Timber Project Essay Research Paper 1

9 September 2017

Timber Project Essay, Research Paper

1. Timber has been a edifice stuff since adult male foremost came out of his cave. The grounds for this are due to timber being a plentiful merchandise and the belongingss it holds, being that lumber is high in strength, light weight, and moderately lasting. Timber can be cut and shaped easy without the usage of machines. Prehistoric adult male found that these belongingss were ideal for edifice houses, boats, and Bridgess. Timber is now has many different utilizations, including paper, furniture, doors, Windowss, cosmetic objects and structural members etc. The utilizations for lumber is eternal and every bit long as the replanting continues and our resources are retained coevalss to come will bask the benefits lumber has given us.

There are two categories of lumber:

Gymnosperms ( Evergreen, deal, conifer )

These are the most crude type of tree, the foliages are in the signifier of acerate leafs they have one chief root and a conelike form to the crown e.g. Douglas fir rather speedy to turn.

Angiosperms ( deciduous hardwood )

These are blooming workss and are more advanced in development than conifers. They have wide foliages, multiple roots and a ball-shaped Crown form. E.g. Oak, Walnut. Slow to maturate and expensive to buy compared to softwood.

In a life tree the sapwood is merely under the bark of the tree. The sapwood is the trees transit system for foods, sugar and H2O. The duramen in the Centre of the bole provides structural stableness for the tree. The sapwood following to the duramen is in the procedure of being converted to duramen. The sapwood has a higher MC than the duramen.

2. Properties of lumber

Tensile strength

The tensile strength of wood is non great. The molecular construction of the cells of the wood tear apart easy but can be compressed with a high sum of force before the wood disfigures. Beams used in utmost tenseness are normally made of steel or re-enforced concrete. Timber can hold utmost fluctuations in strength with different species of wood and different parts of the tree.

3. Compressive strength

The compressive strength of wood in an mean piece of lumber with a denseness of 513 kg/m| has the compressive strength of 30 & # 8211 ; 40N/mX

Timber has a higher compressive strength than tenseness strength due to the wood being cellular. The cells can grip on to each other keeping the wood together. Concrete has a greater compressive strength than lumber but less in tenseness. Old ages ago the wood strength was non known, this lead to the complete specification of many edifices, and blowing valuable resources. With today s engineering stuffs can be used to their maximal possible minimising waste and over specifying.

4. Elasticity

Timber is an elastic stuff, which means when a mass is put on a piece of lumber it deflects and when the mass is removed the lumber returns back to its original place, up to a certain good defined bound of emphasis. The output emphasis point can change on the size, and type of lumber. Timber can change in strength. So frequently the emphasis scaling of the lumber is greatly under estimated.

5. Water Absorption

It is recommended that the wet content of lumber be kept below 20 % , if any greater sum of wet is present so decomposing and insect infestation can happen ; the normal mean wet content is 12 % . The airing of the wood is a really of import facet of design, if lumber is kept dry and ventilated it can last a considerable sum of clip.

The weight of dry wood = Wd

The wet content = MC

The wet weight = Wm

MC = Wm Wd. 100 %

a. Wd

Timber which has wet content of 100 % means that the weight of the H2O is equal to the weight of the wood. It is possible for lumber to hold several hundred per centum MC.

The loss and addition in wet within the wood causes shriveling and swelling in all waies this can do many jobs and have terrible effects

6. Water repellant

Naturally wood absorbs H2O and does non drive, the wood needs sealing with a H2O immune stuff i.e. pigment or varnish. The wood can be treated with preservative to try to battle both insect and fungi onslaught. Preservative intervention of lumber involves presenting sable chemicals into the wood construction protecting it from fungi onslaught. Preservation of lumber is insurance, non an alibi for cutting corners or turning a blind oculus to mistakes in design or craft. No lumber is wholly immune to disintegrate and in much the same manner no preservative intervention provides absolute protection. ( TRADA wood information ) A big figure of interventions available for wood are in the appendix.

7. Conduction of Electricity

Timber does carry on little sums of electricity it is non the cells of the wood, which conducts, it is the wet content in the lumber, which conducts the electricity. Moisture metres use this rule for mensurating the MC of wood.

8. Thermal insularity

Thermal conduction ( K ) is a step of the rate of heat transportation through a given thickness and country of the stuff from FACE to FACE. The units for this are W = Watts, m = meter, mX = country, K = Kelvin, there for W/mK+ . Timber is non frequently used in the building industry for its thermic belongingss it is more normally used for structural and cosmetic grounds. ( See figure 1 )

Figure 1

Bulk Densitykg/m3 Material Thermal conduction ( K ) W/mK Thermal electric resistances ( lk ) mK/W

513 Softwoods & A ; plywood s 0.124 8.07

769 Hardwoods 0.16 6.25

961 Plaster board 0.16 6.25

2260 Concrete 1:2:4 1.44 0.69

1700 Brickwork 1.45-0.73 0.69-1.38

16 ; 24 Expanded polystyrene 0.035 28.6 ; 30.4

Timber is a natural dielectric. Air pockets within its cellular construction make timber a natural barrier to heat and cold. Wood combined with fibreglass insularity provides an first-class dielectric.

Since thermic conduction additions with denseness, lightweight lumber is a better dielectric than heavy lumber. Thermal conduction varies somewhat with wet content and natural features such as cheques, knots and grain. The thermic conduction of steel is about 400 times that of lumber ; concre

Te 10 times, brick and glass 6 times. Mineral wool has 1/3 of the conduction of lumber.

