Treated timber

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New Zealand

Manufacturing / extraction processes

Most treated timber is in its original form (tree) before it is transported to the mill. Once the timber has been cut, it is prepared for the treatment process.The logs are treated in the factory and then packaged into different sizes.The Suppliers can order from H1-H6 (except H2)sized treated timber in NZ.

Cutting Process, Mitre 10, Wellington city

Chemicals Commonly used for preservation treatment

  • Boron salts
  • Copper-chrome-arsenate (CCA)
  • Copper-based (chrome and arsenic free) alternatives (ACQ or Copper Azole)
  • Light organic solvent preservative (LOSP)
Workshop in Fernscape Garden Produces, Petone

There are three main groups of preservatives used by the preservation industry:

  • Timber treated with water-borne preservatives has a wide variety of applications, both indoors and outdoors, for residential, commercial, and industrial structures. Copper Chrome Arsenate (CCA), Ammoniacal Copper Quaternary (ACQ), and Copper azole (CuAz).
  • Timber treated with oil-borne preservatives is used primarily for heavy duty construction and in the marine environment. The most common oil-borne preservatives are creosote and pigment emulsified creosote (PEC). Oil-borne treated products include utility poles, rail sleepers and marine piles.
  • Timber treated with Light Organic Solvent Preservatives (LOSP) includes high value joinery and similar products. LOSP treated products are treated generally in their final form and shape and must only be used out of ground contact. The LOSPs include tributyl tin naphthenate (TBTN), and a number of synthetic pyrethroids like permethrin, deltamethrin, and cypermethrin for termite control.
Timber Productions in Fernscape Garden Produces, Petone

Treatment Processes

  • Pressure Methods
  1. Bethell (Full Cell) Process
  2. Rueping Process
  3. Lowry (Empty Cell) Process
  • Oscillating Pressure Method (OPM) and Alternating Pressure Method (APM)
  • Non-pressure Method
  1. Diffusion Process
  2. Hot and Cold Bath Process
  3. Cold Soak Process

Material properties

Easy to work, light and strong, available in a wide range of species sizes and finishes, treated timber is an excellent insulator and uses less energy in its production than any other building material. It can be finished in a number of different ways, adding both warmth and character to a whole variety of environments.

Cutted Cuboid Treated Timber, Mitre 10, Wellington city


  • It provides long life under hazardous conditions.
  • It is cost efficient.
  • It is versatile - can be used outdoors, indoors, above ground, underground, and in direct contact with fresh or salt water.
  • A variety of finishes provide additional attractiveness.
  • It provides flexibility for design and can economically overcome difficult site situations.
Thin or Thick Pole Treated Timber, Mitre 10, Wellington city


Main Types of Preservative:

  • Modified creosote based preservatives.
  • Light organic solvent based preservatives, e.g. Protim, Vacsol, Impresol, Cuprinol.
  • Copper chrome arsenic preservatives (fixed waterborne preservatives) e.e. Tanalith, Celcure, Sarmix.
  • Preservative compounds of boron or fluoride e.g. Polybor, Sodium Fluoride.

Chemicals Commonly Used for Preservativation:

  • Boron salts.
  • Copper-chrome-arsenate (CCA).
  • Copper-based (chrome and arsenic free) alternatives (ACQ or Copper Azole.)
  • Light organic solvent preservative (LOSP).
  • Creosote.
Sheet Treated Timber, Mitre 10, Wellington city


Treated timber is sawn into a wide range of sizes, which may be used in many ways in landscape construction. These sizes range from 25mm x 25mm though to 300x100mm. Larger cuts such as sleepers or beams may be available to order.

Sawn Timber is available in sizes:

  • 25mm thick boards and battens in widths from 50mm to 30mm.
  • 10mm or 12mm thick by 20 to 50mm wide beads for use in trellis work.
Roughness of Treated Timber, Fernscape Garden Produces, Petone


  • Rough Sawn - which has a coarse surface left by the saw. Some construction timbers maybe roughly sawn. Cladding timber and timber exposed externally may also be obtained with a rough-sawn finish.
  • Planer Gauged - the timber is gauged to the correct finished size, normally with a slightly rounded arris on the corners.


