Preventing Wood Rot in Joists (Decking)

[srohara]

I was wondering if you could please help me, I am currently building a timber deck, my issue is that my bearers will have a minimum clearance of 80mm and a maximum clearance of 400mm. I am joist hanging my joists to limit my height. I am using hardwood F11 joists. I want a product that I can use to help treat and prevent the occurrence of wood rot due to the limited ground clearance of the deck. I have been looking at several products and need some help. Once the deck is built I will not be able to recoat the timber so I need something that will last for a fairly long time. <o:p></o:p>
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My deck is uncovered and will be exposed to rain, the joist that I want to treat are on the underside of the deck and will NOT be exposed to UV rays or any sunlight just rain. Help needed please

[Dirty Doogie]

If one end of the deck is open 400mm you should get enough air flow under your deck to stop any rot on the ground side of the joist.

More than likely a joist will rot first on the top under the decking especially if there are any splits in the top surface caused by nailing/screwing.

In the past I have put a thin bed of polyurethane sealant (Bostick Goldflex or Sikaflex) down over the top of the joist as a damp membrane - these joists have never rotted -yet- but it was pointed out to me that if water got under the polyurethane and couldnt escape then the joist would certainly rot. :C

You can now buy rubberized strips to lay along the top of the joist before you put the decking down which are supposed to do the same thing.

However If you are going to have a few pot plants on the deck (ie continuous damp spots) it might be worth painting all the joists with 2 coats water based bituminous waterproofer (eg Bitkote #3 available at bunnings) and a coat of acrylic paint.

[Marc]

Why don't you dig out some soil from under the lower side? Drain with a pipe or a trench filled with pebbles.

[oohsam]

Digging under joist = This is what I will do. I have an area where the joists/bearers will be lower to the ground than other areas, and I will simply be digging out that line and cover in crushed rock and firming it down. This should be enough protection.
I am also using the rubber protectors...you can pick up strips of rubber for your joist from Clark Rubber real cheap.
peace

[srohara]

The only issue that i am decking over existing paving and some existing concrete paths. Should i just remove the pavers? Is it better to have the deck over the pavers or bare earth in releation to moisture?