WOOD

Wood is a natural material, which is intensively used for millennia in the construction of facilities. Initially, its use was mainly due to its accessibility, in times when there was no such choice +?irokege artificial materials for construction. Today the wood is under construction valued primarily because of its positive attributes to the facility and stay in it. The wood is one of the most healthy building materials. Its positive features, such as the ability to breathe, moisture control, air filtration and purification, the absence of static electricity, a relatively good insulation, prijetnost touch and impart a number of other valuable and ensure its applicability in construction in the future. One of the main characteristics that have the brick and wood, this, that the construction of fast, dry, which means that it is not necessary to wait for the dry parts of the building, and consequently, of course, cleaner.

Physical and mechanical properties of wood

The quality of wood depends on its physical and mechanical properties.

Physical properties of wood are those that depend on how natural forces (heat, light, movement of timber of juice and water, ...). These are:

* Porosity: ratio of total pore volume and the volume of dry wood, it is expressed in%, oak is one of the least porous types of wood, pine is one of the most porous types of wood;
* Density: the spatial relationship between the weight of dry wood without the weight of the pore space and pore wood, for various types of wood is between 0.3 to 0.5;
* Update volume: drying, vpijanju moisture or temperature change in wood volume changes;
* Humidity: the ratio between the weight of water in the timber and the weight of completely dry wood, it is expressed in% humidity also affects the mechanical properties of wood, are separated
of fresh wood,
on semi-timber (up to 30% moisture)
of wood dried in the air (up to 20% moisture)
of dry wood (up to 17% moisture).

When the mechanical properties of wood are considering:

* Compressive strength;
* Tensile strength;
* Flexural strength: Wood has a relatively high flexural strength at low weight of its own, it is still one of the most commonly used materials for bending structures;
* Shear value;
* Modulus: depends on the physical properties of wood and fiber direction.

An important feature is the sustainability of wood, which indicates how long the wood kept unchanged mechanical properties. It depends on:

* Type of wood,
* Physical properties of wood
* Exposure to air, moisture, water, and particularly to changing moisture.

Distribution of timber quality

Given the characteristics which determine the quality of the wood, split wood, designed the structure in three categories, which must be considered when determining the permissible voltage:

1. I. category: very worn wood. Les for this category is used for short sections, where high capacity is necessary, according to static requirements, taking into account the economy works.
2. II. Category: les normal load. Les those categories used in most construction work, except:

* For minor parts where inferior quality of the wood has no harmful effects,
* The elements that are constructive grounds of oversized,
* Ancillary and temporary structures.

3. III. Category: a little worn wood. It is used in all other cases and in cases that are listed as exceptions in the 2nd timber categories.

The quality of the wood must always be prominently marked, and the type of control method for determining the quality of wood and set rules for wood structures.

Dimensions of timber

The building is used:

1. roundwood: to be used in the construction industry in diameters from 8 to 30 cm, length of 16 m;
2. sawn wood: which according to the dimensions in length and in cross-section divided into the following groups:

* Short wood (up to 4 m),
* Long timber (over 4 m in length),
* Full timber (width to 20 cm)
* Wide timber (width between 20 and 30 cm)
* Very large timber (width over 30 cm)
* A small timber (thickness 13 mm),
* Thin wood (thickness between 14 and 20 mm),
* Medium thick wood (thickness between 21 and 35 mm),
* Les thick (thickness over 36 mm).

For boards, the following groups:

* Thin boards (thickness between 9 and 13 mm),
* Boards (thickness between 13 and 40 mm),
* Planks (thickness over 40 mm).

Fasteners

Connection is intended to connect the individual elements of timber structures and prevent the displacement of elements in contact. Binder is static or constructive, depending on where and how to use. Binder, which takes in contact force, called the static coupling agent, one which merely prevents displacement and constructive coupling agent.

Nails - wooden structures used in the nails with a round cross-section and with a flat head. In zabijanju these nails is the wood fibers, interrupt, but only lightly pressed. Nail diameter is determined according to the thickness of thin wood in spoju. In zabijanju be considered proper depth and the appropriate density impacted.

Bolts - are used as static or as a constructive means of coupling. Since the wood drying cramps, the nuts are tightened on several occasions. Minimum cross-section bolts is 10 mm in thickness more than 8 cm and 12 mm. Mutual spacing svornikov oz. distance bolts from the end of construction, must be in the direction of fiber diameters less than 7 and not less than 10 cm.

