Vapor Barrier and slab foundations

[fannanxx]

Vapor barrier are manufactured from plastic material that tend to be smooth. When the material is places between concrete and the ground surface there is no doubt there is a reduction in friction. In structures where there is risk of sliding the reduction in surface friction becomes a concern.

Are there any research papers quantifying the loss of friction when vapor barriers are used?

 

[Ron]

Plastic is not placed below the foundation except in a thickened edge slab, which should not be used if the entire building is subject to sliding.

Plastic is intended to provide a vapor barrier and help with shrinkage cracking by reducing friction restraint for slabs on grade, not the foundation.