Water vs. Structures on slopes

I was reading another recent thread and came across the image below. Not my first time seeing it, as I believe I read the original one or two posts on Wofati.

wofati concept from'build a better world book'

I intend to eventually build a structure whose side elevation will resemble the rendering on the left, so I've thought about this image for a while.

The thing I don't understand is why, in the rendering on the right, water can be simply diverted around the structure, but it can't be on the left--why wouldn't the left-side structure-builder use whatever those same means are to divert water?

Even with the excavated foundation, a well-planned and -executed French drain ought to work. And of course you'd have a gutter at the low end of the roof, with a downspout that channels water off to the side where it can continue downslope unhindered. And there are other tricks we've got up our sleeves as well, like sump pumps. This should all work especially well if the structure is not monstrously large.

And of course there's no reason you need an excavated foundation; you could instead build up a foundation on the downslope side with a retaining wall and backfill, a design which I'm favoring lately:

Am I missing something?

Hi Ned, it is my understanding that the first image of the Wofati is showing how to solve the problem of water intrusion with an underground structure on a slope. Your picture solved the problem by raising the whole structure above ground.

Ned Harr wrote:
The thing I don't understand is why, in the rendering on the right, water can be simply diverted around the structure, but it can't be on the left--why wouldn't the left-side structure-builder use whatever those same means are to divert water? ...

Am I missing something?

I believe this has something do do with how the structure is placed on the lot.

The structure on the left has been place below grade causing the water to run onto the structure basically the roof.

The structure on the right was place higher on grade so that the water runs off before getting to the structure.

When ever we have built a structure we find the highest elevation to build the structure thus avoiding water running into the structure.

Ned Harr wrote:The thing I don't understand is why, in the rendering on the right, water can be simply diverted around the structure, but it can't be on the left--why wouldn't the left-side structure-builder use whatever those same means are to divert water?
Even with the excavated foundation, a well-planned and -executed French drain ought to work. And of course you'd have a gutter at the low end of the roof, with a downspout that channels water off to the side where it can continue downslope unhindered. And there are other tricks we've got up our sleeves as well, like sump pumps. This should all work especially well if the structure is not monstrously large.

I think the point is that the lower the structure, the more and complex are the design features that need to be built in to compensate for the water ingress risk. Simple (minimising the risk) is generally better and will probably end up cheaper.

And of course there's no reason you need an excavated foundation; you could instead build up a foundation on the downslope side with a retaining wall and backfill, a design which I'm favoring lately:

I think if I were building this, I'd be tempted to make the space underneath useful space - root cellar perhaps? rather than backfill, unless I had surplus soil to get rid of.

Nancy Reading wrote:

I think if I were building this, I'd be tempted to make the space underneath useful space - root cellar perhaps? rather than backfill, unless I had surplus soil to get rid of.
So far my idea has been to do an earthen floor on that level with the backfill underneath, acting as thermal mass. I would definitely do this if the site topography is such that there wouldn't be much useful space otherwise (without excavating). But I have had that thought about making it a root cellar or something, in the event there is enough room to justify it, and to use some other means--possibly involving water?--to make a thermal mass under the floor.

Anyway, regarding this:

I think the point is that the lower the structure, the more and complex are the design features that need to be built in to compensate for the water ingress risk. Simple (minimising the risk) is generally better and will probably end up cheaper.

That makes sense to me too but then the same logic applies to Wofati. Why build an underground house at all when above ground is always simpler when it comes to water intrusion?

Ned Harr wrote: Anyway, regarding this:

I think the point is that the lower the structure, the more and complex are the design features that need to be built in to compensate for the water ingress risk. Simple (minimising the risk) is generally better and will probably end up cheaper.

That makes sense to me too but then the same logic applies to Wofati. Why build an underground house at all when above ground is always simpler when it comes to water intrusion?

My understanding of current "best practice" is to build on flat land, then berm up and over the structure for thermal mass. If the structure is an "artificial hollow hill", the water will run off in all directions.

Our house is a badly designed "uncovered artificial hill". My understanding of best building practices is that the ground should always slope away from the building in all directions. Sigh... the north side of our house does this poorly, and we often get water coming into the back workshop, which is an unheated enclosed area.

It's important not to underestimate how far water will travel underground. Our upper field rarely has puddles if it's not actively raining. We don't see the water actively running down the hill. But we know that it's running underground by the wetness halfway down the hill and collecting in every pothole from there, all the way to the winter creek.

Info I got recently does suggest that the type of soil is critical. There are examples of partially, or wholly underground houses dug by human ancestors, but they were in very specific locations, and much of that knowledge has been lost. If my source was accurate, choosing the wrong location resulted in being flooded out, or having things collapse during spring run-off season.