Building ventilation and waterproofing systems
Attic Ventilation — Climate Zone 3B (Henderson)
For Climate Zone 3B (Henderson below 4,000 ft elevation): no rigid board or air-impermeable insulation is required for condensation control at the roof plane. This is a relaxation from colder-climate requirements.
Foundation Waterproofing — When Required
Required only where geotechnical report indicates high water table or severe soil-water conditions. Where required: from finished grade to top of footing or 6 in below basement floor. Options include two-ply hot-mopped felts, 55 lb roll roofing, 40-mil polymer-modified asphalt, 60-mil flexible polymer cement, 1/8 in cement-based fiber-reinforced coating, or 60-mil solvent-free liquid-applied synthetic rubber.
Air Sealing — Blower Door Test Required
Residential units in Climate Zone 3 must achieve 3.0 ACH50 via third-party blower door test. Alternatives: 4.0 ACH50 non-sprinklered, 4.5 ACH50 sprinklered. Qualifying air barriers include: 1/2 in gypsum board, 5/8 in Portland cement stucco, closed-cell spray foam (1.5 in min), and others per IECC C402.6.2.3.1.
Attic Ventilation
Attic ventilation location, size, and calculations must be shown on plans. Table R806.5 is amended for Southern Nevada desert conditions, reducing minimum ventilation ratios compared to base IRC to account for the dry climate.
Foundation Waterproofing & Dampproofing
Section R406.2 (foundation waterproofing and dampproofing) is specifically amended for Southern Nevada conditions. When basements are installed, plans must show a cross-section with materials, exterior waterproofing, and egress window well details.
Flat/Low-Slope Roofing
IRC Sections R905.7 (built-up roofing) and R905.8 (modified bitumen) are amended for local desert climate conditions addressing high UV exposure and extreme heat.