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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?

enter image description here

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:

enter image description here

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:

enter image description here

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

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

  2. Or is it better NOT to run joists underneath but create separate set of footings?

If both are OK, I think #1 is easier to do but costly. #2 is a bit harder due to bunch of cutting but save some materials!!?

Please help.

UPDATE 2

So I did some more search and found this http://www.diydeckplans.com/tags/framing

I was trying to use similar idea. Basically, look like it's OK to have upper beam and lower beam. But in my case, I won't put the beam on the side of the post but it's directly on top of the 4x4 post.

enter image description here

UPDATE 3

This is a new design I just came up with. Basically, starting from the left, I will have 2 joists hanging (left red circle). Then 9 joists laying on top the beams to act as the raiser platform.

enter image description here

On the right side of the deck, there is a large area that is 7" lower. Here are a few points:

  1. I will make the 4x4 posts 7" lower on the right side.

  2. That makes the joists hanging near the house but laying on top of the 3 further beams.

But I have a question about the right red circle area. How should it be connected to the post?

Option A: Can I nail or hang a "beam" to "post"?

Option B: Or do I have to make the post closer now (instead of 5 feet spacing) and that part is an overhang?

Thank you for your patient.

  • It can be as large as the engineer designs for. The part of the raised platform that's over the deck, is supported by the footings for the rest of the deck. If it hangs out past the main deck too far, there will be footings to support the bit that hangs out. If the raised deck is attached properly, it can hang out past the main deck a bit without additional supports. Without seeing the deck from the other side, we can't see the support structure. So there's no way to know for sure how they're supporting it. – Tester101 May 20 '16 at 12:59
  • With my additional information above, I guess what I want to know is: Would it be OK to have 3 "layers" of: 4x8 beams, 2x8 joists (on top of beams), then 2x6 joists on top of below joists. – HP. May 21 '16 at 2:47
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    Any reason you aren't lifting the existing deck? Seems like a massive expenditure of lumber for what will be an odd-looking result. – isherwood May 21 '16 at 3:34
  • Yes, the reason I don't want to lift the deck is that it's close to the house and I want to build a sunroom there. So it's odd to walk outside the sunroom and step up right away – HP. May 21 '16 at 6:03
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Think of it like 1) taller joists, or 2) the second level of a house (without the added load of a second floor). There's no reason why the load from the upper level can't be transferred through the lower level to the footings.

As to size, the upper deck can be as large as the lower deck, and if there's no cantilever on the lower deck the upper can extend to whatever is allowed in local code for cantilever.


Regarding your updated questions...

  1. Yes, that's acceptable, assuming the beams will carry the additional lumber load safely.

  2. No, that would be far more expensive and time-consuming that your other options, the best of which (from what information I have) would be to simply raise the existing deck.

  • I have added some more information in my question – HP. May 21 '16 at 2:46
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Not sure what you are asking, but the footings supporting the deck structure are in the ground under the posts that hold up the beams. Footing size, post size, beam size, joist size are all engineered to support the weight of the structure,and any distances spanned.

If you look at some of the other photos on the website they show posts under the outer edge of the octagonal section supporting it, its not a cantilevered section if that's what you're wondering. You just can't see the framing involved hidden under the ipe decking.

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