Hi,
I'm constructing a frame for some decking 4.8m x 2.6m and mistakenly bought and partly assembled with 2x4 joists. I think I watched a couple of youtube videos first of all which were of people (including professional DIY channels) using 2x4 joists.
Then however I read much more about how 2x4 is not good enough. So I'm thinking of partly re-doing it with 2x6. The frame outline joists would remain 2x4 which I can support at very close intervals with a mixture of posts and footings onto concrete (posts every 1.5m and a footing onto concrete in the middle - so support every 75cm), but for the joists which will be running across the 2.6m span at 500mm centers I was thinking of changing to 2x6. I want to avoid having more than one footing across the 2.6m span because the middle of the deck is over ground that gets very waterlogged and putting in footings will be a lot of work.
But I'm a bit confused because when I look at the maximum unsupported span tables for 2x4 C16 structural joists, they all say its about 1.9m. So one footing in the middle should be more than enough for even 2x4. I already have the outside of the frame up in 2x4 and supported every 1.5 meters by posts (haven't added the extra footings yet) and standing on the joist and even jumping on it I can't feel any real bounce at all.
Other details: the deck is about 6" off the ground at one 4.8m side with a ledger board into a concrete wall, the other side is about 12" off the grond
I'm constructing a frame for some decking 4.8m x 2.6m and mistakenly bought and partly assembled with 2x4 joists. I think I watched a couple of youtube videos first of all which were of people (including professional DIY channels) using 2x4 joists.
Then however I read much more about how 2x4 is not good enough. So I'm thinking of partly re-doing it with 2x6. The frame outline joists would remain 2x4 which I can support at very close intervals with a mixture of posts and footings onto concrete (posts every 1.5m and a footing onto concrete in the middle - so support every 75cm), but for the joists which will be running across the 2.6m span at 500mm centers I was thinking of changing to 2x6. I want to avoid having more than one footing across the 2.6m span because the middle of the deck is over ground that gets very waterlogged and putting in footings will be a lot of work.
But I'm a bit confused because when I look at the maximum unsupported span tables for 2x4 C16 structural joists, they all say its about 1.9m. So one footing in the middle should be more than enough for even 2x4. I already have the outside of the frame up in 2x4 and supported every 1.5 meters by posts (haven't added the extra footings yet) and standing on the joist and even jumping on it I can't feel any real bounce at all.
Other details: the deck is about 6" off the ground at one 4.8m side with a ledger board into a concrete wall, the other side is about 12" off the grond
