Untreated timber

From CollabLandWiki

1 Manufacturing / extraction processes
2 Material properties
3 Format & finish of materials
4 Common fixing methods
5 Durability and maintenance requirements
6 Life-cycle / recycling possibilities
7 List of manufacturers / contractors / suppliers
8 Product information / specifications
9 Visit to City Timber Ltd
10 Precedent 1
11 Precedent 2
12 Precedent 3
13 Precedent 4
14 See also
15 References
16 External links

Manufacturing / extraction processes

Trees takes over hundred years to grown

Wood is quite common material that has been used in Architecture design. There are two kind of wood types, softwood and hardwood. Untreated timber has its natural durability and manufactured out of toxic chemical treatment. It is considered as a perfect ecological material which has been used both indoor and outdoor. New Zealand mainly produces soft pine, so most species has been imported from Australia and overseas. There are several steps of manufacture and extraction processes.

The tree is cut down

Critical analyze the chosen area

Trees take over hundreds years to grown, so the chosen forest area need critical analysis before it is cut down.

Kiln Drying

The temperature of Kiln drying can be adjustable depend on the proprieties of trees themselves. The moisture of laminating stock should keep :12 %< the moisture of laminating stock <18%, so it would not damage the shape of timber. Surface checking is necessary if it is under stress.

Grading

There are severl GL grade numbers for designer to use.e.g.GL8 grade,GL10 grade,GL12 grade

Material properties

Growth rings

With changes of year, trees increased diameter by adding new layer of cell and growth rings. Thus, there are three direction changed while the tree growth. Longitudinal, Radial, Tangential are three directions to describe wood properties.

Heartwood which has darker color and more decay resistance. By contrast Sapwood has lower natural decay resistance.

Untreated timeber will absorb moisture to reach the equlibrium moisture content

Moisture in wood

Moisture content of wood can be vary depends on the different seasonal. Normally, fresh cut wood content around 50%-200% moisture. After drying, the rate will approximately 25%-30%.However, as long as it expose to the environment it will absorb moisture to reach the equilibrium moisture content.

Density can be quite vary depend on different species

Density of wood

Density can be varying within species. It depends on the size and thickness of cell wall. Moreover,Moisture content can affect the density rate. More density means it got more durability.

Strength of properties of wood

Bending

Compression Parallel to Grain

Shear

Side Compression

Format & finish of materials

varnished timber.

kiwila left natural.

ruff-sawin timber.

Most untreated timbers that are used outdoors are hardwoods which produces natural tannin that protects it from the elements and does not usually require a special finish. Some less durable un-treated timbers do require some sort of finish to protect them from the elements.

Common uses for untreated timber is anywhere where human contact is regular or where treated timber has a dangerous effect on the environment.

Such as decks, platforms, board walks, playground structures,furniture, seating chairs.

These uses also effect the type of finish used.

Clear Finishes/Timber Stains

This form of finish is mainly used were protection from the environment is required but there is a desire to keep the natural form of the timber. They come in a range for different purposes and protection.

Penetrating semi-transparent stains

These stains protect the surface of the timber from the elements and still show the texture and grain of the wood. But is only a temporary protection Finnish.

Film-forming transparent finishes (Varnishes)

Varnishes are favorable for being easy to clean and UV resistant meaning better protection.

Film-Forming stains

Similar to diluted paint and has a colour stain but is not very protective.

Oils

Helps protect against weathered look but is high maintenance and needs to be done seasonally.

Paint

Acts as a film over timber protecting it from the elements comes in two types that have different advantages.

oil/solvent based paints work best where there is a hardworking surface as these paints are impact resistant good for furniture.

Water borne tends to be less brittle with age and more durable.

Common fixing methods

Bolts used to connect timber to steel.

stainless steel Bolts used to connect timber to steel.

timber slats screwed down.

Bolts connecting timber to steel.

There is a wide range of timber fixings avaliable. The choice of what type of fixture is used is determined by certain factors such as environmental conditions which will determine how corrosive resistant it will have to be. Where the connection is and whether it will be taking a load or capacity or what material it will be connected to.

Timber to Timber - Glue, Nails, Screws, Bolts, Nail plates

Timber to steel - Bolts, Screws

Timber to Concrete - Bolts, Fired shot nails, Masonry anchors

Bolts most versatile fixing method for connecting to different materials. In timber to timber applications it is often used to attach beams and sometimes used with steel brackets and is the main method for attaching timber to steel. Bolts when used outdoors are required to be galvanized or stainless steel to prevent deterioration.

Nails Used outdoors they must be hot dip galvanized to have sufficient corrosion resistance. frequently used in timber to timber applications.

Screws Main factor to consider is head and thread size. Has a more secure and stronger connection than nails.

Masonry anchors Attaches timber to concrete through the use of expansion in a drilled hole in the concrete securing it.

There are more older traditional ways for fixing timber such as mortise and tension joints that are connected with Dowling the advantages of this allows movement that is experienced with fluctuating moisture levels

Essentially fixing methods are designed for specific purposes

Durability and maintenance requirements

Beneath the water the wood is protected from heat and oxygen but the trasition to air is where deterioration occurs.

