Building a ground level deck

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Old 06-10-09, 10:53 AM
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Question Building a ground level deck

Hi,

I'm looking at building a very VERY low deck. No more than 5 or 6 inches off the ground total (including deck boards). This is necessary to incorporate a new back door opening on to the deck where currently there is a window. I wondering if it is possible to use 4x4 posts and lie them lengthwise on concrete footings instead of using 2x6 or 2x8 joists? The deck boards would then be attached directly to the 4x4's and 2x4's would be used for skirting and rim joists where necessary.

Is this a possible design?

Thanks!
 
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Old 06-10-09, 11:07 AM
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It's doable but would you consider a brick patio instead? What are the measurements?
 
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Old 06-10-09, 11:31 AM
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I thought about a patio (concrete or stone) but I prefer the look and feel of wood. The area is about 18 x 20.
 
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Old 06-10-09, 11:49 AM
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I just looked at your original post again. If you have the footings 2 inches above ground plus 3 1/2" for the 4x4s & another inch for 5/4 decking, that will give you the six inch maximum that you want. It's very close. How level is the ground? You may have to do some grading. A slight pitch away from the house would help with drainage. Leave about 2 inches between the house & the deck.

I would box add 4x4s across at each end of the 4x4 lengths to form a box. 8" sono tubes should be wide enough for the footings. Make sure you go deep enough for the frost line.
 
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Old 06-10-09, 12:37 PM
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Thanks, Pulpo. The ground is fairly level but may require some grading certain areas. I'll have to go down about 48" to go below the frost line.

Any idea how far apart the 4x4's should be spaced? And how far apart should the footings be?

Thanks for your help. Beer 4U2
 
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Old 06-10-09, 03:48 PM
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Spacing the deak posts, header size, frost proofing the sono's, sizing the sono's, :

Building a deck: expert advice from ... - Google Book Search

How Aggregates Prevent Frost Heave

Be aware most composites mold if not enough air ventilation under them. Be safe, G
 
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Old 06-10-09, 04:22 PM
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I agree on the 48" for the depth of the footings. It's 36" here. I was thinking about the distancing. Joists are usually 16" on center. 5/4 decking will spring if there is too much space between the supports. I would go no less than 24" between the 4x4s. Make a test. Put 2 4x4s 24" apart. Lay some 5/4 decking across them. See if there is any give in the decking. If there is go with 16". It's worth the extra time & money.

If you are using 8' 4x4s, I would make the deck 16' instead of 18'. Then I would put a footing at each end of each 4x4, so the middle footing will be where the 2 4x4s meet. Cross pieces can be used anywhere along the length, for extra support if you feel they are needed.
 
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Old 06-10-09, 08:17 PM
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I've done decks that close to the ground, because that's what the customer wanted. But they are difficult, and they get to be fairly expensive.

Drainage is one issue -- you have to slope the grade below the deck away from the house and make the excavation deep enough so that your joists are totally above grade.

Using 4X4's for the joists works, but with most composites you'll have to space the row of 4X4's no more than 16" apart. That's a lot of 4X4's and a lot of footings. I won't span a 4X4 more than 4 feet between the footings. Now you're adding frost into the equation, and those footings have to be 42" deep. THAT'S A LOT OF CONCRETE at $120 to $150 per yard!!

When I do a deck that close to the ground, I wrap the PT 4X4's with Vycor. A 9" wide strip along the bottom first, and then another 9" wide strip from the top down to encase the 4X4. Notice that i start at the bottom and work up, so that the joints of Vycor are on the side, and will shed water.

And ventalation for composite decking -- I won't use ANYTHING less than 1/4" gap between the boards

It's certainly cheaper to pour a slab and be over it. It will cost you about 20% of what the low level deck will.
 
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Old 06-10-09, 09:58 PM
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Thanks, Lefty. I'll be using PT lumber and I'm thinking maybe 2x's are the way to go instead of 5/4 for the decking to prevent the "springiness" Pulpo was talking about. I will test it out though before making a decision.

I will have to cost all of this out. I really don't want concrete so if it is too expensive to do the deck this way I'll have to look at some sort of stone pavers. I've also started looking into the Vycor. It seems like a really inexpensive but useful product. Someone else was mentioning to me that it could be possible to lay 4" of gravel and lay the posts directly on that.
 
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Old 06-11-09, 05:15 AM
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As I mentioned in my first response, the brick is a much better choice.
 
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