Treated timber for landscaping is graded to determine its structural properties. The sawn timber is usually used for building construction, and is required to be hard and stiff. On the other hand, the treated timber sometimes is planed to be thin and smooth to produce some wooden objects. The main requirements are for timber to have the appropriate qualities of strength and stiffness, taking into account natural characteristics such as knots, gum-veins, checks and sloping grain.

Format & finish of materials

A very large number of timber species are used in construction, but not all are suitable for external use, especially where the timber may be in contact with the ground. Where to use the different formal treated timber is depend on what type it is. Timber comes in seven different grades, all of which have diffferent properties and specifications for interior and external use.

Sawn Timber Production made for Construction, Fernscape Garden produces, Petone
Timber Construction on the Ground, Queen's Wharf, Wellington
Timber External Steps, Queen's Wharf, Wellington
Timber Street Frame, ST near Queen's Wharf, Wellington

  • H1.1 & H1.2 - Interior finishing timber, interior joinery, ceiling joisys snd wall framing...
  • H3.1 - Weatherboards, Fascia and Trim

For use in areas with exposure to the weather, and above ground.

  • H3.2 - Structural Decking, Fencing, Externaleams, Pergolas and Gazebos

Above ground use, can be used in areas where it will be exposed or protected from the weather, and in areas where there is a risk of moisture entrapment.

  • H4 - Fence Posts and Landscaping Timber

For use in areas where there will be in grounbd contact, but not for high usage.

  • H5 - Hoouse Piles, Decking Piles, Cribwalls, and Retianing Walls

for use in areas of in ground contact, large exposure to water and moisture, and for use in high usage areas.

  • H6- Marine Piles and Timber

This grade is required for fully submerged piles or timber of any size, especially around the sea where salt water is errosive.


Where to use treated timber? Virtually anywhere timber is exposed to weather, in contact with the ground or under water. Structures in the landscape constructed from timber include:

  • Fences
  • Framing to shulters and roofing timbers
  • Walling lining, cladding fascia
  • Timber decking, pool surrounds
  • Flatforms and boardwalks
  • Poles and posts, haysheds
  • Stumps, sub-floor timbers
  • Playground structures
  • Bridges,railings, marinas, piers
  • Oyster farms, vineyards
  • Pergolas
  • Steps
  • Seating
  • Retaining walls
  • Balustrading or barriers
  • Edging to paths and paving
  • Railway sleepers and wagons, truck floors
  • Water cooling tower in power stations
  • Boats

Common fixing methods

Most fixings are used to connect materials together. Fixing in timber should be selected to be durable particularly in damp or corrosive conditions. We should also consider the location within the structure, its exposure to the weather, and ensure the design is able to be constructed as desired. There are four main junctions commonly used in treated timber:

Fixing Materials (left to right) coach screw; bolt
the connection and fixing of a piece of treated 100x100 timber, attaching to a metal plate in the ground at the children’s playground at Waitangi Park
Some common materials that are used to connect tow pieces of timber together, (right) a flat nail plate; a corner nail plate; Z nails, both left and right; and a joist hanger

  • Timber to Timber
  • Timber to Ground
  • Timber to Concrete
  • Timber to Steel

The most common material used in nail manufacture is cold drawn, low carbon steel. In exterior applications, the metal in some nails may react with extractives in the wood and form stains; e.g. uncoated steel nails can cause black stains. The solution to this problem is to use galvanised or other nail types.

Various special coating treatments also increase nail-holding power and provide corrosion resistance as well as improving appearance. The treatments include:

the connection of a large timber beam, 100x400 approx, at the new extension of the Te Papa and Chaffers Marina, fixing is in connection with a concrete beam

  • electro-plating
  • polymer and other coatings
  • hot dipped galvanising

There are many fixing materials available for joining of timber and other materials. These joining methods range from joining timber to timber and timber to concrete, as well as other materials. The most common fixing methods for small urban backyard landscape, where the timber is being used for a fence, are nails, coach bolts, or normal bolts. Nails come galvanised so that they stand up to the moisture ridden conditions that they will be performing in.

