We have written a short guide on how to make sure you keep your wooden climbing frame, tree house or whatever play equipment you may have created in the best condition for years to come.
We would always recommend buying your wood already treated. The most common treatment for play ground timber is Pressure Treatment. We would highly recommend using pressure treated timber for any playground equipment to ensure a the life of the wood and keep your equipment strong and safe.
What is pressure treatment?
Pressure treatment is a way of treating timber which penetrates through the entire timber and prevents it from being destroyed by fingus or insects. Pressure treatment is a process that uses chemical, but thankfully since 2003, 'CCA' (chrome copper arsenate) chemicals containing arsenic and chromium can no longer be used in the treatment of wood due to certain EU regulations (which are also observed by various governing bodies worldwide).
Tanalised-E treatment (using Tanalith-E preservative) is the most commonly used chemical structure for pressure treating playground equipment - but is also used when treating timber for many different uses such as fencing and other garden structures. This is the European brand of 'copper azole' preservative.
During the pressure treatment process, timber is placed into a vacuum which is then filled with the preservative (usually Tanalith-E) at which point hydraulic pressure is applied forcing the preservative to penetrate deep into the timber. After the preservative has been drained from the vacuum, the timber is left to dry.
What is heat treatment?
Heat treatment is a type of treatment used on some play equipment. Where we would always recommend pressure treatment, heat treatment combined with a stain or painted on treatment will help make the timber last. Heat treatment is where wood is heated under pressure with nitrogen or water vapour to control the drying of the wood. This is usually for a period of 24-48 hours at around 190 to 230 degrees.
The wood fibres after treating under such high heats are made less appealing to insects. The moisture in the wood is lowered as well, meaning reduced risk of the wood deforming from moisture and increasing weather resistance. Fungi needs moisture, oxygen and nutrients to grow so removing one of these elements will prevent fungi from forming. Overall the treatment is favoured by some as it is completely chemical free, but as the treatment generally increases the elasticity of the wood, this can cause the wood to split more easily when nailed so drilling holes carefully is important. Over time, heat treated wood is not as durable as pressure treated wood.
Should I paint on preservatives?
Painting, spraying or wood dipped in preservatives will protect the timber to some extent. This would never protect the wood in the same way that pressure treating does as no outer treatments can penetrate the entire timber to the core. Spraying or brushing on a treatment can extend the life of the wood by up to three years so it is always something worth considering even if the wood has been treated already. It is also something that can be done after a few years to give the timber a weather-proof coating to help protect it as time goes by. the more coats you add, the more protected the wood will become but second or their third coats should always be applied once the first or second has fully dried and/or soaked into the wood. Wood needs to be 'seasoned' or dried before any treatment can be added. Most timber bought will already have been seasoned either by air drying or kiln drying (see our Guide to Timber).
If you are sawing parts of your timber, it is advised to paint a preservative onto the bare ends of the wood that have been freshly cut.
If you are going to use a paint or spray on wood preservative it is essential that you use a preservative that conforms to the European safety standards for children's play equipment (EN-71). If you go to a DIY store, they should be able to tell you if it has been tested according to EN71 safety standards. As a guide, avoid all preservatives that contain cadmium, chromium, lead, mercury, selenium, arsenic, barium and antimony.