Low-Profile Deck Plans. Need Proofreading

BranTheBuilder

Hello everyone.
I live in NJ and I would like to send my plans to my municipal department to apply for a permit. Before I do, though I have a few questions.

-The deck I'm building will be 10'x21'. The 21' side will be attached at the house
-The top of the deck (where people stand on) will be about 10.5" above the ground.
-I have a tight space to work in (10.5" height)

-The ledger I will use will be 2x8 wood and will be 21' wide.
-From there, about 5' down, I plan on putting in 4 footings that will hold an intermediate header joist.
-10' mark, another 4 footings will be placed that will hold the header joist
-The two header joists will be of 2x8 wood.

-Side joists will be 10' and some inches and be made of 2x8 wood.
-The joists themselves will be of 2x6 wood and will be 5' long. 28 of them will be used total and 14 will be placed between the ledger and the intermediate header and another 14 between the intermediate and the header joist. I will stagger the two sets so that they are not running in a straight line (I don't think the wood will be wide enough to hold the nails of both sets in a line)
-The distance between the joists will 16.5"

-The deck boards will be 5/4"x6"

Some questions I have are:
1- Is the plan okay? How are the wood dimensions?
2- What other details should I add?
3- Something that is really boggling me is how deep should the footings be? I'm planning on making the footings with 8" diameter cylinders that are filled with concrete. I'm thinking about making the footings 6" deep and leaving 2" above ground.

joecaption

Go back and add where you live in your profile, just the state will do.

At all cast avoid attaching the deck to the house, far better to make it free standing then there's 0 chance of damage to the house.
ake sure the top of the decking is at least 4" below any door opening or water will get under the threshold.
Your local code officer should be able to tell you the depth you need for the footing.
Footings only 6" deep would not fly anyplace I've ever lived and would do nothing to support that big a deck.

CopperClad

Hi. So you only have 10 1/2'' from the ground level to the top of your decking? If you have a 2x8 header and a 2x6 joist that = 12 3/4'' . Clarify this first please.

mae-ling

The way I build these low profile smaller decks is to use the rim joist (end joist) as the header.
Double your rim joist (2-2x8) and use joist hangers. This way you do not need another beam under it. Also use 2x8 for the joists on a 10' span.
Pour concrete piles using sono-tubes below the frost depth in your area.

BranTheBuilder

Thank you for your reply and help everyone!
I'm in the Central NJ region, and I've updated my profile.
To clarify a confusion from earlier, I will be attaching the joists themselves to the headers. I won't be resting the the joists on top of the header, but rather attaching them to the headers using the joist hangers. If I interpret correctly, think this is what mae-ling was saying.

The reason why I'm asking about the footing being so shallow is that since this is a very low deck, will it need to be "anchored" to the ground, 32" deep as if it were a high-standing deck?

Also, I think I can change the plans around a little bit to make this a free standing deck that is not attached to the house, but sitting right next to it (half an inch apart?). Will this suffice or should I get a permit for it and attach it to the house?

mae-ling

What you are referring to as a "Header" we would call a rim joist. So yes you and I are saying the same thing. I would double it and then use 2x8 for the joists.
If the joists are on top of the "header" we would call that a beam. Header is the term for what is used above a window or door.

It would be best to go with footings (piles) that extend down below the frost line.
Part of the reason for the footing is for heaving of the deck not just anchoring. If you go below the frost line your deck is less likely to heave with frost.
Here you can build a lower deck completely on the ground, and people do, and the heave and are no longer flat.


And make it not attached to the house is also Good.
I take it if it is not attached to the house you do not need a permit, but if it is attached you do?

BranTheBuilder

Ah, okay. Thanks for the explanations! The black and decker book on deck building called it the header, haha.
I'm not sure if I will be able to build even a freestanding without a permit. I will call and confirm once I get the chance.

What about the distance between the footings (5') and the diameter (8")? Are they okay?
And how about the 16.5" between the joists?

Also, I have a slab of concrete that is 5'x10' right in front of the sliding door to my backyard (where I plan to build my deck). I think the people who lived in the house before me were trying to make a deck, but instead put in that slab of concrete as a paver patio. Will I have to break that concrete slab up to put the footings in? or can I build on top of them?

If this will be a freestanding deck, I'm thinking of putting in 4 footings right in front of my door that will hold the "ledger", another 4 in the middle that will hold the intermediate rim joist and the last 4 at 10' away from the door that will hold the rim joist. about 4 of those footings will be in the area where that slab is. What can I do with that?

Thank you!

AndyGump

From what I understand of how you are planning t build this it would not conform to prescriptive measures. Check out THIS link to the DCA-6. A prescriptive deck building guide.

By the way, a free standing deck is still connected to the house, it just does not use the house foundation as one of the main foundation points of the deck.

Andy.

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mae-ling

Not entirely true andy. In one place I lived we built decks that were 1/4" away from the house and not one nail/screw etc. was put into the house.
This was done for tax reasons, if the deck as attached then your taxes went up.


You need to remove the slab, usually they are only 3-4" thick and will not provide adequate footing. I'd put good quality landscape fabric and crushed rock under the entire deck.

BranTheBuilder

Alright then. I'll contact the building and construction committee sometime today regarding the permit.
But how would you go about building it freestanding? Did I describe an adequate way by using the 3 rows of footing?

Also, for conformity, should I change the wood size of the rim joists and ledgers from 2x8 to 2x10 and the joists from 2x6 to 2x8?

jcarlilesiu

Residential building code is going to require that no wood member is closer than 4" to grade.

Based on the information you provided, with the depth of beam/joists, you won't be able to maintain that minimum distance.

BranTheBuilder

Does that mean it must be 4" above the ground? What if I used 2x6 for the joists and dug a few inches of trenches all around?