There are many sources of advice and guidelines for building a timber deck – but I will refer you to several. Wood Solutions provides sensible, technical mainstream expert advice on their website – and The Generalist – who is expert at nothing, but knows a lot about everything- will give you frank and fearless instruction in the do’s and don’ts of timber decks. Another contributor worthy of a read is Ralph Bailey(Guymer Bailey Architects) who produced this outline for Timber Queensland.
Common Issues – Tannins and Metal Filings
Don’t use a grinding disc near a timber deck – or sweep thoroughly afterwards if you do. The first dew or rain will cause carbon stains and black flecks to appear on timber surface as the metal fines run to carbon All timbers leach tannins during rain. Some species – like Merbau – have very dark tannin runs. Other species have brown to milky brown tannins – but tannin leaching is common to all timber species – with the possible exception of Sassafras which they used for clothes pegs when I was a kid. Yes – recycled timbers leach tannins. Seasoned timbers exude less tannins than green timbers, and oiling of timber and sealing end-grain will reduce tannin leaching – but nothing will prevent it. Over time, as the fresh timber case mellows to grey or silver, it will become more tannin-stable. .All timber species will leach tannins into swimming pools and on to galvanised metal balustrading, sandstone walls and copings if the rainwater from your decking runs on to these materials. Washing with a pressure washer regularly will get rid of most of the staining – but it is practically impossible to eliminate or prevent
Its Also a good idea to seal the underside of decking with one coat of oil it will help reduce the likely hood of splitting.