freestanding deck over concrete pad?

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Old 10-28-15, 05:57 PM
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freestanding deck over concrete pad?

we have a boring ~24x12' concrete pad in the back of the house and want to put a freestanding patio deck on top. The doors to the house are about 11" above the patio (raised foundation). I want to build a freestanding deck (permit reasons) ON the concrete pad so I don't have to bust up and haul the concrete away. Everything I've read is very conflicting from "just put sleepers down and build on toep" to "NO DON'T USE SLEEPERS" to "you MUST demo the concrete" or "just build on top" The pad does slope to one side but overall in good condition. I live in Southern CA where we are dry, drier and VERY DRY at the moment but plan on having an el Nino year.
I was looking at this method:
Deck and Cover! - * View Along the Way *

But since I don't want to attach TO the house i wanted to attach a ledger board to the ground and use hanging joists to extend 2x6s out. Then on the opposite side use concrete piers at the edge of the existing concrete that will go into the ground.
OR can i just use concrete piers ON the concrete pad and pour some concrete around the pier?
 
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Old 10-28-15, 06:30 PM
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Wood needs room to breathe or it will rot. How much space do you envision under the deck? Have you thought about dressing up your patio like with a stain instead?
 
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Old 10-28-15, 06:34 PM
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Post some pictures or everyone's going to be guessing.
All forms of decking need air flow under them to prevent mold.
That attachment you posted should have been titled how not to build a deck.
Never ever should a deck, stoop, patio be even with a doors threshold unless it's an enclosed deck!!!
2X's are not below grade rated and will rot out if there's no drainage.
I did not see them remove the siding and install waterproofing all the way below the siding.
 
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Old 10-28-15, 06:56 PM
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I can't attach my pic for some reason. Just says "upload failed"
I plan on having about 10" below the deck and definitely NOT flush with the door. I want it just below the threshold so there will be about a 1.5" drop below the floor.
Or this: https://www.youtube.com/watch?v=tDZ6gwUisCs

stickshift. I don't want to dress up the pad with paint or stain since the house is raised foundation and need something higher. There was a concrete stoop but it was dull and boring. A deck would look nice
 
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Old 10-28-15, 07:01 PM
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Decks are nice if you do not mind the on going maintaince at least every couple of years.
 
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Old 10-28-15, 07:10 PM
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there are ground rated 2x's and it looks like they attached the ledger to the raised foundation portion of the home and not into the studs
 
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Old 10-28-15, 07:25 PM
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Is the slab you have level, or is it crowned/sloped for drainage? If you're looking to build a deck over it, might not be a bad idea to build a couple drains into the interior to prevent standing water from pooling under there.

I'd probably keep the slab intact and put some short (4-5 inch tall 4x4s) piers onto the slab using post bases (seems like something like a simpson half-base bolted down with either red-heads or tapcons should be enough for short piers, but I'm not sure if that'd satisfy code in So Cal, especially L.A. County) set on either 6' spacing. With as short as the piers would be, it might be possible to use some kind of concrete blocks instead, not sure how to really attach that, might require some drilling into the slab to sink short bits of rebar and pour some concrete (wood is more my area of knowledge).

On top of the piers, run 4x4 rails along the 24' axis, using 6' or 12' lengths so any splice points would be centered on a pier, then set 2x6 joists between the rails on joist hangers (20-24" on-center should probably be enough for the kind of working load you're likely to have on a deck, but code may require 16", and joists will be a little under 6' long), then cover the framework with 1-by planking, this should leave you a couple inches below the door threshold (piling snow probably isn't an issue, but dirt and leaves can still pile up a bit so it's advisable, possibly required, to have some drop) while allowing for the best possible airflow underneath given the presence of the slab. Being in CA, Redwood should be readily available in most/all of these sizes.
 
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Old 11-02-15, 06:58 AM
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I'd go with BMGreene's recommendation. I suspect the slab you have is already sloped, but if it's cracked / not in the same plane, I would use some kind of concrete topping mix to make sure no water pools underneath.

PT 4x4's with post bases (with treatment applied to the cut ends) seems like the easiest way to go. No need to do concrete piers blocks, and it would just add complication to the project.

I looked at that link a long time ago when I was building my freestanding deck, and while some of it was helpful, I think they erred by attaching it to the house with a ledger board. There are a couple other links floating around; if you search my posts, I pretty commonly post in threads about floating decks over concrete patios. In this case, with so much room to work with, I think you'll have no problem at all. You can use a beefier structure, which will enable traditional spacing and construction.
 
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Old 11-03-15, 06:31 PM
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it is sloped to the right when facing the house but it is cracked in 3 places. One area does pool a tad but I already had planned on leveling and filling in the cracks. I may go with BM's recommendation or modify it by using preformed concrete piers but use a cardboard form around the pier and fill it with 2-3 inches of concrete.
Still not able to post pics for some reason....
 
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Old 11-03-15, 06:42 PM
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http://www.doityourself.com/forum/el...your-post.html

Pictures are uploaded one at a time and need to be scaled to web quality. A 12 megapixel pic will not upload, a 100 Kb pic will.

My concern with this is that you don't really have a stable base. The slab is movng, cracked and sloped. Your puddling also will cause moisture issues. If you think moisture issues are not an issue talk to my neighbor who is dealing with a 14 year old deck that has never been treated. Its a mess, and we are trying to rehab as best as possible. Your slab is also, only 3 1/2" to 4" thick which is not sufficient as a foundation for any structure.

I would map out the deck and decide where the supports need to be based on the current code for length of support beams. I would chip out the concrete in that area and dig a proper footer to the correct depth for support. Then build your deck using these footers (6x6) notched and through bolted to the support beams.

http://www.awc.org/pdf/codes-standar...Guide-1405.pdf
 
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Old 12-10-15, 12:36 PM
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my pics "fail" to attach for some reason.
But this is the exact situation I have. Other than my door being french doors, this pic in the link would be 90% same as what I have.

http://www.doityourself.com/forum/de...te-slab.html#b
 
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