[EPERRINGTON]

I've never used sonotubes before, but where I live now the building code is recommending a sonotube or like product for the footings of my deck. Frost line is 36 inches so I was planning on digging my hole 48 inches and putting 6 inches or so of rock down first and then the concrete on top.

However, I have seen or read several different opinions on how to install the tubes and by building code office is really giving me anything on how to use them. Place a tube all the way to the bottom of the hole. Place the tube only a foot or so down from grade and fill with concrete. In the second case concrete would be contacting dirt for the bottom 30 inches and then sonotube for the top 12 inches.

What is the preferred method for installing a sonotube? Is there a better method I have missed?

 

[EPERRINGTON]

Opps...forgot the third option I have seen which is more in line to what I have done in the past 5 - 10 yrs ago.

Dig a whole and place concrete in the hole without a tube.

Thoughts?

 

[burnt03]

We had stairs built onto our deck and I dug the holes (about the only skillset I have available to me )

The guy used a "bigfoot" base: http://www.bigfootsystems.com/

He also replaced the footings on the lower deck and tied the upper deck posts into the same footings. He said that we needed a stronger base for those, so he built a plywood box approximately 2' L x 2'W x 18" D for each sonotube.

The ones that I dug out were 6" diameter sonotubes and they had dug the hole, pulled the sonotube up a bit (12-18") and just poured into there. No real base to it, and it was starting to lean a little bit (hence the replacement).

 

[concretemasonry]

Any concrete is a "free-dug" hole will have a rougher surface and can heave even with less than 36" of frost because the frost/soli can grab it and pull it upward.

The best route is Sonotubes to the frosr depth or a "bigfoot" at the bottom to spread the post loads out over a larger are (good for pooer soild), plus you get a larger base area to resist heaving.

Dick

 

[EPERRINGTON]

Thanks for the info. I am thinking about using 8 inch sonotubes with a hole depth of 40-42 inches of concrete and around a 4 inch rock base on top of a soil of all clay. Any concerns?

Should I place the tube on top of the rock or pul the bottom up some?