Shower floor advice

Hi all!
I am building a strawbale, cob, stone, earthbag home in a VERY DIY sort of way.

I’m at the point where I want to start installing the shower area but I’m not sure what I can get away with for under the shower floor.  I’d like to use concrete for the pan or maybe stone with mortar.  Right now I just have the plumbing in and dirt.

I’m wondering if I can just fill with gravel up to a few inches below the drain and then concrete up to the drain (sloping towards the drain.  Do I need to put some type of liner in or is it ok if I just do concrete on gravel as long as I seal the concrete?

Thanks for any advice.  Ive searched online but can’t seem to find anything that is starting with a dirt floor and not framed subfloor.

Kadin

I like the idea of an earthen floor with moss.  Is that possible?

Or maybe a Tataki floor?

Kadin,

Just treat it as a slab on grade:

1. Compact the dirt
2. Add 5-10 cm of baserock (whichever type is available in your area) or mix gravel, sand, old lime/cement mortar and compact it very well
3. You can put some moisture barrier if needed
4. Now you have multiple options:
-you can pour concrete - please add some rebars - at least 10 mm *3/8") on 20 cm grid; I would pour at least 10 cm thick; you can put tiles of your choice on the concrete
-you could use white cement concrete with interesting color aggregate or use lime putty and ground brick and brick particles to make Roman concrete (opus siginum)
-you could lay stone on cement bed (1:3 cement to coarse sand ratio); rough stone would not be practical, it would have to be cut and rather smooth.

Anne Miller wrote:I like the idea of an earthen floor with moss.  Is that possible?

Or maybe a Tataki floor?

Earth floor in a shower probably wouldn’t hold up but I do love the idea of growing moss in the shower!  Maybe on the walls… I’m going to make the lower part of the walls out of stone which would be really cool to have moss growing on it.

Thanks for that Cristobal!  Very helpful.  Under what scenario would you put a vapor barrier in under the shower vs no vapor barrier?  I could see just leaving it with gravel under the cement just in case water were to penetrate under the shower floor.. that way it wouldn’t get trapped above the vapor barrier.   Thoughts?

Kadin Goldberg wrote:Under what scenario would you put a vapor barrier in under the shower vs no vapor barrier?

Normally for slab on grade made of concrete, barrier is used to prevent capillary action of water rising through the concrete and affecting the structure above. It helps in areas with high water table, high rain or soils with higher water capacity. It looks like your house is located on elevated spot on your land and the plants around indicate arid conditions. I would not worry about any barrier.

Cristobal Cristo wrote:

Kadin Goldberg wrote:Under what scenario would you put a vapor barrier in under the shower vs no vapor barrier?

Normally for slab on grade made of concrete, barrier is used to prevent capillary action of water rising through the concrete and affecting the structure above. It helps in areas with high water table, high rain or soils with higher water capacity. It looks like your house is located on elevated spot on your land and the plants around indicate arid conditions. I would not worry about any barrier.

Great, thanks for that clarification.  Yes, we are on a gentle slope and in southern Arizona.  Less than 20 inches of rain per year and no wash or build up of water near the house.  

Much appreciate your thoughts 🙏