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deck on concrete slab

6K views 11 replies 7 participants last post by  Daniel Holzman 
#1 ·
Hi-

I am building a deck over an existing concrete slab that is 3-6 inches thick built with reinforced wire in the concrete.

The beam far from the house will be supported with 12" footers, but the area close to the home has to either be supported by 1 of 2 solutions:
1. a ledger board attached with a combination of through bolts or epoxy anchors into structural masonry (brick and filled CMU block)
2. attach footers with 4x4 post holders directly to the concrete slab

Can anyone shed light on which may be a more preferable solution? I'd like to think the attachment to the slab would be easier, but I'm not sure if it'll be sound or even close to code.
 
#2 ·
Technically, footers close to the house(within a backfill area) would need to be dug down to undisturbed soil. This would be the houses footing depth.
 
#3 ·
Yes, for true footers close to the house full depth is true, but this isn't one of the options.

I either attach to the already existing slab or use a ledger board for the support required close to the house.

Any feedback on one of these two options would be awesome.
 
#7 ·
noname -

Where in the world are you hiding (location would be a clue to get more responses)?

What is the climate and do you have any frost requirements.

What is the size of the deck (span and sf)?

You have already identified these, there are many acceptable options. After you have cleared up the conditions, you will get better responses in stead of guesses.

After that is established, the basic requirements for an attached deck capable of taking the loads the loads imposed on the surface and those forces from the soil and Mother Nature.

Dick
 
#10 ·
Even though it seems like it's the easiest & cheapest method, you can't support the deck off of "footers: on the far end and simply attach it to the patio at the house, especially in an area prone to frost. You have to remove some of the patio to install post holes, or anchor & flash it correctly to the house.
 
#11 ·
Here's your feedback:

1. Don't support it off the slab. That is oh-so very amateur, and it gets dinked every time during an inspection. Towns frown on the practice. Have you spoken to the building department yet? They might tell you right off the bat that they won't issue a permit for it.

2. Google "Prescriptive Residential Deck Design Guide", and look for the various ways to secure a ledger to a house. Most towns follow some version of that document when it comes to decks.
 
#12 ·
The simplest way to support a deck off a concrete slab is to jack hammer a sufficiently large hole through the slab so you can install a footer of appropriate size and depth. This is not really all that difficult, you rent the jackhammer and an auger. As noted previously, if you do not wish to do this, you need to use an approved technique to install a ledger. The building inspector will likely know how to do this, or at least they can point you in the direction of the code. The Prescriptive Guide mentioned is quite good, easy reading, lots of pictures.
 
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