The type of circumstances that the fixing is in will determine what type of fixing is needed, and whether or not this needs to have a KN rating, as in the use with joist hangers for decks and floors.

Durability and maintenance requirements

The durability of most timbers can be improved by chemical treatment, making the timber toxic to rot causing fungi or wood destroying insects thus prolonging the life of the timber.

  • CCA treated timber should be stored in a well ventilated, well drained area away from other materials. The timber should be kept dry while being stored.

Treated timber in correct storage conditions.

  • In order to withstand the longest lifespan possible LOSP treated timber needs to be painted or otherwise protected from the weather.

Boards should be stored in well ventilated areas away from heat flames or sparks.

Treated timber in outdoor situations should be painted, stained or sealed for best performance against discolouration, surface deterioration and dimensional distortion.

Life-cycle / recycling possibilities

The process of treating timber prolongs the life significantly. The life span depends on surface preparation, application, and maintenance. Ensuring that you have correctly used, maintained, resealed and where necessary painted (or oiled) treated timbers. After these steps have been followed the warranted lifespan of the timber varies between 25 - 50 years.

Kauri forest.

Because the timber is treated there can be difficulties when recycling. Treated timber can be reused depending on the estimated lifespan that remains on the timber. Treated timber has been recognized as a problem waste by council’s in New Zealand, therefore it should not be mixed with general green waste for composting. It should not be burnt. Treated timber should be buried away from any rivers, streams, creeks and dams. Disposal to a designated landfill is appropriate.

CCA treatment is being phased out as it contains ingredients which are highly toxic. The chemicals can soak into the soil if it is within contact. LOSP treated timber does not release waste into the environment. Arsenic free treated timber is environmentally and human friendly though it is more expensive and less effective. By using treated timber that is more durable with a longer life span we are demanding fewer trees which are an essential element in the carbon cycle though releasing toxic wastes into the environment. If we decide to use untreated timber, even if it is environmentally friendly, we are requiring more timber from our forests. Here conflict arises.

List of manufacturers / contractors / suppliers

  • Akatarawa Saw Mills

1877 Akatarawa Rd, Akatarawa, Upper Hutt, Ph 04 526 6645.

  • Carters

176 Hutt Road, Kaiwharawhara, Wellington, Ph 04 472 1521.

  • Carter Holt Harvey

640 Great South Road, Manukau City, Ph 09 262 6000.

  • Crightons Building Centre (ITM)

15–19 Hokio Beach Rd, Levin, Ph 04 472 4393.

  • Davis Sawmilling

Main Road North, Featherston, Ph 06 308 9099.

  • Fernscape Garden Products

1-7 The Esplanade, Petone, Ph 06 568 9373.

  • Goldpine

79 Ngaumutawa Rd, Masterton, Ph 06 377 7425.

  • Lumber & Landscaping Supplies

4 Benmore Cre, Manor Park, Lower Hutt Ph 04 563 5050.

  • Mitchpine Products Limited

Foxton Road, R.D. 12, Levin, Ph 06 368 5252.

  • Mitre 10 Mega

25 Bouvevie Street, Petone, Wellington, Ph 04 569 8311.

  • PlaceMakers

38 Tacy Street, Evans Bay, Wellington, Ph 04 387 3189.

  • Prime Pine

Little Sydney Valley, Motueka, Ph 03 528 9134.

  • South Pacific Timber (1990) Ltd

21 Ruru St, Eden Terrace, Auckland, Ph 09 379 5150.

  • Southwood milling

505 High Street, Motueka, Ph 03 528 7082.

  • Whittakers Timber Products

Ph 08 9459 6877.

