It is all about quality; do you want a deck that lasts 5 minutes or a lot longer? Timber used on decks must be able to resist the elements. So it is important that you use timber specifically treated for outdoor conditions.
Compared to hardwood, softwood such as pine has low durability unless it is treated. Fortunately softwood can be used in all decking and pergola situations provided that it is properly treated. For example, timber used for ground posts needs to be stronger and more resilient than the timber used for the floor of the deck. Treated softwood (usually pine) is the most cost effective and popular timber option.
Hardwood is the strongest choice for decking timber. It is generally more expensive than softwood. It is naturally resilient to insect damage and usually possesses a richer timber hue than softwood. Often hardwood is hard to treat but its natural durability means that it will stand the test of time.It is recommended that hardwood be seasoned (usually kiln-dried). Varieties of hard wood popular for decking include Asian hardwood Bartu and Jarrah. As with softwood it is important to protect hardwood decks by staining them regularly with a good quality timber finish such as decking oil or timber stain.
Timber is not your only choice for a deck. Compressed sheeting is a synthetic option that is durable, cost-effective and waterproof. You can cover the sheeting with any finishing material.
Concrete is the best. 100 x 100 hardwood or treated pine at a minimum, as it is at the point where soil meets air that the rot takes place. Put ant caps on the stumps to avoid white ants and rubber on bearers and joists to stop moisture.
If using hard wood decking use hardwood bearers and joists. If using treated pine, use treated pine or Cyprus for the bearers and joists as combining hard and soft wood will cause the deck to bow. Wide timbers can bend so you need either 1. Cuts on the back and or 2. Good oiling before putting down.
Clamping timbers with spacers in between before putting down, makes life easier together with a long deck drill. Put two attachments per plank. Use deck screw or nails. If using nails you have to pre-drill.
Wide timbers are more expensive but last longer. With wide timbers you can cut the two joining pieces on the 45 degree angle so as not to have to break the nail line by attaching both timbers separately. Instead have a joiner through both at the same time.
Don’t be fooled by putting the rough side up. That is to create air between the joists and the deck and face up will collect dirt and become slippery and shorten the life of your deck.
Do not use Miribu as it comes out of native forests in Indonesia and kills monkeys and orang-utans.
A deck should be well oiled so that the water beads. When its stops bending after about a year, it is time for a top up.
You can use no nail attachments but they can be a hassle unless you know what you are doing.
Use natural oils and stains not petrol chemical stains.
Whenever possible, use second hand timbers from a reputable supplier.
Spacing depends on look but should not be less than 3mm to allow for expansion and contraction of the timber.
Choose timber to last.
You could use synthetic timbers but they can look a bit ordinary.
Combine I cup full of metho to four litres of linseed oil. You can always add a little more metho; it is so the wood draws it in and doesn’ t just sit on top.
For a more detailed decking guide visit here