Also, I get the impression there’s an inherent lifetime to these things. If it works for 50 years, you’d consider yourself happy with the result.
It’s like changing your roof; it lasts long enough that you can consider it maintenance-free and only just be wrong (it’ll be a nasty surprise if you buy a very old home without considering when it was done last).
Usually, what will happen is that someone builds an indoors living space in a cellar where this is sub-par and there’s only been chilly storage rooms before, and then get mold in the plaster walls after a few years. The next owner discovers the problem and gets the resulting bill and lawsuit.
The few people knowledgable enough will avoid these houses, while those who don’t are happy that they seem surprisingly cheap.
I've helped with construction of some houses with gravel+filter bedding. There is usually more than one layer of fabric+gravel. It also helps keep the gravel around. The estimated lifetime of the filters I helped putting in is around 150 years. It's a fairly standard way to bed a house in germany outside the cities.
I wonder what the ancient Greeks and Romans thought about the buildings they were building? Did they think that if it was still standing in 150 years they'd be happy? Would they be surprised the buildings were still standing 1000s of years later, or was that what they were hoping for at the outset?
The thing is, back then statics and architectural design were in their children shoes still. So if your roof was 3 tons, your supports had to hold up 300 tons because you had no better way. Nowadays, it holds 15 tons for 3 tons + 12 tons snow, for example, or in more äquatorial areas, it's 3 tons + 1 ton rain water.
It's not hard to make things last when you helplessly overspec because you have no idea how close you are to collapsing and the material quality is extremely unreliable.
It’s like changing your roof; it lasts long enough that you can consider it maintenance-free and only just be wrong (it’ll be a nasty surprise if you buy a very old home without considering when it was done last).
Usually, what will happen is that someone builds an indoors living space in a cellar where this is sub-par and there’s only been chilly storage rooms before, and then get mold in the plaster walls after a few years. The next owner discovers the problem and gets the resulting bill and lawsuit.
The few people knowledgable enough will avoid these houses, while those who don’t are happy that they seem surprisingly cheap.