Pressure Treatment vs Dip Treatment of Outdoor Timber
If you’re buying a timber product to be located outside, whether it’s fencing, a garden shed or an arbour, then Andy Taylor says that you need to know about how the timber is treated and the difference between pressure and dip treatment.
Treating wood is very important, as over time timber will become increasingly susceptible to rot and insect attack which can severely damage it.
Dip Treatment of Outdoor Timber
Dip-treated products are generally cheaper than pressure-treated equivalents as the process of dip treating takes less time, leading to lower labour and storage costs.
Dip treatment is exactly what it sounds like. The shed panel or fence panel is dipped into a treatment bath and is completely submerged. All surfaces are thoroughly immersed before the panel is removed and allowed to dry. This is a fast, efficient and economical way to treat panels, but the treatment is only ever on the surface and is not right through the wood.
However, the treatment will thin and fade over time and most manufacturers recommend annual repeat treatments to comply with their guarantee conditions. They will also advise that you isolate a dip-treated product from the ground using a pressure-treated gravel board.
Although they are cheaper to buy, you need to weigh up what is important to you, whether you want to save money initially or to spend more time and money treating the product annually.
Pressure Treatment of Outdoor Timber
The process of pressure treating, or vacuum pressure impregnation as it is officially known as involves a longer process. Firstly the wood is dried naturally using airflow or a kiln, this removes moisture from the wood so it is ready to be treated.
Next, the wood is placed into a pressure treatment tank, and the air is removed via a vacuum. Then the tank will be flooded with preservative liquid, and finally, the excess fluid is extracted using a vacuum again.
The low pressure of the wood draws the preservative deep into the grain of the wood, making for a fully treated piece of timber.
Pressure-treated products can usually be identified by their green tinge finish when new, but this will fade to a honey brown colour over time, naturally blending into your garden.
Weathering will not affect pressure treatment, so it will last much longer. Although if you do saw or cut a piece of pressure treated timber manufacturers will always advise treating the newly exposed part.
Pressure treatment, by its very nature, is a more expensive process and this will be reflected in the buying price, of course. However, most pressure treated products will come with an extended guarantee which could be up to 15 years.
Dip Treatment vs Pressure Treatment - You Choose
It's all about information, requirements and budget. I strongly believe there is a place for both types of treatment but the important point is that you know what you are buying.
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