Constructive wood

Building materials for structural walls

With many buildings today, the question is not whether wood is used over short distances, but whether wood is used at all. Here, wood competes with other building materials such as concrete, steel and glass. However, today such buildings increasingly no longer pose the competition question of the materials, but the material has to answer questions for these buildings. Today, the questions of climate protection, sustainability, resource efficiency are increasingly the top priority, and other materials also answer all these questions with their arguments.

Building with wood is generally regarded as the ultimate contribution to climate protection. The reason for this is the better energy balance in production compared to other building materials such as concrete, steel or stone as well as the CO2 storage function due to the binding of CO2 in the wood. However, the degree of further processing and above all the upstream chains with the transports are decisive for the climate balance. The combinations of wooden building materials are very diverse and allow a great deal of creative freedom in planning and construction. Timber construction is traditional and modern, inexpensive, healthy and, with wood from Here Proof, very environmentally friendly.

How climate and environmentally friendly building materials and components are depends largely on their upstream chains, i.e. on them

(1) HOW and WHERE the raw materials were obtained,

(2) HOW LONG are the transport routes and what is the transport load in the entire material flow chain and

(3) HOW EFFICIENT is production across the Chain of Custody in terms of energy, water and resource savings.

WOOD FROM HERE directs the focus to the importance of gray energy and, above all, to the current flow of building materials for the overall balance of the building and subsequent use. Wood of short distances or WOOD FROM HERE can provide arguments that cannot be topped. Wood from our regions has clear advantages over other materials and also other wood origins such as wood from Russia or the tropics.

And one thing is certain: material flows can be shortened in a completely different way with wood than, for example, with plastics or metals. WOOD FROM HERE is in this respect an ideal door opener for wood itself and in particular because WOOD FROM HERE provides all the necessary and practical tools and tools for implementation and control, which support the implementation in all planning and Facilitate tendering phases and during construction.

1 / Wooden building materials

Different wooden building materials are used in the various construction methods in timber construction, all of which can be awarded the HOLZ VON HIER certificate.

1. Classic dry (list) lumber

It is mostly used in timber frame constructions or roof trusses. This material is the classic sawmill product and potentially has the shortest routes since it can be produced by almost any sawmill on site. Without proof of origin the short way, even classic sawn timber can come from anywhere in the world, not only in the case of hardwood but also in the case of softwood.

2. Planed goods

This assortment consists of planed and possibly profiled boards of various dimensions. This range is used in particular in the facade area. Planed goods can also be produced by most regional sawmills and therefore have a potentially (!) very low transport backpack. However, this is also partly determined by the special dimensions, since there are certain dimensions that typically come from abroad, such as from Scandinavia ('Nordic dimensions').

Today, however, a large part of the planed goods processed in Central Europe for the construction sector increasingly comes from very long distances. For example, as a "rough planer" for KVH production, many come from Russia. Also planed goods for facades mostly come from very long distances, such as larch planed goods often come from East Russia, Siberia. LINK SIBERIAN LARCH . So also pay attention to the proof of origin for the short distances, such as TIMBER FROM HIER, when it comes to planed facade timber.

3. KVH

KVH is finger-jointed and dried lumber graded. However, KVH is also understood to mean 'solid structural timber' as a product of the monitored KVH quality association with the protected brand name KVH. Each KVH has the advantage that a higher yield of the round timber is possible, since imperfections can simply be 'cut out'. KVH is produced by significantly fewer manufacturers than classic construction timber and has therefore usually come a long way. KVH has also become an internationally traded mass product. Without a tender the Proof of origin for the short distances, like WOOD FROM HERE demands, you can by no means be sure that the KVH that your planner installs actually comes from climate-friendly short distances. Russia, Scandinavia, Belarus, Ukraine, Latvia, Lithuania are important import countries for KVH to Germany, Austria and Luxembourg. It is also important to note that a local manufacturer is no guarantee that the wood will be shipped quickly, as the primary products are often imported today. Only with a WOOD FROM HERE proof of origin, which proves the short distances along the entire (!) chain, can you assume that the wood is climate-friendly and that the distances are short.

The same applies to the following ranges as to KVH, except that even fewer manufacturers can produce this high-tech product for timber engineering. In Central Europe, however, there is sufficient capacity here so that your planner would not have to fall back on products from long distances. But here, too, the tendering (!) with WOOD FROM HERE is extremely important, because otherwise these products can also come from very long, less climate-friendly routes.

4. BSH

BSH stands for glued laminated timber, in which parallel layers of boards are glued together in different dimensions and the resulting beams are planed. Glued laminated timber is primarily used when large spans have to be bridged with slender cross-sections or special requirements are placed on dimensional stability, such as in conservatories

5. MH solid wood

This product was developed in response to the growing trend of KVH. It can be used by architects on an equal footing or equivalent to KVH, as it meets the same requirements in terms of dryness, sorting, quality classes (visible, invisible) and dimensional stability and is subject to quality control.

