Deck question - NF

[dannyboy]

I need to dig 6, 12" diameter, 4 feet deep holes for our deck. I am going to rent a hydraulic auger, the problem is our ground is hard clay. The auger also comes with 6", 8" and 10" bits. Would there be any advantage to first drilling the holes with a smaller bit then following up with the 12" bit?

 

Any comments or suggestions are welcome.

 

Thanks

Dan

[fishnsled]

Not sure but that certainly works when drilling in some materials. I'd be temped to just try with the larger bit, go slow and see what happens. If it seems to be having a problem with the clay then maybe use the smaller bit first. I've never heard of changing bits, just getting a bigger and more powerful machine for the job if necessary.

[Lip-ripper]

For the 12inch diameter holes, are you putting footings at the bottom? If so the post hole auger will be useless.

 

12 inch holes seem like overkill if you aren't putting footings down, i'd just go with 10inch holes and 10 inch sono's.

 

p.s. keep a sawzall handy for any roots you may encounter.

Edited July 27, 2011 by Lip-ripper

[dannyboy]

I am putting in 12" Sonotubes, thanks for hint about the sawzall.

 

Dan

[misfish]

Why 12 inch Danny? Just asking.

 

You can go 8 ,and at the bottom of the hole using a spud,clear out a 12 inch round hole about 8 inches up from the bottom.This will act as an anchor. If you have clay like you say,and you dont do this anchor type style,you will get heving.I use to be a deck builder bfore it got cut throat here.

 

 

Good luck.

[dannyboy]

Thanks for the comments, I plan to open up the 12" hole at the bottom and wrap the sonotube in polyethylene to prevent heaving.

A 12" pier is what someone way smarter than me calculated was best.

 

Thanks,

Dan

[HTHM]

There is no need to wrap the the sonotube in poly, the inside of the tube is poly, that is how one gets a smooth finish on the concrete inside.

Good luck with the project.

HomeHardware in Wellandport should carry what you need.

[Terry]

in many cases it does not help to drill a smaller hole first

 

the center of the auger needs to bite into something to keep the auger strait, if you cut first with a smaller one there is a good chance the auger will jam up on the edges

 

if you get down 4 ft making the bottom wider is not as important..if you have some less then 4ft deep then the wider the bottom the better as it helps to stop the frost from lifting it....

[Harrison]

To the original question, NO. Go right with the 12". In addition to a sawsall, get a spud bar to help jar rocks and hard pack so the auger can lift them out.

 

Get ready for a work out.

[dannyboy]

Thanks guys, 12" all the way then.

 

Sawzall check

Spud bar check

 

Wellandport HomeHardware is where I went to rent the auger as they are great to deal with, unfortunately it is out for repair.

Welland Equipment Rentals was my next call - good to go.

 

Dan