I just built a multi level deck that wraps around 2 sides of my 12' x 24' AG pool. The highest deck on mine is about 2' high. In my case a 48" hight deck would have looked out of place. I built a platform with a step to get up to the deck ladder. worked out great. I used about 25 blocks. more expensive than cement footings but much easier, no digging!. Even with cross bracing I wouldnt feel comfortable with the small size but high deck you describe.
Check out dekblocks web site. They will check your plans for you!!!
You think so? I'm doing three projects right now - 80 feet of replacement fence using mix-in-ground post cement, a wood rick that will stand on eight dek-blocks, and a large deck that will have 19 edge posts on poured footers and collars. I've checked all the options just in the last few days. My choices might be a little different than some, since I'm doing the jobs single-handed and have to make some compromises on ease vs. cost, but...
Minimum on a one-man auger was $60; I had it overnight for $100. A two-man auger is about 2/3s that.
Fence post concrete (mix-in-ground) is high right now, about $6 a sack.
Using delivered concrete for posts is a pain in that you have to have all the posts set and staked before delivery, instead of working them one at a time. You also can't do footers and collars in the same delivery.
I'd like to see how you figure an auger plus crete at $40...
I'm not sure what code is for that height, but if it's freestanding I'd be very uncomfortable with a footing less than 36 inches down.
You said the ground is rocky, though. You might look into larger, shallower footings - perhaps 24 inch square, 8 inches thick, set at least flush with the ground and using heavy-duty post anchors set into them.
Sorry, I'm not trying to be annoying, but your series of posts doesn't make sense. First you said you needed 45 Dek Blocks (= $160), which could be replaced with $40 worth of cement and auger time. This translated into three cement-set posts, which doesn't seem nearly enough for a 12x24 deck, so you must have some other support involved.
So unless I'm missing something or you're changing the rules around, a deck that needs 45 ground blocks can't be similarly supported by three set posts... so you've got additional support/mounting costs somewhere that you're not including. The costs and labor of a large ledger, properly attached to a structure, are considerable, and if you can hang a 12x24 deck on three posts plust a ledger for much less than that original $160, I'd really like to know how you do it.
Three deck blocks per 12 foot span yes. Per joist, not necessarily. If you use 2x6 beams and joists are perpendicular, the beams get blocks and the joists don't. For a 12x24 deck, four 24' beams at 36" on center, 8 Dek Blocks ber beam, is 32 blocks. I think the recommendation was no more than 30" between blocks, so maybe you'll get close to your 45 blocks.
Locally, you wouldn't be to code. 12x24 is large enough to require a permit, and you'd be required to support no more than six feet apart (depending on height above ground) for 2x6 beams. In a 12x24, assuming the 24 is along the house, that's a ledger, then two rows of support posts, five per row. Or ten posts plus a ledger, auger rental, concrete below frost line (floating decks don't need to go below frost line, andchored to a structure do). Locally we can use 8" Sonotubes for post footers, but we don't have frost. Many areas it's
12". If you had to go 36" deep and 12" diameter, rough calculation is six 60lb bags of mix per hole. 60 bags at $3 a bag is $180, 45 Dek Blocks is the roughly the same price.
Wow. Rather auger holes and carry bagged concrete (and mix then pour concrete) than lift Dek Blocks? To each their own I guess. Locally, Dek Blocks are readily available, but even delivered they only add about $30 to the total cost.
But, Dek Blocks aren't everyone's cup of tea. In my case, no frost, near ground-level decks and sand base make for perfect Dek Block conditions. In other areas, traditional concrete footers and posts may make more sense. If you don't want to use them, then don't.
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