# Forum Home Renovation The Cubby House  Cubby posts in stirrups or in ground?

## HouseOB

Hi all, 
I'm planning on building a smallish cubby that has a 2500 x 1200 footprint, and is roughly 3000 to the peak of the angled roof.  It has two 1200 x 1200 platforms, the highest of which is 1500 for the slide. 
There will be 90x90 cypress posts at the 4 corners, as well as 2 more in the middle.  The floor will be checked in 20mm into each post. 
Fairly straight forward, but I'm wondering if it's okay to use stirrups in concrete for the posts, or if they really need to go straight into the concrete themselves?  I know if I use stirrups there won't be as much stability and I will need additional bracing (achieved by be using 45 degree supports all round for this).  The entire back and one side will also be braced with 15mm structural ply, so that alone should give some good stability. 
Is it okay to build it on stirrups/pretty common?   
Otherwise if I shouldn't use stirrups how deep would you set the posts in? 
Cheers!

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## Moondog55

Personally I'd put them straight into rammed earth an not bother with concrete, perhaps a sprinkle of cement powder in the dirt but unless it is straight sand rammed earth foundations are good for something this small. Personal opinion only tho. 
EDIT
at least 600mm or 1/3rd of post height, so a 3000post goes 1000 into the ground

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## HouseOB

Yeah I guess that probably would do it.   
I have a 300 diameter hand auger, would 300 diameter holes that are 900 deep with hand tamped dirt (tamping bar) in them be pretty solid do you think?  
Alternatively if I still did want to use stirrups (I kind of do just for experience because I haven't used them before), do you think a 300 diameter hole 450 deep with 450 length stirrups would be nice and solid?  (stirrup would be 350 into the concrete, 100 above ground).  Maybe I could get away with even less depth considering they normally just sit these cubby's on the ground.

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## SilentButDeadly

Pine posts about 600 to 800 into the ground with plain earth is fine. If you want to get fancy then add a sole plate!   
This survived 85 km/h winds last week with no noticeable movement...and it's not exactly on the ground.

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## Moondog55

300 holes that deep wood be [ intended misspelling] good for most things up to a hurricane IMO 
If you want to experiment with concrete and stirrups there is nothing wrong with that either; it just costs more
But foundation size does depend on the soil type and I can't offer an opinion on that, if there are people building on short stumps in your area go and check the size of their holes perhaps
If these cubbies normally simply sit on the ground then perhaps uplift isn't considered a problem and any stable foundation may do

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## HouseOB

Yeah they seem to rely on the weight of the cubby to hold it down usually.  Which is fine, 1200 wide just seems like a small footprint to me, and at 3m tall feels like you could probably push it over.  Maybe I'm underestimating it  :Smilie:  
Cost wise doing stirrups in a 600 deep hole would cost me $42.50 per hole with concrete/stirrups/bolts.  The ground is pretty clay like there, I'm not sure how that impacts the desired dimension of the hole.   Posts in the ground would cost roughly $12 per post for the extra length, so is cheaper unless they are concreted (at which point it's roughly the same cost). 
My priority is safety, but posts pounded in the dirt would probably be more stable that stirrups anyway since uplift isn't a major concern here.  I guess posts + concrete would be the "best" option if money weren't an issue? 
Regarding a sole plate, that is just a flat plate that goes on the bottom to prevent uplift right?  I guess it helps prevent sinking as well?

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## Moondog55

Sole plate spreads the load over a greater area, 
I find stabilised rammed earth the best for fence posts so i assume the same for poles holding a cubby, you really need to ram hard tho

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## r3nov8or

Sole plate isn't attached to the post, is placed in the bottom of the hole (that is, it doesn't prevent uplift). Traditionally a redgum plate, but they don't make redgum like they used to so you can also use a flat piece of H4 or pour 100 - 200 mm of concrete to create a pad

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## HouseOB

> Sole plate spreads the load over a greater area, 
> I find stabilised rammed earth the best for fence posts so i assume the same for poles holding a cubby, you really need to ram hard tho

  When you say rammed earth, do you mean dig a whole, put the posts in, then put the dirt in and manually ram it as you fill it? (As opposed to ramming the poles in like they do with fences sometimes)

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## Moondog55

Yes  _When you say rammed earth, do you mean dig a whole, put the posts in,  then put the dirt in and manually ram it as you fill it? (As opposed to  ramming the poles in like they do with fences sometimes)_ 
A fencing bar is like a crowbar but with a pad on one end to do the compressing, forces all the air out and makes the dirt very very dense

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## PlatypusGardens

I always think of this when I hear "rammed earth"  :Biggrin:

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## HouseOB

Thanks for the help everyone  :Smilie:

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## davegol

I built almost EXACTLY what you describe a few years ago.
1200x1200 with a sandpit at the bottom and a platform at about 1200 high with pitched roof up to about 3m.
I built it on stirrups with the thought that if we want to remove it, then it's a bit easier.
The thing was as stable as a rock. never moved a mm. didn't even bother with diagonal bracing in the end.
next time I wouldn't bother with concrete or stirrups. 
300mm deep holes and rammed earth. Much easier.