6.CLT

CLT stands for Cross Laminated Timber. These products score with a high degree of prefabrication, short construction times and simple assembly. CLT can be used as a wall, ceiling or roof component to create space, but also as a floor panel and special component. Planners and contractors can thus work flexibly with component solutions and formats.

Current article on CLT: CLT in the Holzzentralblatt .

7. MH solid wood walls

WOOD FROM HERE

Building materials with an HVH certificate are available for classic timber, KVH, BSH, CLT and solid wood walls. There are no limits to the implementation of your planners.

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2 / Construction methods in timber construction

Wooden buildings consist of load-bearing components in different construction methods. In particular, the following should be mentioned:

1. Block construction - traditional and today highly modern construction.

Here the walls consist of individual solid beams. The spectrum ranges from traditional round planks to squared timber of different dimensions, which are connected to one another using various tongue and groove techniques, to complex, supplier-specific system variants such as Lignotrend, Lignatur and others.

2. Skeleton construction - traditional but today again modern "half-timbered construction".

With this type of construction, which also includes the old traditional half-timbered structure, a load-bearing construction is erected from beams, the spaces between which are 'filled in', formerly with a mixture of clay and straw, today mostly with other materials or even glass.

3. Timber frame construction - scaffolding made of wooden stands made of solid wood, KVH or BSH planked with wooden panels

In this type of construction, which is also characteristic of prefabricated house construction, the construction consists of narrow wooden posts, usually measuring 6*20 cm, with crossbars. The stand construction is stabilized on the inside and outside by planking, usually made of chipboard or OSB boards, sometimes in the form of sloping battens. The gaps are filled with insulating material.
This construction is comparatively inexpensive and also very material-saving and can therefore also be used to conserve resources.

4. Timber panel construction - is often used for public and commercial buildings, halls and the like and can compete with reinforced concrete construction

With this type of construction, the walls (and usually also the ceilings) consist of solid wooden walls of different thicknesses between 10 and over 50 cm. The thickness comes from several layers of boards, which are either connected to each other in the same direction with glue or nails (stacked boards) or arranged in alternating layers rotated by 90%, which in turn have different connection techniques, such as with wooden dowels (e.g. ThomaHolz, Holz100, Nurholz and others), glue (cross-laminated wood, CLT) or with metal nails (e.g. solid wood wall). A major advantage of these construction methods is the high degree of prefabrication and the high rigidity, which also allows large construction projects. A disadvantage is the comparatively high raw material requirement and potentially higher transport rucksacks along the processing chain to the construction site.

5. Composite constructions. is used for special requirements in buildings or high-rise construction .

In some cases, wood is used in conjunction with other building materials. This can be, for example, wood-concrete hybrid elements, which are used particularly in high-rise buildings made of wood.

walls

(1) Wooden walls

Wooden buildings consist of load-bearing components in different construction methods. Wood construction methods and very diverse, which illustrates the enormous adaptability of the building material wood. Wooden building materials are light on the one hand and extremely stable on the other. In particular, the following should be mentioned:

Lifespan - Durability . All wall materials, wood, brick, concrete, reinforced concrete, etc. are given the same durability by the Federal Institute for Building, Urban and Spatial Research (BBSR), in the highest category of > 50 years. With all materials, however, the constructive wall protection is very important. For this reason, the wall-insulation-façade should always be viewed as a constructive unit and not evaluated independently of one another. A wooden wall with NaWaRo insulation and a wooden facade can easily last for several generations. There are many wooden buildings that date back to the Middle Ages.

durability and maintenance requirements. A wooden wall itself is just as durable as any other wall. A wooden wall itself does not need to be maintained because, like any wall, it is protected by a facade, preferably a wooden facade.

ease of repair. In principle, the ease of repair or modular interchangeability of wooden building materials is given, but depends on the product design or the type of fastening. Especially with wooden houses, an outstanding feature is that the repairability and changeability is very good. Individual parts can be exchanged easily and effectively.

Safety and behavior in case of fire. Make no mistake: brick, concrete or wood, any building can burn. What health hazards arise and how stable the building is are decisive for safety in the event of a fire. Natural wood does not produce any toxic gases in the event of a fire. In addition, the stability in wooden houses with massive load-bearing wooden beams is optimal and you have plenty of time to leave the building safely, because a protective charcoal coat forms around the heartwood, which protects the wooden framework and maintains its stability for a long time. Oxygen can no longer penetrate the wood and the burning slows down considerably. In the case of massive wooden walls and solid wood walls, the risk of self-ignition of, for example, wallpaper or curtains on the other side of the wall is also greatly reduced. This means that a fire cannot or only with difficulty spread from one room to another. According to the wecobis project database of the Federal Ministry of Transport, Building and Urban Development and the Bavarian Chamber of Architects, natural materials such as wood and stone are optimally compatible with health both in the use phase and in the event of a fire. In the event of a fire, however, the usual fire gases are produced without the highly toxic substances such as, for example, in the case of plastic fires.

