Although there are many countries where wooden houses are common, in others, such as Spain, they are not abundant. Here there are strong prejudices regarding the useful life of a wooden house or its durability. In large part, it is due to the traditional use of brick, concrete and steel, calling into question everything that is not built with these materials.
The first thing to know is that wooden construction has evolved and improved a lot in recent years. Even so, we must keep in mind that today there are many century-old wooden houses in perfect condition. The Japanese temple stands out “Hōryū Gakumonji”Completed in 607 and is the oldest wooden structure that is preserved.
One of the reasons why the construction of wooden houses is experiencing a new boom is related to the bioarchitecture and concern for the environment. Among these advantages, we found that they can be cheaper to build, especially modular and / or prefabricated ones. Bioarchitecture allows to obtain houses with zero consumption, that is, where the costs of heating, air conditioning and even electricity are reduced to the point of almost disappearing. These and other advantages can be found here.
The durability of wood
When referring to the durability of a wood, we are talking technically about the ability of the construction to remain in use within the expected maintenance parameters. In other words, with proper maintenance, the building lasts what was stipulated (10, 50 or 100 years) without major contingencies and continuous renovations.
In the case of wood durability, it is resistance to the action of fungi and rotten insects (xylophages). These are the ones that cause the wood to deteriorate and putrefy.
The appearance of fungi is only possible when it exceeds a moisture content 20%Therefore, in addition to choosing the appropriate treatment, the construction details must also be taken care of so that the exposure to humidity is minimal. For example, it is recommended that, as much as possible, wooden pillars on porches and exteriors should not be in direct contact with the ground. The heads of the beams must be aerated on walls with the possibility of dampness by capillarity, etc.
For centuries, methods have been used to stop the action of these agents, some of them with great success. But it was in the last century that the advancement of chemistry allowed us to better understand the process and to reach really effective solutions to increase the useful life of wooden houses.
Another great advantage that increases the useful life of wooden houses is the ease of making repairs. In these, it is much easier to replace or repair a part that has deteriorated for any reason than to do it in a concrete part.
What factors determine the durability of the wood?
In order for the wooden structure to have a long useful life, it is necessary to pay attention to some important issues:
- Humidity and ventilation control.
- Control of microorganisms and insects.
- Use the right wood.
- The correct assembly or installation. It is common for some «professionals» Faced with a bad installation, blame the material instead of assuming it for your bad work. The original problem is that there are very few real professionals in the wood construction sector, and a lot of ignorance.
The reality of renovations and demolitions
A problem that often goes unnoticed when we talk about the durability of buildings is how long they really stand. The fact that a house can last 200 years, or even 100, does not mean that it will actually last. This reality can also help us to focus the debate a little.
In 2004, the American government published an interesting fact about house demolitions:
- 66% of demolished wooden houses were over 50 years old.
- 66% of demolished concrete houses were less than 50 years old.
- 66% of demolished steel houses were less than 50 years old.
How fire affects a wooden house
To say that fire does not affect a wooden house is a blatant lie. The curious thing is to see how many people do not know that fire also destroys houses and buildings made of other materials.
The fire resistance of a structural element is the time that it is able to continue fulfilling its function of resistance in case of fire. For this, the NBE CPI-96 standard requires Fire Stability (EF) according to a time scale that goes from 30 to 240 minutes.
Wood is classified as combustible and moderately flammable (M3 according to UNE 23.727). With the presence of a flame, it needs a temperature around 300ºC for ignition to occur. Once the fire has developed and produces a rapid combustion of the wood surface and a carbonized layer is created that acts as an insulator for the wood itself..
Contrary to popular belief, the evidence says that the wood used in construction currently does not perform poorly on fire. The wooden houses burn in a predictable way, which is far from a disadvantage.
The collapse of the building can be calculated very accurately and the steps taken during the manufacturing process to improve this behavior. In addition, the products can be used to delay the action of fire, such as varnishes or intumescent paints.
We must know that the large wooden beams that are subject to the action of fire, even if they appear charred, still retain a large part of their physical-mechanical properties, unlike other materials.
Ways to increase the durability of wooden houses
- Choose wood and its quality well. Not all species, not all parts of the same trunk are ideal for construction.
- Keep the structure dry. It is not that it cannot get wet, what we must avoid is that it is continually moist and facilitates adequate ventilation.
- Choose the proper protection against moisture, water, sunlight, insects and fungi. Contrary to popular belief, it does not consist of renewals every year. Sometimes, some of these treatments are applied only at the time of construction.
- Maintenance and periodic renovation of finishes. It is common in all houses, the cement ones are also painted and waterproofing is applied.