Port Phillip Bay Case Study: Choose the Right Timber

Marine Rated Timber

Late last year my colleague Frank Di Stefano and I were asked to be involved in the repair and maintenance of a small private pier on Port Phillip Bay. Interestingly the original pier was not that old, but the reason for repair and maintenance was the wrong timber species was used for the piles, namely Grey Ironbark.

I have had dealings with contractors who specialise in marine construction and often wondered why they specify (White) Cypress Pine for jetty construction. So, we decided to look at the book, Wood in Australia (my timber bible), for an indication why, and sure enough the answer was there in black and white.

• While White Cypress Pine has an in-ground rating of class 2 (expected life span of 15 years to 25 years), it also has a marine rating of class 2. However, a marine class 2 rating has a life expectancy of 41 years to 60 years.
• On the other hand, Grey Ironbark has an in-ground rating of class 1 (25 years plus), but conversely it has a relatively poor marine rating of class 3 with a life expectancy of 21 years to 40 years.

I hasten to add the original Grey Ironbark in the above case did not last anywhere near the Grey Ironbark life expectancy shown in the Wood in Australia book. I might add that the top shelf species for marine applications is Turpentine, which has a marine class 1 rating with a likely life expectancy of 60 years plus. However, Cypress is nearly 50% cheaper.

So, in this case our client used Turpentine where those members were not only immersed in salt water but were also constructed for an above water bathing shed. Cypress Pine, the cheaper option, was then used for immersed piles supporting the pier only.

Why am I relaying the above case when I know it is highly unlikely the readers of this publication will be constructing a jetty? It is to illustrate that we at Bowens can advise on the best cost-effective fit for purpose products to use on any project, particularly where a non-standard product is required.

I also have gleaned over nearly 20 years of inspecting many problem jobs and found on many occasions an inappropriate product was used. If you are in doubt as to what is the best cost-effective fit for purpose product to use, give me a call on 0412550740.