Ask An Expert

Home » Expert Advice » Ask An Expert

I have outdoor Merbau wood garden furniture and decking. How often should this be stained or treated to maintain durability of 25 - 40 years?

Woodsolutions Answer +

Actually merbau is rated Durability Class 1 outdoors, out of contact with the ground, so it would have a probable life of 40+ years without any coating at all – unless you are in a particularly high rainfall area, or the decking is in the path of a watering system. Regular wetting will shorten the life of most timbers. If you leave it without a coating it will turn driftwood grey so you may wish to oil or stain it to keep a more natural colour. While not strictly necessary from a durability point of view, a finish will help to prevent weathering effects such as fine surface cracks or ‘checks’. Any of the products marketed as garden furniture oil or decking oil are suitable. How often you re-coat depends on the level of exposure. A simple test is to sprinkle some water on the timber. If it forms droplets the finish is still doing its job. If it soaks in it’s time to re-coat. However, the timber might start to look ‘hungry’ before you reach that stage.


Under the new revisions for Fire in BCA code clients are requesting commissioned Fire Test reports for solid timber lining products we supply. As the manufactured aspect of these products is soley edge-profiling, surely there is a species-specific test report we can supply instead of commissioning our own for messmate, silvertop ash etc. Can you assist with our obligations as a small timber supplier under the changes to the code?

Woodsolutions Answer +

FWPA has sponsored fire testing on a range of timbers including messmate and silvertop ash  (see attached report). This has been done on behalf of the timber industry so it is not necessary for individual companies to do so. This report and other fire test reports can be found on our website here: https://www.woodsolutions.com.au/articles/fire-test-reports


Are blackbutt posts suitable for a rammed earth footing? Previously I have used ironbark for the horse shelter frames, but supply is a problem. Blackbutt has been suggested as an alternative. 6 lengths cut three sides 3.6 m long. 

Woodsolutions Answer +

Blackbutt is rated Durability Class 2 in the ground according to Australian Standard 5604. This indicates a probable life expectancy of 15 to 25 years. If you are in a dry part of the country and the ground adjacent to the posts is not likely to be damp for long periods, and you can organize some termite protection, this estimate might be significantly exceeded. However, ironbark is rated Durability Class 1 so is a more durable species. There are not many Class 1 timbers that are readily available – other Class 1 options include tallowwood and some of the ‘box’ species (grey box, red box, white box, yellow box). You will find more details about timber properties on our website here: https://www.woodsolutions.com.au/wood-species

Sign up or Login to continue reading the answer.

Displaying 0/0

Show me 10 /20 /30

Haven't found what you're looking for?

If you have not found the answer for your question for in the Search results, please call the Expert Advice line or send us an email for a prompt response.



Call the WoodSolutions Expert Advice line on 1300 414 044*
Available Mon - Fri: 9am - 5pm

*Please note, there is a charge, determined by your telecommunications provider, for these calls.
This service is not available to international callers.

Are you looking for a supplier?

Social Media Feeds