Vapor Barriers Overview

Vapor Barriers

• Vapor barriers are materials that slow down the rate at which moisture can move through a material.
• Vapor barriers are measured in units called "perms" or permeability.
• Vapor barriers help control moisture in basements, ceilings, crawl spaces, floors, slab-on-grade foundations and walls.
• There are three classes of vapor barriers defined by the International Residential Code:
  • Class I: 0.1 perms or less (Impermeable) - examples include glass, sheet metal, polyethylene sheet, and rubber membrane
  • Class II: greater than 0.1 perms and less than or equal to 1.0 perms (Semi-permeable) - examples include unfaced expanded or extruded polystyrene, 30-pound asphalt coated paper, plywood, and bitumen coated kraft paper
  • Class III: greater than 1.0 perms and less than or equal to 10 perms (Permeable) - examples include gypsum board, fiberglass insulation (unfaced), cellulose insulation, board lumber, concrete block, brick, 15-pound asphalt coated paper, and house wrap.

Bonding Agents

• Bonding agents are used to join individual members of a structure without mechanical fasteners.

Thermal Insulation

• Thermal insulation slows down the transfer of heat through a structure's enclosure.
• This can help reduce heat loss and gain from external or internal factors.

R-Value

• R-value is a measure of the material's resistance to heat flow.
• The higher the R-value, the higher the resistance to heat flow.

Insulation Types

• Fiberglass: Made from silicon, glass powder, and glass shards
  • R-Value: 3.1/inch
• Mineral Wool: Not combustible, but not suitable for extreme heat.
  • R-Value: 3.1/inch
• Cellulose: Made from recycled paper and cardboard. It is considered the most eco-friendly insulation type.
  • R-Value: 3.7/inch
• Polyurethane: Uses non-chlorofluorocarbon as a blowing agent and provides excellent insulation.
  • R-Value: 6.3/inch
• Polystyrene: Provides sound and temperature insulation.
  • R-Value: 4.0/inch

Moisture Protection

• Moisture protection involves materials that seal the exterior of a building against moisture intrusion.
• Moisture protection is also referred to as vapor diffusion retarder.

Epoxy Classifications

• Epoxy resins can be classified by type, grade, and class.

By Type

• Type I: Used to bond hardened concrete to other hardened concrete.
• Type II: Used to bond hardened concrete to freshly mixed concrete.
• Type III: Used as binders in epoxy mortars or concrete.

By Grade

• Grade 1: Consists of materials with low viscosity.
• Grade 2: Consists of materials with medium viscosity.
• Grade 3: Consists of materials with high viscosity.

By Class

• Class A: Used for systems that operate below 5°C.
• Class B: Used for systems that operate between 5°C and 15°C.
• Class C: Used for systems that operate above 15°C.

Sealers and Sealants

• Sealers are products applied to surfaces that help prevent water absorption.
  • Types of concrete sealers include: penetrating, acrylic, polyurethane, and epoxy.
• Sealants, often referred to as caulks, fill voids, gaps, cracks, and joints.

Roofing Systems

• Roofing materials deteriorate due to weather exposure. The rate of deterioration depends on the type of material and the environmental conditions.

Types of Roofing Systems

• Steep Slope Roofing: Used on roofs with a slope greater than 0.25 (1:4).
• Membrane Roofing: Used on roofs with a slope less than 0.25.

Test your knowledge on vapor barriers with this quiz. Learn about their function, measurement, and the different classes defined by the International Residential Code. Understand how vapor barriers control moisture in various building applications.