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Discussion Starter #1 (Edited)
Started pouring deck footings this weekend. 12" diameter footings, ~12" deep (warmer climate and a low-level, freestanding deck). The sonotube sections are ~6" long, so they only really contain the top few inches within the hole, and whatever extends above grade.

I'm not using posts on this deck because it's so low; the beam brackets will be directly on top of the footings. So I need to get all the footings well-leveled with each other. Exact height of the footings isn't super critical so long as they match each other.

I poured the first footing, screeded it off level with the top of the top, placed my anchor bolt, and troweled it once the bleed water was gone. Not too long after, I noticed the top surface of the concrete had dropped slightly (~1/8") below the top of the tube.

So, I'm wondering if this "drop" is because the concrete continues to creep out a bit and fill in every last void of the hole, or because it self-leveled a bit and I didn't have the tube flat, or contraction as it dries, etc.

Mostly just curious how to handle setting the heights of the remaining footings so that they end up level with this one? Set the tubes at the same level this one was and assume they will behave similarly? Granted, being off by 1/8" on footings that are 96" apart isn't the end of the world but I'd rather get them as close as I'm able.

 

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Naildriver
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Looks like normal shrinkage. It probably didn't help that you didn't use sonotubes for the full depth, as that would have kept the concrete from spreading out below. If they all shrink that much, which isn't bad, then you would be good to go.
 

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retired framer
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Looks like normal shrinkage. It probably didn't help that you didn't use sonotubes for the full depth, as that would have kept the concrete from spreading out below. If they all shrink that much, which isn't bad, then you would be good to go.
I like the tube just at the top. You get full support from undisturbed soil around the column.
 

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Naildriver
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We had to set 53, each 3' sonotubes for concrete columns for a deck (8' wide and 350' long) in a swamp a couple of years ago, so we had to precast them and set them with a track hoe with a thumb in pre punched holes filled with water. It worked, but I would never have poured concrete in the holes and cap with sonotubes, even if they were dry. The stress was vertical so letting the concrete slather into the hole would have been a waste of concrete.
 

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retired framer
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We had to set 53, each 3' sonotubes for concrete columns for a deck (8' wide and 350' long) in a swamp a couple of years ago, so we had to precast them and set them with a track hoe with a thumb in pre punched holes filled with water. It worked, but I would never have poured concrete in the holes and cap with sonotubes, even if they were dry. The stress was vertical so letting the concrete slather into the hole would have been a waste of concrete.
:biggrin2: The swamp would be an extreme situation. Looks good too.
 

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Naildriver
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Thanks, Neal, it was a bear. The mayor didn't want a straight walkway. She wanted it to follow the contour of the land and around trees, etc. It had to be ADA compliant, too. Lucky for us it was winter and we were walking on ice for most of the project, but below was water and muck.
 
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retired framer
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Thanks, Neal, it was a bear. The mayor didn't want a straight walkway. She wanted it to follow the contour of the land and around trees, etc. It had to be ADA compliant, too. Lucky for us it was winter and we were walking on ice for most of the project, but below was water and muck.
If you had built it straight any shifting would show up fast.
 

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Discussion Starter #9
I would carry on and hope all would react the same way.
Roof shingle makes a good spacer in the bracket or galvanized washers under it.
Thanks. That was more or less my plan. I like the shingles as shims suggestion. Cheap, thin enough to fine tune heights, and should last a long time.
 

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Naildriver
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The shingles will crush somewhat, but you can always add more. and it is a good method of bringing it all up to the level you wanted. Sorry for the hijack.
 

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retired framer
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Thanks. That was more or less my plan. I like the shingles as shims suggestion. Cheap, thin enough to fine tune heights, and should last a long time.
If you are in a cold zone you want the sides of the holes to be smooth when you do a rough pour you don't levels sticking out that could collect water under and still give you a frost heave.
Protect the top of the beams and joists with a peel and stick so water doesn't sit on them. This is not your father's treated lumber.

Flashing against house??:vs_cool:
 

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Why not just notch the beam? When I pour deck footings I don't worry too much about getting them all the same height. As long as they're close its good enough. Wood cuts easy.
 

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Naildriver
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He's not using posts. Direct frame attachment to concrete with brackets.
 

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Discussion Starter #14
Why not just notch the beam? When I pour deck footings I don't worry too much about getting them all the same height. As long as they're close its good enough. Wood cuts easy.
There are no posts. The beams and brackets are directly on the footings to keep the height low. That's why it matters. I can shim brackets a bit, but that's about all the height adjustment I've got.
 

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Discussion Starter #15
Just to close the loop on this, I poured a few more this weekend and finished height dropped about the same amount as the first one, so setting the tops of the forms at a consistent height with the first one I poured seems like the way to go.
 

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We had to set 53, each 3' sonotubes for concrete columns for a deck (8' wide and 350' long) in a swamp a couple of years ago, so we had to precast them and set them with a track hoe with a thumb in pre punched holes filled with water. It worked, but I would never have poured concrete in the holes and cap with sonotubes, even if they were dry. The stress was vertical so letting the concrete slather into the hole would have been a waste of concrete.
WOW! Glad that was you doing that, lol.
 
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If you want to get really particular about it, you can use plastic shims of various thickness to make up the difference across your footings. They go from 1/32" to 1/4". I got particular about it on my deck so used my laser level to shoot a line and measured off of the highest post. Got the exact variance at each footing and used whatever shim thickness I needed.

http://www.acehardware.com/product/...MIueDtnJav1gIVj7XACh0cjgauEAQYBCABEgIhpvD_BwE
 
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