Importance of Timber Treatment | Timber Rot Treatment | Checkatrade
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The importance of timber treatment

First of all, it is essential to understand if the wood is dry (less than 20% humidity), the wood is less likely to rot. For outdoor use, this may not be practical.

First of all, it is essential to understand if the wood is dry (less than 20% humidity), the wood is less likely to rot. For outdoor use, this may not be practical. However, timber rot treatment can be applied to specific wood species. Treatment should not be confused with decorative or protective coatings. In addition to the treatment options, these processes are generally recommended. The overall appearance required determines how the wood is treated.

When considering wood for external applications, it is essential to understand that wood is a variable material. Different species have different characteristics. Some woods, usually many hardwoods, are naturally durable and resistant to decay. Also, due to their density, the treatment for these woods is not necessary. In this article, we’ll have a look at all aspects of wood treatment.

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What is the importance of timber treatment?

Treatment timber is essential for the following reasons.

Enhanced lifespan

Due to the use of preservatives in the production process, treated wood has a much longer lifespan than ordinary wood. This, therefore, increases its useful time. Timber decay treatment is effective in this case as it prevents rot from occurring in the first place.

Insect and fungi resistant

When wood is treated, certain preservatives are used to repel insects and prevent fungi, which often rot the wood. Timber rot treatment is especially effective in dealing with this.

treating external timber


Most people stain the outside of wood to protect it from the weather. However, treated wood already has barriers to prevent this. Over time, you will still need to take steps to maintain this protection. Fire retardant timber treatment also helps protect against fire.


Timber decay treatment provides excellent durability and enables wood to withstand wear.

Prolonged immersion in water

Products such as plywood are well suited to resist erosion from seawater and can be used to build ships.


Due to its strength and weather resistance, plywood is an ideal product for blocking building entrances. This is only achievable once the wood has been treated.

Fire retardant

Some types of treated wood are flame retardant, which increases the burning time and slows down the combustion process. Fire retardant timber treatment is especially important for homes and restaurants.


Treated wood is versatile and can be used in all aspects of construction work. Fire retardant timber treatment is also important to incorporate in construction works for safety.

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What timber to treat?

When wood is often used in damp places, treatment is essential to avoid deterioration of the wood’s quality. Examples include fence posts, window sills, wood in contact with bricks without an effective moisture barrier, wood in farm buildings in contact with fertilizers and silage, construction of bridges, or loading at sea with wood.

Although the risk of rot and insect attack may be low, they are still significant risks. In this case, timber rot treatment can be considered as a valuable safeguard against future maintenance costs. Examples include conventional roofs, tile slats, wall panels, unopened flat roof joists, and first-floor joists. Timber decay treatment goes a long way in preventing these woods from decaying.

Conditioning before treatment

For effective timber treatment, the wood must be in a suitable state absorption of preservatives. For conditioning, the following considerations are important:

Bark removal

To ensure adequate penetration, all bark layers and foreign parts that may prevent the liquid from entering the wood must be removed entirely. This is also essential for exterior timber treatment.

Moisture content and drying

Seasoning and drying are two terms used to describe the same process of reducing the water content of the wood. The air passing through the moist surface of the wood absorbs and removes moisture, leaving the surface of the wood slightly drier than before. Internal moisture moves to the surface and is continuously removed, allowing more dry air to circulate in the wood. When the water content falls to the so-called “fibre saturation point” of about 25-30% (250-300g / Kg), all the water is removed from the voids of the wood (the water remains in the cavity cellular). Water is only contained in the cell wall. Seasoning below the fibre saturation point dries out the cell walls and cause them to shrink.


It is desirable to carry out all machining processes before the actual treatment, including reaming, planning, abutment, etc. If this is not possible, it is recommended to reprocess bare wood by subsequent thorough brushing with suitable preservatives or suitable auxiliary or repair preservatives.

Improved penetrability

For products such as difficult to handle wooden railway sleepers, the most important thing is to obtain sufficient lateral penetration. For some woods, it is often not possible to obtain an appropriate preservative flux from the final grain. By introducing many other entry points along the surface of the wood, the distribution and absorption of preservatives are improved. Usually, this is done using a cutting machine made up of a series of gear rollers with blade rollers which cut the slots parallel to the wood particles.

Timber preservation treatments

The effectiveness of all wood preservatives depends on the permeability and retention of the preservative in the infiltration area. In order to cope with the big differences in the absorption properties of wood, the correct preservatives and methods should be used. Some of the treatment processes include:

Hot and cold bath

The treatment of hot and cold baths in an open water tank is an immersion treatment in which the wood is immersed in a bath where the temperature is raised to around 85 ° C for a certain amount of time. After this, the wood is given time to cool in the preservative, or it is transferred to an adjacent cold preservative tank until it cools. During this process, a vacuum forms in the cell cavity, ensuring the absorption of the preservatives. The use of oil-based preservatives, such as creosote oil, requires proper seasoning of the wood before processing.

Brushing or spraying

Although these are the simplest and easiest methods to use, such an exterior timber treatment is not recommended because the preservative doesn’t penetrate deeply enough to protect the surface of the wood. However, it is useful when wood needs to be processed in the wild, and regular applications can extend its life by several years. Wood preservatives of organic solvents are suitable for this purpose. Proper ventilation is essential, and contact with the skin should be avoided.

Vacuum pressure

Preservative-impregnation vacuum methods have been widely used commercially and have proved to be the most effective means of controlling the depth of filling and penetration of the preservative. The best method generally depends on the characteristics of the wood, the type of preservative required, and the end-use of the specified product. Vacuum pressure is effective for both interior and exterior timber treatment.

Benefits of having a professional do the job

  • You get professional advice on maintenance after treatment
  • You do not have to worry about what method will be used
  • The work is done in a timely and efficient manner
  • All hazards that come with treatments are dealt with
  • Depending on the purpose of the wood you get advice on which type is the best
  • Potentially cost saving as you don’t have to buy the machinery

The treatment of timber is essential for its durability as well as your safety. For more information on timber treatment, you can find your local timber treatment specialist on Checkatrade.

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