thicknesses are possible, but infrequent.
- Large parts. Lengths of 20 meters and even longer can be achieved. In most cases, the limitations are not defined by the material, but by logistics and access to the construction area.
- The pieces are pre-dried until reaching the ideal humidity. This is around 12%, a percentage from which the likelihood of proliferation of fungi and insects is reduced.
- Lightness. Especially if we compare it with other materials used in the construction with steel or concrete. The required base is drastically reduced. To get an idea, I’m3 concrete weighs approximately 2.7 tonnes compared to 450-500 kg CLT (this value depends on the wood used).
- Optimal dimensional stability, especially when compared to other products made of wood. It is due to the manufacturing process itself, to the fact that the pieces are joined in an alternative sense. The variations in the perpendicular direction are minimal and practically 0 in the longitudinal direction.
- Acoustic and thermal insulation. It is due to the natural insulating capacity of the wood. Thanks to this, it is possible that the houses made with laminated panels have a really high energy efficiency and without the need for additional investments.
- Fire resistance. Cross laminated wood manufactured in countries where regulations exist in this regard offer all the guarantees of fire resistance. Times ranging from 30 minutes to 4 hours can be easily achieved, during which the outer layers burn, while the inner layers maintain the structure. In some cases, it is possible that the concrete structure and the sidewalk have already collapsed and collapsed due to the action of fire.
- It is a material fully compatible with other raw materials. Cement, glass, aluminum, steel, etc.
- It does not introduce any toxic component in the construction, favoring much healthier and livable environments.
- Because it is made from small pieces of wood, the use of the tree is much greater. Parts that are otherwise disposable are used.
- Its use as a structural element is certified in most technical building codes.
An advantage that is also often overlooked is that small pieces of wood can be used to form the panel. Allowing a better use of the tree.
CLT Panels Manufacturing
The panels are manufactured in a workshop, that is, in a controlled environment and with specific machinery, and also with numerical control. Thanks to this, higher levels of precision than alternative raw materials are guaranteed.
In addition, all necessary architectural modifications can be made in the workshop. Installation of doors and windows, slots for electricity and pipes, etc.
Cross laminated wood construction
Building cross-laminated wood panel on site is more like assembling a puzzle than traditional construction. It’s because these parts are prepared in the workshop: cut to size, machined and even with doors and sales made. And then they are assembled with the help of cranes.
One of the great advantages is that construction or assembly time is drastically reduced, about 30-40%. On the other hand, a miscalculation can make starting impossible. Measurement, calculations and planning are even more important in this type of construction.
The use of laminated panels in construction is breaking the limitations of wooden construction. Buildings of several floors, and even skyscrapers, they start to become a reality.
Deviations in budgets, both economic and temporary, are much smaller. Especially when the work contains complex elements or structures. It is largely due to the manufacture of the store.
The strength of cross-laminated timber constructions against earthquakes or earthquakes is impressive. It is a much more convenient material in an extreme situation like this.
Another advantage of cross-laminated wood construction is that no waste is generated at the construction site. And those generated at the factory are very small compared to other construction alternatives. Therefore, the environmental impact is reduced. In addition, at the end of the construction’s useful life, it is 100% renewable. In some countries, construction waste represents more than 50% of the total, a situation that needs to be resolved.
With proper care and maintenance, this type of wooden construction has the same service life as any other type of construction or even more. You just need to understand the material and how it can be affected.
Is it necessary to protect laminated wood?
The answer is clearly yes. The wood suffers from moisture if care is not adequate.
For interiors, the use of oils is recommended. And for outdoors, different options are usually used:
- If the wood is going to be exposed directly, the most common is the use of mineral paints.
- Another frequent option is the facade cladding. Some of the options we can use for this are the wood-cement, stone, etc.
What exactly is CLT used in construction?
Can be used in hybrid constructions where it coexists with other materials, such as concrete and steel. And you can also use exclusively to carry out the entire construction. Its use is well documented and can be found both in large buildings and in single-storey houses.
We will find it mainly forming ceilings, floors and walls. This is enabled by versatility in thicknesses in which it can be manufactured.
In addition, having a comparatively lower weight would allow a greater number of floors.