Decking Issues - rusting joist hangers and damp joists

24 Apr 2014
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United Kingdom

I've almost completed my decking frame but noticed a couple of potential issues which I want to address if possible before putting the deck boards on.

1. Joist hangers. I lifted a couple of joists out of their hangers today and noticed a fair bit of rust on the bottom sections which provide most of the support. The hangers are galvanised. I just started reading about modern pressure treated wood having chemicals in it which can prematurely rust galvanised hangers. Most of joists are nailed into them now and would be a nightmare to replace. Is there anyway to address this? Would sticking a couple of 80mm Galvanised nails through from the perimeter of the frame into the joist end offer sufficient support if the hanger fails?

2. Damp joist bottoms. The section of the frame which is closest to the retaining wall (including the ledger board) has ground underneath it which gets very water logged and is much closer to the ground than the side further away from the wall. After a rain fall I can see the the bottom 2 inches of the joists there are damp almost along the entire length. Is this going to be an issue for pressure treated joists and can I do anything about it? I am not sure on the exact rating of the joists but I am presuming that they are not 'ground contact' rated. I was thinking about wrapping the bottoms in plastic but maybe this will just cause condensation and be even worse?
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