How to add reinforcing bearer to existing deck?

daniel007

​I have recently moved into a new house and have just discovered some issues with existing decking.
​The decking is over 1m above the ground.
The joists on one side do not fully go over the bearers. In the worst cases there is as little as 10mm of joist sitting on the outside bearer.
The building inspector suggested bolting a second bearer to the inside of the existing bearer so the joists will be fully supported.
The current span is 3.2m between supports.
The current bearers are 200x45mm.
My question is, should this secondary bearer be the same dimensions as the existing bearer or could I use smaller? 
Could I use 90x45mm, and bolt it every 1500mm, which is the recommended supported span for that size timber?

JacobZ

Hi @daniel007,

A warm welcome to the Bunnings Workshop community and thank you for your question.

I don't fully understand where the joists are sitting in relation to the bearers. Can you upload some photos so our members can better understand the issue and offer our best advice?

Are they sitting on top of the bearers? Or do they run in line with the bearers?

Would this secondary bearer be able to sit on the posts also?

What you are proposing seems like it would work, but I would not be confident in giving you a yes or no answer as it is outside of what is standard in terms of deck building. If you wanted to do this, then you would need to speak with an engineer to determine if it is a viable option.

Due to the height of the deck and the weight-bearing nature of this secondary bearer, I would not advise taking too many liberties and realistically, the safest and best option is to use a timber of the same size as the secondary bearer.

Let me know what you think.

Jacob