Back2Wood.com - wood products
Everything about wood and wood products. why wood is so good and how we can use it more
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.
What occurs wood?
Where wood is produced?