Treated Timber Information / Specifications


The two most common types of treatments used are Copper-chrome-arsenate, CCA and Light organic solvent preservative, LOSP

LOSP Treated 250x50 Plain and Gauged Timber
CCA Treated 100x50 Plain and Gauged Timber

  • LOSP treated timber is used for the lower treatment grades of, H1-H3.1. These timbers are used for the interior of homes and buildings throughout the country. H1-H3.1 graded timbers are not suitable for exposed and outdoor use, as they are not treated to protect the timber under the wet, damp and moisture prone areas that occur in the outdoor area that H3.2-H6 treated timber is used.

  • CCA treated timber is a treatment that is used for the timber being used in the outdoors, where wet moist and damp conditions can be expected. The different grades allow the timber to be used in areas with different levels of moisture content, right up to H6 which is for salt water areas where the timber may be submerged.

Timber comes in seven different common grades in New Zealand, all of which have different properties and specifications for use. These are specified for their use and distribution from the New Zealand Standards Authority. These grades are; untreated, H1.2, H 3.1, H3.2, H4, H5, and H6, ranging from timber with no treatment, right up to a full treatment for areas around in and around salt water, including being submerged. The treated timbers with the most significance to Landscape Architecture, and the ones that be will be using the most of are the H3.2-H6 range.

H5 100x100 Plain and Gauged Posts, as is specified by Wellington City Council for their signage

Landscape Architecture Specific Treated Timber

H4 Retaining Wall 200x50 Tongue and Grove for easy installation
  • H3.1 - Weatherboards, Fascia and Trim

For use in areas with exposure to the weather, and above ground.

  • H3.2 - Structural Decking, Fencing, Pegolas and Gazebos

Above ground use, can be used in areas where it will be exposed or protected from the weather, and in areas where there is a risk of moisture entrapment.

  • H4 - Fence Posts and Landscaping Timber

For use in areas where there will be in ground contact, but not for high usage.

  • H5 - House Piles, Decking Piles, Crib Walls, and Retaining Walls

‘‘For use in areas of in ground contact, large exposure to water and moisture, and for use in high usage areas.

  • H6- Marine Piles and Timber

This grade is required for fully submerged piles or timber of any size, especially around the sea where salt water is erosive.

H3.2 Radiata Decking, 100x40, used on many decks around the country
H4 Fence Pailings, 100x25, used extensively around the country on small to large projects


The specifications for timber use relates solely to the amount of moisture and water that it will be in contact with, both permanently and temporarily.

CCA timber has been approved for use in under the New Zealand Standards Authority, under the NZS 3640, as well as being approved by the New Zealand Environment Risk Management Authority, ERMA.

Anything that is going to come into contact with water and moisture and is of semi permanent presence will need to be of the treated variety. This means the H3.2-H6 range. Depending on the exact type and use of the timber, will determine the actual grade needed or required for the job.

Backyard Landscaping

  • Fence Pailings are an H3.2 or H4 timber.
  • Fence Rails are an H3.2 or H4 timber.
  • Fence Posts ar an H4 or H5, depending on their location conditions.
  • Decking (Radiata) is H3.2 (this needs to be slightly elevated from the ground; it cannot be laid directly on top of soil.)
  • Retaining Wall timber is usually H4, and the best form is Tongue and Groove, which makes for simple construction.
  • Garden Edging will be a H3.2, or even an untreated timber, depending on what type of plants are being grown around it.

Urban Landscaping

  • Post and Piles are H4 or greater, and Wellington City Council now specifies that H5 is to be used to achieve the best results, and for sustainability.
  • Marine Piles are H6 graded and in most cases have concrete bottoms, so that the timber is not constantly submerged.

Fences and Decking are as above.

Costal Landscaping

  • Anything close to in or on water needs to be H6 treated. This will sometimes have to be specially ordered, but is required under law.

