Re-decking - Should I replace my joists?

Hi there,

I'm putting down new decking on our front deck and have noticed that the top 2 millimeters or so on the joists underneath look like they may have dry rot(?). By way of background, the existing decking boards have terrible dry rot. I had a look under the house and all the joists generally seem to be really solid. I think the joists are redgum. I'd prefer not to have to replace them if possible. Grateful for any suggestions or comments on this...

Also - I'm using ACQ treated pine for the decking - could anyone suggest a good stain to give this a 'jarrah' look, or something similar?

Many thanks

Doodle

Hi Doodle and welcome to the forum. What you're calling dry rot is almost certainly not. When the timber gets wet, fungus grows and decays the timber, when the timber dries out, the fungus becomes inactive. Over many wet/dry cycles, the rot gradually spreads. If you've noticed it, and it's dry, it just means the environment is currently dry(not surprising in Brisbane ATM). The two main fungii require min 24% moisture content in the wood and warmish temperatures to grow. True dry rot fungus cannot exist where the temperature regularly exceeds 20º. fungii lesson over!
If its only surface rot, I'd paint the top surface liberally with something like CN Timber oil and then install a rubber strip especcially designed to protect joists and bearers from water damage(get it from Bunnies/Bretts etc).
If any joists are badly split from the old nails, and might not take new nails, you can turn the joist upside down and get a second life out of them.

Cheers
Michael

Many thanks, Michael.