# Forum Home Renovation The Cubby House  Simple cubby house over a sandpit. Thoughts?

## Matto-FNQ

Hi all, 
Question for the Brains Trust. 
My little girl is turning 3, and I want to build her a simple cubby  house. She has a sandpit in the back yard made from treated pine  sleepers that is roughly 2400 x 2400 x 400. It doesn't have much shade  these days so I'm figuring I'll build the cubby over the sandpit. I've  done a search, but can't find much info in the way of high cubby houses. 
The plan is to use 3 posts down each side - the centre one being ~500mm  taller to allow for a peaked roof (which won't be symmetric due to site  issues). The floor will be ~1.6m off the ground - thinking around 2.5m  to the eaves and 3m to the centre peak. This should give her enough  space to play in the sandpit underneath, but keep the overall height of  the cubby reasonable. There won't be any walls as such, it's not  enclosed, just an open platform with a railing around the edge. The  ground slopes slightly from left to right - the sandpit follows the lay  of the ground but the cubby will be squared up. Rough sketch:    
Originally I was going to use timber for everything - 150mm coppers logs  for the posts, treated pine sleepers for the bearers, fence rails for  the joists and decking timber for the floor. The span across the floor  of the cubby is ~2.6m. I've got a heap of left over colourbond roofing  that's no good for anything watertight, but would be perfect as a cubby  roof.  
I now have the option of using shed purlin off-cuts very cheaply. I've  never used them before, so am curious as to what the people here think.  Immediate pros are the cost, they're nice and light, they're easy to cut  to size with a grinder, and they're easy to bolt or screw or weld  together.  
I've been told that I'd be best off concreting stirrups into the ground  instead of just burying the purlin. I've never used stirrups before,  I've always just concreted a coppers log into a hole ~300mm round x  500-odd deep. Anything special I need to know? Use the same sized hole  & amount of concrete as I would otherwise? 
It's a pretty simple project, but as it gets closer I'm getting more and more spooked:  I've  never used the purlins, I can't find any span tables, etc, and I just  don't know whether it'll be strong enough or overkill. I always err on  the side of over-engineering and it's never let me down yet, but it's my  lack of experience with the material that's making me second guess the  design. With the span across the floor I'm guessing I'll probably need 200mm purlins, but 100mm will probably be fine for everything else.At ~3m centre height of the roof, I'm guessing I  should get planning permission from the council. Which will be a real  pain, because it's just a cubby house and I don't have any plans.We're  in a cyclone zone, and now I'm concerned about using the colourbond  sheets on the roof. I know the roofing code for residential houses here  (a mate is a roofer) and am happy I can over-build it, but I'm still not  100% on it. Wondering if I should build a frame and get a PVC or canvas  roof made up to stretch over it (increasing the costs substantially). 
 I'm not sure out of all that, how much is a legitimate concern and how much is just me being overly cautious.  
Thoughts?
Matto  :Smilie:

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## David.Elliott

FWIW; I'd look at the Koppers logs for the posts as per your original thoughts, and go steel from there. 
Having 5-600 of the post in the ground has appeal for me for sideways stability...stirrups, not so much... 
Roofing in salvage colourbond is a good idea, just use more attachments, like every riser rather than every third. It'll be fine.
And make sure whatever the colourbond is attached to is well attached to the frame..
I did just this in my last place for the kids from spare hardwood. Not over a sandbox though. 
The mulberry tree grew up and over it, and it became a favourite hidey hole in the backyard for the kids...even a summer time sleepout...

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