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In a recent experiment, a researcher set out to determine whether treating outdoor timber is worth the effort and expense. The experiment involved six samples of untreated timber and six samples of pressure-treated timber, with three of each group left untreated and three treated with a wood preserver. The samples were placed in three different scenarios: lying horizontally on the ground, placed vertically with the end grain in direct contact with the soil, and placed in a bucket of water. Over the course of three years, the samples were exposed to various weather conditions, including snow, rain, and extreme dry spells.
The experiment aimed to assess the effectiveness of different wood treatment methods in protecting timber from environmental exposure, wood-boring insects, and UV damage. The researcher also explored the reasons for treating timber, including the risk of decay caused by moisture, insects, and microbes in the soil. This article will summarize the experiment setup, environmental exposure, wood treatment methods, and assessment of samples to determine the effectiveness of treating outdoor timber.
Key Takeaways
- Treating outdoor timber can protect it from decay caused by moisture, insects, and microbes in the soil.
- Pressure treatment is one of the most effective ways to make timber last longer in an outdoor environment, but it is more expensive than untreated timber.
- Wood preservers can offer some protection from decay, but they may be less effective than pressure treatment.
Experiment Setup
Preparation of Timber Samples
Three years ago, the researcher prepared six samples of untreated 3×2 timber, three of which were left untreated, and three of which were treated with a wood preserver. Additionally, six samples of pressure-treated 3×2 timber were prepared, with three having the pressure-treated end still on them, and three having a freshly cut end on both sides. The samples were labeled and placed in three different scenarios at the top of the garden.
Application of Wood Preserver
For the samples that were treated with a wood preserver, a generous coat was applied, allowed to dry, and then another generous coat was applied. The end grain was also dunked in the treatment, as recommended on the tin.
Labeling and Placement
Each sample was labeled with a marker pen accordingly and placed in three different scenarios at the top of the garden. The first scenario involved the samples being placed outside, laying on the ground horizontally, so that the side grain of the timber was in contact with the ground. In the second scenario, the samples were placed vertically, so that the end grain was in direct contact with the soil. In the third scenario, each of the samples was placed in a bucket of water. Over the past three years, each of the test pieces has endured all that the British weather had to throw at them, including being buried deep in snow, extreme dry spells where the water in the bucket had completely evaporated, the occasional bit of ice, and of course, lots and lots of rain.
Environmental Exposure
British Weather Conditions
In an outdoor environment, timber can be damaged by various factors, including moisture, wood-boring insects, microbes in the soil, and UV rays from the sun. Moisture absorbed into the wood softens the fibers, causing it to decay. However, if the wood can expel that moisture through evaporation into the air during drier periods, moisture is not normally an issue. Wood-boring insects and microbes that live in the soil will eat away at the wood, causing it to rot away and decay. UV damage causes the wood to turn gray, dry out, warp, crack, and cup. There are a number of wood finishes out there that claim to protect the wood from UV damage, but the truth is that there is no finish that can truly protect the wood from it unless it’s regularly and thoroughly maintained.
Placement Scenarios
To understand the effectiveness of treating outdoor timber, an experiment was conducted with twelve samples of untreated and pressure-treated 3×2 timber. Three of the untreated samples were left untreated, while the other three were treated with a wood preserver. Three of the pressure-treated samples had the pressure-treated end still on them, and the other three had a freshly cut end on both sides. The samples were placed in three different scenarios at the top of the garden: outside laying on the ground horizontally, with the samples placed vertically so that the end grain is in direct contact with the soil, and in a bucket of water.
Over the past three years, each of the test pieces has endured all that the British weather had to throw at them, including being buried deep in snow, extreme dry spells where the water in the bucket had completely evaporated, the occasional bit of ice, and of course, lots and lots of rain. After three years, the samples were examined for decay and insect damage. The samples placed upright with their end grain in direct contact with the soil showed the most decay, with some samples having significant insect damage. The samples placed in the bucket of water showed the least decay, with no significant insect damage. The samples placed horizontally on the ground showed moderate decay, with some insect damage.
Overall, pressure-treated timber is thought to be one of the most effective ways of making timber last longer in an outdoor environment. Pressure treatment forces wood preservatives deep into the wood, making it poisonous to insects, fungus, and bacteria, which gives it its durability. However, pressure-treated wood is more expensive than untreated timber. Applying wood preserver to the timber yourself is a less expensive option, but it may be less effective than pressure treatment. There are also other finishes designed for outdoor use, but they can only be expected to perform well if they are well-maintained over time and not left to deteriorate.
Reasons for Treating Timber
Moisture Damage
When timber is used in an outdoor environment, excessive moisture over prolonged periods can cause damage. Moisture absorbed into the wood softens the fibers, causing decay. Generally, if the wood can release that moisture through evaporation into the air during drier periods, moisture is not normally an issue. However, if moisture is trapped within the wood, it can lead to decay and damage.
