- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 23 Feb 2017
Rubble trench foundation
This is a variation of the trench fill foundation, and is a traditional construction method which uses loose stone or rubble to minimise the concrete requirement and improve drainage. It follows the same approach as a French drain, with a trench that is filled with crushed stone letting any water drain down and away from the foundation.
This approach has been used in various guises for thousands of years but it was popularised in the 20th century by the architect Frank Lloyd Wright, and has been promoted as being more environmentally-friendly than other foundation types.
The bottom of the trench should slope with an even descent of at least 3 cm for every 1 m of trench, which diverts the water towards one point, from which it can be diverted away through an outlet or to a dry well.
The trench should be lined with a geotextile material to prevent the surrounding soil from clogging up the trench and outlet. It is then filled with angular and washed stones of average size 2.5-5 cm, with them being compacted at every 30 cm layer using either a pneumatic or hand-powered tamper.
The washing of the crushed stone is important since it removes sand, silt and other small particles that could build up in the trench over time.
When it reaches around 20-30 cm below grade, the larger blocks of stone can begin to be built up as a continuous wall.
 Related articles on Designing Buildings Wiki
Featured articles and news
How to get results with building life cycle assessment.
Government publishes a prospectus inviting proposals for new 'garden communities'.
The Morandi motorway bridge in Genoa collapses during rainstorm while undergoing maintenance works.
'Developed design' is a phrase coined by the RIBA for their 2013 Plan of Work. But what does it actually mean?
New green paper published aiming to rebalance the relationship between landlords and residents and tackle stigma.
RIBA calls for a comprehensive ban on combustible materials.
Lump sum contracts can be referred to as ‘fixed price’ contracts, although strictly this is not correct. Find out more here.
Ramboll offer guidance to civil engineers on how to make projects 'off-site ready'.
Government announces its Rough Sleeping Strategy, with further funding for social housing.
An overlooked architect who deserves to be celebrated for his wide range of buildings.
The Home Quality Mark ONE technical manuals for new homes are now available.