Deterioration occurs where water can get into the wood, especially around bolts,joins and deepening cracks.

Untreated timber being used for its durability as walkways with in Waitangi Park, Wellington.

Untreated timber doesn't last forever and does need to be replaced as we see at Wellingtons waterfront.

There are two main things that affect the durability of untreated wood. They are fungi and insect attack.

Fungi (or rotting) occurs when there is enough oxygen, moisture and heat available. The most influential factor that we can control to an extent is moisture, as heat and oxygen are usually always present. Therefore the woods that will endure are the driest and the most dense so that that the moisture cannot get in. If the timber has less than 20% moisture, rotting does not occur. The greatest amount of deterioration of timber occurs when water is absorbed through an uncovered end cut, and around bolts or joins in the timber.

The primary concerns in New Zealand for insect attack come in the form of wood-boring beetles, mainly Anobium and Lyctus. Treatments are very effecient at stoping borer. Untreated timber is more at risk but is usually sourced from heartwood at the centre of the trunk where it is the hardest and often contains natural resins (such as the Western red cedar) that make them naturally resistant to borer without any chemicals. Pill bugs (Sphaeroma) can burrow into the timber but treated timber is as susceptable to this as untreated as the bugs do not ingest the wood.

Durability of Untreated Heartwood of New Zealand-grown Timbers

Perishable (<5years) - Silver birch, Tawa, Corscican pine, Ponderosa pine

Non-durable (5-10years) - Eucalyptus regnans, Oak, Pukatea, Radiata pine, Douglas fir, Kauri, Western red cedar

Moderately Durable (10-15years) - Eucalyptus globulus, Silver beech, Macrocarpa, Californian redwood, Rimu

Durable (15-20years) - Eucalyptus saligna, Hard beech, Red beech, Southern rata

Very Durable (>25years) - Robinia, Silver pine

Very Durable Imported - Jarrah, Teak, Kwila

Untreated timber doesn't require maintenance which is a huge benefit for landscaping in public spaces. The down side to this quality is that, like everything outdoors, it does need to be replaced eventually.

Life-cycle / recycling possibilities

Untreated timber is cut and milled, then transported straight to the timber merchant, therefore the product is free from any chemicals. Because untreated timber is environmentally friendly and the timbers suitable are very hard and naturally durable, most untreated timbers are suitable for recycling.

The sustainability of untreated timber is not prosperous and has seen the use of treated timber increase greatly. The reason being that it is more economical to grow a pine for 15 years and treat its timber to last 150 years than it is to grow a rimu for 400 years and its timber last for the same amount of time untreated. This is a big motivation for untreated timber to be reussed.

Marcrocarpa railway sleepers recycled to form steps along Wellingtons Waterfront.

Untreated timber shredded to make garden mulch.

Untreated pine used as temporary stakes.

A common example of recycling is when the Macrocarpa railway sleepers are used to achieve the aged look in peoples gardens or within the city landscape, as is the case with Wellingtons Waterfront. Often when an old building made of rimu or kauri is demolished, the untreated wood is sold and made into furniture.

Untreated timber can also be chipped and shredded into a range of landscaping mulches for gardens.

An untreated timber that cannot be recycled is pine. Pine is a soft wood and needs to be treated to endure. It is used untreated when its use is temporary but needs to be non toxic, for example garden stakes.

List of manufacturers / contractors / suppliers

City Timber Ltd

210 Thorndon Qy Thorndon Wellington Phone number: 0-4-473 7987

Woodlink Importers

5 Seaview Rd Seaview Lower Phone number: 0-4-566 9699

CedarCorp Canada Ltd

65 Nelson St Petone Phone number: 0-4-566 8010 [1]

Lumber & landscaping Suppliers Ltd

4 Benmore Crescent Manor Park Lower Hutt Phone number: 0-4-563 5050

Midway Timber Ltd

3 Western Hutt Rd Petone Lower Hutt 0-4-576 9633

Midway Timber Ltd

3 Western Hutt Rd Petone Lower Hutt Phone number: 0-4-576 9633

Product information / specifications

Some timber species used for landscaping

Balau: decking, exposed beams, handrails,balustrading for decks, bridge construction

Ironbark: electric fences, wharf and bridge construction

Jarrah: decking, exterior framing, railway sleepers, power poles, bridge and wharf construction

Karri: exterior framing, decking

Kwila: decking, exterior joinery, posts, beams

Macrocarpa: decking, weatherboards

'Saligna' (Blue Gum): outdoor furniture, decking

Turpentine: wharf piling, wharf decking

Western Red Cedar: finishing timber, roof shingles, weatherboards, joinery, shakes, garage doors

Timber can be sawn into different sizes according to different uses in construction.

Exp:Sizes for Decking

65mmx19mm, 90mmx19mm , 90mmx32mm, 140mmx19mm,140mmx32mm

Visit to City Timber Ltd

City Timbers Ltd on Thorndon Quay in Wellington, imports exotic, mainly untreated timbers. They recieve the timber cut into planks from New Zealand mills and from overseas. They make trimmings and resize the timber on request. Redwood is their main product but also stocked marcocarpa, NZ Kauri, jarrah, tawa, saligna and kwila.

