Underground bunker help needed!

[Freakyclown]

Hi,

I have decided in a few years time that when moving into a new house with a fairly well sized garden i would like to build a large underground bunker into the garden. (my wife said ok :)) Ideally the buker will include storage for one vehicle (accessed via ramp from front driveway) and split into 2 floors (underground) and a shed/garage built on top (to hide the entrance and provide a normal garage)

has anyone got any references for this kind of building?

ive been looking around and doing some research, this is a LONG term building plan so im in no hurry and havent even finalised the ideas in my head yet let alone drawn up plans and intend to do the actual building over a few years due to costings.

What i need to know is what kind of pitfalls and thigns to look out for.

Ive been looking into construction methods too... I am looking at making each level 7/8 feet high so here are two methods i have thought of....

dig the trenchs 14/16 feet deep and fill with concrete and then dig out the middle then somehow attach a central floor.

or

dig out 7/8 feet deep and then do the trench idea

or

dig the whole lot out then use something like Thermalite blocks (are they ok for this kind of thing?)

would using sleepers as the middle flooring be ok?

also how to handle water/heat/cooling/power/drainage/other

any pointers will be appreciated.

fc

[mrcheerful]

Read this bit:

like there are substantial problems from side pressure (no, you can't use thermalite blocks) and water table level, bear in mind you would also need a drive about a hundred feet long to give a reasonable slope in, plus the whole thing would flood without a pump at the bottom of the slope.

An underground bomb shelter is a practical idea, accessed by a ladder. Several companies do something that looks like a submarine, you just dig a big hole and drop it in, and fill up again.

mrcheerful

[John Stumbles]

Perhaps you could install a vehicle lift to lower/raise your car to/from the underground level.

Watch out for the smartly dressed chap with the fast car and flashy woman at his side. They always get you in the end, even though you thought you had him strapped down securely to the circular saw table. :-)

[RichardS]

yes, normally after you have just taken the time and trouble to explain your whole world domination master plan to him.

some people! just rude.....

-- Richard Sampson

email me at richard at olifant d-ot co do-t uk

[Freakyclown]

HAHAHAH

thanks for the link i shall check it out when i get home.

I dont think your thinking large enough though i dont want one of those little sub things, nor a ladder access! Im planning single/two floor building basically underground 3 comftable sized rooms on each and ive decided the garage above wouldnt be a good plan so its now moved to the side (onto solid earth) and will only be used as access via steps.

Ideally the place will sustain living for 2 adults and 3 children.

Unfortunatly i am limited by the fact i do not yet have the house/garden so i cant confirm plans, i am meerly investigating what would be required to excavate and build such a place.

the types of materials and methods are what are important right now, and anything that might be an issue, obviously if i stay above the water table there wont be much problem of water pooling on the lower floor!

to help you envisage the type of thing im thinking of it would be best to think of a cross nuke bunker/panic room/laboratory/extended living area.

and maybe a spy torture chamber ;)

heh thanks for the help guys!

FC

[John]

There is a company down the road from me who used to design nuclear shelters for the home buyer. I think they are on the web - something like A&F Engineering or AF Group if memory serves correctly. They should be able to help you Try af_group at btinternet.com

[Peter Taylor]

Freakyclown wrote

etc snipped

Have you thought about buying a house on a slope, so that you could drive in on the level? No flooding problems either. Plenty like that round here. If you were lucky enough to live on a chalk hill, you could dig out the chalk and wouldn't have to worry too much about the sides collapsing.

A structure this size and depth needs to be designed by a Structural Engineer, and it would be best to talk to one before you make any other moves. My guess is he would almost certainly go for reinforced concrete construction. If built in concrete blockwork for this height, the blocks would need to be hollow, with continuous vertical voids packed with concrete and reinforcing rods, and also probably projecting piers for that height. Thermalite would not be strong enough.

Also it would need structural waterproofing, possibly with Bituthene sheeting, and PVC waterstop joint seals etc (e.g. Servicised

suspended floors could be insitu concrete too, but it would be a pain to do the formwork. Wide precast slabs would be better, or you could use beam and block if the span is not too great.

HTH Peter

[nightjar]

If you want to hide the entrance, put an hydraulic lift in the garage, then no ramp is required for the vehicle.

Nope. Thought about in the 50s/60s though.

....

Remember to build a second exit, well clear of anything that might fall across it. Something may happen to prevent you getting out of the main one. If you want to hide that too, cover it with a few inches of soil. Making it open inwards will allow the soil to fall in and, if anything does cover the hole, it gives you a chance to work on it.

You might want to have CCTV to give you a view of the outside.

That will depend entirely upon the type of ground. If it is granite, you can just carve the rooms out of the rock. If it is sand, you will need to drive sheet piling in to support it while excavating inside. You need expert advice whatever soil you end up with.