Precedent 1 - Treated Timber Use Along The Wellington Waterfront


Location: Queens Wharf, Wellington Waterfront. Taken: 16 July 2006. Here treated timber can be seen in a structural form, used to construct and support a bridge along Queens Warf Waterfront. The likely treatment of this timber is H5 or H6. this is able to be determined by its situation, being near and above the sea, with the possibility of splashes and/or submersion. The size of the pieces of timber used will be an engineering requirement due to the amount of people using it daily, its weight, and size. It has successfully been used here in a structural and supportive way. This is not the most aesthetical, but the job is completed to satisfactory requirement.
Location: Waitangi Park Children’s Playground, Wellington Waterfront. Taken: 18 July 2006. Within the children’s playground you can see some H4 or H5 timber piles being used to construct and support the walkway at Waitangi Park. Treated timber has had to be used due to the amount of moisture that will be stored up in and around the base of the piles, where they meet the sand and footing. This could cause problems if the timber was not treated. Due to what the timber is in contact with, the treatment will need to be effective enough to stop it rotting and self destructing, therefore making the walkway unsafe. This construction has been done well and the minimal elevation of the walkway has meant that the construction and underside of the walkway is well hidden, and out of site, but this will also add to the moisture content.
Location: Wellington Waterfront, Rowing Club Island. Taken: 16 July 2006. In this photo it can be seen how timber, and more precisely treated timber can be used effectively in the landscape, without being just a construction material, or common fence type. Here pieces of 50x200 H5 or H6 have been bolted onto the concrete edges of the Rowing Club Island, and act as a fence and barrier from the sea, as well as a Landscape Architecture feature. I think this fence/wall has been well completed. It helps to illustrate the height of the high tide, by the water marks left on the timbers front faces.
Location: Queens Wharf, Wellington Waterfront. Taken: 16 July 2006. This feature is the entrance to the Queens Wharf car park which is situated underneath Queens Wharf. The access in and out to the waterfront is via this entrance/exit. Pieces of 150x25, most probably H3.2 or H4, treated timber have been used to act as the boundary and barriers to this entrance, and act as a fence on the top of the wharf, to stop people falling into the access way. The timber will not need to be more than H4 as its moisture content and situation will not require a timber of greater grading. This timber is not being used in a structural manner, but more in an aesthetic way, to signify the entrance and the make an interesting pattern.
Location: Jack Greens, West side of the City to Sea Bridge, Wellington City. Photo Taken: 18 July 2006.This is a planter box at Jacks Green, which has been constructed using treated timber to create a retaining wall. The 100x100 H4 or H5 posts line the corners and are placed at some points along the walls. This is to hold the weight and pressure of the soil and trees planted within them. The moisture content that will be evident within the planter box is the determining factor as to the timber grade needed. This will hold up under the conditions and intense moisture that is present and the extreme conditions that it will experience in its waterfront location.
Location: South end of the City to Sea bridge, Wellington Waterfront. Taken: 16 July 2006. The use of H4 or H5 treated timber in poles on this bottom end of the city to Sea Bridge is evident from inspecting it. The treated timber has been used here in a more sculptural and aesthetic way, as a part of the bridges design. The amount of moisture that will be collected around the base and junctions of this feature will be high, as the concrete wall and timber creates a barrier with no through flow. The treated timber is being used to support and hold up old railway sleepers which are the feature of this part of the City to Sea Bridge.

Treated timber in Waitangi Park


1. Waitangi park,fence separating playground from pathway.
5. Waitangi park,pergola
2. Waitangi park,bench
3. Waitangi park,wharf corridor
4. Waitangi park,steps
6. Waitangi park,pathways

1. This fence acts as a boundary between a pedestrian path and the childrens playground.Its ideal height and durability protects the saftey of children yet is unobtrusive to the public.The material is ideal for its purpose and its construction is interesting and tasteful.

2.These bench seats are a repetitive element around the park.Simple and functionable,these benches made with a treated timber seat will have a long lifetime and will be appreciated by many.

3.This treated timber corridor provides an excellent barrier from extreme weather yet does not prevent the public from viewing the harbour.The corridor wall is chemically treated to prolong the life of the timber and prevent weathering.