Insects and Microbes
Insects and microbes that live in the soil can feed on wood, causing it to decay and rot. This is why timber should not be left in contact with the ground. Insects and microbes that live in the soil will eat away at it, and it’s why things like fence posts rot away at ground level. It’s generally where the wood is in contact with soil where it will rot away and decay.
UV Damage
UV rays from the sun can damage the wood fibers, causing it to dry out, warp, crack, and cup. Wood that is outside generally turns gray over time because of UV damage. Unless you give it a bit of a rub down and apply some kind of finish or coating on a pretty regular basis, UV damage will cause the wood to not only gray but also dry out, warp, crack, and cup. There are a number of wood finishes out there that claim to protect the wood from UV damage, but the truth is that there is no finish that can truly protect the wood from it unless it’s regularly and thoroughly maintained.
Wood Treatment Methods
Pressure Treatment
Pressure treatment, also known as tanalising, is a process where wood preservatives are forced deep into the wood. This makes the wood more durable and resistant to insects, fungus, and bacteria. Pressure treatment is effective in protecting the wood from moisture and wood-boring insects. However, it does not offer any protection from UV damage and is more expensive than untreated timber.
Self-Applied Preservers
Wood preservers can be applied by the user to protect the wood. However, this method is less effective than pressure treatment. The preservatives in wood preservers do not penetrate deep into the wood like pressure treatment, making it less durable. Applying wood preservers is also not effective in protecting the wood from UV damage.
Alternative Treatments and Finishes
There are other treatments and finishes available in the market, such as Croso and Creo, which offer excellent protection from fungal growth and insect damage. However, the sale of Croso has been prohibited due to it being considered a carcinogen. Other finishes, such as stains and paints, offer some protection from moisture and UV damage but not from insects. Penetrating finishes, such as oils, repel moisture and help protect from UV damage but not from insects. It is important to note that all finishes require regular maintenance and should not be left to deteriorate. Another option is to use naturally resistant species of timber, such as Cedar, White Oak, Eepe, Teak, or Ioko. However, these species are expensive to buy in the UK.
Assessment of Samples
The experiment involved six samples of untreated 3x2s and six samples of pressure-treated 3x2s. Three of the untreated samples were left untreated, while the other three were treated with a wood preserver. The pressure-treated samples were split into two groups, with three having the pressure-treated end still on them and the other three having a freshly cut end on both sides.
The samples were placed in three different scenarios at the top of the garden. The first scenario involved laying the samples on the ground horizontally, so that the side grain of the timber was in contact with the ground. The second scenario involved placing the samples vertically, so that the end grain was in direct contact with the soil. The third scenario involved placing each of the samples in a bucket of water.
Over the past three years, each of the test pieces has endured all that the British weather had to throw at them, including being buried deep in snow, extreme dry spells where the water in the bucket had completely evaporated, the occasional bit of ice, and of course, lots and lots of rain.
After three years, the samples were examined for decay and insect damage. The first scenario, where the samples were placed upright with their end grain in direct contact with the soil, showed the most decay. The untreated samples had the most decay, followed by the samples treated with wood preserver. The pressure-treated samples had the least decay, with no visible decay on the samples with the pressure-treated end still on them.
In the second scenario, where the samples were laid horizontally on the ground, the untreated samples had the most decay, followed by the samples treated with wood preserver. The pressure-treated samples had the least decay, with no visible decay on the samples with the pressure-treated end still on them.
In the third scenario, where the samples were placed in a bucket of water, the untreated samples had the most decay, followed by the samples treated with wood preserver. The pressure-treated samples had the least decay, with no visible decay on the samples with the pressure-treated end still on them.
Overall, the experiment showed that pressure-treated wood is the most effective way of making timber last longer in an outdoor environment. While wood preservers can offer some protection, they are not as effective as pressure treatment. It is also important to note that pressure-treated wood does not offer any protection from UV damage and is more expensive than untreated timber.
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Conclusion
In his experiment, Keith from the past set out to determine whether treating outdoor timber is worth it and whether pressure treatment on timber actually works. He prepared six samples of untreated 3x2s and six samples of pressure-treated 3x2s, placing them in three different scenarios at the top of his garden: outside laying on the ground horizontally, with the samples placed vertically so that the end grain is in direct contact with the soil, and in a bucket of water.
After three years of enduring all that the British weather had to throw at them, including being buried deep in snow, extreme dry spells, and lots of rain, Keith examined the samples for decay and insect damage. He found that the pressure-treated samples had less decay and insect damage than the untreated samples, indicating that pressure treatment is an effective way to make timber last longer in an outdoor environment.
However, Keith also noted that pressure-treated wood does not offer protection from UV damage and is more expensive than untreated timber. Applying wood preserver to the timber yourself is a less expensive option, but it is less effective than pressure treatment and does not offer protection from UV damage. There are also other finishes available, such as croso and film finishes, but they require regular maintenance to perform well over time.
Overall, Keith’s experiment suggests that pressure treatment is an effective way to protect outdoor timber from decay and insect damage, but it is important to consider the cost and lack of UV protection.