Thread: Which timber to use?

Not sure about supply, but I'll chuck out Ironwood (it's a wide range of "hard" species) or Redgum as options too.

Blackbutt and tallowood?? You got a good bank account??

If the local mill is offering those species chances are that's because its available locally and hence the species most likely used originally. Although from my time in Sydney I don't remember Tallowood being that common in Sydney. Both of those species will last you another 100 years if well built, you are really just choosing the colour/grain you like best.

It also depends if you are using the posts in the round or squared as some species will need to have the sapwood removed to prevent borers. You can check your preferred species for durability, hardness and susceptibility to borers here: http://www.timber.net.au/index.php/species.html

For what its worth I'd also consider bloodwood, White mahogany and spotted gum. Wait for someone with more experience than me to chime in though.

For outdoor inground use tallowood posts are the go and Blackbutt rails. Untreated Blackbutt post will not last long in the ground due to rot and termites only problem with tallowood is it will react with galvanised fittings and will stain timber.
Tim

Tallowood. It's durability is why it's used for window sills.

Thanks for you input guys, much appreciated! I'm leaning towards the tallowwood, although a little worried about the potential staining from gal supports, and possible borer attack. The prices quoted for tallowwood from my local supplier seemed reasonable, however this might be due to a lower grade timber? I'll have a look though before I buy.

Thanks again for your help.

Originally Posted by MK I

although a little worried about the potential staining from gal supports, and possible borer attack.

You could paint the gal bits - it'll make them last longer too.

AFAIK, borers in TW are only a concern for sapwood - maybe do some more research. I reckon TW will leave Blackbutt for dead durability wise. It's also very stable when drying (and you can bet your life you'll be buying green) and doesn't check much on the ends which is what will let the rain into the timber.

Yep, i was just looking at the link from crowash and searching sapwood v heartwood. I'm sure my supplier would remove the sapwood when dressing. I like the idea of painting though. Some of the gal hardware doesn't look the best anyway. Does anyone know where to buy good quality stirrups, connectors, etc?

Tallow is definitely better in the weather. It's more stable than blackbutt and less likely to check badly. Back when I used to build decks, etc we often found that Sydney blue gum would last better as decking than blackbutt. SBG has a nominally lower durability rating but is more stable, so checks less, so ends up with less water sitting in cracks.

Re gal fittings: blackbutt will also stain those, as will most Aussie hardwoods. Basically, anything that has a substantial tannin content will stain gal. You can tar the surfaces that will touch timber, using plain old blackjack. This makes bolts last a lot longer too. The only catch is you have to be careful to not get tar where you don't want it.

If you don't like tar, it'd probably be possible to do something with a two pack urethane over the gal before assembly. I could see that working.

ETA: Oh and pre-coating things like mortises and tenons (anything that might catch water) is a good plan if durability is your aim.

Thanks for that Sumbloak, some things to think about. Much appreciated!

Mark