Why should I use a below-slab vapor barrier in a desert/arid climate?
Regardless of the climate, water vapor is constantly evaporating off the water table below ground creating a100% RH environment below the slab. 100% RH under the slab and a conditioned space in the building, creates the exact same moisture diffusion scenario in the desert as it does in any other climate. Whether we are in Seattle or Phoenix, due to the pressure difference inside the building compared to below the slab, water vapor is pulled up into the building like a slow vacuum. Without a low permeance below-slab vapor barrier to protect the building, moisture vapor can cause flooring failures, indoor air quality issues, and reduce energy efficiency. Contact your local Stego Representative to learn more on this subject.