4. Steps add a rhythm or pace to the experience. The substantiality of the timber makes one feel at ease when stepping up onto the path. The timber is reliable and can withstand all conditions.

5. The angles of treated timber on the pergola provide a space to retreat from the weather. This is a shady resting place creating an additional dimension to the landscape. This is shown by the shadows it cast and the height it adds. The structure could only be made from the strongest and reliable of products.

6. Pathways provide a disciplined journey. The designers of the park will have wanted the public to experience specific elements and though the use of pathways this can be achieved. This experience is enhanced through the repetition of timber, change in path direction and raised platform.

Precedent 3


Fixing Timber to steel
Fixing Timber to concrete
Fixing Timber to timber
When the atmosphere and the moisture corrode too much on treated timber, it costs molds even they have been well treated.
Treated timber creates a really comfortable space.
Examples of different fixings used in treated timber
Examples of different fixings used in treated timber
Examples of different fixings used in treated timber

My precedent is Queen's Wharf in wellington city and some treated timber in use everywhere. Basicly I just showed a range of fixed timber joints and they are pretty much four main methods for fixing you can see in landscape furnitures which based on treated timber. Also, Queen's Wharf is an open and relaxble exterior space in Wellington, most of the structrue there including the bridge are used in treated timber. Dring daytime, Wood actually absorb sun temperatrue a lot so it's a good place for having picnic as well. Because of the sea moist, some of the timber got moss growing on them but it's the hardest part for treated timber because they can't last that long like concrete or some other materials normally used in exterior.

Precedent 4

User:Echo Liu

Timber fencing as a gate, Garden supply, Petone

Timber Construction on the Ground, Queen's Wharf, Wellington
Timber External Steps, Queen's Wharf, Wellington
Timber Street Frame, ST near Queen's Wharf, Wellington

Treated timber house construction, Garden supply, Petone
Timber house frame as a wall, Garden supply, Petone


The treated timber is used in different areas depends on what type it is. Bascially, the formats and properties of treated timber include its size, colour and lustre, and roughness. There are 7 different types (H1-H6), except H1.1 and H1.2 are used in the interior architecture and industral furniture making, the other 5 types (H3.1, H3.2, H4-H6)are used wildly in landscape.

Where to use treated timber in landscape? Virtually anywhere timber is exposed to weather, in contact with the ground or under water. Structures in the landscape constructed from timber include:

  • Fences
  • Framing to shulters and roofing timbers
  • Walling lining, cladding fascia
  • Timber decking, pool surrounds
  • Flatforms and boardwalks
  • Poles and posts, haysheds
  • Stumps, sub-floor timbers
  • Playground structures
  • Bridges,railings, marinas, piers
  • Oyster farms, vineyards
  • Pergolas
  • Steps
  • Seating
  • Retaining walls
  • Balustrading or barriers
  • Edging to paths and paving
  • Railway sleepers and wagons, truck floors
  • Water cooling tower in power stations
  • Boats



1. Fernscape Garden Products

2. PlaceMakers Evans Bay

3. Mitre 10 Wellington

4. "Notes for Builders, Timber Treatment Requirements" Page 4-5, Mitre 10 supply

5. "Landscape Construction" Page 41-47 Page 130-137

6. "Treated Timber Frame Foundations" D.C.Airey and R.C.Cooney Page 5-11

7. "Wood Preservation in New Zealand" NZ Forest Service Information Series No. 72 Page 9-11

8. "Construction materials" JM Illston & PLJ Domone,Spon Press,London 2001.Pages 515-520










18.BRANZ Ltd consumer helpline 04 237 1170

External links


Manufacturing / extraction processes

The treatment of timber has been around as long as the use of wood in construction. Preserved wood has been dated back to the days of Ancient Greece and Rome. Since then we have made many modern advancements in the wood preservation industry. Today, treat wood in a pressurized cyldrical chamber. The first step of pressurized wood treatment is to simply load the wood into the chamber. Once the lumber is loaded, a vacuum is used to remove any air that is within the chamber. The chamber is then filled with the chemical, usually CCA (Chromated Copper Arsenate) and CA (Copper Azole). Once the chamber is filled, pumps apply pressure to the wood which treats the wood as thouroughly as possible. The chamber is then pumped of its chemical into storage tanks for later use. Vacuums are applied again removing any excess chemicals. The wood is then removed and then dries with time. The treatment process is then complete.

