Ward R. Malisch Concrete Construction Symposium (Part 1)-The Evolution of Vapor Retarder Placement Below Concrete Slabs-on-Ground (Recorded presentation)

The Evolution of Vapor Retarder Placement Below Concrete Slabs-on-Ground (Recorded presentation)

Video Transcription

Video Summary

Peter Craig, an expert on moisture-related flooring issues, discusses the evolution of vapor retarder placement under concrete slabs. Historically, placing a vapor retarder directly beneath a slab was discouraged due to concerns like slab curling, cracks, and longer finishing times. Past ACI guidelines advised additional granular layers to manage these issues. However, evidence showed these layers could lead to costly flooring problems due to moisture migration. Craig highlights that regardless of groundwater levels, concrete naturally reaches high humidity, emphasizing the necessity of vapor retarders to prevent moisture issues. He explains prevalent moisture problems exacerbated by VOC regulations, rapid schedules, and adhesive failures, costing the industry hundreds of millions annually. Current standards now require vapor retarders directly below slabs for moisture-sensitive areas. Despite persisting concerns, Craig asserts that addressing these is cheaper than repair costs from flooring failures, underscoring the continued significance of proper vapor retarder usage.

Keywords

vapor retarder

concrete slabs

moisture issues

flooring failures

ACI guidelines