Saligna and jarrah were recommened to last the longest in the landscape.

The stockyard was all contained indoors as to prevent any deterioration. It was also quite small reflecting the amount of untreated timber being used in comparison to treated timber where the stockyards are outdoors and a lot bigger with more stock but less variety.

Precedent 1

Averill Clarke

This detail in the asphalt along Wellington's Waterfront was created using untreated timber. Wellington has an image and theme, especially along the waterfront and untreated timber supports it. The look is very industrial and utilitarian, with subtle details and repetitive use of simple forms and colours. Bright yellow paint transforms ordinary objects into focal points amongst a wash of greys and browns. The pedestrian passageways are wide and modern with a deconstructuralist theme; sucessfully and modestly building the new alongside the aging. This creates a visible history of the former port.

I think untreated timber was a suitable choice for this detail as it is flat and unobstructing both physically and visually. The colour of the timber fits very well with its surroundings and makes time visible as it fades and slowly develops signs of wear. Being that this is a public and highly used area, untreated timber is beneficial in that it requires no maintenance and does not disturb the programme of the site.

A Marae is a place that needs to be peaceful and uninterrupted. Now that the city has expanded and the land is expensive and difficult to obtain, this Marae has found itself in the middle of the industrial section along Thorndon Quay. They have tried to separate their space from the city and one way they have done this is by using untreated wood around its boundary.

I think that using the untreated wood in its natural form, unsawn, has made the Marae stand out amongst its city surroundings very efficiently and peacefully. From the outside the organic linear form is so much softer than the concrete blocks around it and the colour is unexpected among the artificial brightness of advertising. From inside the Marae grounds the fence differentiates the two spaces. I think the naturalness of the wood also acts psychologically - if you can't see the traffic and the city, their sounds and presence are reduced.

In this case the choice of untreated timber was mostly visual, the same effect would not be achieved with treated sawn timber.

Waitangi Park in Wellington has a river flowing around the outside of it. It is representing the old Waitangi river that used to flow in this area, and is the reason for the park's name. The reeds planted in it were placed in rows to act as a filtering system for the storm water that is channeled into it and out to the sea. The whole process is very ecological. On the banks of this unearthed river John Wardle Architects have used untreated timber blocks.

This was very sensible and is in keeping with the environmental theme of the park as untreated timber does not have chemicals and will not contaminate the water that is being filtered. I think that the less chemicals we can use the better, and if not for such a focus on economics, untreated wood would be used more often.

The look of untreated timber also suits the theme of Waitangi Park. It is a colour that is found in New Zealand soil, clays and plants. It creates another visual reference to nature and pre-European times which the design of the park is aiming for.

This sculpture along Wellington's Waterfront is very reminiscent of growing trees. There is no finish, no colouring and no chemicals added and so as well as looking more like a tree it is literally closer to being a real tree. As this timber is weathered by rain and heat its textures will evolve and become more distinctive. The colour will also progress, showing its age. All along the waterfront, the untreated timber will be doing the same thing. This generates a familiar feel in the overall area and gives a synchronisation to the landscape.

I think that this use of timber could have been done using treated wood but that would have caused the meaning to be lost. It also would go against the whole theme that the different designers of the waterfront are taking into consideration.

The 'City to Sea Bridge' links Wellington's Civic Square to the Waterfront. Civic Square is paved with orange bricks giving it a busy, bright character. The Waterfront is composed of quite dark and similar colours drawing peoples' attention to the sea. The bridge is a transition between the two. It is the neutral grey colour of untreated timber but has a lot of detailing with in the wood, similar to the brick patterning. These details form cubby holes that children crawl into, and bigger ones which people rest in.

Because people are in such close contact with the wood, it needs to be untreated. The chemicals used in some treatments of wood are strong and should be avoided. This is the same reason that playgrounds are made from chemical-free timber. I think that the same effect could have been achieved with treated wood but untreated was chosen because of this health hazard.

Here is another example of untreated wood being used instead of treated because of its harmful chemicals. The hand rail attached to the wall is used by many people daily and cannot afford to be treated. The colour of the timber is also appropriate. It fits in well and is not obtrusive to the overall look.

Another reason that treated wood can be used in this situation is that untreated wood tends to be very hard and difficult for water to penetrate. As long as wood can stay dry on the inside, it is safe from fungi which causes rotting.

Precedent 2

Liam Hosford

This sculpture is a new addition to Wellington’s water front. It is good evidence of recycling untreated timber form the wharf. The use of this untreated timber in a dominant vertical element and placed into a grove like formation links it to its original situation of growing as a tree and will look more like a tree as it ages. The fixtures on this sculpture are also interesting as they prop the timber above the ground almost as if its floating.

This is the main bridge entering Waitangi Park and shows how kwila slats can be used in mass to serve several purposes. Such as shelter from wind, rain and sun and allowing interesting shadows to be casted. Also being situated above water it is good evidence of untreated timber being used in environmental issue situations where chemicals in treated timber pollute the environment and water ways.