cibula11

Are there precast concrete piers that I can use for a deck construction. I thought I could save time if I had the holes dug and then I could set a precast pier in the hole and backfill with rock and soil.

Kerrylib

Take a look at Dek-blocks. They are for a "floating" deck, rather than an anchored one. They look like little piramids that are notched out on the top to hold 2x material across them either way, or a 4x4 vertically.

These just sit on top of the ground. I'm sure they have a limit as to how high above ground you can go.

Also I assume that you're going to have issues if your ground has any instabilities.

cibula11

Yeah, we live in Iowa so code says the footing has to be 40" below ground level. Its a nice thought though.

mudmixer

They are also not permitted in many areas because too often people set them on fill and they sink.

This is especiialy true where people make the mistake of attaching the deck to the house and the deck footing settlement damages the house. - One of the reasons for a code.

If you want good support dig down to firm soil.

cibula11

Is there a certain type of concrete I should use. I was thinking of getting the fast setting quickcrete. It cures solid in 40 minutes. I figure I could at least start to build the frame after an hour.

cibula11

I think I can get away with just 3 post on a 12x20 deck. The one side I will be using a ledger. I will use 2x12 for joists and beams so that I only have to dig 3 posts instead of 6 if I were using smaller joists. Does that sound right?

Philphine

can i use those dek blocks if they're going to sit on a concrete surface (i'm im ky.)? i'd like to make my deck a little bigger and had planned on using them for 3-5 posts where the deck would overhang the edge of the driveway about 1ft.

Square Eye

You can use the Deck blocks on a concrete surface.
You need to drill for centering pins though..
Drill the exact center of the bottom of the blocks, then drill the floor in the exact center of the post location.
Use a matching sized pin (a cut off bolt or barstock) in the floor with the block set over them.
This will keep the posts from being kicked out or from being easily pushed sideways.

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mudmixer

If you set the blocks on a slab and support a deck that is attached to the house, you can run into practical and code problems. This is even if your slab is stong enough.

From a practical standpoint - Any frost heaves or settlement can and will heave the deck. This can cause distortion and loads applied the the house and disruption of flashing, sealing, etc.

From a code standpoint - Two different supports for a deck (house and patio) do not comply if there are frost requirements.

Philphine

the two supports would be regular posts set in concrete like normal, with the 3-5 posts i mentioned on the side of the drive on those dek blocks. the deck comes flush to the house, but not attatched to it as best i can tell.

in a way it might be attatching it to the house, or to the detatched garage actually. what i'm wanting to do is... there's a loft over the garage with a deck around part of it, that kind of overhangs the regular lower deck. i'd like to widen the lower deck up flush with the garage so i have more overhang bettween the two decks. i hope to make it easier to work out either spiral or strait stairs bettween them. so i guess if i can do this the stairway would become an attachment.