(2) Brick walls - for comparison

Brick walls usually consist of plain bricks, bricks with mineral wool filling or bricks with perlite fillings and masonry mortar to connect and fasten the bricks. The bricks themselves consist of the natural materials clay, lime and stone powder.

The bulk density for pure bricks is 550 – 1,400 kg/m3 (average 740 kg/m3), for bricks with mineral wool filling around 705 kg/m3 (at 54% filling) and for bricks with perlite filling around 806 kg/m3 ( at 47% filling), 574 kg/m3 (62% filling) and 391 kg/m3 (78% filling). Bricks exist as well as brick clinker bricks for facades.

Lifespan - durability. According to the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR): > 50 years.

durability and maintenance requirements. Brick walls that are plastered as usual are very hard-wearing when exposed to the weather.
The amount of maintenance required depends on the type of plaster and paint finish

ease of repair. Brick walls should be repaired or renovated by a specialist if there are damage such as cracks or the like. Simply sticking plastic insulation onto clinker facades can have serious consequences, such as condensation, with possible consequences such as mold growth and damp walls

Safety and behavior in case of fire . Bricks are not combustible.

(3) Reinforced concrete walls - for comparison

The use of reinforced concrete instead of unreinforced concrete is necessary if tensile stresses occur in a component that could lead to a sudden failure of the overall load-bearing capacity. With reinforced concrete, the wall thickness can be specified flexibly. Depending on the construction specification, 40 – 300 kg of steel per m3 of concrete is embedded as a stabilizing element per 1 m3 of concrete. The main advantage of reinforced concrete is its high fire resistance. The main disadvantage is the risk of cracking. The dead weight increases the required amount of reinforcing steel and can lead to deformation in slender constructions due to the formation of cracks. A composite structure or prestressed concrete is more suitable here. Prestressed concrete differs from reinforced concrete in that the steel inserts are prestressed according to plan. This bridges the tensile stress and greatly reduces cracking and component deformation. Another risk is steel rust in the concrete. This can be a problem, especially in areas with traffic (e.g. multi-storey car parks, halls) in zones close to the ground, due to rainwater or slush containing de-icing salt. Remediation of the affected areas is possible but expensive.

Lifespan - durability. According to the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR): > 50 years.

Durability and maintenance effort . Reinforced concrete is usually durable. Reinforced concrete requires little maintenance when it comes to technical construction protection.

Ease of Repair . If cracks form in the concrete or corrosion of the steel in the structural steel, this is only tolerable if it does not endanger the stability. Repairing the affected areas is possible but expensive. If necessary, other stabilizing measures are to be taken here or the affected parts of the building are renewed. Steel that is embedded in concrete will or should always contain corrosion protection in public buildings for safety reasons

Safety and behavior in case of fire. Reinforced concrete itself does not burn. Nevertheless, with the steel content in the concrete, you have to start encasing it with flame retardant materials in order to ensure full stability in the event of fire, also because Steel has the disadvantage of suddenly losing its stability and yielding when exposed to excessive heat.

(4) Lightweight concrete bricks/hollow blocks/slabs - for comparison

Lightweight concrete has comparatively low bulk densities of between 800 and 2000 kg/m³, which are caused by the aggregates in the lightweight concrete. These additives are perlite, fly ash from power plants and also plastics such as polystyrene granules. Additives such as fly ash from power plants contaminated with heavy metals or plastics are not always harmless, especially when the lightweight building blocks are installed indoors. German and European producers have to comply with the health regulations of the EU. The compressive strength is one of the most important properties of concrete, this is of course lower in lightweight concrete. The advantage of lightweight concrete compared to normal concrete, however, is the comparatively low dead weight and lower thermal conductivity. However, lightweight concrete has two disadvantages, on the one hand its unfavorable behavior when absorbing moisture and its low level of sound insulation.

Lifespan - durability. According to the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR): > 50 years.

Durability and maintenance effort . Without the appropriate structural protection, concrete is sensitive to the weather (e.g. sensitive to forest). Concrete walls, like other exterior walls, require facade protection. In any case, concrete walls must be very well insulated and shielded from the weather. When using concrete building materials in the wall-insulation-façade system, it is important to ensure that no condensation forms. Since on concrete walls today particularly like thermal insulation composite systems and Plastic insulation (EPS, XPS, etc.) is applied, special attention must be paid to this. Concrete walls absorb moisture particularly well. This not only promotes mold growth, but also micro-cracks or larger cracks in the concrete can occur in the event of frost. Damp concrete walls have greatly reduced insulating properties. Saving at this point is not financially worthwhile in the long run, especially with concrete walls.

Ease of Repair . If lightweight concrete components are damaged, the only option is usually to replace them

Safety and behavior in case of fire. Concrete components themselves are classified as non-combustible with high fire resistance. However, there is no pure concrete wall without insulation and facades. If, for example, plastic insulation is applied to the wall (e.g. without flame retardants), this can have serious consequences in the event of a fire. Due to the then very high temperatures (plastic burns dripping), there can also be a risk of cracking and increasing instability in concrete walls and especially concrete slabs. The ability to reconstruct can also be impaired after a fire.