Lavelles1.JPG Lavelles4.jpg Lavelles5.jpg Lavelles6.jpg

Material properties

There are many beneficial properties of treated timber:

Easy to work with

Working with treated timber is simple compared to working with metal due to the many fastening opportunities and not having to weld. Also Timber offers many ways to make the product more aesthetically pleasing compared to similar alternatives.

Example of a stain application to treated timber


Compared to other building materials such as steel and other metals treated timber is very lightweight


Treated timber offers amazing strength under harsh conditions.

Takes less energy to produce than many other building materials

Production of steel, aluminum and other metals that sometimes take the place of timber in an application take much more energy to pruduce with much greater pollution.

Forest saved by the use of treated timber

Saves forests in the long run due to longer lifespan

Due to the long lifespan of treated timber less trees are being cut down to fill the same need.



  • Indoors
  • Outdoors
  • Above ground
  • Under ground

In contact with Salt and Fresh water

Many sizes

Treated timber comes in all shapes and sizes for many different types of applications. Some popular sizes for non commercial use are:

  • 2X4
  • 4X4
  • 2X6
  • 2x8
  • 2X12

However treated timber can be purchased in much larger diameters to fit the needs of commercial use.

Format & finish of materials

There are many different types of treatment that are utilized for different applications

Green treating:

Green treating protects the wood from rot and is especially useful
Green treated Lumber

where wood contacts the ground or is in contact with mositure on a regular basis.

Pressure Treating:

Pressure treating protects the wood from repeated stress such as a footing for a deck.

Typically these treatments contain toxic chemicals that are meant to repel insect and fungi infestation.
Pressure treated Lumber

Typical Uses for treated timber

  • Fences
  • Framing of Shelters
  • Pergolas
  • Trellis'
  • Decking
  • Retaining Walls
  • Steps
  • Seating
  • Edging of Pathways
  • Fence Posts

Common fixing methods

When using treated timber the environment would be typically corrosive to natural wood. This corrosiveness may be due to water, pressure, temperature etc. but requires fasteners that can hold up to the corrosiveness as well if not better than the treated timber itself.

There are typically 4 ways to utilize fasteners with timber.

  • Timber to Timber
  • Timber to Concrete
  • Timber to Steel
  • Timber to ground

Timber to metal.jpg Timber to ground.jpg Timber to concrete.jpg Timber to timber.gif

Most fasteners used outdoors are galvanized steel due to its ability to resist corrosion.

  • Nails
  • Screws
  • Bolts
  • Nail Plates
  • Joist hangers

Galvanized-screws.jpg Galvanized-nails.jpg Galvanized-bolts.jpg Galvanized-joists.jpg

Due to a chemical reaction that occurs aluminum fasteners should be avoided in use with treated timber products.

Durability and maintenance requirements

No additional maintainance is needed for the resistance of fungi and termites with treated timber, but there are a few things one can do to prolong the lifespan and enhance the beauty of the treated timber product.

Stain and sealing a deck
  • Apply a water treatment chemical every 2 years
  • You can use a wood brightener to enhance the beauty of the wood
  • Apply an end-cut solution to treat the cut ends of the timber
  • You can also paint or stain the wood

Life-cycle / recycling possibilities

Treated timber has a lifespan that is far greater than that of untreated wood. In fact manufacturers warranties can be as long as 30-40 years, and in some cases if it is installed on a house one would be covered for as long as they own their home.

Some landfills will not take some products treated with CCA (Copper Chromium Arsenate) but some manufaturers have alterered the composition of CCA to make them safe to throw away.

Treated sawdust and shavings are not meant to be used in composting as the resulting soil produced will contail remnants of the CCA treatment.

