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-   -   Deck without ground support (http://www.diychatroom.com/f19/deck-without-ground-support-145163/)

Orest 05-28-2012 07:52 PM

Deck without ground support
 
2 Attachment(s)
Hi guys,

Looking for advise on building a deck. I currently have a condo patio with a raised (~3.5' high) that is approx. 180 sq ft of grass. Its north facing and ground floor so needless to say the grass never grows very well back there so I got approval to replace with a deck. As I have to go through 3 other owners patios to get to the street, getting an excavator is out of the question and I can only haul materials in and wheelbarrow dirt out. I've attached a rough sketch of the dimensions of the proposed deck as well as a picture of a section to give you an idea of what I'm talking about. I'm hoping to dig out just enough dirt (~6") to allow me to use joist hangers to attach to the 8x8 frame with a fabric underlay to prevent weed growth. My questions are:

1. Can I essentially dig out just enough to dirt to near rest the 2x6's on and attach joist hangers to the 8x8 interior frame without using an additional ledger board?
2. Given the dimensions (8.5' - 10' wide), can I use 2x6 joists spanning 16"-12"?
3. Planning on using redwood cedar decking with camoflage fasteners, has anyone used these before?
4. Do I need to lay any gravel down or is a fabric liner enough for below the dirt?

Thanks for all your help! I am just a do-it-yourselfer so I've just picked up enough to get everything figured out.

Orest

oh'mike 05-28-2012 08:20 PM

What does your city require for clearance under a deck?

Orest 05-28-2012 08:36 PM

They don't have a requirement (can be placed directly on ground).

oh'mike 05-28-2012 08:43 PM

That's good---next question---

Taxes--here a free standing deck is taxed at a lower amount than one that is attached to the building with a ledger board.

Is that the case where you are?

Next question--don't you hate it when someone answers a question with a question?:laughing:

There are several good deck builders on here that will chime in soon---most of my work is inside the house---Mike---

hand drive 05-28-2012 09:19 PM

if there is a way to add gravel underneath the deck and have an exit somewhere for any water build up then that is the best way for a deck that close to the ground.

cortell 05-28-2012 10:41 PM

If you want this deck to last, raise it above grade. If you think Cedar is going to stand up well to long term moisture, read #2 in the following article.

http://bct.eco.umass.edu/publication...ns-about-wood/

KevinPh 05-29-2012 09:40 AM

I would just do a free floating deck and not attach it to the ledger board. You absolutely need to have the deck rest on a 4-inch bed of gravel for drainage, otherwise it will rot. The deck should sit above the level of the surrounding soil because again, it will rot. You can put a layer of landscape fabric on top of the gravel to prevent weed growth if you want, but it likely is not necessary.

If you want the soil to be at the same level as the top of the deck, you should protect the sides of the deck with a vapor barrier.

Orest 05-30-2012 02:43 AM

Thanks for all the replies! I guess a couple of my questions would be if that using joist hangers attached to the 8x8's and across a 9' span would be strong enough without ground support? I could do: http://www.doorsixteen.com/2009/04/26/instant-deck/ which uses conventional blocks and do free floating as suggested. I'm surprised at the number of free floating decks I find that where they arn't using a gravel underlay, or perhaps thats only needed if the deck completely sits just on gravel?

Thanks guys

GBrackins 05-30-2012 03:32 AM

I noticed you said condo .... do you have a condo association? if so the first thing I would do is check with the association before doing anything.

here is the Prescriptive Residential Wood Deck Guide http://www.awc.org/publications/DCA/DCA6/DCA6-09.pdf as published by the American Wood Council and is based upon the 2009 International Residential Code.

as Cortell said ground level decks do not last! When a deck is close to the ground ventilation is difficult. Moisture tends to become trapped under the deck (even with gravel). The increased moisture cause the wood to swell, the top of framing members exposed to the sun and wind tend to dry out and shrink. This differential moisture content typically causes ground level decks to twist and cup. I'd be willing to wagger you'd get no more than 5 years out of the deck built on the ground. A buddy of mine wanted a deck so bad he failed to heed my advise and built one any way, that was 3 years ago and he needs to repair it now. He's taking it out and putting in a concrete patio with stone pavers.

Good luck with your project!


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