The entire raw material process is closed without involvement of chemicals and can thus guarantee a friendly and sustainable production. This structure is very unique among the otherwise globalized ways of the timber industry.
In fact, sprinkler systems have been shown to be one of the primary factors in limiting fatalities and fire damage in structures of all types. Injury rates (per 1,000 fires) by sprinkler protection status and building material combustibility shows again how sprinklers have the best effect in preventing deaths.
A study that examined the rate of injury from hotel, motel and aged care home fires in America and Canada from 1980 to 1998 found that the presence of sprinklers had a greater impact than the combustibility of the building material.
Fire can also raise the temperature of steel enough to compromise its strength, with a reduction in its load carrying capacity by one third when heated above 540°C causing beams to buckle and floors to collapse.
Just because steel is a non-combustible material does not mean it is unaffected by fire. The thermal conductivity of steel is significantly greater than wood (200-1000 times more). This creates a thermal bridging effect, allowing heat from a fire in one part of a building to spread rapidly to other parts.
In light timber frame constructions the walls and floors are typically encased in non-combustible gypsum plasterboard to provide protection from fire. This provides the same level of fire resistance as a completely non-combustible material.
An additional benefit to heavy timber is the ease of repair after a fire. The charred sections can visually be assessed and evaluated for residual capacity, and the damaged timber can then be cut away and replaced. This is in contrast to steel, which buckles under extreme heat.
Charring creates a protective layer that acts as insulation and delays the onset of heating for the cold layer below. With continued exposure to fire the char layer grows, increasing the insulation and slowing down the burning rate, providing greater time for escape or intervention.
Heavy timber constructions have an inherent level of fire resistance. This resistance increases with the thickness of the wooden elements because when timber is exposed to fire the outer layer burns and turns to char.
A common concern raised in regard to the use of wood as a building material is whether or not there is an increased risk of fire.
The outer wall components are resistant to fire from the inside for more than 90 minutes, due to the inbuilt 84 mm thick sacrificial layers, which burn at 0.9 mm per minute under optimal ventilation conditions. The sacrificial layers delay the fire reaching the load-bearing core layer by approximately 93 minutes.
The conclusion was that wood is three to five times more resistant to fire than concrete or bricks. A thick wooden block does not burn, but only becomes charred on the surface. Wood’s fantastic static properties are also retained much longer at extremely high temperatures in comparison with reinforced concrete structures, for example.
On the outer side, the solid timber façade component has board panels with a thickness
of 29 mm, inlaid and dowelled with the two soft wood fibreboards (Gutex Multiplex-top), each 22 mm thick. The fire performance of the soft wood fibreboards according to DIN EN 13501-1 corresponds to class E. The nominal bulk density of Gutex Multiplex-top is approximately 200 kg/m3.
As part of the IBA Hamburg, the “WOODCUBE” was intended take on a clear structural form and act as a prototype. This gave rise to the distinct cube shape, which ensured a high recall value. The building’s cubature is enhanced by irregularly spaced, freely overhanging balconies. These are designed in such a way as to give the impression that they swing out of the basic shape.
Possibility of Conversion
Due to the large floor spans, almost every type of room layout can be achieved within the building. Every floor features different types of apartments. As there are no load-bearing walls, room structures can be changed at any time. Some of the apartments are also set up in such a way that, if required, they can be made completely accessible without major alteration work.
Above the basement, which is a waterproof concrete tank, almost all of the load-bearing construction components are made of timber elements, with the exception of the staircase core. The basement contains space for storing bicycles and technical and supply rooms, along with a laundry room and storage spaces for the apartments.
Large windows that run the width of the balcony and smaller square, or rectangular windows that seem to be arranged without reference to one another, break up the façade. The vertical openings for the building services installations are in ducts on the eastern and western outer walls. The bathrooms and kitchens are arranged around these ducts. Overall, the cubic form of the building makes it very compact.
The apartments on the west side of the second and third floors were joined together vertically to form a maisonette. The fourth floor, however, is designed as a closed unit. Each apartment has at least one balcony on a corner of the building and oriented east, south, or west. The roof, which is covered with a photovoltaic unit, is not accessible.
As far as I can trace it, all the well preserved buildings were built with slow and traditional methods. The minimum requirement was to cut the trees in winter while the moon is waning. Even better are the days just before the New Moon in Capricorn.
The 'Abbrandlerhoefe' however, those farms which needed to be rebuilt hastily after a fire and couldn't possibly be built that way. Harvesting hay happens in midsummer when the heat causes the fermentation of hay and its combustion. Therefore building wood needed to be logged in the hot part of the year and often didn't even have time to dry properly. This does influence the quality and longevity of the building.
A project of this kind and needed to be planned carefully and was worked on over a period of time. All the accumulated experience of farmers, talented carpenters and trades people contributed to a lasting building. Due to this tradition and attitude of our ancestors, we now have buildings hundreds of years old and still functioning.
Time was scarce too. Large farmer families, including the farmhands and animals, needed to have a new roof above their heads before the next cold winter would descend from the glaciers and surrounding mountains. Over many centuries, building a farm in a very short time was only an exemption due to a catastrophe. A farm was built for many generations to come, not just the grand kids.
Living and surviving in this harsh and steep alpine environment has always kept these people closely knit. After such a disaster, neighbors would work together and help the owners to log the trees and swiftly start working on the new building which was then called the 'Abbrandlerhof'.
This sometimes causes the hay to ignite all by itself and is called spontaneous combustion. Quite a few stately and very old farm houses have turned to ash and rubble in this way. For most of the 'Salzburger' alpine farms, there is an existing privilege. In the case of a burned down farm, the farmer is allowed to cut trees for building materials in the state forest free of charge.
In the hot and humid midsummer days when thunderstorms are brewing, farmers often have to rush and bring in the still moist hay before a downpour. This way the hay might not get soaked in the rain, however a much more dangerous threat to the hay barn and farm buildings is lurking: A bale of hay only half dry starts fermenting and in just a few short hours develops an incredible internal heat.
Holz100 Canada Inc.