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In very wet climates, such as those in parts of Scandinavia, the tradition is to dig a thin trench all along the concrete basement walls/foundations and put a s
by marvin 6y ago
In very wet climates, such as those in parts of Scandinavia, the tradition is to dig a thin trench all along the concrete basement walls/foundations and put a sheet of reinforced plastic along the outside of the wall. Then fill in outside this sheet with gravel, which doesn't hold moisture in the same way that dirt does.
The property still needs to face downhill, to allow gravity to drain away the water so it doesn't sneak in and get stuck against the walls, but this is a nice passive system to greatly reduce the humidity in basements. I don't think it would work well for a basement built in marshland, then you'd probably need pumps or active air circulation.
This is basically what you described in your point 3, just pointing out here that this technique works well even in climates that have 200 days of rain per year. Admittedly the temperature figures into it; it probably wouldn't work with both 200 days of rain and average temperatures of 25 celcius.
- formerly_proven 6y agoThis is common construction in Germany as well, with a drainage pipe near the bottom of the gravel all around the house, which provides a low-restriction path for water to escape.
- zaarn 6y agoI would add, having helped with some houses relatives were building, that usually a fabric filter is put in as well, usually multiple layers, so that dirt has no chance of sneaking into the gravel. The cellars also have accessible pipes that can let water leave the cellar easily (installed at the lowest point of the cellar, so the floor is slightly tilted, as well as a replacable one-way valve to keep water from coming in the same way (IIRC it's weight activated, it only drains if more than about a liter of water is inside the pipe wanting to go out.
- calvinmorrison 6y agoFunny, I have heard them called French Drains
- martin_a 6y agoI think that's the English word for that, yes. In Germany we normally call it "Drainage" which is also a French word. Don't know what we Germans got with France and trenches... ¯\_(ツ)_/¯
- richiebful1 6y agoFranco-Prussian War, World War I, World War II...
- kyrieeschaton 6y ago"French" actually refers to the (American) popularizer, Henry French.
- stan_rogers 6y agoGenerically, it's usually "weeping tile".
- daniellarusso 6y agoFrom the surname of the implementor.
- pkaye 6y agoHere is a YouTube of a drainage system in the US. But a lot of older houses and mass manufacturered houses probably don't have them. https://www.youtube.com/watch?v=keghWP_sVzg https://www.youtube.com/watch?v=keghWP_sVzg
- brtkdotse 6y agoOur house has a full cellar with the above solution done 20 years ago. Not a spec of humidity in there. Here's a concept sketch: https://isodran.se/uploads/6d9bc8cf5f18260f6fa65d828eeb69b8.png https://isodran.se/uploads/6d9bc8cf5f18260f6fa65d828eeb69b8....
- daniellarusso 6y agoWhat kind of dirt is your soil?
- mannykannot 6y agoDoes the soil not infiltrate into the gravel over time, clogging it? Or does the water still flow better than through unmodified soil after this happens?
- ceosearch 6y agoThe solution is to wrap the gravel with filter fabric, which will prevent it from being clogged over time.
- krisroadruck 6y agowouldn't the filter fabric get clogged over time?
- mannykannot 6y agoI would guess that a clogged membrane is more of a barrier to water flowing into the gravel than flowing out, as reverse-flushing is often a (partially-)effective measure to restore the flow in a clogged filter.
- marvin 6y agoAlso, 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.
- zaarn 6y agoI'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.
- nemo44x 6y agoSame technique with building a retaining wall in a yard. Dig about 1 foot (30cm) along the wall, plastic sheet liner, fill with gravel. Then add a few inches of soil on top for grass, etc. This prevents the wall from slowly leaning away from the side with earth on it, pushing it. Especially important in climates that freeze. The gravel provides extra space for ice to expand into.
- stevehawk 6y agothis technique is the same in the US. unfortunately this article is the epitome of someone building a house with no idea of how to build a house.
- 2rsf 6y agoThis is done even in Israel, a middle eastern country with not too much rain. They usually use some kind of flexible cement on the walls instead for plastic sheets though. If you do that while building the cost is not significant, you don't need significant digging and the materials are not expensive.
- daniellarusso 6y agoHow tall are the basements?
- 2rsf 6y ago2.5 - 3 meters from the inside, I guess 0.5 - 1 meters more in total.
- nabla9 6y agoIn wet/cold climates like in Nordics you also have to consider where the dew point will be inside the structures. Even if water does not get in, the temperature difference between inside and outside can create dew point that resides somewhere inside the wall, ceiling or floor. Then you have water from the air condensing inside the structures and ruining the house.
- hinkley 6y agoIn the Midwest where it’s flat, you build this way and then install a sump pump at one edge to lift the water up and transport it down “slope” (which may be a 1% grade) I’m pretty sure in some of these houses the pump sees the same water multiple times.