Bunker foundations

[marshman]

you don't need to have the French drain and the 40mm stone, that only helps to keep it dry inside and stop water pressure outside,
you do need mesh in the walls, if one wall has a shrinkage crack that ran from top to bottom that wall could fold in under the load
against it and as your measurement show six inch concrete wall in the longest run and not tied to a concrete roof,
then that is most likely what will happen.

 

[concretekeef]

Jim, I feel that you need to re-evaluate this project before you bury yourself in a soil and timber tomb. I applaude your vision yet the practicalities are more complex than you assume.
If you intend to use this as extra living space, then please consider using the services of an architect who will design your structure to suit your needs.
Yes, it will cost more.
Yes you may have to compromise.
Yes you will need to get planning permission.
Yes you can still build it yourself.

 

[ColJack]

similar theme ( and not strictly hijacking ), I've thought about digging something similar to a swimming pool in my back yard, then block and beaming over it, waterproof membrane and lawn laid over top..

useing it as a water tank for "grey" water.. ( flushing loos, watering the lawn etc.. )

 

[JohnD]

I have been thinking about this, and although shuttering, setting out reinforcement and laying concrete is not especially complex, I don't see how a DIYer could hope to support the sides of the excavation while working, assuming not equipped to drive in sheet piling or something. I suppose you could make the hole twice as big as you need, with sloping sides. An ordinary JCB hired by the day with operator wouldn't dig deep enough from the flat.

Is there a DIY method i haven't thought of?

 

[Deluks]

Lots and lots of plywood, 9x3's and a very big spade!

 

[marshman]

Is there a DIY method i haven't thought of?

one long post hole auger,
one meter length of 200 x 6mm wall steel pipe with a plate welded on one end and screw cap the other with small hole in it,
2 cwt of fertilizer and xxxx plus a long fuse,

but you'll have to buy in soil to back fill.

 

[JohnD]

this sort of thing?

 

[marshman]

you could build a round structure like they use to build old well's & shaft laying the bricks from the top down.

 

[Balenza]

Hello,

I'm very new and inexperienced to this game but could anyine please help with advice.

I have a large space and would like to dig a hole, approx 14ft x 10ft x 7ft deep. What would be ideal for foundations, walls, damp proofing etc? I plan to cover the roof in earth with a small doored access hatch of about 2 1/2 ft x 2ft 1/2 ft.

I was planning on using concrete for the floors and walls and ply with timber supports for the ceiling. How can I concrete vertically (for the walls????

Any advice would be HUGELY appreciated!

Thanks!

Jim

You need to shutter this with formwork . Like this......

PERI (German) is a good system and available for hire. It won't need a lot of steel reinforcing as the dimensions are small.

You say 7 foot deep. This is not that deep for an excavation but you need experience to evaluate the soil conditions and how it will stand up to becoming water logged after the excavation has taken place.

In summertime in the hot weather an excavation bank may produce a small crack, possibly not even visible to the eye and may be totally safe.

However in wet conditions everything changes.
The crack only needs water to seep in ,perhaps overnight.
If your lucky the bank will collapse during the night. If not then you may be in the hole when it does.
Its dangerous work and something best left to people with experience.

Having said all that because your dimensions are small the dig should be relatively safe as the corners are self supporting.
These are the safe points in a square dug hole and incapable of collapsing providing the ground is reasonably stable. An experienced excavator driver will know what you are dealing with the moment he drops the bucket into the ground. So listen to him.

I do this for a living incidentally. Ho hum.
We could complete something like this in 2 days from excavation on a green field to walls completed and fully decked out.