...

I would go for the concrete beam and block system, used in much modern house construction.

Again, it all depends on what you want this bunker for. An emergency retreat for a few days is going to have entirely different needs from a nuclear bunker, intended to shelter a family for three months. The former can rely on air being piped from outside and just about everything you need can be stored. The latter needs to be almost entirely self-contained and essentially self-sustaining. Look at some of the self-sufficiency books for ideas.

You would probably find some useful information from researching WW2 fortifications. The Cabinet War Rooms in London are an excellent example of a large bunker, but there were plenty of smaller ones. Of course, the easiest solution is to buy up one of the Cold War government bunkers and build a house on top, although a lot of those have been snapped up by companies offering long term secure archiving.

Happy paranoia.

Colin Bignell

[The Natural Philosopher]

My sister built a house in Germany that had a basement that was essentially underground.

The way they did it was to excavate a large hole first, line that with sand blinding, then a DPM, then a shitload of polystyrene, and the concrete.

It was warm and dry and very comfortable. The biggest problem was blocked street sewers backing up into the basement sinks bogs and showers. Not the fault of the construction, just one of those things under the councils control

So make sure you have good drainage for any water you may use. Its wise to do this type of construction near the top of a hill, to prevent neighbours higher than you flooding you with shit, if the pipe gets blocked lower down.

[Freakyclown]

Many thanks guys for all the advice, i have been up all night chatting to a friend about the design.

If the garden is large enough then i wouldnt needs the 2nd floor making construction much easier! However if the garden is fairly small i will have to make space up with going down a floor.

Ive given up completly on the underground garage now insted going for a garage offset from the bunker with an inspection pit which might hold the doorway to the bunker.

After a bit more research i realised thermalite blocks would be useless and had kinda settled on digging the whole thing out with temp shoaring up and then building a waterprooflayer covered in a cement flooring and with the walls made from those blocks with the holes and metal rods driven down between them to give lateral strength.

Construction of a single floored place would be ideal and could easily be made to look like i was just digging a large pond or something so neighbours wouldnt be too suspicous. Also what kind of planning permissions would one need for somthing like this, obviously i would have checked out and rerouted any works goign through the site.

I do like the idea of the escape hatch, as long as it was secured properly so people wouldnt fall in through it.

Anyway thanks again for the ideas and comments.

FC

[mrcheerful]

The professional bunkers have an outward opening hatch with a twenty ton jacking device, just in case.

mrcheerful

[Freakyclown]

they also tend to have large missles too....mmm..do ebay sell those? i could use them to aquire some more land for a bigger base! did i say base i ment underground storage shed!

fc

[Richard Savage]

Have a look at

for some design ideas. My brother-in-law supplied the furniture for this site just to give you an idea of what can be done with a load of reinforced concrete!

Rgds Richard

[nightjar]

That will be the difficult bit. You would need to get full planning permission, building regs approval, etc., which is one reason I suggest it would be easier to buy a government surplus bunker and build a house on it. I believe that some even come with the house, which was there to explain the roads on satellite pictures.

Quarter inch steel plate, hinged to fall away from you and a couple of big bolts should do the trick. Alternatively, bring it out of the side of a bank. Some of the Home Guard Auxiliary Unit bunkers were done that way.

BTW, don't forget the gun slit at the end of the entry corrridor :-)

Colin Bignell

[Bill]

In message , nightjar writes

An added benefit will be the mines in the flower border, should keep the neighbours cats from scratching around in the garden.

[Richard Savage]

nightjar

Actually more to disguise them from the passing public than hide them from satellites. Most were built during the 50's and the entrances of these two facilities were typical of the standard Ministry of Works building put up to disguise the real nature of what went on there.

and

[N. Thornton]

The car could stay above ground, with enough garage width to also allow comfortable access.

Regards, NT

[N. Thornton]

A round stucture has better floor area to wall area ratio, and due to the wall shape needs thinner walls than the square version. A round house would suit a central atrium plus rooms off that layout.

OTOH curved rooms cost more to fit and furnish. A good compromise might be a hexagon or octagon shape: advantages of round still present, if not quite as much, but all rooms now have straight walls.

Your top window could be an above ground run of cloche or greenhouse containing plants, with light coming through all the gaps. Greenhouse would have gauze floor, or the cloche would look like an ordinary cloche.

Regards, NT

[IMM]

You can fit a cess tank and pump the sewerage up and over into the drain. Any sewerage because of blockages are your own.

[IMM]

Best not to insulate the walls and allow the earth to keep the place warm and also cool. Above the structure it is best to cover with foam insulation about 1 foot under the ground covering all of the garden. Best in a cone shape. Then the influence of the air above is minimised and the effect of the earth around maximised.