Shackles - we do a flat or round steel is used only by the temporary structures.

Plates - wooden dowels work in healthy and dry wood of superior quality. In the design of dowels should be considered dead weight tonnage of basic wood and dowels. Steel plates are quite different in form and method of installation

Adhesives - the best coupling agent. For gluing wood structures used casein glues and adhesives from synthetic resins. Perfect union should not be burden on the transverse joint, because it can be even the smallest tension bursts. Les by glued, can contain more than 15% humidity. Contact surface must be easily and accurately fabricated to fit as much as possible. The thickness of contact, a maximum of 0.2 to 0.8 mm. The best result obtained adhesion at temperatures of 18 to 25 degrees Celsius. At work we need to fully consider the adhesive manufacturer's instructions.

Wood as a building material and its protection

When designing wooden elements, which we built the house, should be considered a construction wood preservatives. This timber should not be in direct contact with the ground, but generally it is necessary to design the facility so as to minimize the wood exposed to moisture and weather and other impacts from the surroundings. This prevented the possibility of developing timber pests at critical points and ensure longer durability built facility.

Each timber, also new, it is necessary to protect against pests, excluding those wood species that have inherently sufficiently protective substances. This is particularly true for items that will be free and will be more fully exposed in the surrounding areas. Special protection is also needed in the wood, which used as building or decorative element in damp areas. Protect the wood surface by impregnation, impregnating with special coatings for wood, impregnated surface and can further protect the coatings to wood and decorative paint. If we are to achieve the most natural look, the decorative coating of wood, of course, be avoided. It impregnation always choose according to the location of wood components and the intended impact of exposure. The means of protection must penetrate deep into the wood, since the only way to fully protect and make resistant. How deep they penetrated protective equipment, depending on the type of wood treatment method and its humidity. It is therefore important that as a building material choice of quality wood elements. Mechanical properties of wood: # - Strength.

# - Elasticity


This category includes those characteristics that occur when the wood work of a foreign - mechanical forces. Wood offers the resistance forces, and this resistance is called the mechanical properties of wood. Strength:
It is an important mechanical property that applicable particularly in building structures (roof, wooden bridge).
When trying to break wood or worry us offers resistance, which we call the strength of wood.
If we want the timber to affix any other body, called the resistance of wood hardness.
Types of wood in hardness:
Very soft wood: pine, spruce, fir, linden.
Soft wood: larch, birch, alder.
Medium-hard wood: elm.
Hardwood: hornbeam, maple, oak, walnut.
Very hard wood: fiddle.

Hardness is sometimes desirable - especially when the products are exposed to abrasion (parquet, wooden stairs, sills, etc.)..

Undesirable in itself but because of wood processing causing increased tool wear and more energy (for example, sawing oak hard or soft lime).

Cepljivost timber:
Cepljivost the separation of wood in the longitudinal direction. Cepljivost is sometimes desirable. The vaccine produce firewood, staves for casks, shingles for roofing, wine cola, cepanice ... Undesirable in the joinery and rezbarstvu.

The flexibility of wood:
Elasticity is a property of wood that under the influence of external forces change their dimensions and return to the original dimensions when the external forces to stop working.

Tree species:
Flexible wood: walnut, linden, alder, birch.
Medium flexible wood: beech, oak, spruce.
Poor flexible wood: pine, poplar.
The flexibility of wood occurs in the force of sleepers, German sports gear ...
Toughness:

The wood in the development of Don 't break is tough. Sometimes the tough wood species manufactured skis (autumn).

Tough wood: ash, birch, willow.
Brittle wood: beech, pine, maple. What occurs wood?

A tree is a living being and as all living things on earth, is also a tree of cells.

Tree wood makes just under the tree bark.

There is a special, very thin layer of soft tissue, wrapped kipod bark from tree roots to the thinnest twigs. This layer kambij said. Kambij a layer of living cells to multiply and thus on the one hand make wood on the other bast or live part of tree bark.
Here (in kambiju) is the transformation of sugars, which are incurred in the Journal of the trees in the cellulose fibers, building cell walls of wood.

Cells that are still alive at the beginning, but soon die, woody and strong sticks together with other cells, which have delayed the tree in its interior.