Also treated timber should not be burned except in approved commercial incinerators.

The only recycling alternative is to reuse the treated timber, which is feasible due to its long lifespan.

List of manufacturers / contractors / suppliers


  • Lavelle

115 31st St S Fargo, ND


  • Simonson Lumber Co

2360 Main Ave Fargo, ND

  • Crane Johnson Lumber Co

3300 Main Ave Fargo, ND

  • Stenerson Lumber Co

1701 1st Ave N Moorhead, MN

  • Lowe's

5001 13th Ave S Fargo, ND

  • Home Depot

4700 17th Ave SW Fargo, ND


  • MBC Contracting

1709 1st Ave N Fargo, ND

  • H&S Contracting

627 Center Ave Moorhead, MN

  • TEM Industries

1008 19th St N Moorhead, MN

  • Abbot Arne Schwindt Inc.

2205 SE Main Ave Moorhead, MN

  • Municipal Industrial Contracting

3902 3rd Ave N Fargo, ND

Product information / specifications

For this example the gradings will be based off a brochure from a manufacturer because in the US gradings are not uniform for the most part.

Use Categories

Example of treated timber
  • UC1-------- Interior furniture, millwork
  • UC2-------- Interior beams, flooring
  • UC3A------ Coated millwork, siding, trim
  • UC3B------ Decking, walkways, railings, fence pickets
  • UC4A------ Fence posts,deck posts, poles
  • UC4B------ Utility poles, building poles, permanent wood foundations
  • UC4C------ Freshwater pilings, foundation pilings, utility poles in semi-tropical environments
  • UC5A-5C--Piling, bulkheads
  • UCFA------ Fire resistant framing
  • UCFB------ Fire resistant siding, shake roofing, stairways


Specifications in this case are found according to application and then subdivided into how much moisture, pressure, etc. the timber can take in a given application.



An example of the decorative additions possible with treated timber. The pergola along with the fence offers a decorative toush that serves a function other than aesthetics

Fences mainly serve to divide property for some purpose such as to keep something in or out. Treated timber is perfect for this application as it is strong and durable in the harsh conditions that a fence would encounter in the upper midwest United States.

Treated timber can withstand the harsh winter conditions that are present in the area. This example illustrates the versatility of treated timber when used on a slope. This versatility is far greater than many other materials such as wraught iron and is far less expensive. The treated timber in the photo also shows the many options there are to customize the timber to meet the aesthetic needs of the user. This photo was taken in Duluth, MN
This photo shows how simple a fence can be with the use of treated timber depending on the application. This fence is a very cost efficient way to build a fence due to its long life (more than likely longer than 40 yrs). It also uses far less material than a full panel fence. This tyoe of fence is popular in the area around acerages, not neccesarily to contain or protect against any particular thing, but more as an aesthetic touch to divide properties.
This photo is simply an example of how treated timber can be used in conjunction with other materials to create a unique look.


User:bdusek08 Decks are a very popular addition to any residence. Decks not only beautify the land but also adds functionality because it is often an activity area. Timber decks come in a wide variety of sizes and colors which basically makes them completely customizable. Decks can't be built on almost any sized building. Many colors of the lumber are available such as mahogany, pine, redwood, teak, light gray, and cedar. The color feature is optional but is recommended because it does prolong the life of the wood. If one chooses to go without a color it is still gives that "rustic" look to the house but is still subject to weathering and insects.

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Common Decking Activity

  • Pool Decking
  • Courtyard Decking
  • Barbecue Area
  • Porches
  • Patio Area
  • Pergolas
  • Any Much More!

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Retaining Walls


West Dining Center, NDSU Fargo, ND
Treated timber is a great option for the construction of retaining walls. Other materials used in retaining walls are durable and provide a good asthetic, but treated timber is also light and easily constructed.
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Lavelles Building Materials Company

Arch Wood Protection, Inc.- Material Saftey Data Sheet

Wolmanized Wood Product Guide

Wolmanized Wood website

External links