Can I frame over an existing deck with a new deck to raise the level?

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I was looking at below photo and realized they basically put the trim joists of the platform on top of the bottom joists / beam. Is that allowed? I thought you have to actually put footings for the raised platform.

Anyhow, if this method is OK, is there limitation on how big the platform could be?

Credit: centralctdecksandporches.com

UPDATE 1

Sorry for being unclear and the photo example above is not a good representation of my question. So here is a drafted plan for my deck that I just drew in Google Sketchup:

There are more on the right side of it. But it's the idea. I basically have 4 beams. Joist span is 9 feet except the middle, which has 2 beams spacing of 7 feet apart because of some trees.

Now I want to build a raiser like below:

I assume it will be 7" high. My question now becomes:

Can I just put a new 2x6 joists on top of the 2x8 joists below but running 90 degree across?

Or is it...

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The rule, at least here in the US, is a cantilever can extend no more than 1/3 the supported length (so, you could go ~3 feet further). Personally, I try to keep cantilevers no more than 2 feet, regardless of total supported length: while it might be OK structurally, it will likely sag the further you go, and can feel bouncy.

To do the best job, get some 12 foot 2x8s and sister them with the existing joists (run them the entire length, nailing with galvanized nails at the top and bottom every 16 inches). Then put a double joist hanger at the ledger against the house.

One of the critical things with a deck cantilever is how you attach the railing posts at the end of the cantilever. You will be nailing a 2x8 rim joist at the end to finish the deck, but you need to make sure the posts for your railing are tied in securely to the joists, and not just the rim joist. The method can vary depending on whether your existing railing posts are notched into the decking or...

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