The interior of the tree is therefore made up of dead woody cells.

In biological terms these cells provide support creature, created by, and serve him for a lot of things, in technical terms, they represent a raw material for further processing of wood, from felling the trees and cutting in its logs. Where wood is produced?

Les mainly produced in the trees.

Formed in some bushes and other plants, but these plants are not attractive to nadalnjo predeljavo wood.

A tree is a plant species specific. All my life growing in its interior and hard wood manufactures. Tree wood made from special material, which is called cellulose. Wood consists of cellulose around as the line of beam, the beam from the beam in tanji+?ih ... and so on to the thinnest thread and fiber. Thinner fibers, of course, represent the cellulose fibers.

The truth is, a tree found in many other substances.

What substance is cellulose?

Cellulose is a substance that is built like a chain. < Chain consists of its articles. just as chain composed of cellulose smaller units, which in this case called monomers. in what follows, we will be limited primarily to those types of deciduous trees more frequently found in the application, then the products that surround us daily. These types of deciduous trees are: beech, oak, ash, maple, elm, cherry, walnut.> Durability of wood Durability of wood is a property of wood, which tells how the wood resistant to rotting and decay and how long retain their original properties. Durable wood is naturally more resistant to rotting and decay, while, non-perennial wood decay faster. Lesov permanent feature is that the longer withstand the conditions that are favorable for the initiation of decay (high humidity timber, favorable temperature). This feature exploited everywhere where the wood is constantly in contact with moisture, either in the soil, water or air. Thus, in such species produce a variety of poles, piling, kostrucije exposed to rain and the like. Les essentially destroying insects, fungi, weather conditions (rain, sun, air) and mechanical wear. No wood is safe from pests, only more and less resistant. Permanent lesov are: oak, chestnut, acacia, larch, pine, some elm, walnut ... decidedly non-perennial lesov are: poplar, linden, fir, beech, maple, and ash.> Strength of wood Strength of wood is a property that tells how much load is transferred timber before rupture. The solid wood delegate much of the burden before the break, and, conversely, weak wood does not transfer large loads. On the strength of the wood greatly influenced by gravity (density) of wood. Heavier, denser lesov therefore, are more solid than the lighter lesov. After solid lesov se+?emo when building various structures, furniture, and everywhere there, where the wood transferred much of the burden. Solid wood, the wood is oak, ash, Brest, beech, acacia, Gabra, larch.Hardness of wood Hardness of wood is a property that tells what kind of wood surface provides resistance to a force with which it operates in this area. Such a force can be a tool by which the processed wood, which drsamo shoes, for example Mon floor or effort which zabijamo nail into the wood. Lasa species could be roughly divided into hard and soft. Hard lesov difficult to cultivate and are more resistant to surface wear. Soft lesov and easier process, the surface are prone to wear and are generally easier on hard lesov. Hardwood rule uporabljmo for flooring, staircases, furniture ... while more soft wood packaging, construction wood, carved, modeling and so on. Hard lesov are: hornbeam, acacia, pear, oak, elm, beech, ash, maple ... Soft lesov are: spruce, fir, pine, larch, linden, poplar, alder, birch, chestnut, willow, ... Higroskopi|?nost wood Higroskopi|?nost the property, which indicates that the timber is capable of absorption and transmission of water, then drying and moisture. Wood can absorb water from the air (humidity), but can absorb water, which is in liquid form. This is the process of wood moisture. Then les nabreka. It is also suitable timber okolo+?|?inah emitting water into the air, then dry. In doing so, convulsions, usually bang and is being developed. When logs raz+?agajo in boards, the wood in the damp boards. Such boards should be before they processed into products dry. To do this, to explain to a bunch of boards, among them the lateral insert molding. Thus prepared wood then air-dried, or in specific indoor (drying), at higher temperatures. Only in ovens dried wood is ready for processing into products such as furniture, floor coverings, doors, windows .. Dried wood can be in the moist air or water re-wetting. Man and forest have been have always been closely linked. Forests have been in all periods of human refuge, represented les multilateral and of vital raw materials. In biological terms, the forest habitats of various tree and other plant and animal species that inhabit a habitat (biotope) and during which the Government of biological balance. Forest ecosystem is considered as biology, the use of wood for the manufacture of items and technologies.

Wood can save our planet!