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## SilentButDeadly

> Sole plate isn't attached to the post, is placed in the bottom of the hole (that is, it doesn't prevent uplift).

  River Red Gum soleplates here! ...and whilst the gal screws survive...uplift is indeed prevented. Yes we were a bit mad... 
I may have even installed a pergola on foundations that consisted of the longest Pryda stirrups I could find, quite large chunks of RRG soleplate bolted to said stirrups and then buried in 'rammed earth'...still hasn't blown away despite facing the worst of the wind and having shade cloth on top...

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## r3nov8or

" as long at the gal screws survive " 
Have you dug them up lately to check?

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## johnc

> When you say rammed earth, do you mean dig a whole, put the posts in, then put the dirt in and manually ram it as you fill it? (As opposed to ramming the poles in like they do with fences sometimes)

  Throw a shovel full into the hole and ram with the flat end of the bar until hard and then repeat. Done properly in some soil types there will be no soil left over despite the space the post takes. It is actually the way split posts are put in unlike the modern rammers that you drill to the size of a round post then get pushed in by the machine.

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## PlatypusGardens

As a couple of electricity poles were being replaced in the neighbourhood I was surprised to see 
1) How little of them were actually in the ground 
2) They were not concreted in  
Did not get a chance to see how the new ones were set in the ground, but I would assume some sort of mechanical "ramming" was involved.   :Smilie:

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## sol381

> I always think of this when I hear "rammed earth"

  Not their best album but still very underrated. Rob halford could smash posts in with his voice.

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## PlatypusGardens

> Not their best album but still very underrated. Rob halford could smash posts in with his voice.

  
Who underrates it?  :Unsure:   
Sure, it's quite a leap from previous albums, but definitely took things to a whole new level.
"Screaming for vengeance" and "Defenders of the faith" before it were both heading in this direction, away from the old school British Heavy Metal sound. 
KK Downing and Glenn Tipton's guitar work is outstanding on this and the following Painkiller album.
The cover of Johnny B Goode is hilariously insane and absolutely brilliant.  
This was around the time I discovered Judas Priest and started listening to them properly, so it's a special album to me.
Afterwards I started going through the back catalogue.
Have a lot of them on vinyl.
Including that one.    :Smilie:

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## sol381

there are some who dislike it.. blood red skies is probably one of their best songs ever.  i have a lot of their stuff on tape..just dont have a tape deck anymore.

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## r3nov8or

Seem 'em live? Time is getting shaky, but think I saw them 4 years ago for a headline tour and then at the last Soundwave in Feb last year.

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## sol381

Yeah saw them at brisbane ent ctre.  They did a gig at eatons hill after soundwave which im annoyed i missed as a mate of mine said it was way better than the ent ctre gig. Old buggers can still rock.

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## sol381

How the hell did we go from cubby houses to heavy metal.. Oh yeah...PG.

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## PlatypusGardens

Thread split  :Brava:

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## r3nov8or

> How the hell did we go from cubby houses to heavy metal.. Oh yeah...PG.

  Yep, it was PG

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## r3nov8or

> Thread split

  It's gotta go in the Metalwork forum, surely...

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## PlatypusGardens

> It's gotta go in the Metalwork forum, surely...

  
Nice one

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## Bloss

> As a couple of electricity poles were being replaced in the neighbourhood I was surprised to see 
> 1) How little of them were actually in the ground 
> 2) They were not concreted in  
> Did not get a chance to see how the new ones were set in the ground, but I would assume some sort of mechanical "ramming" was involved.

  An old post I know, but just read it - Generally from 2-3metres, but quite a bit of engineering involved see http://www.ausgrid.com.au/~/media/Fi...0NUS/NS220.pdf (Page 173 for depths of holes) and http://www.ausgrid.com.au/~/media/Fi...0NUS/NS128.pdf

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