what about clay in the soil

hi everyone,

i am planning to build a small earth integrated house and i am digging for it.

the question is : now dug 1,5meter deep and i reached the clay i am afraid of digging more. i was planning to dig 2meters deep. i will for sure make a french drain on the ground but will it be enough to drain water when soil is full of clay ?

should i stop to dig but then i will not be under the ground level and will have the roof stepping out the ground. it is in a hard slope

Some photos an d / drawings will help us to understand what you are doing.
I cannot work it out.

If you are building on a "hard slope", some of your roof will have to be above existing grade unless you dig several meters deep at the uphill end. Mounding the removed soil around the house in a gentle slope will change the finished grade level near the house, so you don't need to dig fully into the ground to get good coverage. Are you trying to have the house be close to invisible from above, or just well integrated with the landscape? Will your door be above grade at the downhill side (it should for reliability)?

Since you have clay subsoil, I would absolutely put a good layer of gravel and drains all around the walls and under the floor.

Hi , thanks for the replies !

unfortunately i cannot post pictures.


of course a part of my roof will be above grade as for my door.
i was trying the back wall which is uphill side to be fully underground but finally i decided to stop digging where i reached. i hope it will be enough protected from water coming down the hill when i will cover it with the soil i removed
about the drain i saw many talking about putting vertically drains behind walls and cover all the surface under the ground of the house with gravel.
but i was planning just to make a trench all around the house 30cm down my ground level and make that kind of drain do you think it will be enough ?
even thinking not putting polyethylen on the ground but only walls and roof.. i saw on YT glenn kingiser having all his interior design in earth style and i liked it.

it is raining here since yesterday and i dont see water staying in the digged hole so i hope drain will not be such a big deal

thank you for your help

You can keep digging to make the roof as low as you originally planned, even in clay.  As the other poster mentioned, make sure you have drainage and water management plans.

Also if you can design your roof such that the water and the slope drain in the same direction that will help reduce water coming from the high side.  Look up "Mike Oehler" for more design ideas and details for designing underground houses.

Larger overhangs on your roof will also help to reduce the need for drainage, you don't need to drain away water that never makes it to your foundation.

Yes, you can dig as deep as you are able at the uphill end; just be aware that this will increase the likelihood of water wanting to get into your walls or floor. I would consider it imperative to use a good layer of fast-draining material like gravel all around and under the floor.
I would not depend on a swale to divert all of the water coming from uphill, though it would probably help. No matter how tight the soil packs when undisturbed, freshly placed backfill will be looser and allow water to get through it, and once a channel is started, it will always be a path for leaks.

In an underground house you will not have visible overhangs to divert water, but extending the roof membrane at least a meter or so, and well beyond the area you dug out, would help. I would slope the roof in the same direction as the hill as much as possible; even starting at the uphill end with that slope and then transitioning to shed water to the sides would make a difference. Sloping the roof to drain back into the hill would be the worst possible configuration.

If you compact the soil used for the build up of a culvert or swale in thin layers, it may be waterproof.
As suggested use a plastic membrane on the soils around the higher ground and cover it with compacted soil, it may also help.