The three most widely available and suitable exterior lumber choices, not treated with chemical preservatives, include Western red cedar, redwood, and cypress. Your geographic location will determine the availability and cost of these materials.

What timber is good for outdoor use?

Exterior timber

Treated pine is the perfect material and it comes in a number of grades depending upon how you're going to use it. H4 should be used when the timber comes into contact with the ground. Common products of this grade are sleepers and posts. H3 is for use above ground and comes in a couple of finishes.

Can any timber be used outside?

In general, any wood will work for an outdoor project if it's kept dry and regularly maintained However, some woods do have a higher resistance to decay than others.