Mentions:

Timber Datafile P1 Timber Species and Properties of the NAFI Timber Manual Timber Species and Properties

9. Thermal Motion

By and large the thermic motion of lumber is little about 13.3mm / metre which make this an ideal stuff for an country with a big temperature scope i.e. a roof infinite with the temperature runing from every bit low as 10|C up to 40|C lumber is an ideal stuff for this intent. Expansion articulations are non usually required even in big constructions. A rise in temperature of 1.C can cut down the strength of lumber by 0.3 % .

10. Acoustic belongingss of lumber

Acousticss is the scientific discipline of all hearable sounds. Room acoustics is control of wanted sounds within a room. The control of unwanted sounds in a edifice is sound insularity. Timber can play a big portion in both room acoustics and sound insularity.

An of import acoustical belongings of lumber is its ability to muffle quivers. The cellular web of meshing pores converts sound energy into heat energy by clash, the quiver of the fibers causes heat.

Wood has more muffling capacity than most structural stuffs. Muffling reduces the inclination of constructions to convey quivers long distances ; it besides reduces the magnitude of resonating quivers, bettering the public presentation of wood paneling as a brooding surface.

Mention: Timber Datafile P1 Timber Species and Properties, NAFI Timber Manual.

11. Cell construction

Structural burden can be supported by utilizing cylinders in the signifier of pipes, this is true for the construction of a tree within the monocular construction of the tree there are 100s of cannular cells running longitudinal to the tree bole, this type of cell construction gives the tree its natural strength. The lumber fibers are composed of cellulose and hemicelluloses and these are bonded together basically by lignin.

Softwoods by and large contain more lignin than hardwoods

The mean proportions in dry wood are:

45 to 60 % Cellulose

10 to 20 % Hemicelluloses

20 to 35 % Lignin

( Ref 7 ) ( pg 31 )

12. Lastingness

The lastingness of lumber is merely concerned with the duramen and non the sapwood. The sapwood of most species is non really lasting and should non be used in open conditions. In BS EN 350-1, is the usher to natural lastingness, which is split into 5 categories for the lastingness of the lumber?

Class 1. V Durable Ebony

Class 2. Durable Mahogany American

Class 3. Reasonably lasting Mahogany African

Class 4. Slightly lasting Maple

Class 5. Not lasting European Ash

The most common type of debasement is fungi onslaught which can go on anyplace. When the wet content of the wood reaches over 20 % the common manner to forestall the wet making this high is to air out the lumber, so any wet can vaporize. Preservative intervention is discussed in the appendix.

13. Suitability

Joinery of lumbers ; both hardwoods and deals can be used for joinery plant. Softwoods can be selected for its belongingss. If the coating is to be painted the type of wood is non excessively of import due to fact that the grain will non be seen. Softwood lumbers are normally used in this case. Hardwoods are normally left their natural coloring material and treated with preservative or coated with a clear varnish to widen their life anticipation. The coloring material and type of grain are of import when choosing a type of hardwood. When high-class joinery work is involved. Timber can be prepared ; unsmooth sawn or planed, each is suited for a different type of plants i.e. :

Rough sawn lumber would be used for roof trusses and floor joists which are strictly structural and non normally seen. Cheap deals are normally used for this type of work. This lumber is treated due to it being portion of the construction of the edifice.

Planed lumber, which is more expensive to bring forth whether deal or hardwood can be used in, furniture, Windowss, hedging boards, door liners, step instances etc and many more different merchandises.

Workss of a windmill in Poland the chief beams are oak and the dentitions are apple wood.

14. Economic considerations

Timber is a natural merchandise, a renewable energy resource it can be regenerated over clip, the deals like pine are comparatively speedy to turn but the hardwoods are slower to turn and hence more expensive to buy.

Conveyance and edifices are the major manufacturers of C dioxide because they are the chief energy users. In the UK, edifices account for around 50 % of the state & # 8217 ; s C dioxide emanations.

Timber can assist to run into the menace of planetary heating in three ways:

Trees absorb C dioxide and release O into the ambiance through the natural procedure of photosynthesis ( See fig 1, ref 7 ) . A immature tree, turning in a decently managed wood, is a more effectual vehicle for C dioxide soaking up than a mature wood.

Converting lumber into a useable edifice stuff takes far less energy, it generates less C dioxide, than virtually any other alternate including aluminum, steel and concrete.

Once installed, wood is an highly effectual insulating stuff with a really high energy efficiency. Indeed, lumber framed houses are widely recognised as being top performing artists. ( Ref: 5 )

( Ref 7 )

Britain has an active, booming forest sector, but the fact remains that we presently import about 80 % of all the lumber we use in this.

+ 69 % , derives from cone-bearing woods located chiefly in Scandinavia, Canada and Russia.

+ 3 % derives from deciduous woods in Europe and North America.

+ 8 % , is imported from tropical parts.

+ There are an estimated 223 sawmills in the UK the forest country sums to about 10 % of land country

+ Forests Forever is a run by Britain & # 8217 ; s lumber industry to assist safeguard the woods of the universe, by back uping forest direction and regeneration undertakings. Correctly harvested, the lumber is non damaging the planetary environment. Wood is a renewable resource ; it is organic, non-toxic, reclaimable and biodegradable.

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