Durability

In human history, wood has always been an important building material. There are many examples of wooden buildings from around the world, including China, that have lasted for centuries in all types of climate. They provide evidence that wood construction can last virtually forever, providing it is designed and built properly to meet specific climatic conditions, and maintained appropriately over its full life cycle.

Design, specification, treatment and maintenance need to be carefully considered for the different climatic conditions. Appropriate design, material selection, construction, and maintenance will ensure that wood is safe from the decay and mould associated with exposure to excessive moisture, as well as from the termite infestations found in the southern China regions.

Durability depends on protecting wood from excessive moisture. Building envelopes should be designed to prevent water vapour condensation within envelope cavities and to allow any dampness to dry out. In wet climates, more steeply sloped roofs, large overhangs and rain screens can be used. As with any building system, the building envelope must be sealed against rain penetration around windows, doors, and other exterior wall openings, including roof penetrations and balconies.

In areas with termite hazard, effective prevention and control can be achieved with appropriate design and construction practices. In recent years, multiple lines of defense have been developed and integrated into modern wood construction to ensure moisture and termite resistance.

Exterior wood products used for decks and other landscaping projects are either made from naturally durable wood species, such as the heartwood of China fir, Western red cedar and yellow cedar, or pressure treated with chemical preservatives.

Strict regulations on environment and human health ensure these chemicals are benign to humans but resistant to insects and fungi. Good design, workmanship, and maintenance are also critical for prolonging the service life of outdoor wood products.

Modern wood frame construction has a good record of durability

Modern systems of wood frame construction also have a good record of durability. This building type has a long history in Europe and North America, and there are still houses standing from the original developments. Many North American and European wood houses are over a hundred years old.

Progress in design, material use and treatment, construction techniques and maintenance have been made in recent decades to make sure that wood buildings can endure indefinitely.

A survey on wood building service lives

Buildings are rarely demolished because they are beyond repair, or have become structurally unsound. Generally it is to make way for a larger or more modern building. Simple to maintain and repair, wood buildings are easily renovated to adapt to new requirements. At the end of their economic service life, they can be demolished, with recovered materials being reused, recycled or used as biomass energy.

Durability survey in China

Forintek carried out a durability survey of wood frame houses in China during 2006 and 2007. Results demonstrated that, with the durability measures introduced into the relevant codes and standards in China, including the Shanghai Technical Specification for Wood-Frame Construction, wood construction in China is durable.

Distribution of 94 non-residential buildings by age class and structural material

The main hall of Nanchan Temple, near Wutaishan, Shanxi Province, China, built in 782 AD Tang Dynasty, the oldest existing wooden building in China
The main hall of Nanchan Temple
near Wutaishan, Shanxi Province
built in 782 AD Tang Dynasty
the oldest existing wooden building
in China
Fogong Temple Wooden Pagoda of Ying County, Shanxi Province, China, built in 1056 AD Liao Dynasty, the oldest existing high-rise wooden building in the world
Fogong Temple Wooden Pagoda of Ying County, Shanxi Province, China
built in 1056 AD Liao Dynasty
the oldest existing high-rise
wooden building in the world
Stave Church, Urnes, Norway, built in 1150 AD, post and beam structure
Stave Church, Urnes, Norway, built in 1150 AD, post and beam structure

 
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