This topic has seen much public and professional debate on which is the better option, with most manufactures recommending that you should let the timber weather for a couple of months before fixing the timber. This suggestion has a few possible reasons behind it, which include:
- Allowing the timber to acclimatise to the environment before it is fixed, so that it can reach its “Equilibrium Moisture Content” or EMC. The timber’s EMC is relative to the humidity and temperature of the surrounding air. By allowing it to sit for a couple of months, the timber should settle to the EMC of the environment and help reduce the movement of the boards.
- Allow for the tannins in the timber to leech out and the grain to open up so that when the timber is oiled it is able to penetrate deeper. When timber is freshly planed into decking boards, they produce a glazed surface (often called mill glaze) caused by the milling process. Mill Glaze can be observed by dropping some water onto the surface of the timber, if it soaks into the timber then the mill glaze has been removed, if it however beads up then it is still present, and will cause the decking oil to just sit on top of the timber and not penetrate.
- The timber will end up going grey to some degree (depending on how long it was left to weather); this is a natural process and happens to all timber that has been left uncoated. Many people are off put by this fact as it requires them to clean the deck with a grey deck cleaner (see cleaning grey & weathered timber), however it is almost always recommended that you clean your deck before oiling it, especially if trades people have been using it throughout the building process, which will most likely result in all types of stains.
On the other hand some people recommend that it’s okay just to oil and lay it straight away, arguing that it doesn’t really make any difference when you oil the timber. Some reasons why people decide to oil the timber straight away include:
- The natural colour of the timber is preserved, as the timber is not allowed to go a grey colour.
- There is no added time spent on having to clean the weathered boards, although it is recommended that you do clean the deck before oiling anyway however this might not be as vigorous and time consuming as cleaning weather decking boards.
- Oiling timber straight away is recommended during the middle of a heat wave, which will help prevent the timber rapidly drying out which can cause cupping, splitting and checking of the decking boards.