Ground screws (foundation)

[gotham]

Anyone ever worked with ground screws? They are big in the solar industry where they are working in a big field and putting in hundreds with heavy equipment. I've seen the small DIY ones but it seems like I would want to go below the frost line (36" here).

I'm looking to build a treehouse with no tree. A vertical column, probably a steel tube with a couple outriggers to keep it up. I was planning on 3 concrete footings but the location is fairly inaccessible. Manually digging the footings plus carrying the concrete and mixing will be a ton of work so I'm willing to put some effort into installing the ground screws.

 

[mike93lx]

My folks had a building put in for their hot tub with ground engaging piles. They get driven in with a skid steer using a special attachment.

Worked great for that. Just need to find someone to do them

 

[kaymccampbell]

Technopost is one franchise. They work great. You will need 4 posts installed. A larger center and 3 small ones to guy it. Or you could build a Space Needle with just 3 smaller posts. You can do it yourself, if you have a gear reduction auger for your skid. Buying the posts may be a problem, as I've never seen any independent suppliers of them.

 

[Stuart in MN]

I think they're more commonly called helical piers or helical piles. My only experience with them is using them as the base for street light poles, but they are an interesting alternative for buildings too. I haven't seen any that are DIY, they typically require a hydraulic attachment on a Bobcat or front end loader.

 

[jkeyser14]

I had them put in for my deck posts which had to go into 12' of fill dirt. They are called helical piers or helical pillings. Mine were put in by Techno Metal Post's regional installer. Price was $250 each for posts with a 5000 lb engineer stamped field test report.

They were put in with a little walk behind machine. Definitely not DIY.

 

[larry4406]

I was involved with a project in Miami Beach FL. The house was supported by helical piers/pilings whichever term you prefer. The tops of the piers were connected via steel and concrete grade beams after piers were set, then house construction commenced.

A bobcat attachment was used to install them. There was a device that measured the torque resistance of the earth on the pier which determined when it was "good enough".

 

[gotham]

I think a ground screw has little threads similar proportions to a wood screw. The helical pile has a big flatish thread

This place has some of the shorter DIY style screws as well as the longer screws. https://www.bayo-s.com/screws-tools

I was hoping to DIY. If I need to hire it out I might as well go for concrete.

 

[mike93lx]

I think a ground screw has little threads similar proportions to a wood screw. The helical pile has a big flatish thread

This place has some of the shorter DIY style screws as well as the longer screws. https://www.bayo-s.com/screws-tools

I was hoping to DIY. If I need to hire it out I might as well go for concrete.

The advantage of screws is no digging no mess, no concrete truck. Just a dingo or a bobcat to drive them in and done.

 

[gotham]

I can't easily get a bobcat into where I want it as it's in a pretty steep area with a lot of scrub oak.

 

[matt_i]

Sounding like shovels, pickaxe, generator, a concrete mixer and some bags of quick crete. Don't have to place all the concrete in 1 shot.

I'd go for just one big footing, rebar cage around it to keep it all together.

1" threaded rods sticking out to bolt to a gussetted flange that's integral to the steel tube.

Hopefully not too rocky.

 

[gotham]

I was thinking a main footing like you describe plus two more for outriggers. I expect it will be rocky and I'm not looking forward to digging. I figure (3) 36" deep sonotubes is less digging than one big block.

 

[Di Trut]

I used these Pylex DIY screw piles for a project in the yard. Installed 4 of them by myself with a lenth of 2x4

https://pylex.com/en/products/10555-adjustable-pylex-50-black

 

[gotham]

I used these Pylex DIY screw piles for a project in the yard. Installed 4 of them by myself with a lenth of 2x4

https://pylex.com/en/products/10555-adjustable-pylex-50-black

How much $ per screw if you don't mind me asking? I'm not sure I can get that big screw past what I expect to be fairly rocky soil.

 

[kaymccampbell]

$35 each from Crapazon. Free shipping with a 10 pack.

 

[matt_i]

I made one of those a few years back.



Used for keeping the family watercraft on a mooring ball during a weeks' vacation.



It does not work *at all* in a rocky bottom lake...must be sand.

This one screws in with a very large T-handle, another square tube which engages the square tube on the end.

 

[jbwilkins]

This will make putting in a screw pretty difficult......

 

[theoldwizard1]

How well they work will depend on the soil type and the wind load as well as connection to other "screws".

 

[jimindm]

I am not sure I would overthink it to far.

You want a tree house type structure, with out a tree. On a steep hill with scrub trees.

What is the use? How big is it going to be?

If this is just a little place to hang out for the kids, that is one thing. If its going to be a kid mansion, or a place that ten adults are going be in it for a hunting season is another.

How much wind is there, where you want to build it? If its going to be on the side of a hill, how steep, and how does the water run off?

My FIL years ago lived out side of a small town. The town decided to replace play ground equipment because a kid got hurt on a nother towns not far away. It was a tower like structure that had about a 40ft slide off one side. Had monkey bars, and a net for climbing, along with the ability to climb up the inside. I would say the whole tower was maybe 25 feet tall, and about 5-7 feet square.

It originally had like telephone poles in the corners that went down into the ground. The day we removed it we chainsaw of the poles at ground level, lowered it onto a flatbed and hauled it to the farm. He bolted some longer two by something to the base of the tower and stood it up. Be bolted the slide back on and cut a few holes in the different climbing levels of the tower. That thing stood in the yard for years. Every grandkid that has graduated HS or college has had a picture includes with that play structure.

The area was a typical farm house, A few trees around the house and farm field surrounding the house. That tower stood the test of time. They sold the house several years ago, but as we go check the farm ground from time to time, that tower is still there.

 

[Sumboodie]

I had them put in for my deck posts which had to go into 12' of fill dirt. They are called helical piers or helical pillings. Mine were put in by Techno Metal Post's regional installer. Price was $250 each for posts with a 5000 lb engineer stamped field test report.

They were put in with a little walk behind machine. Definitely not DIY.

They rent them here for DIY. It's just a glorified post hole augers that screws them in.
Biggest difference is they have a pressure gauge so you can tell if it's in good ground.