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Can We Predict the Amount of Shrinkage

Predicting the amount of shrinkage is complicated, and general advice may not apply in individual cases.

Detailed information on experimental assessment of soil shrinkability and additional technical information can be found in BS 1377 (BSI 1990), BRE Digests 240 (BRE, 1993), 241 (BRE 1990), 298 (BRE, 1999), 361 (BRE, 1991), 412 (M Crilly, 1996) and NHBC (1995).

Action to Take

DO

• Take specialist advice before starting major building work

• Consider the effects of laying impermeable drives, paths or hard standing on the rainfall reaching the soil below and changing its moisture content.

• Seek expert advice before planting trees near to the house. The safe planting distance will depend on the tree species, type of house foundation and soil composition.

• Ensure foundations of new constructions or extensions are designed for the shrinkable clay soil conditions that are present.

DO NOT

• Plant potentially large trees next to the house.

• Remove mature trees that pre-date the construction of the house before taking advice. Tree management by crown reduction or thinning may be better than removal because it will maintain a stable soil moisture profile, ask for expert advice from arboriculturalists (tree surgeons) see http://www.trees.org.uk/index.php

Subsidence Index | Problematic Soils Index | Shrink/Swell Index | Diagnostic Characteristics | Geographic Occurrence | Mitigation | Key Contacts & Expert Advice | Photo Gallery | Essential References & Further Reading