Rubble trench is a cheap and effective foundation that combines drainage with load distribution. The basic principle of it has been around for thousands of years but American architect Frank Lloyd Wright brought it into the 20th century.

1. The Trench

The trench should run underneath all the external load bearing points, continuously around the full perimeter of the building. Any internal load bearing points (underneath the house) can simply rest on undisturbed earth (stable soil cleared of top soil) so the amount of digging needed is minimal compared to your standard concrete slab.

The minimum depth of the trench is determined by the local frost-free depth. This is the depth where the temperature never descends to zero C° so any water ending up in the trench will therefore not freeze. The bottom of the trench then needs to slope with an even descent of at least 3 cm for every 1 meter of trench, diverting the water towards one point. From then on the water can be diverted away from the foundation through an outlet to either daylight or to a dry well.
2. Filter Fabric Geotextile

The trench must then be lined with a geotextile to prevent any of the surrounding soil from clogging up the trench and outlet. This geotextile is really the only non-natural material that you need for this foundation to work properly. The trench would probably work quite well without it for at least a while but any silting would gradually reduce the trench’s ability to drain away water, e...