Hygrothermal
Slab Vapor Proofing Design Consulting
Hygrothermix
Engineering Predictable Slab Moisture Outcomes
Through Predictive Hygrothermal Modeling
Successful slab systems begin long before concrete is placed. Hygrothermix works alongside architects, engineers, and design teams to assist in developing under-slab moisture control systems that deliver predictable long-term moisture performance—not simply satisfy prescriptive vapor retarder permeance and thickness requirements. While most under-slab specifications focus on membrane properties, ours focus on the performance that ultimately matters: the slab's internal relative humidity.
ASTM E1643 recognizes that under-slab moisture control should be based on project-specific environmental conditions rather than prescribed solely by product characteristics. Hygrothermix applies advanced hygrothermal modeling to evaluate these conditions, helping design teams compare alternatives, optimize under-slab assemblies, and often reduce unnecessary construction costs while maintaining long-term moisture protection.
Because environmental conditions beneath every slab are unique, prescriptive specifications must be intentionally conservative. Our project-specific analyses replace conservative assumptions with physics-based modeling, allowing under-slab moisture control systems to be optimized for the conditions of each project.
Our analyses consider groundwater conditions, soil moisture storage and capillarity, capillary breaks, insulation type and location, vapor retarder design, concrete mix design, floor coverings and adhesives, and the building's operating conditions. Together, these variables govern the coupled heat and moisture transport that determines the slab's long-term relative humidity profile.
By simulating decades of building operation, Hygrothermix predicts the slab's internal relative humidity profile before construction begins. This gives project teams the confidence to make informed design decisions while reducing the risk of moisture-related flooring failures, mold growth, and other durability issues.
Our objective is not simply to specify a vapor retarder—it is to help design teams achieve predictable slab moisture performance.
Services
Choose from our menu of free design assistance options
Specification Review
Design Assistance
As-Built Report
We'll analyze your current under-slab specification (03300 or 07260) for performance and value. We'll let you know if your specification is achieving the slab moisture RESULTS* your projects and clients require.
Provide our consultanting team your project-specific details including the soils report, subbase selection, insulation (if any), vapor retarder, concrete mix design, flooring covering, and indoor operating conditions, and we'll help you confrim/modify your design to achieve the desired in-situ slab moisture RESULTS* for the life of your building.
Use our system and we'll inspect your installation and provide an as-built report verifying your installation and detailing the expected slab moisture content RESULTS* for the life of your building.
*We don't guess. We use advanced hygrothermal modeling to determine your slab's moisture content projected out at any point into the future life of your building.
Engineering predictive modeling requires assumptions regarding project-specific boundary conditions. Where project conditions are not explicitly known, conservative engineering assumptions are applied to produce realistic and defensible performance predictions.
Hygrothermix provides building science consulting, hygrothermal analysis, and project-specific design recommendations in support of the project design team. Hygrothermix is not the Engineer of Record unless separately retained in that capacity where permitted by law.
WUFI
Hygrothermix utilizes WUFI® software in our analyses. It is the gold standard for building envelope system design verification modeling.
WUFI is a family of software products that allows realistic calculation of the transient coupled one- and two-dimensional heat and moisture transport in walls and other multi-layer building components exposed to natural weather. WUFI is an acronym for Wärme Und Feuchte Instationär—which, translated, means heat and moisture transiency. WUFI software uses the latest findings regarding vapor diffusion and moisture transport in building materials. The software has been validated by detailed comparison with measurements obtained in the laboratory and on IBP’s outdoor testing field.
Our team has utilized WUFI for slab consulting and design services since its inception.
